Patent Publication Number: US-11035429-B2

Title: Compression spring assembly and methods of using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. application Ser. No. 15/861,056, filed Jan. 3, 2018, the entire contents of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     (1) Field of the Invention 
     The instant invention generally relates to compression spring systems and more particularly to a compression spring assembly including a polymer spring element for use in a dispensing pump. 
     (2) Description of Related Art 
     Dispensing pumps for various liquids, lotions, gels, etc. are known in the art. They generally comprise a body portion which is seated on the neck of a container, a co-acting nozzle portion which slides relative to the body portion, and a spring structure which biases the co-acting nozzle portion to its normal rest position. To dispense the material in the container, the user manually depresses the nozzle which forces the material from the inside of the body portion outwardly through the nozzle. When the nozzle is released, the spring forces the nozzle portion back to its normal resting position. Most of the pump system components are typically formed from polymer materials, with the exception of the spring, which is typically formed from metal. The plastic components are easily recyclable. However, the presence of the metal spring in the pump assemblies has been found to impede or slow the recycling process due to the need to separate the metal spring from the other plastic components. Accordingly, there is a need in the industry for all plastic spring systems for use in various devices such as dispensing pumps. 
     SUMMARY OF THE INVENTION 
     An exemplary embodiment of a compression spring assembly according to the present invention includes a slotted tubular spring element formed from a tensile polymer material, and first and second loading cones received at opposing first and second ends of the slotted tubular spring element. In some embodiments, both the spring element and the loading cones may be formed from polymer materials, making the spring assembly more easily recyclable. 
     In the exemplary embodiment, the slotted tubular spring element is cylindrical in shape and has a uniform wall thickness. The loading cones are generally conical in shape and preferably have at least one wall section with a wall angle of no less than 11 degrees. Wall angles of less than 11 degrees tend to create a friction lock while wall angles of greater than 11 degrees minimize stroke length and increase overall spring assembly diameter. The exemplary embodiment includes loading cones with a first frustoconical pre-loading wall section having a wall angle of greater than 11 degrees, and a second frustoconical primary loading wall section having a wall angle of 11 degrees. 
     The loading cones are axially compressible toward each other within the open ends of the slotted tubular spring element whereby the slotted tubular spring element radially expands in tension to create an opposing radial contraction force. Deformation of the tubular spring walls elastically stores energy which will return the spring to its normal at rest shape when released. When released, the spring element elastically contracts, in turn creating an axial extension force, and returns the cones to their normal at rest positions. 
     Some embodiments of the spring assembly include a spring element having strain reducing ribs extending along the opposing edges of the longitudinal slot. The ribs may include outwardly convex surfaces extending both radially outward and circumferentially outward from the slot edges. This embodiment further includes a first thinner wall thickness at the slot edges and a second thicker wall thickness diametrically opposed from the slot edges. The arcuate surface along with the increasing wall thickness moving away from the slot edges, more evenly distributes strain throughout the spring element and extends the life cycle of the spring element. 
     Further embodiments of the spring element may also have a thicker central area for added strength midway between the ends. 
     Other embodiments of the spring assembly include a spring element which is hyperboloid in shape. 
