PURIFIED WATER SUPPLY SYSTEM

Abstract: A purified water supply system (10) includes a reverse osmosis unit (12) which receives tap water (22) and produces purified water (26) and reject water (28). The purified water is then supplied to a purified water chamber (34) within a storage vessel (14), wherein the purified water chamber is separated by a movable barrier (41) from a reject water chamber (42). One or more faucet valves (16) are opened to open a discharge path (70) permitting purified water to then flow through a discharge spout (72). A control valve assem­ bly (18) applies reject water under sufficient pressure to the reject water chamber to force purified water from the vessel through the discharge path, and maintains the pressure with­ in the vessel substantially less than tap water line pressure to permit use of a light weight and economical storage vessel. In some embodiments, when the discharge path is closed, the control valve substantially relieves pressure within the vessel to minimize backpressure to the reverse osmosis unit.

Description: BACKGROUND OF THE INVENTION This invention relates generally to improvements in purified water supply systems of the type having a reverse osmosis unit for producing purified water from an incoming supply of ordinary tap water or the like. More particularly, this invention relates to an improved purified water supply system having control means for providing effective delivery of purified water for use, while limiting fluid pressures within the system in a manner permitting relatively lightweight and economical system components. Water purification systems in general are relatively well-known in the art for use in producing a supply of purified water from ordinary tap water or the like. Such water purification systems commonly include a reverse osmosis unit connected to an incoming tap water supply, wherein the reverse osmosis unit produces two separate water outflows including a purified water supply, and a waste or reject water supply, sometimes referred to as brine, with impurities concentrated therein. In purification systems of this type, the production of purified water is normally relatively slow whereby the purified water outflow is typically coupled to and stored within an appropriate storage vessel ready for dispensing when desired through a manually operated faucet valve or the like. Such purification systems are normally intended for installation into the compact cabinet space beneath a standard residential kitchen sink, with the faucet valve mounted on or at the sink in an accessible position for use. Examples of water purification systems of this general type are found, for example, by reference to U.S. Patents 4585554 and 4595497. In such water supply systems, the storage vessel for the purified water commonly includes a purified water chamber and a reject water chamber separated from each other by a movable barrier, such as a resilient diaphragm or bladder or the like. For example, US-A-4585554 discloses a purified water supply apparatus including a reverse osmosis unit having a water inlet, a purified water outlet and a reject water outlet a storage vessel the interior of which is divided by a movable barrier into a purified water chamber and a reject water chamber, whereby movement of said barrier as water is supplied to the purified water chamber and withdrawn from the reject water chamber and vice versa allows corresponding changes in the relative volumes of the purified water chamber and the reject water chamber, a faucet valve movable between open and closed positions, and conduits interconnecting said reverse osmosis unit, said storage vessel and said faucet valve, whereby water can flow to said purified water chamber from said purified water outlet, water can flow from said purified water chamber to said faucet valve, water can flow from the reject water outlet of the reverse osmosis unit to the reject water chamber of said vessel and water can flow from said reject water chamber to a drain, a reject water flow control valve being disposed in a said conduit providing communication between said reject water outlet and said reject water chamber, said reject water flow control valve being movable between a seated position permitting a restricted flow of reject water from said reject water outlet to said reject water chamber and an unseated position permitting substantial flow of reject water from said reject water outlet to said reject water chamber, a reject water drain valve being disposed in a said conduit providing communication between said reject water chamber and said drain and being movable between an open position permitting reject water flow to the drain from the reject water chamber and a closed position preventing reject water flow to the drain from the reject water chamber. In these prior systems, while the faucet valve is closed, the purified water expands and fills the purified water chamber to expel reject water from the reject water chamber for flow to a suitable drain. However, when dispensing of purified water is desired, for example, for cooking, drinking, etc. the faucet valve is opened to create an open discharge path communicating the purified water chamber to an open discharge spout or the like. At the same time, other valve components in the supply system function to supply a substantial flow of reject water into the reject water chamber thereby providing a fluid driving medium capable of forcing the purified water through the open discharge path to the discharge spout. In the past, however, this substantial reject water flow into the reject water chamber for purified water delivery purposes has resulted in at least temporary pressurization of the reject water chamber to a level substantially equalling tap water line pressure. In domestic or residential water supply systems wherein the top water line pressure is typically within the range of about 2.7 to 10.2 bar (40 to 150 psi), the storage vessel is thus subjected to a substantial fluid pressure during normal operation of the water supply system. Such pressurization of the storage vessel has required relatively rugged vessel constructions of metal or reinforced plastic or fibreglass materials, whereby the storage vessel has constituted a major cost component in the water supply system. Moreover, the presence of relatively high fluid pressures within the storage vessel enhances the risk of occasional failure of system components such as valves, seals, etc. resulting in water leaks and accompanying risk of water damage. Still further, in the past, water supply systems of this general type have proposed the use of complicated valve arrangements with multiple independently operated valve components required to control the various system water flows and pressures. Unfortunately, minor irregularities in the operation of a single valve component such as leakage due to entrapped grit at a valve seat or other sealing surface, can result in system failure. In most available purified water supply systems, such system failures have required time