Abstract:
An air-driven dual diaphragm pump comprises a pump body with a first air passage leading to a first air cavity with a first diaphragm, a second air passage leading to a second air cavity with a second diaphragm, and a reciprocating shaft which connects the first and second diaphragms. A diaphragm installation tool for the dual diaphragm pump comprises a plate which fits atop the pump body. A groove in a surface of the plate opposite from and nonadjacent to the pump body extends from the location of the first air passage to the location of the second air passage. A hole located within the groove at the location of either the first air passage or the second air passage extends through the plate. Pressurized air entering the pump body is redirected by the groove and the hole to always enter the first air passage, rather than the second, thereby slowly filling the first air cavity and positioning the second diaphragm for installation.

Description:
BACKGROUND 
       [0001]    The present invention relates generally to diaphragm pumps, and more particularly to tools and methods for installing diaphragms for diaphragm pumps 
         [0002]    Diaphragm pumps are commonly used to pump fluids such as oil, grease, and water. Diaphragm pumps comprise at least one pumping chamber with a wall comprising a deformable diaphragm, a fluid inlet, and a fluid outlet. The diaphragm is driven to cyclically expand and contract the pumping chamber, while the fluid inlet and outlet are controlled by inlet and outlet check valves, respectively. Expansion of the pumping chamber creates a partial vacuum which draws fluid into the pumping chamber through the inlet, while the outlet check valve prevents fluid from being drawn into the pumping chamber against the pumping direction of the diaphragm pump. Contraction of the pumping chamber expels fluid from the pumping chamber through the outlet, while the inlet check valve prevents fluid from exiting the pumping chamber via the inlet. Diaphragms are conventionally clamped in position between adjacent sections of the diaphragm pump. 
         [0003]    Dual diaphragm pumps comprise two connected diaphragms on opposite cycles. Each diaphragm forms a wall of a separate pumping chamber, such that a first pumping chamber fills while a second pumps, and vice versa. Air-driven dual-diaphragm pumps move both diaphragms with pressurized air which is alternatingly pumped and exhausted from air cavities behind each diaphragm. 
         [0004]    Diaphragm installation for diaphragm pumps conventionally involves forcing diaphragms into installation positions such that they are under considerable strain, then clamping them into place on the diaphragm pump in a seal. Pump diaphragms are commonly constructed of rubber, Teflon, neoprene, plastic, and similar materials, and can require large forces to deform. Consequently, installation frequently requires specialized equipment capable of exerting large forces to position a diaphragm for installation. This installation process can cause damage to the diaphragm, and the necessary specialized equipment may include expensive, cumbersome clamps and vices. In addition, the large forces conventionally required to position pump diaphragms can pose safety risks. 
       SUMMARY 
       [0005]    The present invention is directed towards a diaphragm installation tool for an air-driven dual diaphragm pump. The air-driven dual diaphragm pump comprises a pump body with a first air passage leading to a first air cavity with a first diaphragm, a second air passage leading to a second air cavity with a second diaphragm, and a reciprocating shaft that connects the first and second diaphragms. The diaphragm installation tool comprises a plate that fits atop the pump body. A groove in a surface of the plate opposite from and nonadjacent to the pump body extends from the location of the first air passage to the location of the second air passage. A hole located within the groove at the location of either the first air passage or the second air passage extends through the plate. Pressurized air entering the pump body is redirected by the groove and the hole to always enter the first air passage, rather than the second, thereby slowly filling the first air cavity and positioning the second diaphragm for installation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIGS. 1   a  and  1   b  are simplified cross-sectional views of a diaphragm pump at two times during a pumping cycle. 
           [0007]      FIG. 2  is a partially exploded cross-sectional view of the diaphragm pump of  FIG. 1 , showing a diaphragm installation tool used to install a diaphragm. 
           [0008]      FIG. 3  is an overhead view of the diaphragm installation tool of  FIG. 2 . 
           [0009]      FIG. 4  is a cross-sectional view of the diaphragm installation tool of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]      FIGS. 1   a  and  1   b  depict diaphragm pump  10 , comprising main valve  12 , pump body  14  (with air passages  16   a  and  16   b ), air cavities  18   a  and  18   b,  diaphragms  20   a  and  20   b,  shaft  22 , air covers  24   a  and  24   b,  and pumping structures  26   a  and  26   b,  which include fluid covers  28   a  and  28   b,  fasteners  30 , fluid cavities  32   a  and  32   b,  check valves  34   a - 34   d,  and fluid passages  36   a - 36   d.    FIG. 1   a  depicts a transitory position of diaphragm pump  10  wherein fluid cavity  32   a  has been filled with fluid, and fluid is beginning to be pumped from fluid cavity  32   a  into fluid passage  36   c,  and drawn from fluid passage  36   b  into fluid cavity  32   b.    FIG. 1   b  depicts a transitory position of diaphragm pump  10  wherein fluid cavity  32   b  has been filled with fluid, and fluid is beginning to be pumped from fluid cavity  32   b  into fluid passage  36   d,  and drawn from fluid passage  36   a  into fluid cavity  32   a.    
