Patent Document

BACKGROUND OF THE INVENTION 
     In the past, piston paint pumps of the type having a paint pumping piston required periodic lubrication of the paint pumping piston by a user who was instructed (by the owner&#39;s manual) to insert a spout of an oil can into an opening in the pump housing and align the spout with the top of the piston where it projected from a nut or bushing supporting the paint pumping piston and retaining the top seal of the paint pumping piston assembly. Such a lubrication procedure was found to be inconvenient and therefore less likely to be performed as often as appropriate. Because the oil was stored in a can separate from the pump, it was also inconvenient for a user to locate the oil can when lubrication was intended to be performed. 
     The present invention overcomes deficiencies of the prior art by providing an on board lubrication system on the pump. The system includes an oil reservoir and a prepositioned permanently installed spout located to deliver the oil to the piston-bushing interface upon exercise of the system by the user to deliver a predetermined amount of oil to the piston-bushing interface. 
     SUMMARY OF THE INVENTION 
     The invention includes an on board apparatus having a lubrication reservoir and lubricant dispensing mechanism operable to deliver a predetermined volume of oil to the piston-nut interface in a piston paint pump. A pushbutton extends through an aperture in the pump housing to enable the user to move the predetermined volume of oil from the reservoir to the piston-bushing interface. A filler tube and cap is provided in the pump housing to enable a user to initially fill and periodically refill the oil reservoir. The cap preferably has a breather valve to prevent a vacuum in the reservoir, which would interfere with the operation of the lubrication system. 
     In one embodiment, a transparent or translucent oil reservoir is mounted adjacent an aperture in the housing to enable viewing of the level of oil in the reservoir. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a piston pump useful in the practice of the present invention. 
         FIG. 2  is a fragmentary view of a diagram of a prior art apparatus and method for manually lubricating a piston paint pump. 
         FIG. 3  is an exploded fragmentary view of a portion of a prior art piston paint pump with a front cover removed to show details of a piston and bushing to be lubricated using the present invention. 
         FIG. 4  is a front perspective view of an assembly including a piston paint housing cover with the lubrication system of the present invention installed therein. 
         FIG. 5  is a rear elevation view of the assembly of  FIG. 4 . 
         FIG. 6  is a top plan view of the assembly of  FIG. 4 . 
         FIG. 7  is a side elevation view of the assembly of  FIG. 4 . 
         FIG. 8  is a rear perspective exploded view of the assembly of  FIG. 4 . 
         FIG. 9  is a perspective view from the rear and above a housing for a lubricant dispensing mechanism useful in the practice of the present invention. 
         FIG. 10  is a top plan view of the housing of  FIG. 9 . 
         FIG. 11  is a rear elevation view of the housing of  FIG. 9 . 
         FIG. 12  is a perspective view from the front and above the housing of  FIG. 9 . 
         FIG. 13  is a side elevation view of the housing of  FIG. 9 . 
         FIG. 14  is a front elevation view of the housing of  FIG. 9 . 
         FIG. 15  is a section view of the housing of  FIG. 9 , taken along line  15 - 15  of  FIG. 11 . 
         FIG. 16  is a section view of the housing of  FIG. 9 , taken along line  16 - 16  of  FIG. 13 . 
         FIG. 17  is a view similar to that of  FIG. 15 , except showing certain parts installed in the housing. 
         FIG. 18  is a view similar to that of  FIG. 16 , except showing certain parts installed in the housing. 
         FIG. 19  is a side view of a lubricant dispensing piston useful in the practice of the present invention. 
         FIG. 20  is a section view of a discharge nozzle useful in the practice of the present invention. 
         FIG. 21  is an end view of a cap for covering an inlet to a lubricant reservoir in the practice of the present invention. 
         FIG. 22  is a section view along line  22 - 22  of  FIG. 21 . 
         FIG. 23  is a side view of a breather valve element useful with the cap of  FIG. 21 . 
         FIG. 24  is a section view of the breather valve element taken along line  24 - 24  of  FIG. 23 . 