consuming and costly disassembly of complicated valve components for repair purposes. There exists, therefore, a significant need for an improved purified water supply system designed for reliable delivery of purified water from a storage vessel of relatively lightweight, cost-efficient construction, wherein the system includes means for limiting fluid pressures in the storage vessel to pressure levels substantially below tap water line pressure. Moreover, there exists a need for such a system wherein the structure and movements of controlling valve components are simplified and adapted for reduced likelihood of failure. The present invention fulfils these needs and provides further related advantages. In accordance with the invention there is provided a purified water supply apparatus including a reverse osmosis unit having a water inlet, a purified water outlet and a reject water outlet a storage vessel the interior of which is divided by a movable barrier into a purified water chamber and a reject water chamber, whereby movement of said barrier as water is supplied to the purified water chamber and withdrawn from the reject water chamber and vice versa allows corresponding changes in the relative volumes of the purified water chamber and the reject water chamber, a faucet valve movable between open and closed positions, and conduits interconnecting said reverse osmosis unit, said storage vessel and said faucet valve, whereby water can flow to said purified water chamber from said purified water outlet, water can flow from said purified water chamber to said faucet valve, water can flow from the reject water outlet of the reverse osmosis unit to the reject water chamber of said vessel and water can flow from said reject water chamber to a drain, a reject water flow control valve being disposed in a said conduit providing communication between said reject water outlet and said reject water chamber, said reject water flow control valve being movable between a seated position permitting a restricted flow of reject water from said reject water outlet to said reject water chamber and an unseated position permitting substantial flow of reject water from said reject water outlet to said reject water chamber, a reject water drain valve being disposed in a said conduit providing communication between said reject water chamber and said drain and being movable between an open position permitting reject water flow to the drain from the reject water chamber and a closed position preventing reject water flow to the drain from the reject water chamber, characterised in that said flow control valve and said drain valve are mounted within a common valve housing for generally coaxial linear movement, and actuator means is provided for actuating said reject water flow control valve and said reject water drain valve, said actuator means being mounted within said common housing and movable generally coaxially with said flow control and drain valves, said actuator means being responsive to pressure changes in a said conduit providing communication between said purified water chamber and said faucet valve and being arranged to regulate the pressure level within said vessel to a pressure level substantially below tap water line pressure by opening said drain valve in response to rising pressure acting on said piston member, whereby when the faucet valve is open to allow water flow from said purified water chamber, said actuator means is moved towards a first position in which it places said flow control valve in its unseated position and said drain valve in its closed position and when the faucet valve is closed to prevent water flow from said purified water chamber said actuator means can move towards a second position, in response to increased water pressure in the purified water chamber and the conduit providing communication between the purified water chamber and said faucet valve, the actuator means in said second position placing said flow control valve in its seated position and said drain valve in its open position, said actuator means comprising a piston member and having a piston stem movable with the piston member and coupled to said flow control and drain valves. In a preferred arrangement, the inlet of the reverse osmosis unit is coupled to a supply or ordinary tap water or the like. The reverse osmosis unit operates in a known manner to produce dual water outflows, namely, the purified water supply with impurities substantially removed, and a supply of reject water or brine with impurities concentrated therein. The purified water supply is stored within the storage vessel ready for dispensing, for example, through a discharge path which can be opened upon operation of one or more faucet valves, whereas the reject water supply is ultimately discharged to an appropriate drain. The storage vessel comprises a relatively lightweight and preferably compact tank container defining an internal purified water chamber and a reject water chamber separated from each other by a movable barrier. The produced purified water supply is coupled for flow into the purified water chamber, whereas the produced reject water supply is coupled to an improved control valve assembly disposed along the purified water discharge path. The control valve assembly responds to the operational state of the faucet valve or valves to direct the reject water supply to the reject water chamber or, in the alternative, to the drain. Importantly, the control valve assembly incorporates fluid pressure regulator means for limiting the fluid pressure within the reject water chamber to a pressure level substantially below tap water line pressure, thereby correspondingly regulating the fluid pressure within the entire storage vessel. More specifically, the control valve assembly responds to opening of the faucet valve or valves to supply reject water at a substantial flow rate to the reject water chamber in the storage vessel. This substantial reject water flow rate is effective to pressurize the reject water chamber to a sufficient fluid pressure level to provide the driving medium expelling purified water from the storage vessel for flow along the discharge path. However, the control valve assembly maintains the pressure within the reject water chamber at a pressure level substantially below tap water line pressure to avoid subjecting the pressure vessel to relatively high fluid pressures. In one embodiment of the invention, the selected maximum reject water chamber pressure level is maintained when the faucet valve or valves are closed. In other embodiments of the invention, the control valve assembly operates to substantially relieve the fluid pressure within the storage vessel when purified water dispensing is halted. In preferred constructions, the control valve assembly includes a piston member associated with the purified water discharge path and adapted for movably responding upon fluid pressure changes along that path attributable to opening of the faucet valve or valves. This movement of the piston member displaces a slotted valve head