         [0011]    Diaphragm pump  10  is an air-driven dual diaphragm pump for a fluid such as oil or grease. Air is pumped into diaphragm pump  10  from an external pump (not shown) via main valve  12 . Main valve  12  is an air valve which switches between two phases illustrated in  FIGS. 1   a  and  1   b.  Diaphragm pump  10  operates in half-cycle phases. In the first phase ( FIG. 1   a ), main valve  12  directs pressurized air into air passage  16   a,  and exhausts air from fluid passage  16   b.  In the second phase ( FIG. 1   b ), main valve  12  directs pressurized air into air passage  16   b,  and exhausts air from fluid passage  16   a.  Air passages  16   a  and  16   b  are hollow channels through pump body  14 , which is a rigid structure formed, for instance, from cast metal or hard plastic. Shaft  22  extends through a bore in pump body  14 , and slides between two positions illustrated in  FIGS. 1   a  and  1   b.  Shaft  22  is anchored to diaphragms  20   a  and  20   b,  which are made of a deformable material such as rubber, Teflon, neoprene, or plastic. Diaphragms  20   a  and  20   b  form air cavities  18   a  and  18   b,  respectively, with pump body  14 . Air cavities  18   a  and  18   b  are spaces of variable size between diaphragms  20   a  and  20   b,  respectively, and pump body  14 . Air cavities  18   a  and  18   b  expand and contract as air is pumped and exhausted via air passages  16   a  and  16   b.    
         [0012]    Diaphragms  20   a  and  20   b  are clamped in place between air covers  24   a  and  24   b  of pump body  14 , and fluid covers  28   a  and  28   b  of pumping structures  26   a  and  26   b,  as shown. Fasteners  30  affix air covers  24   a  and  24   b  to fluid covers  28   a  and  28   b,  anchoring diaphragms  20   a  and  20   b.  Air covers  24   a  and  24   b  and fluid covers  28   a  and  28   b  are portions of pump body  14  and pumping structures  26   a  and  26   b,  respectively, which abut each other and form a seal with diaphragms  20   a  and  20   b.  Pumping structures  26   a  and  26   b  enclose fluid cavities  32   a  and  32   b,  which are spaces of variable size with one wall comprised of diaphragm  20   a  or diaphragm  20   b,  respectively. Pumping structures  26   a  and  26   b  need not be formed as single units, and may comprise multiple separate parts. As diaphragms  20   a  and  20   b  shift between the two states depicted in  FIGS. 1   a  and  1   b,  fluid cavities  32   a  and  32   b  expand and contract. Fluid enters cavities  32   a  and  32   b  through check valves  34   a  and  34   b  from fluid passages  36   a  and  36   b,  respectively. Fluid exits fluid cavities  32   a  and  32   b  through check valves  34   c  and  34   d,  into fluid passages  36   c  and  36   d,  respectively. Check valves  34   a - 34   d  prevent fluid backflow opposite the pumping direction of diaphragm pump  10 , and may take any conventional form, such as diaphragm check valves, swing check valves, and ball check valves. Fluid passages  36   a - 36   d  are hollow passages or tubes through pumping structures  26   a  and  26   b  which carry a pumped fluid such as oil or grease to and from fluid cavities  32   a  and  32   b.    