         FIG. 25  is an assembly view, partly in section, of the breather valve element of  FIG. 23  and the cap of  FIG. 21 . 
         FIG. 26  is a perspective view from the front of an assembly of a cover of a piston pump with a second embodiment of the present invention. 
         FIG. 27  is a perspective view from the rear and slightly below of the assembly of  FIG. 26 . 
         FIG. 28  is a perspective view from the rear and above of the assembly of  FIG. 26 . 
         FIG. 29  is a partial section view of the lubrication delivery system of  FIG. 28  taken along line  29 - 29 . 
         FIG. 30  is a rear perspective view from above of a third embodiment of the present invention installed in a cover of the piston pump. 
         FIG. 31  is an exploded view of the parts of  FIG. 30 . 
         FIG. 32  is an exploded view of a lubricant reservoir and cover from  FIG. 30 . 
         FIG. 33  is a view of the parts of  FIG. 32  secured together. 
         FIG. 34  is an exploded perspective view from below of a breather valve and cover of  FIG. 32 . 
         FIG. 35  is a fragmentary section view of the lubrication delivery system taken along line  35 - 35  of  FIG. 31 . 
         FIG. 36  is a fragmentary section view taken along line  136 - 136  of  FIG. 30 . 
         FIG. 37  is an exploded view corresponding to  FIG. 36 , showing a fill tube cover removed from a fill tube useful in the practice of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the Figures, and most particularly to  FIGS. 1 ,  2 , and  3 , a prior art piston paint pump  30  may be seen. The particular pump shown in  FIG. 1  is a Model  1920 , available from the assignee of the present invention.  FIG. 2  shows an illustration from the owner&#39;s manual wherein the user is directed to insert a spout  32  of an oil can  34  into an aperture  36  in a cover  38  of a pump housing  40  for periodic lubrication.  FIG. 3  shows an exploded view of the front of a paint pump (with the cover removed) in which a paint pumping piston  42  is received in and passes through a nut or bushing  44 . The lubrication is to be applied to the piston in the region where it projects from the bushing  44 , to minimize wear that would otherwise occur between the paint pumping piston  42  and the bushing  44 . With the paint pumping piston  42  and bushing  44  recessed within housing  40 , such prior art lubrication was found to be inconvenient. 
     Referring now to  FIGS. 4 through 8 , an on-board lubrication system  46  according to the present invention may be seen. System  46  is preferably permanently installed in or on the pump  30 , more particularly, in or on the pump housing  40 , and most desirably on the cover  38 . System  46  preferably includes a lubricant reservoir  48  located internal to the housing  40  of the pump  30 . Reservoir  48  has an inlet  50  and an outlet  52 . System  46  also includes a lubricant dispensing mechanism  54  having an inlet  56  connected to the outlet  52  of the reservoir  48  and mechanism  54  has an outlet  58  for delivering a predetermined minimum amount of lubricant to the paint pumping piston  42  adjacent the bushing  44  per activation. The system  46  also may have an actuator  60  located exterior of the housing  40  for activation by a user. In one embodiment, the present system provides about 0.01 cubic inches of liquid lubricant per stroke of the actuator  60 . User instructions for that system recommend that the user initially activate the actuator between 2 and 5 times to lubricate the piston  42 . User instructions go on to recommend pressing the actuator  60  once for every eight hours of pump operation. 
     The lubricant dispensing mechanism  54  preferably has a housing  62  containing an inlet check valve  64 , an outlet check valve  66 , a lubricant delivery piston  68  and a return spring  70  for piston  68 . Each check valve may be formed by a ball having a spring urging the ball against a seat to block flow in one direction i.e., from the ball towards the seat, and to permit flow in the opposite direction i.e., from the seat towards the ball. The seat may be formed in an end of a threaded fitting received in the housing  62 , it being understood that the threads are omitted from some of the figures for simplicity. 