of a reject water flow control valve from a flow limiting position to a fully open position permitting relatively high flow of reject water into the reject water chamber of the storage vessel. At the same time, the piston member movement directly or indirectly results in displacement of a reject water drain valve to a closed position thereby insuring sufficient pressure rise in the reject water chamber to expel purified water through the open discharge path. Subsequent closure of the faucet valve or valves is accompanied by return movement of the piston member to reseat the slotted valve head in the flow limiting position to restrict reject water flow into the reject water chamber. The reject water drain valve initially remains in the closed position upon valve head closure to issue full reseating thereof after which time the drain valve is unseated to prevent further pressure rise in the storage vessel. In some embodiments of the invention, the drain valve opens sufficiently to maintain chamber pressure within the storage vessel at a selected threshold pressure below tap water line pressure. In other embodiments, the drain valve is opened fully to relieve storage vessel pressure substantially to an atmospheric pressure level. The control valve assembly has a simplified construction adapted for reliable, substantially failsafe operation of the various valve components therein. More particularly, the pressure responsive piston member, the slotted valve head controlling reject water flow into the storage vessel, and the reject water drain valve are arranged in an inline configuration for substantially coaxial linear motion. Movement of the piston member is transmitted directly to the slotted valve head and further is transmitted directly to the drain valve to provide positive mechanical actuation. Other features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention. In such drawings: FIGURE 1 is a diagrammatic view illustrating an improved purified water supply system embodying the novel features of the invention; FIGURE 2 is an enlarged fragmented vertical sectional view illustrating construction details of one preferred faucet valve assembly; FIGURE 3 is an enlarged fragmented vertical sectional view depicting construction details of a lower portion of the faucet valve assembly of FIG. 2; FIGURE 4 is an enlarged fragmented vertical sectional view depicting a preferred control valve assembly for use with the invention; FIGURE 5 is a further enlarged fragmented sectional view depicting the control valve assembly in an open position during purified water dispensing; FIGURE 6 is an enlarged fragmented vertical sectional view similar to FIG. 5 but depicting control valve assembly movement upon termination of purified water dispensing; FIGURE 7 is an enlarged fragmented vertical sectional view similar to FIG. 4 and depicting one alternative embodiment of the control valve assembly for use with the invention; FIGURE 8 is a further enlarged fragmented vertical sectional view of the control valve assembly of FIG. 7, and depicting the control valve assembly in an open position during purified water dispensing; FIGURE 9 is an enlarged fragmented vertical sectional view similar to FIG. 8 and depicting control valve assembly movement upon termination of purified water dispensing; FIGURE 10 is another fragmented vertical sectional view similar to FIG. 4 but depicting another alternative form of the invention; FIGURE 11 is a further enlarged fragmented vertical sectional view similar to FIG. 10 and depicting the control valve assembly in an open condition; FIGURE 12 is an enlarged fragmented vertical sectional view similar to FIG. 11 but depicting control valve assembly movement when purified water dispensing is terminated. FIGURE 13 is still another fragmented vertical sectional view similar to FIG. 4 but depicting a somewhat simplified alternative embodiment of the invention; FIGURE 14 is an enlarged fragmented vertical sectional view similar to a portion of FIG. 13 and depicting the control valve assembly in an open position during purified water dispensing; and FIGURE 15 is an enlarged fragmented vertical sectional view similar to FIG. 14 and showing reclosure of the control valve assembly at the conclusion of purified water dispensing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in the exemplary drawings, an improved purified water supply system is referred to generally by the reference numeral 10 in FIGURE 1. The water supply system 10 includes a reverse osmosis unit 12 for converting an ordinary tap water supply or the like into a relatively pure supply of water which is stored temporarily within a relatively lightweight and compact storage vessel 14. The purified water within the storage vessel 14 is delivered on demand for use by operation of a faucet valve assembly 16. Importantly, in accordance with the invention, a control valve assembly 18 functions in cooperation with the faucet valve assembly 16 to insure reliable delivery of the purified water from the storage vessel 14, while limiting the fluid pressure within the storage vessel to a pressure level substantially less than tap water line pressure. The improved purified water supply system 10 of the present invention is designed particularly for use in residential and other domestic applications to produce a ready supply of relatively pure water from ordinary tap water or the like. The system 10 utilizes the reverse osmosis unit 12 to convert an incoming supply of ordinary tap water into dual water outflows including a supply of relatively pure water and a waste or reject water supply, sometimes referred to as brine, having impurities concentrated therein. The purified water supply is normally coupled to and stored within the storage vessel 14 ready for use on demand for drinking, cooking, etc. Moreover, in reference to one aspect of the present invention, the purified water supply can be coupled to multiple use sites such as an icemaker or a chilled water station of the type included in many modern refrigerator units. The control valve assembly 18 operates in conjunction with opening and closing of an appropriate faucet valve at each one of the multiple use sites to insure reliable purified water delivery. The water supply system 10 advantageously utilizes the generated supply of reject water as a driving medium for expelling purified water from the storage vessel 14, when dispensing of purified water is desired. However, the control valve assembly 18 regulates the supply of reject water to the storage vessel in a manner limiting maximum storage vessel internal pressure to a threshold level substantially less than tap water line pressure. Accordingly, the reject water supply is used to provide a sufficient driving force to the stored purified water for dispensing purposes, while maintaining internal vessel pressures relatively low, thereby avoiding internal pressures at tap water line pressures which can range between 2.7 - 10.2 bar (40-150 psi). The use of relatively low vessel pressures beneficially permits economic storage