CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit under 35 USC §119(e) U.S. Provisional Application Ser. No. 61/889,899 filed Oct. 11, 2013, which is incorporated by reference herein in its entirety.
FIELD AND BACKGROUND OF INVENTION The present invention relates to pumps, and in particular to diaphragm type pumps. Diaphragm pumps are known in the art, for example U.S. Pat. Nos. 5,279,504 and 6,327,960 illustrate prior art diaphragm pumps. However, there is nevertheless a need for diaphragm pumps which are more economical to construct and offer improved performance characteristics.
SUMMARY OF SELECTED EMBODIMENTS OF INVENTION One embodiment of the invention is a diaphragm pump including at least three body plates and at least two diaphragm assemblies positioned between the at least three body plates. A series of drive fluid passages communicate with a drive side of the two diaphragm assemblies and a series of pumped fluid passages communicate with a pump side of the two diaphragm assemblies. There is an inlet check valve communicating with said series of pumped fluid passages and an outlet check valve communicating with said series of pumped fluid passages. In one alternative embodiment, at least one of the body plates is a doubled faced plate having either drive fluid passages on both faces or pumped fluid passages on both faces.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-section of one embodiment of the diaphragm pump, including a reservoir and a driver.
FIG. 2 is an exploded view of one embodiment of the diaphragm pump.
FIG. 3 is an exploded view showing a drive fluid face of a body plate.
FIG. 4 is an exploded view showing a chemical fluid face of a body plate.
FIG. 5 is an enlarged view of one embodiment of the diaphragm assembly.
FIG. 6 is a cross-section showing one example of a leak detection path.
FIG. 7 is a first cross-section of the FIG. 1 diaphragm pump illustrating the drive fluid passages.
FIG. 8 is a second cross-section of the FIG. 1 diaphragm pump illustrating the pumped fluid (or chemical) passages.
FIGS. 9A to 9C illustrate one embodiment of a pressure gauge assembly.
FIG. 10 is a cross-section of an alternative embodiment of the diaphragm pump.
DETAILED DESCRIPTION OF SELECTED EMBODIMENTS FIG. 1 illustrates one embodiment of the present invention, the diaphragm pump 1. In FIG. 1, the diaphragm pump is illustrated being used in combination with fluid reservoir 80 and driver or motor 100, but neither the motor, nor the reservoir need form part of the present invention. The motor 100 seen in FIG. 1 is a pneumatic, pilot valve controlled motor such as disclosed in U.S. Pat. No. 6,736,046, Pilot Control Valve Utilizing Multiple Offset Slide Valves, which is incorporated by reference herein in its entirety. Motor 100 includes the pilot valve 101 which controls pressurized air driving piston 102 in a reciprocating manner. Piston stem 103 transmits the reciprocating force to the equipment being driven by motor 100. The u-cup seal 104 prevents the loss of air pressure from around piston stem 103 to the exterior of motor 100. While the illustrated motor is a pilot controlled pneumatic motor, virtually any motor providing reciprocating motion, whether pneumatic, hydraulic, electric, or otherwise, could be employed.
The illustrated embodiment of fluid reservoir 80 is formed of a reservoir body 83 which includes a fluid space 88, a drive side 82 which makes a sealed connection with motor 100, and a pump side 81 which makes a sealed connection with diaphragm pump 1. This embodiment of reservoir body 83 further includes the vent plug 86 and drain plug 87. Vent plug 86 allows the fluid in the fluid space 88 to remain at the exterior ambient pressure (e.g., atmospheric). Extending through reservoir body 83 is plunger 90. On one end, plunger 90 is connected in a conventional manner (e.g., mating threads) to the piston stem 103 of motor 100. The quad-ring seal 93 acts to prevent movement of fluid from reservoir space 88 into motor 100's interior. The end of plunger 90 opposite piston stem 103 engages and is sized to move within the drive fluid passage 85 formed in reservoir body 83. This end of piston stem 103 includes the center passage 92 which is open to the end of plunger 90 and extends into plunger 90 at least as far as the series of radial passages 91 which extend transversely through the diameter of plunger 90. Thus, it will be understood that when radial passages 91 are outside of drive fluid passage 85 (as suggested in FIG. 1), there is a fluid path from reservoir space 88, through radial passages 91, center passage 92, and into drive fluid passage 85. In preferred embodiments, the drive fluid is an oil such as a conventional hydraulic fluid or a mineral oil.
