Patent Publication Number: US-2019168949-A1

Title: Propel/repel dispenser

Description:
FIELD OF THE INVENTION 
     The invention relates to a screw-operated propel/repel dispenser for dispensing a highly viscous product, such as a substantially solid or solid product. More particularly, the invention relates to a screw-operated propel/repel dispenser having an improved screw which prevents breakage of the screw when a user operates the dispenser to move the screw in a repel direction when the elevator of the dispenser is in a lowermost repel position, i.e., the user mistakenly turns the screw in the wrong direction placing stress and/or pressure on the screw. 
     BACKGROUND OF THE INVENTION 
     Screw-operated dispensers are known in the art. They are useful for dispensing products such as lip balms, cosmetics and the like. 
     In a screw-operated dispenser of the prior art such as shown in  FIGS. 1, 2 and 2A , product to be dispensed sits within a tubular body  1  of cylindrical or other shape. The product is supported in the body by an elevator  3  which travels inside the body along the body&#39;s length. The elevator is threadably engaged with a shaft  5  of a dispensing screw  7  having a turn member  9 . The threaded shaft  5  extends inside the tubular body along the body&#39;s length. The thread along each revolution thereof has a squared or straight angled edge to engage a mating thread in the elevator. Turn member  9  is seated in a dispenser base  11 . In response to the turning of the base  11 , which serves to rotate turn member  9 , the elevator  3  is moved upward (propelled) or downward (repelled) depending on the direction the base  11  is rotated. 
     In operation of the above-described dispenser, a user turns the base  11 , in which the turn member  9  is seated, causing the threaded shaft  5  of the screw  7  to turn, and thereby cause the elevator  3  to travel along the thread  13  inside the tubular body with concomitant movement of the product up or down from the dispensing opening in the body. The amount of product dispensed from or retracted into the body is proportionate to the extent to which the base  11  and turn member  9  are rotated. 
     A problem in the prior art propel/repel dispensers may occur when the elevator  3  is positioned at the bottom of the screw shaft  5 , or repelled until it is in such position, and a user rotates or continues to rotate the base  11  and turn member  9  in a repel direction, that is in the wrong direction. This incorrect rotation may place stress and/or pressure on the screw which may result in breakage of the screw at the point of engagement between the thread on the screw shaft and the thread in the elevator. This will render the dispenser inoperable. Once the dispenser is inoperable, any undispensed product is wasted. 
     It would be advantageous to provide a screw-operated dispenser that prevents or eliminates the accidental breakage of the screw when a user rotates the base and turn member in the wrong direction, and in particular one that does not require complex and expensive dispensing structures. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a screw-operated dispenser that has a thread structure which prevents or eliminates breakage of the screw in the event a user rotates the dispenser&#39;s screw in a repel direction when the elevator is in the lowermost repel position. 
     The invention comprises an improved threaded screw which is simple in structure and does not require costly additional parts or manufacturing and assembly steps to achieve the desired elimination of breakage of the screw. 
     Accordingly, a propel/repel dispenser is provided having an improved threading on the shaft of the screw. The screw thread in at least the lowermost about 1 to about 1.75 revolutions, preferably about 1.5 revolutions, of the screw thread adjacent the shoulder of a hub in the screw is chamfered so as to provide in the thread surface a bottom edge which is inclined or slanted and not at a right angle to a side wall of the thread. In the event a user causes the turn member to rotate in a repel direction when the elevator is movably engaged with the thread in a lowermost position on the screw shaft, the chamfered edge in at least the lowermost revolutions of the thread of the screw will cause the engaged elevator thread to override by sliding over or around the screw thread, thereby preventing breakage of the screw shaft and maintaining the operability of the dispenser. 
     The improved screw of the invention works particulary well when the hub of the screw is increased in length. This provides for additional spacing at the base of the screw shaft between the elevator and the bottom wall of the tubular body. This structure prevents the elevator from engaging the bottom wall of the tubular body and subjecting it to unwanted downward pressure which may cause the screw to break in the event the user turns the screw in the wrong direction. The lengthened hub may be provided by having two or more stacked hubs or by increasing the length of a single hub. The stacked hubs may provide for a sturdier screw and dispenser. 
     In use of the propel/repel dispenser of the invention, the product is stored within the tubular body. The product is supported in the body by the elevator as a support which travels inside the body along the body&#39;s length. The elevator is received on a threaded shaft of a dispensing screw of the invention. The shaft of the dispensing screw is inside the tubular body. At the end of the screw is a turn member. The turn member is fitted into a base which in conjunction with the screw is connected to the tubular body. The base has a mating configuration to maintain the turn member in place in the base and to cause the turn member to rotate in response to rotation of the base by a user. 
     Rotation of the turn member of the dispensing screw turns the threaded shaft which causes the elevator to move up or down inside the tubular body with concomitant extension or retraction of the product from the open dispensing end of the body. 