vessel construction of lightweight molded plastic or the like, to correspondingly reduce the overall cost and complexity of the water supply system. As shown generally in FIGURE 1, in one preferred system arrangement, a tap water supply line 19 of a standard residential water supply system or the like is coupled to an inlet throttle valve 20. This throttle valve 20 is normally open to permit tap water flow through a feed conduit 22 to an inlet 24 on the reverse osmosis unit 12. The reverse osmosis unit 12 includes an internal membrane (not shown) which functions in a manner known to those skilled in the art to separate the incoming water tap water into the purified water supply and the reject water supply. The purified water supply is discharged from the reverse osmosis unit 12 through an outlet conduit 26, whereas the reject water is discharged through a separate outlet conduit 28. The purified water supply produced by the reverse osmosis unit 12 is coupled by the conduit 26 for flow alternately to a filter unit 30 containing carbon filter material or the like, or through a conduit 32 into a purified water chamber 34 within the storage vessel 14. As shown best in FIG. 1, this storage vessel 14 comprises a relatively lightweight tank container formed from a pair of cup-shaped sections 35 and 36 mounted one on top of the other in facing relation and securely connected by a circumferential band 38 or the like fastened about outwardly radiating, mating flanges 39 and 40. A movable barrier 41 such as a cup-shaped resilient diaphragm or the like has its periphery trapped between the flanges 39 and 40 and functions to divide the internal volume of the vessel 14 into the purified water chamber 34 and an upper reject water chamber 42. The reject water supply produced by the reverse osmosis unit 12 flows through the reject water conduit 28 to an associated inlet port 44 of the control valve assembly 18. As will be described in more detail, the control valve assembly 18 redirects the reject water supply through an appropriate conduit 46 for flow into the reject water chamber 42 of the storage vessel 14, or, in the alternative, through a drain conduit 50 to the faucet valve assembly 16 ultimately for discharge to an appropriate drain through a drain tube 52. Similarly, the control valve assembly 18 is connected inline with a discharge path through which purified water may be discharged for the storage vessel 14, wherein this discharge path may lead to multiple sites of use of the purified water such as the faucet valve assembly 16 via a primary discharge conduit 54, or for alternate flow through a secondary discharge conduit 58 to an alternative use site 60, for example, such as an icemaker or a chilled water drinking station in a modern refrigerator. In general operation of the water supply system 10, when the faucet valve assembly 16 and other purified water faucet valves or the like are closed, the reverse osmosis unit 12 produces purified water which expands and fills the purified water chamber 34 in the storage vessel 14. During this filling process, reject water produced by the reverse osmosis unit is coupled to the faucet valve assembly 16 for flow through the drain tube 52 to drain. At the same time, reject water within the vessel reject water chamber 42 is expelled by the expanding purified water chamber for flow through the control valve assembly 18 and further to drain. When the purified water chamber 34 becomes substantially filled, the movable barrier 41 advantageously contacts a pressure plate 61 forming a portion of the inlet throttle valve 20 to move a throttle valve member 62 to a closed position throttling or halting incoming tap water flow to the system. A further description of the structure and operation of the inlet throttle valve 20 is found in the inventor's U.S. Patent 4,595,497 and copending application Serial No. 848,351, filed April 4, 1986, now U.S. Patent 4,743,366, which are incorporated by reference herein. As shown in FIGS. 1-3, in one preferred form, the faucet valve assembly 16 is normally mounted on the drain board 17 or the like of a sink and includes a movable valve handle 64 biased by a spring 65 (FIG. 2) toward a position permitting a valve member 66 (FIG. 3) to be carried by a spring 77 to a normally closed position. However, when the faucet handle 64 is depressed to the dotted line position shown in FIG. 1, the handle 64 bears against and depresses a tubular valve stem 68 having a stop 69 thereon for displacing the valve member 66 to an open position, as viewed in dotted lines in FIG. 3. In this open position, the valve member 66 permits flow of purified water from the vessel 14 through the associated conduit 54, and upwardly though a now-open discharge passage 70 for discharge through a discharge spout 72 (FIG. 1). In this dispensing position, as will be described in more detail, a substantial reject water flow is directed into the vessel reject water chamber 42 at a sufficient pressure to provide a fluid driving medium for forcing the purified water to flow in a reliable, accurate matter through the now-open discharge path. Alternately, as depicted with respect to the remote use site 60, the purified water discharge path may direct the purified water to one or more additional points of use upon appropriate opening of a faucet valve (not shown) or the like at that remote use site. Upon termination of purified water dispensing at the faucet valve assembly 16 and/or at other use sites, the system reverts to a normal mode as described previously wherein the purified water chamber 34 is refilled with produced purified water. In this mode, using the illustrative faucet valve assembly 16, reject water produced by the reverse osmosis unit 12 as well as water within the reject water chamber 42 are coupled via the drain conduit 50 to drain via the faucet valve assembly 16. As shown in FIGS. 2 and 3, this reject water flow passes upwardly through the tubular valve stem 68 for discharge into a vented receiver 73 thereby providing an air gap for the drain portion of the system. From the receiver 73, the reject water spills into a drain path 74 for passage to and flow through the drain tube 52. Conveniently, for purposes of brevity, the structure and operation of the exemplary faucet valve assembly 16 has been described briefly herein, it being understood that various faucet valve assembly arrangements may be used in the system of the present invention. However, the illustrative faucet valve assembly (FIGS. 1-3) provides a preferred construction corresponding generally with that shown and described in the inventor's U.S. Patent 4,585,554, and copending application Serial No. 848,360, filed April 4, 1986, and related continuation application Serial No. 125,777, filed November 25, 1987, which are incorporated by reference herein. Moreover, it will be understood that multiple faucet type valves may be used for purified water dispensing at multiple sites of use, although only one reject water drain arrangement is required. As shown in one preferred form in FIGS. 4-6, the