The embodiment of diaphragm pump 1 seen in FIG. 1 generally comprises a series of body plates 5 with diaphragm assemblies 50 positioned between the body plates. FIGS. 2 and 7 better illustrate how this embodiment includes four body plates 5A to 5D. As best seen in FIG. 2, a series of bolts 38 pass through apertures 39 in body plate 5A to 5C, engage threaded apertures in body plate 5D, and secure the body plates together. The body plates 5 may be constructed of any material suitable to the pressure and corrosive conditions of anticipated use. In one non-limiting embodiment, certain body plates exposed to corrosive fluids are constructed of a corrosion resistant material (e.g., 316 stainless steel) while other body plates exposed only to drive fluid may be constructed of a stronger and/or less expensive material (e.g., 4140 steel). The body plates 5 will typically have a series of internal passages (described in detail below) allowing fluid to move between the perimeter area 6 of the body plate to at least one face 7 of the body plate. As is common with most diaphragm pumps, a first fluid or a “drive” fluid will act on one side of the diaphragm(s) to cause displacement of the diaphragm. In FIG. 1, the drive fluid originates in reservoir 80 and is placed under pressure by plunger 90. A second fluid or a “pumped” fluid is moved through the pump by displacement of the diaphragm. The pumped fluid is the fluid being employed in the chemical, industrial, or other process utilizing the pump. When referring to a side of a diaphragm or a face of a body plate exposed to drive fluid, this may be described as the “drive fluid side” of the diaphragm or body plate. Likewise, the side of a diaphragm or a face of a body plate exposed to pumped fluid, may be sometimes described as the “pumped fluid side” of the diaphragm or body plate. As the pumped fluid is typically a chemical composition, the pumped fluid side is more often simply referred to as the “chemical side” of the diaphragm or body plate face.
FIG. 10 illustrates a slight modification to the embodiment seen in FIG. 1. In FIG. 10, the plunger 90 is solid, i.e., does not have the center passage 92 or the radial passages 91 formed in the plunger. Rather, the radial passage 91 in FIG. 10 is placed through the section of the reservoir wall forming drive fluid passage 85. Additionally, the FIG. 10 embodiment illustrates the addition of a replaceable bushing 105 between plunger 90 and the interior wall of drive fluid passage 85. In one example, replaceable bushing 105 is formed of a material such as steel or a ceramic.
FIG. 7 is a cross-section illustrating a series of internal passages in the body plates 5 on the drive fluid side 9 of the body plates. Depending on their position, different body plates may have different sets of passages. For example, body plate 5B is seen having a co-planar passages 12 (i.e., passages generally in the plane of the plate) on each face and traverse passages 13 passing though the plate generally perpendicular to the co-planar passages. On the other hand, body plate 5D has the main drive fluid inlet 34 (which joins with the drive fluid passage 85 of reservoir 80 as seen in FIG. 1), a short transverse passage 13, and a co-planar passage 12 for further distributing drive fluid to other body plates. The embodiment of FIG. 7 further illustrates how the tubular connector bushing 22 forms part of a transverse passage 13 traversing body plate 5C. Connector bushing 22 includes o-rings 23 and backup rings on each end which seal with body plates 5B and 5D. Although connector bushing 22 is one example of an efficient manner to establish a fluid path through body plate 5C, there are of course other conventional techniques for creating such a sealed fluid path.
The path of drive fluid into diaphragm pump 1 is apparent in FIG. 7. Fluid enters inlet 34 of body plate 5D where it is directed to diaphragm assembly 50 via the short transverse passage 13. Drive fluid is also directed via co-planar passage 12 in body plate 5D, through hydraulic bushing 22, into co-planar passage 12 and transverse passages 13 in body plate 5B, where the fluid ultimately acts against the two diaphragm assemblies 50 facing body plate 5B. It can be seen in FIG. 7 and FIG. 2 how a series co-planar passages 12 are formed on the faces of body plate 5B adjacent to diaphragm assemblies 50 in order to distribute drive fluid against the drive side of the diaphragm assemblies 50. It will be understood that these are the terminal end of the drive fluid passage and sometimes are themselves referred to as drive fluid passages. Likewise, the entire path from inlet 34 to passages 12 on the face of the body plates may be considered the drive fluid passage. It can be seen how in the illustrated embodiment, co-planar passages 12 (including passages on the faces of the body plates) and transverse passages 13 form a means for distributing drive fluid against the diaphragm assemblies. As suggested above and illustrated in the FIG. 7 embodiment, body plate 5B has both faces configured to distribute drive fluid against the diaphragm assemblies, whereas body plate 5D (the body plate closest to plunger 90) only has one face configured to distribute drive fluid against the diaphragm assemblies. Nevertheless, the figures illustrate merely one preferred embodiment and not all embodiments need have double faced body plates, single faced body plates, or a combination of the two.