         [0013]    Diaphragm pump  10  pumps fluid from fluid passages  36   a  and  36   b  through fluid cavities  32   a  and  32   b  by expanding and contracting fluid cavities  32   a  and  32   b  through deformation of diaphragms  20   a  and  20   b.  Fluid passages  36   a  and  36   b  may carry identical fluids from a shared source, or may carry fluids—potentially different fluids—from different sources. These fluids are pumped as indicated by arrows in  FIGS. 1   a  and  1   b.  Diaphragm pump  10  operates in phases determined by states of main valve  12 , as described above. When diaphragm pump  10  operates in the first phase ( FIG. 1   a ), pressurized air passes through air passage  16   a  to fill air cavity  18   a,  exerting pressure on diaphragm  20   a  which forces it to the left, contracting fluid cavity  32   a.  This contraction expels fluid from fluid cavity  32   a  into fluid passage  36   c  via check valve  34   c.  Check valve  34   a  prevents fluid from exiting fluid cavity  32   a  through fluid passage  36   a.  Diaphragm  20   a  is attached via shaft  22  to diaphragm  20   b.  As air cavity  18   a  fills and pushes diaphragm  20   a  leftward, shaft  22  draws diaphragm  20   b  leftward as well. Air is exhausted from air cavity  18   b  via air passage  16   b  as air cavity  18   b  contracts. The deformation of diaphragm  20   b  expands fluid cavity  32   b,  drawing fluid from fluid cavity  38   b  via check valve  34   b.  Check valve  34   d  prevents fluid from entering fluid cavity  32   b  through fluid passage  36   d.    
         [0014]    In the second phase of diaphragm pump  10  (see  FIG. 1   b ), main valve  12  switches the direction of airflow through air passages  16   a  and  16   b,  pumping air into air cavity  18   b  and exhausting air from air cavity  18   a.  Diaphragms  20   a  and  20   b  are accordingly forced rightward, filling fluid cavity  32   a  from fluid passage  36   a,  and pumping fluid from fluid cavity  32   b  out into fluid passage  36   d.  Diaphragm pump  10  switches between the first and the second phase when a pilot switch (not shown) switches the state of main valve  12  from the first phase ( FIG. 1   a ) to the second ( FIG. 1   b ), or vice versa. This pilot switch may be any conventional mechanical, pneumatic, or electrical switch which causes main valve  12  to switch states in response to a change in position of diaphragm  20   a,  diaphragm  20   b,  or shaft  22 . In some embodiments, the pilot switch comprises two pneumatic or mechanical pilot valves which toggle the state of main valve  12  in response to diaphragm  20   a,  diaphragm  20   b,  or shaft  22  reaching a maximum extension. 
         [0015]    Diaphragm pump  10  can accept a wide variety of diaphragms  20   a  and  20   b  which may vary in dimension and flexibility. Diaphragms  20   a  and  20   b  may, for instance, vary slightly in undeformed radius, and can be constructed of pliable materials, or of rigid materials requiring large forces to deform. Diaphragms  20   a  and  20   b  can be installed by hand if diaphragms  20   a  and  20   b  either fall naturally into installation positions between air covers  24   a  and  24   b  and fluid cover  28   a  and  28   b,  or are easily deformed into position. In other cases, diaphragms  20   a  and  20   b  may require considerable force to deform into installation positions, as described below with respect to  FIG. 2 . A diaphragm installation tool capable of positioning a diaphragm for installation in these more difficult cases is provided below. 
         [0016]      FIG. 2  is a simplified cross-sectional view of diaphragm installation on diaphragm pump  10  using diaphragm installation tool  48 . Diaphragm pump  10  comprises main valve  12 , pump body  14  (with air passages  16   a  and  16   b ), air cavities  18   a  and  18   b,  diaphragms  20   a  and  20   b,  shaft  22 , air covers  24   a  and  24   b,  pumping structures  26   a  and  26   b,  fluid covers  28   a  and  28   b,  fasteners  30 , fluid cavities  32   a  and  32   b,  check valves  34   a - 34   d,  and fluid passages  36   a - 36   d,  as described with respect to  FIGS. 1   a  and  1   b.  Fluid cover  28   a  includes fastener socket  38  and fluid cover groove  42 , air cover  24   a  includes fastener hole  40  and air cover groove  44 , and diaphragm  20   a  includes bead  46 . 
         [0017]      FIG. 2  depicts the same diaphragm pump  10  described above with respect to  FIGS. 1   a  and  1   b.  In  FIG. 2 , pumping structure  26   a  is shown detached from pump body  24   a  for the installation of diaphragm  20   a.  Diaphragm  20   a  includes bead  46 , a radially outer retaining bulge spanning at least a portion of the outer circumference of diaphragm  20   b.  In one embodiment, bead  46  forms an annular rim extending across the entirety of the outer circumference of diaphragm  20   b.  In other embodiments, bead  46  comprises a plurality of bulges distributed across the outer circumference of diaphragm  20   b.  Diaphragm  20   b  has a similar annular bead or rim. 
