Abstract:
A retainer for holding a pump body onto a container is formed with an annular trough having a passage offset from the axis of the retainer and permitting escape of build-up pressure in the container to the outside. The trough has a radial surface in which the passage terminates. An annular laminate layer of gas-permeable/liquid impermeable material is secured to the radial surface covering the passage.

Description:
FIELD OF THE INVENTION 
     This invention relates to a pump dispenser adapted to be mounted on a container and having passive means for venting gas pressure from the container to the outside. 
     BACKGROUND OF THE INVENTION 
     With container mounted manual pump dispensers, it is now common to use gas-producing substances, for example, hydrogen peroxide which generates gas when it comes in contact with water containing iron. The stress produced by such positive pressure can result in deformation of the container, cracking, leakage and so on. The problem is particularly acute where, in order to reduce cost or environmental impact, thinner-walled containers are used. 
     U.S. Pat. No. 5,752,629 to Michael E. Hardy issued May 19, 1998 deals with the need for passive means to vent gas buildup in containers having pump dispensers attached. Specifically, the Hardy patent provides gas-permeable material preferably in a frame over an opening in the container cap provided in the pump dispenser. 
     While in the past mechanical means have been used to permit venting of the outside air into the container, such venting means are usually only open upon the actuation of the trigger, for instance. Such mechanical means would also vent built-up gas pressure to the outside. However, during periods of storage the trigger is never actuated and, hence, the mechanical means does not operate to permit venting of built-up gases to the outside. 
     It is an object of the present invention to provide in a pump dispenser passive means—as opposed to mechanical means—for venting built-up gases from the container without appreciably altering the structure of the pump and without permitting leakage of liquid product if the container tips over. 
     SUMMARY OF THE INVENTION 
     The invention is, of course, described in the claim language appended hereto. Briefly, for a pump dispenser having an inverted cup-shaped cylinder with a piston operable therein and having a downward intake tube, the invention is a retainer slidably receiving the intake tube and supporting the cylinder. The retainer has a spool-like shape with a central sleeve and a curved peripheral surface at its upper end secured to a curved surface at the lower end of the tubular support. The retainer has an annular trough concentric with its axis and features at least one passage through the retainer offset from the axis and ending in a horizontal surface of the trough to permit gas to vent from inside the container to the outside. An essential of the invention is a layer of gas-permeable, liquid-impermeable material secured to the horizontal surface over the end of the passage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and features of the invention will be clear to those skilled in the art from a review of the following specification and drawings, all of which present a non-limiting form of the invention. In the drawings: 
     FIG. 1 is a sectional view of a pump dispenser embodying the invention; 
     FIG. 2 is an enlarged sectional view of the retainer assembly including the gas-permeable material; 
     FIG. 3 is a bottom plan view of the retainer assembly with the material partly broken away; 
     FIG. 4 is a greatly enlarged fragmentary view of a portion of FIG. 2; 
     FIG. 5 is a sectional view of an alternate pump dispenser having a modified form of retainer assembly; 
     FIG. 6 is an enlarged sectional view of the retainer assembly of the pump dispenser of FIG. 5; 
     FIG. 7 is a top plan view of the retainer assembly of FIG. 6 with the material partly broken away; and 
     FIG. 8 is a greatly enlarged fragmentary view of a portion of FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A pump dispenser embodying the invention is shown in FIG.  1  and generally designated  10 . It comprises a pump body  12 ,and a shroud  14 . The pump body includes the inverted cup-shaped cylinder  16  which is integral with a tubular support  18 . The tubular support has a cut away portion  20 . The lower end is cylindrical and formed on its outer surface with a series of ridges  22 . A spool-like retainer  24  is formed with an annular well  26  having inward ridges  28  to inter-engage with the ridges on the lower end  22  of the tubular support to firmly hold the tubular support. 
     The retainer is formed on its lower end (FIG. 2) with an outward annular flange  30  having a grooved undersurface  30 A. A screw cap closure  32  has an opening  34  in its top wall which receives the lower end of the retainer, above the flange  30 . The closure and retainer are, thus, rotatably related so that the dispenser can be installed on a container by screwing on the closure  32  while the pump may be held from movement. 
     A piston  36  operates in the cylinder  16 . It has a stem in the form of a downward intake tube  38  which is slidably received into axial opening  40  in the spool-like retainer  24 . At its upper end the intake tube  38  is provided with a check valve compartment holding a check valve ball  42  which seats in the chamber in a well known manner. A spring  44  biases the piston  36  downward. 
     From an upper portion of the cylinder a delivery tube  46  extends forwardly and terminates in a nozzle fitting  48  which receives a nozzle cap  50 . A movable check valve  52  is provided in the forward end of the delivery tube  46  as described in U.S. Pat. No. 5,687,877 assigned to our assignee. A trigger lever  54  is pivoted to the pump body and has rearward arms  55  by which, upon pulling the trigger, the piston can be raised to accomplish the pumping action. The shroud  14  may be attached to the pump body  12  in a manner described in the U.S. Pat. No. 5,890,632 also assigned to our assignee. 
     It is well known in the art as exemplified in the U.S. Pat. No. 4,161,288 to McKinney to provide on the intake tube  38  longitudinal grooves to, when the trigger is pulled and the piston raised, permit air to pass into the container by way of such grooves. This is thoroughly disclosed in the McKinney patent with special reference to FIG. 2 thereof, and comparable structure is employed in the present pump dispenser for such mechanical venting, though not shown in detail here. 