control valve assembly 18 comprises an assembled multi-part valve housing 75 adapted for mounting in any suitable manner onto the top or discharge side of the filter unit 30. This valve housing 75 defines a lower inlet port 76 in flow communication with the purified water chamber 34 in the storage vessel 14 via the filter unit 30 and the purified water conduit 32. From the inlet port 76, the purified water is free to flow initially into a pressure chamber 78 and then to a pair of pure water outlets 80 and 81 leading respectively to the faucet valve unit 16 and to the remote use site 60. Purified water flow through these outlets to the use sites is turned on and off, of course, by the operational state of faucet valve members at those use sites. Additional pure water outlets may be provided, as desired. A pressure responsive piston member 82 defines a movable wall lining one side of the pressure chamber 78 within the control valve housing 75. As shown in FIG. 4, the outboard face of this pressure responsive piston member 82 is lined by a fabric reinforced resilient diaphragm 84 mounted on the housing to accommodate piston member displacement with respect to the pressure chamber 78. The inboard face of the piston member 82 is exposed to an internal chamber 85 vented to atmosphere through a vent 86. A biasing spring 88 reacts between the housing 75 and the inboard side of the piston member 82 for urging the piston normally in a direction reducing the volume of the pressure chamber 78. The movable piston member 82 carries an elongated stem 90 which projects through the housing 75 in a direction away from the pressure chamber 78. The stem 90 extends upwardly through a seal diaphragm 89 into a reject water flow path 92 communicating between the reject water inlet 44 and an outlet 93 leading to the storage vessel 14, and further through a valve seat 94 disposed along the flow path 92 before terminating in an upper stem portion 90′ of somewhat enlarged diameter. A valve head 96 of a reject water flow control valve is slidably carried on the valve stem 90 below the upper stem portion 90′ and is normally biased by a spring 97 reacting between the underside of the valve head 96 and lower shoulder 98 of the stem 90 to urge the valve head 96 toward the seat 94. The valve head 96 has a slot 99 in the face thereof to permit a restricted or limited reject water flow through the flow path 92 when the valve head 96 is on the seat 94. The valve head 96 is maintained in this flow limiting position by the combined action of the biasing spring 97 and the piston member 82 when the fluid pressure in the pressure chamber 78 is relatively high, namely, when all faucet valves for dispensing purified water are closed. However, when one of the faucet valves is opened, the pressure in the chamber 78 is reduced whereby the piston member 82 descends to decrease the chamber volume. This displacement of the piston member 82 draws downwardly on the stem 90 to slide a shoulder 100 on the lowermost end of the enlarged stem portion 90′ into contact with the valve head 96. Further downward motion of the stem 90 unseats the valve head 96 to a fully open position, as viewed in FIG. 5, thereby permitting a substantial flow rate of reject water through the flow path 92 and into the reject water chamber 42 in the storage vessel 14. This substantial flow, as previously described, provides the fluid driving medium to force purified water through the selected open faucet valve. When the above-described dispensing flow of purified water is initiated, an upper drain valve 101 within the control valve assembly 18 is positively seated in a closed position to halt passage of reject water to the drain. More specifically, as viewed in FIGS. 4 and 5, opening movement of the lower valve head 96 is accompanied by downward motion of the upper stem portion 90′ to spaced relation with a support piston 102 connected to the drain valve 101. When this occurs, a valve spring 104 displaces the support piston in a downward direction to carry the drain valve 101 into seated relation with an associated valve seat 106 closing a drain path 108 leading from the reject water flow path 92 to the drain conduit 50 and ultimately to the drain. Accordingly, the substantial flow of reject water is guided in its entirety into the reject water chamber 42 of the storage vessel, resulting in expansion of the reject water chamber at a sufficient pressure to contract the size of the purified water chamber 34 and force the purified water from the vessel through the now-open discharge path. Importantly, the closed drain valve 101 insures the presence of sufficient fluid pressure with the reject water chamber to provide the necessary fluid driving medium. However, the open condition of one or more faucet valves for purified water dispensing prevents any significant pressure rise in the vessel 14 during this mode of operation. When dispensing of purified water is halted, the appropriate faucet valve or valves are closed to correspondingly close the discharge path for the purified water. This closure of the discharge path is accompanied by a pressure rise along the discharge path including the pressure chamber 78 within the control valve assembly 18. The increased pressure in the pressure chamber 78 is attributable to continued flow of reject water into the reject water chamber 42 and eventually rises to a level sufficient to cause the piston member 82 to undergo a return displacement increasing the volume of the chamber 78, as viewed in FIG. 6. During this movement, the stem 90 is displaced back toward its original position permitting the associated valve head spring 97 to reseat the valve head 96 of the valve seat 94. As a result, the valve head 96 is returned to the flow limiting position permitting a slow flow of reject water through the valve head slot 99. After reseating of the valve head 96, the continued albeit slow reject water flow into the reject water chamber 42 causes the vessel pressure to continue to rise. This results in a corresponding slow continued pressure rise within the pressure chamber 78, thereby displacing the piston member 82 and its stem 90 further with respect to the now-seated valve head 96. The upper portion 90′ of the stem protrudes upwardly through a seal unit 110 and eventually moves into contact with the underside of the drain valve support piston 102. When this occurs, further pressure increase in the pressure chamber 78 causes further displacement of the stem portion 90′ sufficiently to open the drain valve 101 relative to its seat 106. In this embodiment, the drain valve 101 is opened by an increment sufficient to achieve partial pressure relief within the reject water chamber 42 bleeding a small amount of the reject water therein. The drainage bleed of reject water occurs when the vessel pressure reaches a predetermined threshold selected to be substantially below tap water line pressure and continues in sufficient quantity to maintain vessel pressure at the set threshold pressure to drain reject water from the vessel 14 as the purified