BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to a hydraulically driven diaphragm pump that pumps permeate water from a reverse osmosis membrane filter to a holding tank.

DESCRIPTION OF RELATED ART

Reverse osmosis (RO) water purification systems are used to remove impurities. Figure 1 shows a conventional RO system which has a reverse osmosis membrane 10 coupled to a source of feed water 12. The source of water 12 is typically municipal tap water. The system contains an osmotic membrane which separates impurities from the feed water into purified or permeate water and a concentrate of impurities called brine. The permeate water is then stored within a holding tank 14 or other means of accumulating the purified water while the brine water is continuously discharged to drain.

The osmotic membrane has a relatively low porosity, such that the membrane creates a significant drop in pressure as the water passes through the membrane. When the system is used at a location with low municipal water pressure, the resultant pressure of the permeate water passing through the membrane can be too low to even fill the tank. For this reason, many RO systems include a pump 16 to increase the pressure

of the feed water and the resultant permeate water produced by the RO membrane. Conventional RO pumps are typically driven by an electric motor that is plugged into a municipal source of electrical power. Municipal power may not always be available to the end user, thereby rendering an electric motor based system inoperable. Additionally, electric motors are relatively expensive and increase the overall cost of the system. It would thus be desirable to have a non- electrical pump that would increase the pressure of the permeate water produced by a reverse osmosis water filter membrane and filter system.

SUMMARY OF THE INVENTION

The present invention is a diaphragm pump that increases the pressure of the permeate water produced by a reverse osmosis water filter. The pump has a diaphragm that separates a permeate chamber from a brine chamber. The permeate chamber has an inlet port coupled to the permeate output port of the reverse osmosis filter, and an outlet port that is coupled to a tank for accumulating the permeate water produced by the filter. The brine chamber has an inlet port coupled to a brine outlet port of the filter, and an outlet port coupled to drain.

In operation, brine water flows into the brine chamber of the pump from the filter. The flow of brine water moves the diaphragm pushes the permeate water within the pump into the holding tank. When the diaphragm reaches a stroke position, a valve opens and allows the brine water within the brine chamber to drain through the brine outlet port. The permeate water pressure is greater than the drain pressure so that the permeate water from the filter moves the diaphragm back into the intake position, wherein the valve is closed and the brine water again fills the brine chamber to repeat the cycle.

The system includes a flow restrictor that eliminates back pressure that may otherwise prevent the diaphragm from moving to the intake position. The pump includes a spring loaded linkage assembly that latches the valve into the open and closed positions when the diaphragm moves past predetermined locations within the pump.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, wherein:

Figure 1 is a schematic of a reverse osmosis water purification system of the prior art;

Figure 2 is a schematic of a reverse osmosis water purification system of the present invention;

Figure 3 is a cross-sectional view of a diaphragm pump of the present invention;

Figure 4 is a cross-sectional view similar to Fig. 3, showing an over center linkage mechanism prior to opening a valve of the pump;

Figure 5 is a cross-sectional view similar to Fig. 4 showing a spring assembly latching the valve into an open position;

Figure 6 is a cross-sectional view similar to Fig. 5 showing the pump filling with permeate water;

Figure 7 is a cross-sectional view similar to Fig. 6 showing the linkage mechanism prior to closing the valve;

Figure 8 is a cross-sectional view similar to Fig. 3 showing a spring assembly latching the valve into a closed position.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings more particularly by reference numbers, Figure 2 shows a reverse osmosis water purification system 20 of the present invention. The system includes a reverse osmosis membrane 22 coupled to a source of feed water 24. The feed water is typically water from a municipal water source. The osmosis membrane 22 removes impurities from the feed water to create permeate water and brine water. The permeate water is typically stored in a tank 28. The tank 28 may be a simple container, a pressurized bladder filled accumulator or any other means of storing the permeate water. The tank 28 typically has a spigot to allow the user to remove the permeate water.

The membrane 22 has a relatively low porosity which creates a significant pressure drop. To increase the pressure of the permeate water, a permeate pump 30 is coupled to the filter 22 and the tank 28. The permeate pump 30 has a brine inlet port 32 coupled to a brine outlet port 34 of the membrane 22 and a brine outlet port 36 connected to drain. Although a drain is described, it is to be understood that the outlet port 34 may be routed back to the inlet of the membrane 22 or another component of the reverse osmosis system. The pump 30 also has a permeate inlet port 38 coupled to a permeate outlet port 40 of the membrane 22 and a permeate outlet port 42 connected to the tank 28. The permeate pump 30 is driven by the pressure of the brine water from the membrane 22 to increase the pressure of the permeate water that is supplied to the tank 28. The brine outlet port 34 of the membrane 22 is preferably coupled to the brine inlet 32 of the pump 30 by a flow restrictor 29. The flow restrictor 29 significantly reduces the flowrate of brine water into the pump 30. As an alternate

embodiment, the flow restrictor can be incorporated into the brine inlet port 32 of the pump 30.

Figs. 3-8 show a preferred embodiment of the permeate pump 30. The pump 30 has a housing 44 that is preferably assembled from an end piece 46 that is screwed into an outer shell 48. The housing 44 also includes inner chamber members 50 and 52. Chamber member 50 includes brine ports 32 and 36. Likewise, the outer shell 48 has permeate ports 38 and 42. Fittings 54 are inserted into the ports and attached to the housing members 48 and 50. Attached to the fittings 54 are flexible hoses (not shown) that couple the pump 30 to the membrane 22, the tank 28 and the drain.