The embodiment of diaphragm assemblies 50 seen in the figures is perhaps best understood with references to FIGS. 4 and 5. In this embodiment, the diaphragm assembly includes three separate diaphragm “layers” (i.e., separate individual diaphragms), chemical side diaphragm layer 51, center diaphragm layer 52, and drive side diaphragm layer 53. Additionally, the strainer plate 54 is positioned against the drive side diaphragm layer 53. The strainer plate serves at least two primary functions. First, it tends to more evenly distribute the pumped fluid. Second, it provides a more robust surface for sealing against the o-ring 57 (see FIG. 7) on the pumped fluid face 8 of the body plates. In one preferred embodiment, strainer plate 54 has a flat side abutting against the body plate and a slight concave curvature abutting the diaphragm layers. FIG. 4 suggests how strainer plate 54 includes a series of apertures 55. FIG. 3 shows the opposite face of strainer plate 54 seen in FIG. 4. FIG. 3 illustrates a web of grooves 56 which communicate with apertures 55 and act to distribute drive fluid across the face of strainer plate 54 which rests against diaphragm layer 53. FIG. 3 also illustrates a series of annular sealing grooves 58 formed near the perimeter of strainer plate 54. These sealing grooves 58 are best seen in the detail of FIG. 6. This detail shows sealing grooves 58 on strainer plate 54 engaging diaphragm layer 53 and similar sealing grooves 58 on the face of body plate 5C engaging diaphragm layer 51. It can be understood how these grooves 58 form a seal with the diaphragm layers when opposing body plates are compressed together by bolts 38 (FIG. 2).
In one preferred embodiment, each diaphragm layer is an approximately 10 mil thick sheet of 316 stainless steel. However, the diaphragms could be made of any number of suitable materials, including as nonlimiting examples, steel or an elastomer material. Diaphragm assembly 50 could alternatively be formed of one, two, or more than three diaphragm layers. One example of strainer plate 54 is a 125 mil sheet of stainless steel with the above described apertures and grooves formed therein.
FIG. 7 also illustrates a series of bleed passages 19 which have both a co-planar component and a transverse component within the body plates 5. One end of the bleed passages are in fluid communication with either the drive fluid side of the diaphragm assembly or the chemical side of the diaphragm assembly, while the other end of the bleed passages terminate with bleed screws 75. The bleed passages provide paths for air to be forced out of the pump when priming the pump (i.e., filling it with fluid) prior to commencing operation. One preferred embodiment of bleed screws 75 include the bleed poppet 76 and biasing spring 77. The bleed poppet 76 and spring 77 function to provide slight resistance when air is being removed. When a bleed screw 75 is loosened, poppet 76 may move against spring 77 to open the bleed passage. When the bleed screw 75 is tightened, poppet 76 is held in the closed position. As suggested above, the bleed passages are in communication with both the drive fluid side of the diaphragm assemblies 50 and the chemical side of the diaphragm assemblies 50 in order to allow air removal on both sides of the diaphragm assemblies.
FIG. 8 is another cross-section of diaphragm pump 1 which illustrates the internal passages associated with the chemical side of the diaphragm assemblies 50. The chemical or pumped fluid enters the diaphragm pump 1 via a one-way valve which is in this embodiment, check valve 41. Check valve 41 is an “intake” or “inlet” valve in the sense that fluid can flow into pump 1 through this valve, but is blocked from flowing out of pump 1 through this valve. As suggested in the detail of FIG. 8, this embodiment of check valve 41 is a poppet type check valve generally including the poppet and spring configuration of FIG. 9C. Of course, many other conventional or future developed one-way valves could be employed in the alternative. Fluid entering check valve 41 will be directed through the chemical co-planar passages 16 (via connector bushing 22 in the case of the co-planar passage in body plate 5C). The body plates 5A and 5C further have a series of distribution passages 18 communicating between the co-planar passages 16 and the chemical faces 30 of the body plates. As is visible on close inspection of FIG. 8, chemical faces 30 have a slight concave or inward (toward distribution passages 18) curvature. For example, in the embodiment of diaphragm pump 1 where the diaphragm assemblies 50 have a diameter of approximately four inches, the radius of curvature of the chemical face may be about 32 inches (i.e., a 32 inch radius of curvature). Obviously, this is merely one example radius of curvature and this may vary greatly based on different facts, including the diameter of the diaphragm assembly 50 (e.g., larger diaphragm assembly diameters will generally correspond with a greater radius of curvature). It can also be seen in FIG. 8 that the co-planar passages 16 communicate with a discharge one-way valve, again the check valve 40 in this embodiment. As with the drive fluid passages, connector bushings 22 form a chemical fluid passage through body plate 5B. Thus, the chemical fluid passage traverses through body plate 5B which has drive fluid faces. Check valve 40 is similar in construction to the poppet type check valve 41 described above and is a “discharge” valve in that it allows flow only in a direction out of pump 1. The check valves form a means for allowing one-way fluid communication. In the illustrated embodiment, the diaphragm pump has a single inlet check valve 41 in body plate 5A and a single outlet check valve 40 in a different body plate 5C. However, other embodiments could have multiple inlet/outlet check valves in the same or different body plates. The path from the inlet check valve, to the chemical side of the diaphragm assemblies, and to the outlet check valve, may be considered as the pumped fluid (or chemical fluid) passage.