water chamber 34 refills. The specific threshold pressure can be selected by appropriate design of the surface area of the piston member 82 and the forces applied by the various springs in the system. Accordingly, the embodiment of Figures 4-6 maintains the vessel pressure level substantially at the preset threshold refilling of the purified water chamber 34 when all of the faucet valves in the system are closed. This selected preset threshold will normally be chosen at about 1.1 to 1.7 bar (17-25 psi) -- a pressure level significantly below tap water line pressure to avoid applying relatively high fluid pressures to the storage vessel 14 -- and further selected to avoid undue backpressure applied to the reverse osmosis unit during normal production of purified water. This relatively low threshold pressure can be offset economically by moderate increases in membrane surface area provided in the reverse osmosis unit. However, if minimum backpressures are desired upon the reverse osmosis unit, the threshold pressure in the reject water chamber can be set lower, with corresponding decreases in purified water delivery rate during dispensing procedures. Figures 7-9 depict one alternative construction for the reject water drain valve used in the purified water system, with the remaining system components being otherwise identical to those shown and described in Figures 1 to 6. In this embodiment, a drain valve 120 is biased by a spring 122 toward a normal fully opened position relative to an associated valve seat 124. This drain valve 120 is maintained in the open position during normal refilling of the vessel 14 with purified water to correspondingly minimize backpressure applied to the reverse osmosis unit 12. However, during dispensing of purified water upon opening of one or more faucet valves in the system, the drain valve 120 is moved to a fully closed position to insure generation of sufficient pressure in the vessel 14 for proper purified water delivery purposes. More particularly, as shown in FIG. 7, the drain valve 120 is carried by a lower support piston 126, in the same manner previously described with respect to FIGS. 4-6. However, the support piston 126 and the drain valve 120 are biased toward an open position by the spring 122 within a chamber 123 and reacting between the seal unit 110 and the underside of the support piston 126. Accordingly, when the system faucet valves are closed such that purified water is not being dispensed, the drain valve 120 is fully opened to permit substantial drainage flow of reject water through the drain path 108, thereby maintaining the vessel pressure at a substantially minimum pressure approaching atmospheric pressure. When purified water is dispensed, the pressure within the pressure chamber 78 falls to cause the piston member 82 to be drawn into the pressure chamber 78. As previously described with respect to FIGS. 4-6, such piston member movement pulls the stem 90 including its enlarged upper stem portion 90′ in a downward direction for positive and substantial displacement of the slotted valve head 96 to the fully open position. However, in the embodiment of FIGS. 7-9, during this downward stem motion, an upper abutment 130 such as a screw head or the like on the upper end of the stem portion 90′ engages a land 132 of the support piston 126 to draw the support piston and the drain valve 120 carried thereby to the positively closed position. This positively closed position is achieved, in this embodiment, by sliding motion of an O-ring 120′ on the drain valve which slides into and effectively locks within a shallow groove 124′ in the valve seat structure. Alternately, the O-ring may be mounted in the valve seat structure and the groove formed in the drain valve 120. In either case, in this configuration, the control valve assembly permits a substantial reject water flow through the path 92 into the reject water chamber 42, while the drain valve 120 is closed, to insure fluid-activated delivery of the purified water from the storage vessel. Reclosure of the system faucet valve or valves halts purified water dispensing such that the pressure rises within the pressure chamber 78 to return the piston member 82 to its original position. This piston member movement initially reseats the slotted valve head 96, followed by continued upward movement of the stem 90. The abutment 130 on the upper stem portion 90′ eventually contacts the support piston 126 and displaces the piston 126 with the drain valve 120 back to the fully open position. Importantly, this drain valve opening is postponed in time until after full seating of the valve head 96 to reinstitute regulated flow along the path 92 by means of the valve head slot 99. The locking engagement between the O-ring 120′ and the groove 124′ retains the drain valve in the closed position, despite pressure rise in the reject water chamber and the force applied by the spring 122. However, the support piston 126 is driven by the upward motion of the abutment 130 to dislodge the O-ring 120′, at which time the combined effects of pressure and the spring 122 pop the drain valve 120 back to the fully open position. The fully opened drain valve 120 thus relieves pressure within the vessel 14 for minimum backpressuring of the reverse osmosis unit. A check valve 136 (FIG. 7) is provided at the inlet port 76 to the control valve assembly to prevent loss of pressure in the pressure chamber 78 until subsequent flow of purified water for dispensing purposes is desired. Another alternative embodiment of the control valve assembly is shown in FIGS. 10-12, wherein the control valve assembly includes a modified drain valve arrangement for fully opening a reject water drain valve 140 during normal refilling of the storage vessel with purified water. In this version, the control valve assembly again includes a pressure chamber 78 within which a significant fluid pressure is maintained separate from the water storage vessel by means of a check valve 136 or the like. The normal fluid pressure within this pressure chamber 78 positions the piston member 82 and its stem 90 for normal spring loaded seating of the slotted valve head 96 disposed along the reject water flow path 92, all in the manner described previously with respect to FIGS. 1-9. During this mode of operation, reject water is permitted to flow through the valve head slot 99 at a limited flow rate for further passage through the drain path 108 and past the drain valve 140 to drain. During purified water dispensing, the pressure in the pressure chamber decreases causing the piston member 82 to draw the enlarged upper stem portion 90′ into engagement with the valve head for positive valve head movement to the open position (FIG. 11). However, in this embodiment, a region of the stem 90 is hollow to include an upper vent port 142 disposed within a small control chamber 144 between the seal unit 110 and a support piston 146 for the drain valve 140. The hollow stem also includes a second or lower vent port 148 positioned normally above the valve head 96 at the upstream