     Attention is now directed to FIG. 2 herein which is an enlargement of the retainer  24 . Inward from the annular well  26  the retainer is formed with an axial sleeve  56  which defines the intake-tube-receiving opening  40  referred to above. Surrounding the upper portion of the sleeve  56  are a plurality of outward radial ribs  58  to reinforce the sleeve  56 . Outward from the sleeve the retainer is formed with a barrel  60  which extends below the grooved annular surface  30 A of the flange  30 . In assembly, a flat annular gasket  63  is fitted against the grooved surface  30 A of the flange  30  and snugly embraces the lower end of the barrel  60 . 
     Attention is now directed to an area in which an essential of the invention lies. Extending upward surrounding the barrel  60  is an inverted annular trough  64  (FIG. 2) concentric with the axis of the retainer. The upper surface  66  of the trough is flat and radial with respect to the axis. At a plurality of positions, upward passages  68  (FIGS. 3,  4 ) are formed in the retainer, extending from the surface  66  upward into the annular well  26 . This constitutes a passage for gases which may build up in the head space of the container due to gases being generated or coming out of solution in the liquid product in the container. 
     To permit such gas to pass into the annular trough  64  around the gasket  63 , the barrel  60  is formed with at least one longitudinal notch  70  (FIG. 2) on its exterior. The radial surface  66  of the trough  64  is covered with a laminate  72  (FIG. 4) formed of complementary annular shape. 
     The material of laminate  72  is selected of known compositions as being permeable to gas but not permeable to liquid. Illustratively, the laminate may be a layer  74  of porous expanded PTFE with a backing of woven polypropylene fabric  76  The polypropylene layer is placed contiguous to the surface  66 . Polypropylene is chosen to be in harmony with the polypropylene of the retainer itself. In assembly, the polypropylene is welded to the surface  66  of the inverted trough. The welding technique, preferably ultrasonic, is as generally described in the prior art with a preferred technique employed by Performance Systematix, Inc. of Caledonia, Mich. 49316. The process leaves lines of indentations  78  in the laminate  72 . These may circumscribe each hole  68 , or may follow both the inner and outer periphery of the annulus (not shown). 
     In being disposed against the surface  66  all the way around the annular trough  64 , the laminate, of course, covers the upward passages  68  and controls the passage therethrough of any media. During periods of storage of the container and pump, gas may communicate freely through the notch  70 , through annular trough  64 , through the laminate  72  into upward passage  68  and finally into the annular well  26  which is open to the atmosphere by virtue of the cut-out  20  and various passages between the retainer and the tubular support  18  through which gas may sneak. Being thus relieved of pressure, the container on which the dispenser is mounted is not subject to misshaping, splitting or other damage caused by internal pressure. 
     Second Embodiment 
     The second embodiment shown in FIGS. 5 through 8, with the exception of differences in the retainer, is generally similar to the structure of the first embodiment in FIGS. 1 through 4. The pump dispenser of this second embodiment is generally designated  110  in FIG.  5 . It comprises a pump body  112  and a cover  114 . The pump body includes an inverted cup-shaped cylinder  116  which is supported on a lower half  118  of the dispenser body. The lower half  118  is formed with an opening  120  in the front thereof and is formed with a downward circular recess  122  into which is secured the upper portion of a retainer  124 . The retainer is formed at its lower end with an outward flange  130  with grooved undersurface  130 A and is received into the opening  134  in the top wall of a screw-type closure  132 . 
     Operating in the cylinder  116  is the piston  136  which has a downward intake tube  138 . At the upper end the intake is formed with a chamber which loosely receives and seats a check valve ball  142  in the usual manner. Spring  144  urges the piston downward. Adjacent the upper end of the cylinder  116  a delivery tube  146  extends forward and terminates in a fitting  148  receiving a nozzle cap  150 . The forward end of the delivery tube is provided with a check valve  152  as described in the McKinney patent. A trigger lever  154  is pivoted to the pump body and has a rearward arm  155  which operates the piston. 
     Focusing now on the spool-like retainer structure  124 , an enlargement of which is shown in FIG. 6, the retainer is formed with an inward floor  158  which supports an axial sleeve  160  which defines the opening  140 . Outward from the sleeve  160  the retainer is formed with an annular downward trough  164  concentric with the axis of the retainer. The trough terminates downward in a radial surface  166  which is formed with downward passages (FIG. 7)  168 . Each passage  168  communicates with an upward annular well  169 . Inward from the well  169  a barrel  170  extends downward and is notched at  171 . A gasket  167  is provided as with the first embodiment. 
     The radial surface  166  of the trough  164  is covered with a laminate  172  formed in complementary annular shape. Illustratively, the laminate may be a layer  174  of porous expanded PTFE with a backing of woven polypropylene fabric  176  The polypropylene layer is placed contiguous to the surface  166 . Polypropylene is chosen to be in harmony with the polypropylene of the retainer itself. In assembly, the polypropylene is welded to the surface  66  of the inverted trough. The welding technique, preferably ultrasonic, is as generally described in the prior art with a preferred technique employed by Performance Systematix, Inc. of Caledonia, Mich. 49316. The process leaves lines of indentations  178  in the laminate  172 . These may circumscribe each hole  168 , or may follow both the inner and outer periphery of the annulus (not shown). 
     In being disposed against the surface  166  all the way around the annular trough  164 , the laminate, of course, covers the upward passages  168  and controls passage of media therethrough. 
     During periods of storage, the gas may pass through the notch  171 , through inverted annular well  169 , through the passages  168 , the laminate  172  and finally into the annular trough  164  which is open to the atmosphere by virtue of the cut-out  120 . Being thus relieved of pressure, the container on which the dispenser is mounted is not subject to misshape, splitting or other damage caused by internal pressure. 
     Variations in the invention are possible. Thus, while the invention has been shown in only two embodiments, it is not so limited but is of a scope defined by the following claim language which may be broadened by an extension of the right to exclude others from making, using or selling the invention as is appropriate under the doctrine of equivalents.