Abstract:
A diaphragm pump for a pumped shower waste, comprises a diaphragm housing ( 12 ), a diaphragm ( 34 ) removably held in the diaphragm housing ( 12 ), an openable cover ( 16 ) on the diaphragm housing ( 12 ) for accessing the diaphragm ( 34 ), an electric motor ( 14 ), a connecting member ( 40 ) positioned in the diaphragm housing ( 12 ) and movable by the electric motor ( 14 ), and a non-screw-threaded twist and lock fastener ( 62 ) which releasably engages the diaphragm ( 34 ) with the connecting member ( 40 ). The diaphragm ( 34 ) can thus be disengaged and removed from the connecting member ( 40 ) without the use of a screwdriver.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a diaphragm pump, particularly but not exclusively for use with a pumped shower waste. 
     BACKGROUND OF THE INVENTION 
     Diaphragm pumps per se are well known. However, the diaphragm is relatively weak and requires replacing once it reaches the end of its operational life. The diaphragm is typically held to a connecting rod, driven by an electric motor, by a machine screw and large diameter washer. To replace the diaphragm, a diaphragm housing in which the diaphragm is held is first opened, and then the screw is removed by typically, a screwdriver providing the screw has a suitable recess in its head. The diaphragm can then be removed from the housing, and replaced. The screw with washer is reinserted through the connecting rod into a nut located on the inner surface to reengage and retain the diaphragm with the connecting rod. 
     However, a significant problem is encountered by installers and maintenance workers in that the diaphragm pump itself is often located in awkward, hard to reach places, such as under flooring, between joists, and in corners. This makes it complicated to insert and correctly orientate tools, and it is also often difficult to find a suitable purchase to enable release of the screw and washer. 
     Moreover, once released, it is difficult to extract the screw and washer without them being fumbled and lost in the space around the pump, or to reliably retain the backing nut in position. 
     Re-engagement of the screw, after replacement of the diaphragm, can be equally as difficult. 
     The present invention seeks to provide a solution to this problem. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a diaphragm pump for a pumped shower waste, the pump comprising a diaphragm housing, a diaphragm removably held in the diaphragm housing, an openable cover on the diaphragm housing for accessing the diaphragm, an electric motor, a connecting member positioned in the diaphragm housing and movable by the electric motor, and a non-screw-threaded twist and lock fastener which releasably engages the diaphragm with the connecting member, so that, when removal is required, the diaphragm can be disengaged from the connecting member without the use of a screwdriver. 
     Preferable and/or optional features of the present invention are set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is an elevational side view of one embodiment of a diaphragm pump, in accordance with the present invention; 
         FIG. 2  is a scrap view from above, in cross-section, of a cover engaged with a housing of the pump and a diaphragm located within the housing; 
         FIG. 3  is a perspective view of the pump shown in  FIG. 1 , with the cover removed and showing the diaphragm; 
         FIG. 4  is an exploded perspective view, similar to  FIG. 3 , showing a fastener and the diaphragm removed from the housing; 
         FIG. 5  is a perspective view of a connecting member which interconnects an electric motor drive gear train of the pump with the diaphragm; 
         FIG. 6  is a plan view of the connecting member; 
         FIG. 7  is a perspective view of the diaphragm, from the front; 
         FIG. 8  is a sectional view of the rear of the diaphragm, taken along the diameter; 
         FIG. 9  is a perspective front view of the fastener; and 
         FIG. 10  is a perspective rear view of the fastener. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring firstly to  FIGS. 1 to 3  of the drawings, there is shown a diaphragm pump  10  which comprises a diaphragm housing  12  having an electric motor  14  mounted at the rear of the housing  12  and an openable cover  16  closing the front of the housing  12 . A valve body  18  is located on the front of the cover  16  for connection to pipework. The valve body  18  is in fluid communication with the interior of the diaphragm housing  12  through the cover  16 . The valve body  18  is described in detail in British patent application GB0522845.7, and thus further description is omitted. 