The pump 30 has an internal flexible diaphragm 54 that separates a permeate water chamber 56 from a brine water chamber 58. The flow of water in and out of the permeate chamber 56 is controlled by one-way valves 60 and 62, located within the permeate ports 38 and 42, respectively. Within the brine water chamber 58 is a valve linkage assembly 64. The linkage assembly 64 moves a valve 66 relative to the brine outlet port 36. Both the diaphragm 54 and the outer shell 48 are preferably constructed from a material that will not contaminate the permeate water as the water is pumped through the chamber 56. The diaphragm 54 also completely seals the permeate chamber 56 from the linkage assembly 64, so that the components of the assembly will not contaminate the permeate water. The seal chamber 56 thus significantly prevents the contamination of the water by the pump. Additionally, because the pump 30 is driven by the brine water, the pump 30 of the present invention will not contaminate the permeate water with oils, lubricants or other substances typically found in a conventional water pump.

The linkage assembly 64 includes a linkage arm 68 pivotally connected to a piston 70 by pin 72. The piston 70 is attached to the diaphragm 54 so that the diaphragm 54 and piston 70 move in unison. The linkage arm 68 is also pivotally connected to the housing 44 by pin 74, and to a lever 76 by a spring assembly 78. The lever 76 is coupled to the valve 66 and is pivotally connected to the housing 44 by pin 80. The spring assembly 78 includes a compression spring 82 that is captured by members 84 and 86, which are pivotally connected to the arm 68 and lever 76. The spring 82 can move between the compressed position shown in Fig. 3 to the extended position shown in Fig. 4.

The end of the lever 76 has an aperture (not shown) that receives a neck portion 88 of the valve 66. The aperture is larger than the diameter of the neck 88 so that the end of the lever 76 can slide along the valve 66. The end of the lever 76 is captured by valve flanges 90 and 92. The valve 66 also has a stem 94 that slides within a slot 96 in chamber member 52, allowing the valve 66 to move between an open position and a closed position.

In operation, the valve 66 is initially in the closed position shown in Fig. 3. The spring 82 is in the extended position and exerts a force on the lever 76 to maintain the valve 66 in the closed position. The closed valve 66 allows brine water to flow into the brine chamber 58. The pressure of the brine water is greater than the pressure of the permeate water within the permeate chamber 56, so that the resultant force exerted on the diaphragm 54 by the brine water moves the piston 70 toward the outer shell 48. The movement of the diaphragm 54 reduces the volume of the permeate chamber 56 and pushes the permeate water within the chamber 56 through the outlet port 42 and into the tank 28. The one-way valve 60 prevents the permeate water from being pumped back into the membrane 22.

As the piston 70 moves toward the shell 48 and pumps the water out of the chamber 56, the arm 68 rotates and the spring 82 becomes aligned with the pin 74. As shown in Fig. 4, the spring 82 is compressed as the spring assembly 78 becomes aligned with the lever 76. The piston 70 and arm 68 continue to move until the spring assembly is no longer aligned with the pin 76, at which point the spring 82 releases to the extended position shown in Fig. 5. Movement of the spring 82 rotates the lever 76 in a clockwise direction which causes the lever 76 to slide up the neck 88 and engage the flange 92 to push the valve 66 into the open position shown. Rotation of the lever 76 induces a sliding movement of the lever end along the neck of the valve 66. The ability of the lever 76 to slide along the neck while the piston 70 is moving allows the diaphragm 54 to fully deplete the chamber 56 before the valve 66 is subsequently opened.

As shown in Fig. 6, when the valve 66 is opened, the brine water within the chamber 58 flows through port 36 and into the drain. The drain pressure is lower than the pressure of the permeate water, wherein the resultant force of the permeate water within the chamber 56 pushes the diaphragm 54 away from the shell 48. The movement of the diaphragm 54 pushes the brine water out of the brine chamber 58. The brine outlet port 36 is preferably significantly larger than the brine inlet port 38 so that the fluid resistance is greater through the inlet port 32 than the outlet port 36. In the preferred embodiment, the outlet port 36 has an area approximately 50 times greater than the area of the inlet port 32. Thus the flow restrictor 29 prevents pressure build-up in the brine chamber as the brine continues to flow. Movement of the diaphragm 54 also moves the piston 70 and rotates the arm 68 and lever 76 in a clockwise direction to compress the spring 82. As shown in Fig. 7, the piston 70 continues to move until the spring assembly 78 is no longer aligned with the lever 76, at which point the

spring 82 expands to rotate the lever 76 in a counterclockwise direction. As shown in Fig. 8, rotation of the lever 76 causes the lever end to engage the flange 90 and close the valve 66. When the valve 66 is closed, the brine water again flows into the pump 30 and increases the pressure within the chamber 58. The increase in chamber pressure pushes the diaphragm 54 toward the shell 48, wherein the process is repeated.

The spring assembly 78 provides a latching function that opens and closes the valve 66 when the diaphragm 54 reaches the intake and stroke positions within the pump. The spring 78 has a greater compression and resulting release force when the valve 66 is opened than when the valve 66 is closed, because of the relative location of the arm 68 and the lever 76 during the intake and compression strokes. Not as much force is needed to close the valve, because the counteracting water pressure is less when the valve is closed than when the valve is opened. The lower spring force created when closing the valve 66 reduces the wear on the moving components and increases the life of the pump.

The pump of the present invention provides a means of increasing the pressure of the permeate water within a reverse osmosis water purification system without requiring electricity. Additionally, the pump is relatively quiet compared to conventional electrically driven pumps of the prior art.

While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.