Another aspect of the illustrated embodiment is a diaphragm leak detection technique best understood viewing FIGS. 4 and 6. FIG. 4 suggests how diaphragm layers 52 and 51 have a leak detection aperture 62 as does body plate 5C. Thus, if diaphragm 51 ruptured or otherwise leaked fluid, a fluid path exists between diaphragm layer 51 and 52, through their apertures 62, and ultimately to the leak aperture 62 in body plate 5C. This leak detection path is better seen in the cross-section of FIG. 6. The detail insert illustrates how fluid may travel between diaphragm layers 51 and 52 and ultimately into leak detection passage 67 in body plate 5C. As the leaked fluid fills passage 67, the increasing pressure will be registered by pressure gauge 65, thus notifying operators of a leak issue. Additionally, FIG. 4 shows the alignment pin 64 engaging the diaphragm assemblies 50 and body plates 5 through the alignment apertures 63. The alignment pins 64 ensure that the leak detection apertures through the diaphragm layers and into the leak detection passages of the body plates are all properly aligned.
One embodiment of pressure gauge 65 is seen in more detail in FIGS. 9A to 9C. This pressure gauge 65 will include gauge stem 69 which houses poppet 70 biased in the closed position by spring 77. When pressure on poppet 70 is sufficient to overcome the force of spring 77, poppet 70 will be lifted and o-ring 72 moved out of the sealing position. Fluid may flow through poppet apertures 71 and the gauge stem 69 to act on the pressure sensing elements of the gauge. A bleed screw 75 and ball 78 also engage valve stem 69. It can be seen how tightening of bleed screw 75 causes ball 78 to block the passage through bleed screw 75 and how loosening of bleed screw 75 would allow space for fluid to flow around ball 78 and out of the bleed screw.
The operation of the pump will be described by starting with FIG. 1. As suggested above, driver 100 will move plunger 90 in a reciprocating path within drive fluid passage 85. On the suction stroke, plunger 90 will be withdrawn from fluid passage 85 to the extent needed to expose radial passages 91 to reservoir space 88. This action simultaneously produces a slight vacuum in fluid passage 85 such that fluid in reservoir space 88 is drawn into radial passages 91, through center passage 92, and into drive fluid passage 85. On the power stroke, plunger 90 moves toward diaphragm pump 1 and the radial passages 91 enter the confines of fluid passage 85. Because of the close tolerance between the outer diameter of plunger 90 and the inner diameter of fluid passage 85, the drive fluid in passage 85 is pressurized as plunger 90 moves toward pump 1. The magnitude of the pressure imparted to the diaphragm assemblies is regulated by controlling the distance plunger 90 extends into fluid passage 85. For example, in the embodiment of FIG. 1, the end of plunger 90 threading into piston stem 103 allows rotation of plunger 90 to shorten or lengthen plunger 90 relative to piston stem 103, and thus plunger 90's travel into fluid passage 85.
Viewing FIG. 7, the pressurized drive fluid is transmitted through co-planar passages 12 and transverse passages 13 to ultimately impart force against the drive fluid side of diaphragm assemblies 50. Viewing FIG. 8, the diaphragms 51 to 53 will flex toward the curvature 30 in the chemical face of the body plates. This pressurizes the fluid on the chemical side of pump 1 and will cause the discharge of a given volume of fluid from discharge check valve 40. On the suction stroke of plunger 90 (FIG. 1), a lower pressure condition tends to be formed on the drive fluid side of pump 1 and the diaphragms 50 are pulled away from the chemical face of the body plates. This action lowers the pressure on the chemical side of pump 1 and will draw in a given volume of fluid through intake check valve 41. The pump phase will then be repeated as plunger 90 transitions back to a power stroke.
In the illustrated embodiments, the diameter of all the body plates is equal or approximately equal, as is the diameter of all the diaphragm assemblies. However, this feature is not required for all embodiments. The diameters of the body plates or diaphragm assemblies are considered approximately equal if they are within, alternatively 5%, 10%, or 20% of one another. PCT Serial No. PCT/US14/60077, filed Oct. 10, 2014 and entitled, “Scalable Pumping Mechanism Utilizing Anti-Synchronized Poly-Diaphragm Stack,” is incorporated by reference herein in its entirety.