     The cover  16  is releasably attached to the diaphragm housing  12  by a two-part ring clamp  20  or similar device. The ring clamp  20  includes two arcuate elements  22  which in use extend in a circumferential direction around the top and bottom of the diaphragm housing  12 . One end of one of the arcuate elements  22  includes a hook  24 , and one end of the other arcuate element includes an opening  26  for receiving the hook  24 . The other ends of the arcuate elements  22  have tabs  28 , each with an aperture  30 . To close the ring clamp  20 , the hook  24  and opening  26  are engaged, the tabs  28  are aligned, and a screw-threaded fastening device (not shown), such as a nut and bolt, is located in the apertures  30  to fasten the tabs  28  together. 
     The cover  16  and diaphragm housing  12  include complementarily shaped circumferential outwardly extending perimeter flanges  32  between which a, typically thermoplastic elastomer, diaphragm  34  is trapped. The two arcuate elements  22  of the ring clamp  20  include channels  36  in which the cover  16  and diaphragm housing flanges  32  can be received as a tight fit. Consequently, when closed, the ring clamp  20  urges the flanges  32  of the cover  16  and the diaphragm housing  12  together, to fluid-tightly clamp a perimeter edge  38  of the diaphragm  34  therebetween. 
     With the ring clamp  20  released and the cover  16  removed, the diaphragm  34  is exposed, as can be seen in  FIG. 3 . 
     The diaphragm pump  10  also includes a, typically moulded plastics, connecting member  40 , which is connected to a drive gear train mechanism (not shown) connected to an output shaft (not shown) of the electric motor  14  and which extends through the diaphragm housing  12  to engage the diaphragm  34 . As best seen in  FIGS. 5 and 6 , the connecting member  40  includes a substantially triangular body  42 , a circular diaphragm plate  44  at one end of the triangular body  42 , and a spigot  46  which is formed centrally on the diaphragm plate  44  and which projects away from the triangular body  42 . 
     The diaphragm plate  44  of the connecting member  40  has a smooth planar face  48  which, in use, contacts the diaphragm  34 , and the smooth face  48  includes a smoothly radiused perimeter edge  50  to prevent abrasion and chafing of the diaphragm  34 . 
     As understood from  FIGS. 4 ,  7  and  8 , the diaphragm  34  is generally dished, with the front face  52  opposite the cover  16  being typically concave when the pump  10  is deenergised or when the diaphragm  34  is removed from the pump  10 . The rear face  54  of the diaphragm  34  opposite the front face  52  includes two concentric arcuate, typically ring shaped, sealing ridges  56  positioned around a central diaphragm aperture  58 . The diaphragm aperture  58  receives the spigot  46  of the connecting member  40 . The spigot  46  is generally cylindrical and includes two diametrically opposite bayonet or wing elements  60 . Each wing element  60  projects radially outwardly and has a generally dovetailed lateral cross-sectional shape. 
     The diaphragm pump  10  further includes a twist and lock fastener  62  which engages the diaphragm  34  with the connecting member  40 . As best seen in  FIGS. 4 ,  9  and  10 , the fastener  62  includes a generally cylindrically shaped tubular portion  64  for receiving the spigot  46 , and a diaphragm flange  66  extending radially outwardly from one end of, and around, the tubular portion  64 . 
     The tubular portion  64  of the fastener  62  includes two symmetrically opposite tracks  68  formed in a bore of the tubular portion  64 , and shaped to receive the wing elements  60  of the spigot  46  of the connecting member  40 . Each track  68  includes a short channel  70  which extends into the bore of the tubular portion  64 , in parallel with the cylindrical axis of the tubular portion  64 , from the edge of the tubular portion  64  adjacent the diaphragm flange  66 . The short channel  70  includes a generally dovetailed lateral cross-sectional shape, dimensioned to complementarily match the dovetail shape of the wing element  60  of the connecting member spigot  46 . A short sharply inclined cam surface  72  leads off from the channel  70 , partway along the bore and in a generally circumferential direction. A longer shallowly inclined cam surface  74  follows contiguously on from the sharply inclined cam surface  72 , and a locking recess  76  is formed contiguously with the shallowly inclined cam surface  74  to provide a step back towards the diaphragm flange  66 . 