     The lubricant reservoir  48  may be a hollow tube connected to a fitting  74  projecting through the housing  40  (more particularly the housing cover  38 ) and in fluid communication with inlet  56  of the mechanism  54  (through the inlet check valve  64 ). The fitting  74  is secured to cover  38  by a conventional nut  76 , with it being understood that fitting  74  has external threads (not shown) mating with internal threads (also not shown) on nut  76 . Nut  76  may be made of any suitable material, for example, nylon. A cap  78  (also with internal mating threads, not shown) is received on a projecting end of fitting  74  exterior of cover  38 . A breather valve  80  is attached to cap  78  to prevent a vacuum from forming in reservoir  48  as the lubricant is drawn from the reservoir  48 . 
     Referring now also to  FIGS. 9-18 , various views of the housing  62  may be seen. Housing  62  has a first mounting aperture  82  and a second mounting aperture  84  to secure the mechanism  54  to the cover  38  using conventional machine screws. A stepped bore  86  is sized to receive the lubricant delivery piston  68 , while allowing the actuator portion  60  to project out of the housing  62 . Although not shown in these views, it is to be understood that bore  86  is threaded to receive a threaded plug  88 , shown schematically in  FIG. 8  and in section in  FIG. 17 . It is also to be understood that inlet  56  and outlet  58  are each threaded to receive respectively, inlet check valve fitting  90  and outlet check valve fitting  92 , each of which are threaded, as shown in the section views of  FIGS. 17 and 18 . Housing  62  may be formed of any suitable material, such as aluminum. 
     Inlet check valve  64  includes the inlet check valve fitting  90 , which provides a valve seat  91  on an inboard end thereof, and a ball  94  and spring  96 . Outlet check valve  66  includes the outlet check valve fitting  92  and a ball  98  and spring  100 . A valve seat  102  for outlet check valve  66  is provided by a step in the bore of outlet  58  in housing  62 . 
     Referring now to  FIG. 19 , the lubricant delivery piston  68  has a stem  104  forming actuator  60 , and a groove  106  to retain an O-ring  108  (shown in  FIG. 17 ) to seal the piston  68  against the bore  86 . 
     Referring now to  FIG. 20 , outlet check valve fitting  92  is shown in more detail in cross section. Fitting  92  has a through bore  110  and a first end  112  which has external threads  114  to mate with the internal threads of outlet  58  in housing  62 . Through bore extends from the first end  112  to a second end  116  which may have an enlarged perimeter or drip lip  118 . Drip lip  118  prevents oil from running back from the second end  116  towards the first end  112 . Fitting  92  also serves as a discharge nozzle and, when installed, is located adjacent to and directed at the paint pumping piston  42  proximate the bushing  44 . Fitting  92  may be made of any suitable material, such as brass. 
     Referring now most particularly to  FIGS. 21-25 , details of a breather valve and cap assembly  120  may be seen. Assembly  120  (shown in  FIG. 25 ) is preferably made up of the cap  78  and breather valve  80 .  FIGS. 21 and 22  show a rear and section view, respectively of the cap  78 , which has a central through bore  122  and an offset through bore or breather hole  124 . Cap  78  has internal threads indicated by dashed line  126  sized to mate with external threads (not shown) on fitting  74 . Cap  78  may also have flutes  128  projecting radially and extending axially on the exterior of cap  78 . Cap  78  may be made of any suitable material, such as nylon 
     Breather valve  80  is shown in a side view in  FIG. 23 , in a section view in  FIG. 24 , and is shown installed in cap  78  in  FIG. 25 . Breather valve  80  has a stem  130  connecting an umbrella-like flange  132  to an enlarged head  134 . Breather valve  80  may be made of any suitable material sufficiently soft to function as a vacuum breaker valve, and is available as a fluorocarbon part from Vernay Laboratories, Inc. of 120 E. South College Street, Yellow Springs, Ohio 45387 as model VA 4687. In operation, flange  132  will lift away from cap  78  to permit ambient air to enter the lubricant reservoir  48  via breather hole  124  when lubricant is drawn from the reservoir  48  thus preventing a vacuum from forming in the reservoir  48 . 