side thereof (FIG. 10). Downward motion of the valve stem 90 to open the valve head transitions the lower port 148 to a position below the valve head 96 (FIG. 11) thereby exhausting the pressure within the control chamber 144. When this occurs, a spring 150 reacting between a portion of the housing and the drain valve support piston 146 functions to displace the drain valve 140 to a positively closed position. The drain valve 140 thus insures that the substantial flow of reject water through the open path 92 is guided into the storage vessel to provide the fluid driving medium for dispensing the purified water. When the purified water dispensing is halted, the pressure chamber 78 is repressurized in the same manner described previously. As a result, the stem 90 returns in the upward direction to permit reseating of the slotted valve head 96. Further upward travel of the stem 90 retransitions the lower port 148 to a position at the upstream side of the valve head 96 and therefore repressurizes the control chamber 144 associated with the upper vent port 142. Such repressurization of the chamber 142 overcomes the drain valve spring 150 to positively re-open the drain valve 140, thereby relieving vessel pressure. A further alternative preferred form of the invention is shown in FIGS. 13-15 wherein a simplified drain valve 160 is formed integrally on the upper stem portion 90' of the elongated valve stem 90. In this version of the invention, the geometry of the drain valve 160 is designed for rapid closure when the valve head 96 is opened during purified water dispensing. Moreover, the drain valve 160 is formed to insure substantially full closure of the valve head 96 when purified water dispensing is halted, prior to reopening of the drain valve. More specifically, similar to the embodiments previously described, FIGS. 13-15 depict the reject water flow regulating valve head 96 mounted on the valve stem 90 for sliding movement under the influence of a biasing spring 97 into normal, substantially closed seated relation upon the valve seat 94. In this normally closed position, when purified water dispensing is halted and the purified water chamber in the storage vessel 14 (FIG. 1) is being refilled, the valve stem 90 extends above the valve head 96 and merges with a diametrically enlarged upper stem portion 90′. In the embodiment of FIGS. 13-15, this upper stem portion 90′ extends through a seal unit 110 into an upper region of the control valve assembly to terminate in the integrally formed drain valve 160 positioned in operative relation with a valve seat 124 unit including an O-ring seal 120′ or the like. In operation, when purified water dispensing is desired, one or more of the purified water faucet valves is opened to result in a pressure drop within the lower pressure chamber 78 of the control valve assembly. When this occurs, the piston member 82 descends into the pressure chamber 78 to draw the stem 90 in a downward direction with a sliding action through the still-closed valve head 96. Sufficient downward displacement of the stem 90 moves the shoulder 100 thereon into bearing engagement with the valve head 96 to displace the valve head from the closed position (FIG. 13) to an open position (FIG. 14). At the same time, such downward movement of the valve stem 90 displaces a groove 160′ in the drain valve 160 from an open position generally aligned with the valve seat O-ring 120′ (FIG. 13) to a position spaced below the O-ring (FIG. 14) whereby the drain valve is moved to a closed position wherein the O-ring 120′ is sealingly engaged with a cylindrical upper head of the drain valve. Accordingly, the above-described movement of the valve stem 90 results in closure of the drain valve 160 followed shortly by opening of the valve head 96. When the valve head 96 is fully opened, as viewed in FIG. 14, the drain valve head engages the O-ring 120′ near a trailing edge of the drain valve 160. Opening of the valve head 96 permits a substantial reject water flow into the reject water chamber of the storage vessel 14 (FIG. 1) to correspondingly displace purified water from the storage vessel through the open faucet valve or valves. The drain valve 160 remains closed throughout this dispensing cycle to insure positive and reliable purified water dispensing yet the fluid pressure within the storage vessel 14 remains substantially below tap water line pressure due to the open nature of the faucet valve. When purified water dispensing is halted upon faucet valve closure, the fluid pressure within the storage vessel starts to increase due to the continued reject water flow past the open valve head 96 and the closed nature of the drain valve 160. This pressure rise is reflected in the pressure chamber 78 causing the piston member 82 to move upwardly. The piston member 82 thus displaces the valve head 96 back to the closed position as viewed in FIG. 15 to restrict reject water flow to the cross sectional area of the valve head slot 99, as previously described. The axial length of the head portion of the drain valve 160 is sufficient to maintain closure of the drain valve path 108 (FIG. 15) until the valve head 96 is fully seated on the valve seat 94. Further pressure rise within the vessel and the pressure chamber 78 displaces the piston member 82 and stem 90 further in the upward direction ultimately to re-align the drain valve groove 160′ with the O-ring 120′ thereby reopening the drain valve and relieving the fluid pressure in the storage vessel. Importantly, this drain valve reopening occurs at a storage vessel pressure threshold substantially below tap water line pressure, due to the design characteristics of the spring-loaded piston member, to prevent exposure of the storage vessel to high fluid pressures. Moreover, a check valve 136 may be again provided at the inlet port 76 of the pressure chamber 78 to prevent chamber pressure loss until subsequent purified water dispensing is initiated. However, the check valve 136 is not required in this embodiment since the piston member 82 responding to pressure within the chamber 78 will open the drain valve 160 by a small increment sufficient to achieve partial pressure relief within the reject chamber, in the same manner as described with respect to FIGS. 1-6. In all of the above-described embodiments of the invention, the valve head 96 of the reject water flow control valve and the reject water drain valve are arranged for simple and reliable operation. All of the valve components are aligned generally coaxially for actuation in a linear manner upon movement of the pressure responsive piston member. Importantly, the valve head 96 is fully reseated in each embodiment prior to drain valve reopening. Accordingly, the improved purified water supply system of the present invention provides means for regulating the pressure of a purified water storage vessel to maximum pressure level substantially below tap water line pressure. In this manner, the storage vessel is not subjected to high pressure levels and can thus be constructed from lightweight materials.