     The screw-operated dispenser of the invention is configured such that the turn member when caused to be rotated in one direction propels the elevator and product supported thereon upward and out of the container through the top opening in the tubular body, and when turned in a second and opposite direction repels the elevator downward to a lowermost position on the threaded shaft. If a user mistakenly rotates the turn member in a repel direction when the elevator is in a lowermost position, the lower chamfered revolutions of the screw thread allow the thread of the elevator to override or to slip past the thread on the screw shaft. Therefore, such incorrect rotation of the turn member will not place stress and/or pressure on the engaged threads of the screw, thereby preventing breakage of the screw shaft and rendering the dispenser inoperable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of the specific non-limiting embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structures are indicated by like reference numbers. 
         FIG. 1  shows a side view of a prior art screw. 
         FIG. 2  shows a cross-sectional view of the screw of  FIG. 1  in operating engagement with an elevator in a prior art propel/repel dispenser. 
         FIG. 2A  is a detail view of the screw and elevator as shown in the circled portion  2 A of  FIG. 2 . 
         FIG. 3  is a perspective view of a tubular body and base of a propel/repel dispenser of the invention. 
         FIG. 4  shows a side view of a screw of the invention. 
         FIG. 4A  is a detail view of the lowermost revolutions of the screw thread adjacent the shoulder of the hub of the screw as shown in the circled portion  4 A of  FIG. 4 . 
         FIG. 5  is a cross-sectional view of the elevator of the propel/repel dispenser of the invention. 
         FIG. 6  is a cross-sectional view of a propel/repel dispenser of the invention having assembled therein in operating engagement the screw as shown in  FIGS. 4 and 4A  and the elevator as shown in  FIG. 5 . 
         FIG. 6A  is a detail view of the screw engaged with the elevator as shown in the circled portion  6 A of  FIG. 6 . 
         FIG. 7A  shows a partial bottom perspective view of the elevator engaged with the thread on the shaft of the screw of the invention when the elevator is in a substantially lowermost repelled position. 
         FIG. 7B  shows a partial top perspective view of the elevator engaged with the thread on the shaft of the screw of the invention when the elevator is in a substantially lowermost repelled position. 
         FIG. 8A  shows a partial bottom perspective view of the elevator engaged with the thread on the shaft of the screw of the invention when the elevator is in a partly propelled position along the threaded shaft. 
         FIG. 8B  shows a partial top perspective view of the elevator engaged with the thread on the shaft of the screw of the invention when the elevator is in a partly propelled position along the threaded shaft, and a double stacked hub structure is also shown. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Having described the invention in general terms, a description of presently preferred embodiments is set forth with reference to the drawings. 
     Referring to  FIG. 3 , a perspective view of a propel/repel screw-operated dispenser of the invention is shown. Tubular body  20  is shown in the preferred form of a cylinder. A base  22  is attached in a conventional manner to tubular body  20  to allow rotation of base  22  in relation to body  20 . For convenience of discussion, the propel/repel dispenser will be described and shown in terms of a lip balm stick applicator. Necessarily variations in size and shape are possible depending on the use of the product contained in the dispenser. For example, conventional lip balm applicators have a body size of approximately ⅝″ in diameter and 2″ in length. The tubular body is, as well as the other parts of the applicator, preferably manufactured from plastic as conventionally known in the art. Body  20  has an open dispensing end  24 . A removable cap (not shown) fits on top of the body  20  extending the length of the body and engaging projections  23  and seating on the shoulder of base  22 , thereby providing an aesthetically pleasing appearance. 
     Dispensing screw  26  includes a turn member  28 , shaft  29  having a screw thread  30  formed therewith, and a hub  32  between the shaft  29  and turn member  28 . Hub  32  includes a shoulder  32   a . In the embodiment shown, the hub  32  is comprised of two substantially similar hub structures in stacked relation. Turn member  28  includes a plurality of parallel ridges  34  which mate with a plurality of corresponding parallel ridges (not shown) in the inside of base  22  as discussed below. Screw  26  is preferably a one piece injection molded plastic structure, a preferred plastic being polypropylene. 
     Referring, for example, to  FIGS. 4, 4A, 6 and 6A , screw  26  is seated in base  22  such that ridges  34  of screw  26  engage the corresponding ridges in base  22 . This prevents the rotation of screw  26  in base  22  and allows rotation of base  22  to rotate screw  26 . Base  22  with screw  26  are attached to body  20  by insertion through an opening  33  in a bottom wall  35  of the tubular body  20 . As best shown in  FIGS. 6 and 6A , hub  32  includes a bead  33   a  which fits through opening  33  and which holds base  22  and screw  26  within body  20 , i.e. the arrow head shape of bead  33   a  prevents removal of base  22  and screw  26  from body  20 . Base  22  acts as the portion of the dispenser which a user will turn to cause turn member  28  to rotate which causes shaft  29  to rotate. Accordingly, shaft  29  of screw  26  lies in a vertically fixed position inside body  20  and is rotatable by means of base  22  in conjunction with turn member  28 . 
     Also present inside body  20  is a product support or elevator  36  which is threadably engaged with threaded shaft  29 . Elevator  36  moves along the length of body  20  in response to turning of base  22  and thereby turn member  28 . Elevator  36  and body  20  are structured to cooperate in a conventional manner to prevent elevator  36  from rotating about the axis of screw shaft  29 . For example, ribs  21  can be present on the interior wall of body  20  which interact with projections  25  on the exterior of elevator  36  to maintain elevator  36  in a non-rotating position as it moves up or down shaft  29 . The product to be dispensed sits in and on top of elevator  36 . 