         [0018]    Diaphragms for dual-diaphragm pumps are often installed and replaced in pairs. A first diaphragm can ordinarily be installed without any specialized tools, so long as the opposite diaphragm is not yet installed.  FIG. 2  depicts a diaphragm  20   b  already installed, and diaphragm  20   b  in the process of installation. Diaphragm  20   b  may, for instance, be installed by attaching diaphragm  20   b  to shaft  22 , and removing pumping structures  26   a  and  26   b.  Shaft  22  can then be slided back and forth through pump body  14  to adjust the position of diaphragm  20   b  relative to air cover  24   b  and fluid cover  28   b,  and in particular the position of bead  46  relative to fluid cover groove  42  and air cover groove  44 . When bead  46  is aligned with both grooves, pumping structure  26   b  is brought into place, and air cover  24   b  is secured to fluid cover  28   b  with fastener  30  to clamp diaphragm  20   b  in place in a seal. 
         [0019]    As mentioned previously, installing a second diaphragm can be more complicated. Once diaphragm  20   b  is installed, in some cases diaphragms  20   a  will align naturally for installation, such that bead  46  falls into place between fluid cover groove  42  of fluid cover  28   a  and air cover groove  44  of air cover  24   a.  In these cases, diaphragm  20   a  can be installed without using diaphragm installation tool  48 . Often, however, diaphragm  20   a  will not align immediately for installation. Bead  46  of diaphragm  20   a  may, for instance, be located at a radius greater than the distance from shaft  22  to fluid cover groove  42  and air cover groove  44 , such that diaphragm  20   a  must be deformed into a concave or convex shape to align diaphragm  20   a  for installation. In other cases, diaphragm  20   a  may be positioned too far from air cover  24   a  when diaphragm  20   b  not under strain, necessitating that diaphragm  20   b  be deformed to bring diaphragm  20   a  into an installation position. 
         [0020]    As depicted in  FIG. 2 , diaphragm  20   a  must be drawn or deformed into position so that bead  46  aligns with air cover groove  44 . Air cover groove  44  is a groove or plurality of grooves in air cover  24   a  which provides a recess for bead  46  of diaphragm  20   a.  Fluid cover  28   a  similarly features fluid cover groove  42 , which serves the same purpose on the opposite side of diaphragm  20   a.  Once bead  46  of diaphragm  20   a  is aligned with air cover groove  44 , fluid cover  28   a  and air cover  24   a  are clamped together such that bead  46  is retained in the space formed by fluid cover groove  42  and air cover groove  44 , thereby securing diaphragm  20   a  in the position depicted in  FIGS. 1   a  and  1   b.  Fasteners  30  are inserted through fastener holes  40  into fastener sockets  38  to anchor air cover  24   a  to fluid cover  28   a.  Fasteners  30  may, for instance, be bolts or screws which thread into threaded fastener sockets  38 . 
         [0021]    Diaphragm  20   a  is positioned relative to air cover  24   a  and fluid cover  28   a  using diaphragm installation tool  48 . Diaphragm installation tool  48  is a plate which forms an airtight seal between main valve  12  and pump body  14 , and which biases the direction of airflow from main valve  12 , as described below with respect to  FIGS. 3 and 4 . As depicted, diaphragm installation tool  48  is inserted for diaphragm installation by removing main valve  12 , positioning diaphragm installation tool  48  in a desired orientation, and then reattaching main valve  12  such that diaphragm installation tool  48  is clamped between main valve  12  and pump body  14 . In other embodiments, diaphragm installation tool  48  may take any form which biases and restricts the flow of air into pump body  14 , such as a replacement for main valve  12 , or a removable cartridge insertable into the body of main valve  12  without detaching main valve  12  from pump body  14 . 
         [0022]    Diaphragm installation tool  48  overrides the directionality of airflow into pump body  14 , directing air into air passage  16   b  and preventing any air from entering air passage  16   a.  Diaphragm installation tool  48  also restricts the flow rate of air into air cavity  18   b,  so that air cavity  18   b  fills slowly. As pressurized air fills air cavity  18   b,  diaphragm  20   b  is slowly forced to the right, drawing shaft  22  and diaphragm  20   a  to the right as well. Because diaphragm installation tool  48  diverts air into air passage  16   b  and air cavity  18   b  at much less than the full pumping airflow rate of diaphragm pump  10 , a technician using installation tool  48  can precisely position diaphragm  20   b  (and therefore shaft  22  and diaphragm  20   a ) for installation of diaphragm  20   a.  As depicted, diaphragm  20   b  moves slowly rightward so long as pressurized air is provided to diaphragm pump  10  through installation tool  48 , drawing shaft  22  and diaphragm  20   a  to the right as well. By shutting off the supply of pressurized air to diaphragm pump  10  when diaphragm  20   a  comes into position for installation (i.e. when bead  46  is aligned with fluid cover groove  42  and air cover groove  44 ), a technician can set up diaphragm  20   a  to be clamped between fluid cover  28   a  and air cover  24   a.  In one embodiment, diaphragm installation tool  48  is reversible: to install diaphragm  20   b,  diaphragm installation tool  48  can be inserted in an opposite direction to bias airflow towards air passage  16   a,  instead of air passage  16   b.    