     Referring now to  FIGS. 26 ,  27 ,  28  and  29 , a second embodiment of the present invention may be seen. In this embodiment, a larger reservoir  140  (preferably formed of a transparent or translucent material, such as a polypropylene polymer) is used to store the lubricant. A fill fitting  142  is provided on the top of the cover  38 , and may include a cap and breather as described above with respect to the first embodiment. With this embodiment, a window or opening  144  in cover  38  may be provided to enable a user to view the level of lubricant (typically oil) remaining in the reservoir. Fill tube  146  preferably has an  0 -ring  148  to seal against a reservoir lid  150 . A piston  152  has a spring  154  to return the piston to the rest position after an extension  156  is depressed to deliver lubricant as described above. In this embodiment, a cylinder  158  has an inlet port  160  closed when the piston  152  is actuated. A poppet  162  serves as an outlet check valve and is urged against a valve seat  164  by a spring  166  acting against poppet valve cap  168 . The outlet tube delivers the lubricant to the interface between the paint pumping piston and its supporting bushing, as described above with respect to the first embodiment. It is to be understood that all materials in contact with the lubricant (typically a lubricating oil) must be compatible with and not degraded by the lubricant used. 
     Initially the reservoir  140  may be filled with separating oil, available from Wagner Spray Tech Corporation, 1440 Fernbrook Lane, Plymouth, Minn. 55447, as part number 0516915. Optionally, the reservoir may be refilled with light household oil, if desired. 
     Referring now to  FIGS. 30-35 , a third embodiment of the present invention may be seen. In this embodiment (which is similar to the second embodiment) a reservoir  170  is preferably formed of a transparent or translucent polymer material, and may have a cover  172  permanently bonded to a main housing  174  (as shown in  FIG. 33 ) after a breather valve  176  is installed, as shown in  FIG. 34 . With this embodiment the window or opening  144  in cover  38  may be provided as with the second embodiment. A fill tube  178  may have an O-ring  180  to seal the proximal end of the fill tube  178  against the reservoir cover  172 . A fill tube cover  182  may be used to close the distal end of the fill tube after lubricant is stored in the reservoir. Referring most particularly to  FIGS. 31 and 35 , a cylinder  184  (corresponding to cylinder  158  in the second embodiment) has inlet port  160  closed by the piston  152  when the piston  152  is actuated. The piston moving in front of and blocking the inlet port serves as an inlet check valve in this embodiment. The poppet  162  serves as the outlet check valve and is urged against the valve seat  164  by spring  166  acting against poppet valve cap  168 . The outlet tube  186  (whose position is represented by dashed circle  188  in  FIG. 35 ) delivers the lubricant to the interface between the paint pumping piston and its supporting bushing, as described above with respect to the first and second embodiments. A spring  190  provides a return force for piston  152  when actuator or pushbutton end  192  of piston  152  is released by a user. The reservoir  170 , cover  172 , and fill tube  178  may each be made of a polypropylene polymer, while the fill tube cover  182 , valve cap  168 , poppet  162  and piston  152  may each be made of an acetal polymer, such as is available under the trademark Delrin from DuPont. 
     Referring now most particularly to  FIGS. 36 and 37 , fragmentary section views with the fill tube cover  182  both installed and removed from the fill tube  178  may be seen. Cover  182  may have a slot to permit rotation using a conventional flat bladed screwdriver. When cover  182  is rotated, a pair of dogs are released from cam surfaces in an upper end of the fill tube  178 . One dog  194  and a corresponding cam surface  196  may be seen in  FIG. 37 . It is to be understood that cover  182  has a flange  198  with an outside diameter that is sized to closely interfit with an inlet diameter of an inlet end of fill tube  178  to prevent leakage of liquid lubricant in the event that the paint pump is tipped or positioned to orientations other than as shown in  FIG. 1 , for example, for transportation or storage. 
     This invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention. For example and not by way of limitation, oil is the preferred lubricant for the practice of the present invention, however, other similar lubricants are to be included within the scope of the present invention.

Technology Category: 2