     An outer surface of the tubular portion  64  of the fastener  62  includes spaced splines  78  or other gripping elements by which a tool, such as a spanner, pliers or a lockable wrench such as a “Mole” grip, or alternatively if of sufficient strength, a user&#39;s fingers can grip and twist the fastener  62 . 
     A rear face  80  of the diaphragm flange  66  of the twist and lock fastener  62  includes an arcuate, typically ring shaped, sealing ridge  82 , similar to the ridges  56  on the rear face  54  of the diaphragm  34 . 
     The rear face  80  of the diaphragm flange  66  of the fastener  62  includes a smoothly radiused perimeter edge  84  to prevent abrasion and chafing of the diaphragm  34 . 
     With the ring clamp  20  released and the cover  16  removed, the diaphragm  34  is placed into the diaphragm housing  12 , and the spigot  46  of the connecting member  40  is received in the diaphragm aperture  58 . The perimeter edge  38  of the diaphragm  34  is located on the perimeter flange  32  of the diaphragm housing  12 . The twist and lock fastener  62  is offered up to the spigot  46 , so that the dovetailed wing elements  60  are received in the dovetailed channels  36  of the tracks  68 . The diaphragm  34  is thus sandwiched between the diaphragm flange  66  of the fastener  62  and the diaphragm plate  44  of the connecting member  40 . With the dovetailed wing elements  60  received in the dovetailed channels  36  of the tracks  68 , the fastener  62  is positively located on the spigot  46 . 
     As the fastener  62  is pushed further onto the spigot  46  and hard against the diaphragm  34 , the wing elements  60  leave the short channels  70 . At this point, the fastener  62  is twisted, in this case, in a clockwise direction, so that the wing elements  60  ride up the sharply inclined cam surfaces  72  and pass onto the shallowly inclined cam surfaces  74  of the tracks  68 . As twisting of the fastener  62  continues, the wing elements  60  travel along the respective shallowly inclined cam surfaces  74 , thus further compressing the diaphragm  34  between the diaphragm flange  66  of the fastener  62  and the diaphragm plate  44  of the connecting member  40 , before finally dropping into the locking recesses  76 . The wing elements  60  are thus positively located in the locking recesses  76  due to the diaphragm  34  being placed under compression by the fastener  62 , and the diaphragm  34  is liquid-tightly clamped by the fastener  62  to the diaphragm plate  44  of the connecting member  40 . 
     The ridges  56  and  82  on the rear faces  54  and  80  of the fastener  62  and the diaphragm  34  result in the formation of a tortuous path, and localised increased sealing compression forces on the diaphragm, thereby further preventing or limiting the possibility of liquid passing between the fastener  62  and the diaphragm  34 . 
     To release the twist and lock fastener  62 , the tubular portion  64  is gripped and the fastener  62  is turned anti-clockwise. The wing elements  60  are forced out of the locking recesses  76 , and thus travel back along the tracks  68  until the fastener  62  can be slidably removed from the spigot  46 . The diaphragm  34  can then be easily lifted away from the diaphragm housing  12  for maintenance or replacement. 
     The spigot of the connecting member can have the tracks, and the fastener can have the wing elements. In this case, the tracks are formed in the exterior surface of the spigot, and the wing elements project radially inwardly. 
     The spigot and the fastener can each include a wing element and a track. However, this is less convenient, since orientation of the fastener relative to the spigot is fixed. 
     Since the fastener has no screw-threads for engagement with the connecting member, flat or cross-bladed tools, such as screw-drivers, are no longer required. It is thus far easier to access the diaphragm pump and, with a twist and lock fastener, it is simple to remove and replace the diaphragm. Due to the relatively large size of the fastener, it is also far more unlikely that the fastener will be lost. It is thus also easier to relocate the fastener on the spigot, particularly when the installer cannot see the installation directly and is working by feel alone. 
     The embodiments described above are given by way of examples only, and further modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined by the appended claims. For example, only a single wing element and corresponding track can be provided, or more than two wing elements and respective tracks can be provided.