         [0023]    In the depicted embodiment, diaphragm  20   a  is installed by inserting diaphragm installation tool  48  between main valve  12  and pump body  14 , supplying main valve  12  with pressurized air until diaphragm  20   a  is in a correct installation position, and then clamping diaphragm  20   a  between air cover  24   a  and fluid cover  28   a,  and fastening air cover  24   a  to fluid cover  28   a  with fasteners  30 . Installation tool  48  is then removed. More generally, diaphragm installation tool  48  may be any removable tool which restricts the flow of air, and biases that airflow towards only one of air cavity  18   a  or air cavity  18   b.  Diaphragm installation tool  48  is a simple, inexpensive component which allows diaphragm  20   a  to be aligned for installation using only the ordinary motion of shaft  22  and diaphragms  20   a  and  20   b.  This reduces the possibility of damage to diaphragm  20   a,  as well as safety risks associated with applying large, nonstandard forces on diaphragm  20   a  with vices or clamps. 
         [0024]      FIG. 3  is an overhead view of one embodiment of diaphragm installation tool  48 , comprising plate  100  with groove  102 , hole  104 , alignment points  106 , and tabs  108 . Plate  100  is formed of a deformable material such as rubber or soft plastic to form a compressive seal between main valve  12  and pump body  14 . Plate  100  is substantially flat, but can include raised or recessed alignment points  106  which help to orient diaphragm installation tool  48  relative to main valve  12 , pump body  14 , or both. Alignment points  106  fit with corresponding protrusions or depressions in main valve  12 , pump body  14 , or both. Groove  102  is an elongated trench in the top surface of plate  100 , and extends, when diaphragm installation tool  48  is in use, from the opening of air passage  16   a  to the opening of air passage  16   b,  as shown in  FIG. 2 . Hole  104  is a small-diameter passage through plate  100 , located at one end of groove  102 . Tabs  108  are tabs or flaps which extend from plate  100 , and which are not covered by main valve  12  when diaphragm installation tool  48  is in position, as shown in  FIG. 2 . As depicted, tabs  108  are marked with arrows indicating the direction in which diaphragm installation tool  48  biases airflow. 
         [0025]    Groove  102  directs air to hole  104 , such that only air passage  16   b  receives pressurized air from main valve  12  while diaphragm  20   a  is being installed (see  FIG. 2 ). Diaphragm installation tool  48  can be reversed to provide air only to air passage  16   a,  for the installation of diaphragm  20   b.  Diaphragm installation tool  48  biases airflow, such that air always enters pump body  14  via the selected air passage, regardless of the state of valve  12 . The small diameter of hole  104  admits only a limited flow rate of air into air cavity  18   b,  allowing the position of diaphragms  20   a  to be carefully controlled by halting the supply of pressurized air to diaphragm installation tool  48  when diaphragm  20   a  is properly aligned, as described above with respect to  FIG. 2 .  FIG. 3  also shows sectional line  4 - 4 , which passes through groove  102 . 
         [0026]      FIG. 4  is a cross-sectional view of diaphragm installation tool  48  through section line  4 - 4 .  FIG. 4  depicts plate  100 , groove  102 , and hole  104 , as described with respect to  FIG. 3 . Groove  102  extends partway through plate  100 , and provides a path for air to travel from either outlet of main valve  12 , through hole  104 , into air passage  16   b.    
         [0027]    Diaphragm installation tool  48  provides a simple, inexpensive solution to the problem of diaphragm installation. Diaphragm installation tool  48  redirects a fine stream of pressurized air into air cavity  16   b,  slowly filling cavity  16   b  and forcing diaphragm  20   b  rightward. This movement pulls shaft  22  and diaphragm  20   a  rightward as well, drawing diaphragm  20   a  into an installation position without applying harmful forces directly to diaphragm  20   a.  Diaphragm installation tool  48  uses the ordinary operational motion of diaphragms  20   a  and  20   b  and shaft  22  to align diaphragm  20   a  for installation, minimizing safety risks and avoiding damage to diaphragm  20   a.    
         [0028]    While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.