     Embodiments of the present polymer compression spring may be advantageously used in dispensing pumps for various liquids, lotions, etc. In some exemplary embodiments, all of the components of both the dispenser pump and the compression spring assembly are molded from the same plastic material making the entire dispensing pump easily recyclable in a single plastic material classification. Exemplary plastic materials include polypropylene (PP), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). However, the disclosure should not be considered to be limited to these materials. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming particular embodiments of the instant invention, various embodiments of the invention can be more readily understood and appreciated from the following descriptions of various embodiments of the invention when read in conjunction with the accompanying drawings in which: 
         FIG. 1  is a plan view of an exemplary compression spring assembly in accordance with the present invention; 
         FIG. 2  is a perspective view of the slotted tubular spring element in an at rest condition; 
         FIG. 3  is a perspective view of the slotted tubular spring element in a radially expanded condition; 
         FIG. 4  is a top view of the spring element; 
         FIG. 5  is a front view thereof; 
         FIG. 6  is a side view thereof; 
         FIG. 7  is a cross-section view thereof taken along line  7 - 7  of  FIG. 4 ; 
         FIG. 8  is an enlarged plan view of the loading cone; 
         FIGS. 9-12  are sequential views of the compression spring assembly being axially loaded and released; 
         FIG. 13  is a cross-sectional view of an exemplary dispensing pump incorporating the present compression spring assembly; 
         FIG. 14  is a front view of another exemplary embodiment of the slotted tubular spring element including strain reducing ribs; 
         FIG. 15  is a top view thereof; 
         FIG. 16  is a side view thereof; 
         FIG. 17  is a perspective view thereof in a radially expanded condition; 
         FIGS. 18 and 19  are side and front views thereof showing the bending vectors of the ribs when the spring element is expanded; 
         FIG. 20  is an illustration showing initial axial compression of the spring assembly; 
         FIG. 21  is another illustration showing full axial compression of the spring assembly; 
         FIG. 22  is a plan view of another exemplary compression spring assembly including a hyperboloid spring element; 
         FIG. 23  is a perspective view of the hyperboloid slotted spring element; 
         FIG. 24  is a front view thereof; 
         FIG. 25  is a top view thereof; 
         FIG. 26  is a cross-sectional view thereof taken along line  26 - 26  of  FIG. 25 ; 
         FIG. 27  is a perspective view of another exemplary dispensing pump incorporating the hyperboloid compression spring assembly; 
         FIG. 28  is a perspective view of still another exemplary spring element; 
         FIG. 29  is a perspective cross-sectional view thereof; 
         FIG. 30  is a side cross-sectional view thereof; 
         FIG. 31  is a top view thereof; 
         FIG. 32  is a side view thereof; and 
         FIG. 33  is a front view thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, an exemplary embodiment of the present compression spring assembly is generally indicated at  10  in  FIG. 1-12 . According to the present invention, the compression spring assembly  10  comprises a slotted tubular spring element  12  formed from a tensile polymer material, and first and second loading cones  14 ,  16  received at opposing first and second ends of the slotted tubular spring element  12 . In some embodiments, the loading cones  14 ,  16  could be formed from non-plastic materials, depending on the implementation. However, in the preferred embodiments as disclosed herein, both the spring element  12  and the loading cones  14 ,  16  are formed from polymer materials. Exemplary plastic materials include polypropylene (PP), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). However, the disclosure should not be considered to be limited to these materials. In particular, the various components may be molded from HDPE and/or LDPE, making the entire spring assembly more easily recyclable. 
     In the exemplary embodiment, the slotted tubular spring element  12  is cylindrical in shape and has a uniform wall thickness (best illustrated in  FIGS. 2 and 4 ). The spring element  12  includes a single longitudinal slot  18  which extends the entire length of the tube to define parallel opposing slot edges  20 ,  22 . The slot  18  allows the element  12  to expand radially upon the application of an axial force at the first and second ends thereof. The inner wall edges are chamfered  24  to facilitate sliding of the walls over the loading cone surfaces  14 .  16  (best illustrated in  FIG. 7 ). 
     The loading cones  14 ,  16  are identical in shape and are symmetrically inverted to provide opposing axial compression and extension forces on the tubular spring element  12 . Referring to  FIG. 8 , the loading cones  14 ,  16  (only  14  is shown) are generally conical in shape and preferably have at least one wall section (primary loading wall)  26  with a wall angle θ 1  of no less than 11 degrees. In the present embodiment, a wall angle of less than 11 degrees tends to create a friction lock while a wall angle of greater than 11 degrees minimizes stroke length and increases overall spring assembly diameter. It should be understood that the critical wall angle for the primary loading wall  26  is based on the type of material used, i.e. polymer or metal, and other factors such as surface finish, shape of wall chamfers, etc. The angle must be selected such that the spring force from the spring element  12  overcomes friction as well as displacement of the applied axial load. The exemplary embodiment, which has an intended use in dispensing pumps for viscous liquids, includes loading cones  14 ,  16  with a first frustoconical pre-loading wall section  28  having a wall angle θ 2  of greater than 11 degrees, and a second frustoconical primary loading wall section  26  having a wall angle θ 1  of 11 degrees. The steeper pre-load angle θ 2  facilitates the initial expansion of the spring element  12 . 
     Turning to  FIGS. 9-12 , the loading cones  14 ,  16  are axially compressible toward each other within the open ends of the slotted tubular spring element  12  whereby the slotted tubular spring element  12  radially expands in tension to create an opposing radial contraction force.  FIG. 9  illustrates an initial at rest state.  FIG. 10  illustrates initial pre-load and outward expansion of the spring element.  FIG. 11  illustrates full axial compression and load. Deformation of the tubular spring element  12  elastically stores energy which will return the spring element  12  to its normal at rest shape when released. When released as illustrated in  FIG. 12 , the spring element  12  elastically contracts (inward), in turn creating an axial extension force, and returns the cones  14 ,  16  to their normal at rest positions. 