Claims: A purified water supply apparatus including a reverse osmosis unit (12) having a water inlet (24), a purified water outlet (26) and a reject water outlet (28) a storage vessel (14) the interior of which is divided by a movable barrier (41) into a purified water chamber (34) and a reject water chamber (42), whereby movement of said barrier as water is supplied to the purified water chamber and withdrawn from the reject water chamber and vice versa allows corresponding changes in the relative volumes of the purified water chamber and the reject water chamber, a faucet valve (16) movable between open and closed positions, and conduits (22, 26, 28, 32, 46, 50, 54, 76, 78, 80, 92, 108) interconnecting said reverse osmosis unit, said storage vessel and said faucet valve, whereby water can flow to said purified water chamber (34) from said purified water outlet (26), water can flow from said purified water chamber (34) to said faucet valve (16), water can flow from the reject water outlet (28) of the reverse osmosis unit to the reject water chamber (42) of said vessel and water can flow from said reject water chamber (42) to a drain (52), a reject water flow control valve (94) being disposed in a said conduit providing communication between said reject water (28) outlet and said reject water chamber (42), said reject water flow control valve (94) being movable between a seated position permitting a restricted flow of reject water from said reject water outlet (28) to said reject water chamber (42) and an unseated position permitting substantial flow of reject water from said reject water outlet (28) to said reject water chamber (42), a reject water drain valve (101) being disposed in a said conduit providing communication between said reject water chamber (42) and said drain (52) and being movable between an open position permitting reject water flow to the drain (52) from the reject water chamber (42) and a closed position preventing reject water flow to the drain (52) from the reject water chamber (42), characterised in that said flow control valve (94) and said drain valve (101) are mounted within a common valve housing (75) for generally coaxial linear movement, and actuator means (82, 84) is provided for actuating said reject water flow control valve (94) and said reject water drain valve (101), said actuator means being mounted within said common housing (75) and movable generally coaxially with said flow control (94) and drain (101) valves, said actuator means being responsive to pressure changes in a said conduit (32, 30, 76, 78, 80, 54) providing communication between said purified water chamber (34) and said faucet valve and being arranged to regulate the pressure level within said vessel to a pressure level substantially below tap water line pressure by opening said drain valve (101) in response to rising pressure acting on said piston member (81), whereby when the faucet valve (16) is open to allow water flow from said purified water chamber, said actuator means is moved towards a first position in which it places said flow control valve (94) in its unseated position and said drain valve (101) in its closed position and when the faucet valve (16) is closed to prevent water flow from said purified water chamber (34) said actuator means can move towards a second position, in response to increased water pressure in the purified water chamber and the conduit (32, 30, 76, 78, 80) providing communication between the purified water chamber (34) and said faucet valve (16), the actuator means in said second position placing said flow control valve (94) in its seated position and said drain valve (101) in its open position, said actuator means comprising a piston member (81) and having a piston stem (90) movable with the piston member and coupled to said flow control (94) and drain valves (101). The apparatus of claim 1 wherein said stem is slidably received through said flow control valve (94) and includes a shoulder on said stem for contacting said flow control valve (94) to displace said flow control valve into said unseated position upon movement of said faucet valve to said open position. The apparatus of claim 2 wherein said drain valve (101) is carried integrally with said stem (90). The apparatus of claim 1 wherein said actuator means is connected with said flow control valve and said drain valve with provision for lost motion between said drain valve and said flow control valve such that said actuator means moves said drain valve (101) to said closed position and then subsequently moves said flow control valve (96) to said unseated position during movement of the actuating means to said first position and such that said actuator means moves said flow control valve (96) to said seated position and then subsequently moves said drain valve (101) to said open position during movement of the actuating means from said first position to said second position. The apparatus of claim 1 wherein said actuator means is arranged to move said drain valve (101) to a partially open position when the pressure level in said storage vessel reaches a predetermined pressure level substantially lower than top water line pressure. The apparatus of claim 1 wherein said actuator means is arranged to move said drain valve (101) to a fully open position subsequent to movement of said flow control valve (94) to said seated position upon movement of said faucet valve (16) from said open position to said closed position, said drain valve (101) in said fully open position substantially relieving the pressure within said storage vessel. The apparatus of claim 6 further including a check valve (136) at a position upstream of said piston member (81) in relation to the direction of water flow from the purified water chamber (34) to said faucet valve (16) for isolating said piston member (81) from said storage vessel when said drain valve (101) is moved to said fully open position.

Inventors: BURROWS BRUCE D, BURROWS, BRUCE D.
Applicants: BURROWS BRUCE D, BURROWS, BRUCE D.
Application year: 1988
Main classification: B01D61
IPC codes: B01D61