     In use, base  22  and turn member  28  are rotated in a propel direction thereby rotating threaded shaft  29  causing elevator  36  to move upward along shaft  29  inside body  20  and raise the uppermost portion of product out of dispensing end  24 . Following dispensing of product, the base  22  and thereby turn member  28  is rotated in the opposite direction to repel the elevator  36  downward along shaft  29  until the product no longer extends out of opening  24 . When the dispenser is full of product or fully repelled when product has been partially dispensed, the elevator  36  will be in a lowermost position as shown, for example, in  FIGS. 6, 7A and 7B  where a bottom portion  36   a , see e.g.  FIG. 6A , of the elevator  36  is adjacent to the shoulder  32   a  of hub  32 . Hub  32  has a sufficient length or height which allows the downward extension of the elevator  36  to be positioned above the top surface of turn member  28 . 
     The thread  30  on shaft  29  is a single thread generally having top wall, side wall and bottom wall surfaces. The top wall surface and bottom wall surface are substantially at a right angle to the side wall surface and have a substantially square profile, except at the bottom portion as discussed below. The thread  30  engages thread  38  in the inner channel  37  of elevator  36  for moving the elevator upward and downward along the thread  30  on shaft  29  upon rotation of base  22  and turn member  28 . In a conventional screw  7  as shown in  FIGS. 1, 2 and 2A , the thread  13  has the same wall configuration for each revolution along the entire length of the shaft  5 , including at the base of the shaft as shown in detail in  FIG. 2A . This presents a problem when the elevator  3  is moved to or in a lowermost position on the shaft and a user rotates turn member  9  in a repel or wrong direction. This action provides stress and/or pressure on the screw  7  which can result in breakage of the screw shaft  5  rendering the dispenser inoperable and causing a waste of any undispensed product. A user may be dissatisfied with the dispenser, the waste of the product and/or the need to purchase a new product. 
     The screw  26  of the invention prevents breakage of the screw shaft when a user rotates the base  22  and turn member  28  in the wrong direction. The thread  30  on shaft  29  of the invention in at least the lowermost revolutions of thread  30  on shaft  29  are chamfered at the bottom edge of the thread as best seen in  FIGS. 4 and 4A . This chamfered thread provides an edge  40  to the thread which is inclined or slanted, i.e., not at a right angle to the thread side wall and not having a generally square profile. The chamfered edge is provided to at least the lowermost about 1 to about 1.75 revolutions of the thread. Preferably, the chamfered edge is provided to about 1.5 revolutions of the lowermost revolutions of thread  30 . The thread ends on or adjacent to the shoulder  32   a  of hub  32 . When a user turns the base  22  in a repel direction when the elevator  36  is in a lowermost position, i.e., in the wrong direction, the thread  38  of the elevator  36  upon the pressure of the turn will override or slip over, i.e., move past, the thread  30  due to the chamfered edge  40  of the lower revolutions of thread  30 . The thread  38  of the elevator does not, therefore, engage the thread  30  of the shaft  29  when the user turns the base in the wrong (repel) direction. This structure and action prevents breakage of the screw shaft. Continued dispensing operation occurs when a user recognizes their error and reverses the turn direction of the base  22  to propel the elevator upward along the thread  30  on shaft  29 . The chamfered edge  40  does not prevent the upward motion of the elevator  36  along thread  30  on shaft  29 .  FIGS. 7A and 7B  show, in absence of the tubular body  20  and base  22  for clarity, the elevator  36  positioned adjacent the shoulder  32   a  of hub  32  as shown in  FIG. 6A .  FIGS. 8A and 8B  show, also in the absence of body  20  and base  22 , elevator  36  moved partway upward on shaft  29  along thread  30 . 
     In a preferred embodiment, hub  32  can be provided with a length or height to provide shoulder  32   a  at a height sufficient to maintain the bottom surface of elevator  36  above the top of bottom wall  35  of body  20 . This increased length may be provided by having two or more hubs formed in a stacked configuration such as shown in  FIGS. 4 and 8  or by increasing the height of a single hub structure (not shown). The stacked configuration is preferred as providing a sturdier structure. This also serves to prevent interference between the elevator and other structure which may be present on the top of bottom wall  35  such as upward projections  42  or structure present on the top of turn member  28 . 
     The invention provides a dispenser of simple construction which provides the desired function of dispensing while preventing breakage of the screw and which can be made at a reasonable cost. The invention provides an improved dispenser by modification of existing components such that no additional materials are required or added steps in assembly. The features of the invention may be incorporated into existing molds and, thus, the structure and assembly are inexpensive and not complex while providing an improved dispenser. 
     The exemplary embodiments herein disclosed are not intended to be exhaustive or to unnecessarily limit the scope of the invention. The exemplary embodiments were chosen and described in order to explain the principles of the present invention so that others skilled in the art may practice the invention. As will be apparent to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.