     Turning to  FIG. 13 , embodiments of the present polymer compression spring  10  may be advantageously used in dispensing pumps  100  for various liquids, lotions, etc. contained within a bottle or other container (not illustrated). In some exemplary embodiments, all of the components of both the dispenser pump  100  and the compression spring assembly  10  are molded from the same plastic material making the entire dispensing pump  100  including the spring assembly  10  easily recyclable in a single plastic material classification. 
     The dispensing pump  100  comprises an accumulator cup  102  having a dip tube receptacle  104  and ball valve  106  at a lower end thereof. A tubular guide  108  is received in the upper end of the accumulator cup  102 , and the tubular guide  108  is secured on a container neck (not shown) with a threaded cap ring  110 . The present compression spring assembly  10  is received and guided within the tubular guide  108 . As noted above, the angle θ 1  of the loading wall  26  of the loading cones  14 ,  16  is a critical factor in determining overall spring assembly diameter. As seen in this pump embodiment  100 , the spring assembly  10  fits within the inner walls of the guide  108  which in turn must fit within the neck of the container. Accordingly, the wall angle, spring element material and profile are all factors in determining this specification. A piston rod  112  is received axially through the loading cones  14 ,  16  and the tubular spring element  12  and extends through the bottom of the guide  108  into the accumulator cup  102  wherein the terminal end is fitted with a piston  112  which forms a seal with the inner wall of the accumulator  102 . A nozzle head  116  is secured to the upper end of the piston rod  112  and received over the upper loading cone  16 . 
     In operation, a forcible downward compression of the nozzle head  116  causes a corresponding downward axial movement of the upper loading cone  16  and outward deflection and loading of the spring element  12  as per the illustrations earlier described in  FIGS. 9-12 . Upon the subsequent release of the nozzle head  116 , the tubular spring element  12  elastically contracts back to its normal at rest shape and position (see also  FIG. 12 ), causing a forcible upward movement of the upper loading cone  16 , piston rod  112 , piston  114  and nozzle head  116  back to their normal at rest positions. The pump assembly  100  and ball valve  106  operate as known in the art to draw material up from the dip tube  104  and dispense the material through the nozzle head  116 . 
     Turning now to  FIGS. 14-21 , some embodiments of the spring assembly  200  may include a modified slotted tubular spring element  202  having strain reducing ribs  204 ,  206  extending along the opposing edges  208 ,  210  of the longitudinal slot  212 . The ribs  204 , 206  may include symmetrical convex surfaces extending both radially outward  204   a ,  206   a  (See  FIGS. 15 and 16 ) and circumferentially outward  204   b ,  206   b  (See  FIG. 14 ) from the slot edges  208 ,  210 . This embodiment  202  further includes a first thinner wall thickness  214  at the slot edges  208 ,  210  adjacent the strain ribs  204 ,  206  and a second thicker wall thickness  216  diametrically opposed from the slot edges  208 ,  201  (See  FIG. 15 ). The arcuate surfaces  204   a ,  204   b ,  206   a ,  206   b  along with the increasing wall thickness moving away from the slot edges  208 ,  210  more evenly distributes strain throughout the entire spring element  202  and extends the life cycle of the spring element  202 .  FIG. 17  illustrates the spring element  202  in an expanded loaded state.  FIGS. 18 and 19  illustrate the movement vectors (arrows) associated with the corners of the slot edges  208 ,  210 . The reduced material volume in these areas allow these corners to more easily deform and reduce strain. The present spring element  202  is used in combination with the same loading cones  14 ,  16  as previously described.  FIGS. 20 and 21  show axial compression of the present embodiment  200  with exemplary loading cones  14 ,  16 . The present spring assembly  200  can be used in the same types of dispensing pumps  100  as described above with improved spring longevity. 
     Referring now to  FIGS. 22-27 , other embodiments of the compression spring assembly  300  include a slotted tubular spring element  302  which is hyperboloid in shape, i.e. having a smaller (narrower) diameter at the center and symmetrically larger diameters at the ends, and first and second opposed loading cones  304 ,  306 . The spring element  302  has a uniform wall thickness (See  FIGS. 25 and 26 ) and includes a single longitudinal slot  308  ( FIGS. 23 and 24 ) which extends the entire length of the tube, allowing the spring element  302  to expand radially upon the application of an axial force at the first and second ends thereof. The curved spring wall of the hyperboloid spring  302  is provides a stiffer loading profile (higher loading profile) using the same amount of plastic material as compared with the earlier described cylindrical shape ( FIGS. 1-12 ). The inner wall edges are also chamfered  310  to facilitate sliding of the spring element  302  over the loading cone wall surfaces  304 ,  306  (See  FIG. 26 ). The hyperboloid shape of the spring element  302  works more efficiently with loading cones  304 ,  306  having a single frustoconical loading wall  312  with a somewhat steeper wall angle θ 3  ( FIG. 22 ). The preferred embodiment as illustrated shows a wall angle θ 3  of greater than 11 degrees. As noted above, the particular wall angle θ is selected based on the tensile characteristics of the spring element  302  as well as material and surface finishes. The exemplary embodiments are intended to be illustrative but not limiting. 
     Turning to  FIG. 27 , the present hyperboloid compression spring assembly  300  lends itself to be advantageously used as an exterior spring return in certain dispensing pumps  400  for various liquids, lotions, etc. As described above, in many exemplary embodiments, all of the components of both the dispenser pump  400  and the compression spring assembly  300  are molded from the same plastic material making the entire dispensing assembly easily recyclable in a single plastic material classification. 
     Referring to  FIG. 27 , the dispensing pump  400  comprises an accumulator cup  402  which is secured within the neck of a container  404  with a threaded closure  406 . A nozzle head  408  is received on a piston stem  410  which extends through the closure  406  and into the accumulator  402 . The loading cones  304 ,  306  of the present hyperboloid compression spring assembly  300  are integrated into the opposing exterior surfaces of the closure  406  and the top end of the piston stem  410  and the hyperboloid slotted tubular spring element  302  is snap received over and around the piston stem  410  and upward cone extension  304  of the closure  406  so that it engages the ramped loading cone walls  304 ,  306  of the piston stem  410  and closure  406 . 
     In operation, a forcible downward compression of the nozzle head  408  causes a corresponding downward axial movement of the upper loading cone (piston stem head)  410 / 306  and outward deflection and loading of the spring element  302  similar to the illustrations earlier described in  FIGS. 9-12 . Upon the subsequent release of the nozzle head  408 , the tubular spring element  302  elastically contracts (radially inward) back to its normal at rest shape and position, causing a forcible upward movement of the upper loading cone (piston stem)  410 / 306  and nozzle head  408  back to their normal at rest positions. The piston pump assembly  400  operates as known in the art to draw material up from a dip tube connection  412  and dispense the material through the nozzle head  408 . 
     Turning to  FIGS. 28-33 , another exemplary embodiment of the spring element is illustrated and generally indicated at  500 . Spring element  500  is generally similar to the spring element  200  illustrated in  FIGS. 14-21   
     Spring element  500  includes a single longitudinal slot  502  which extends the entire length of the tube to define parallel opposing slot edges. The slot  502  allows the element  500  to expand radially upon the application of an axial force at the first and second ends thereof. The spring element  500  may include strain reducing ribs  504 A,  504 B extending along the opposing edges of the longitudinal slot  502 . The ribs  504 A,  504 B may include symmetrical convex surfaces extending both radially outward and circumferentially outward from the slot edges. The illustrated embodiment further includes a first thinner wall thickness at the slot edges adjacent the strain ribs  504 A,  504 B and a second thicker wall thickness diametrically opposed from the slot edges (See top view  FIG. 31 ). The arcuate surfaces along with the increasing wall thickness moving away from the slot edges more evenly distributes strain throughout the entire spring element and extends the life cycle of the spring element. Referring to  FIGS. 29 and 30 , the spring also has a tapered increasing thickness from the top and bottom towards the middle. A thicker middle bulge  506  can be easily seen in the  FIGS. 29 and 30  cross-sections. The wall thickness is symmetrical about a transverse centerline as shown in  FIG. 30 . Adding the extra material on the inner surface of the spring element  500  increases the strength without increasing the maximum diameter of the spring when compressed within the accumulator. 
     It can therefore be seen that the exemplary embodiments provide unique and novel compression spring assemblies in which all the discrete components may be molded from a single plastic material to facilitate single stream plastic recycling. Further, the all plastic compression spring assemblies can be advantageously used in all plastic dispensing pumps which can then also be easily recycled. 
     While there is shown and described herein certain specific structures embodying various embodiments of the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.