Abstract:
The dispenser comprises a hollow body formed adjacent its upper end with an inward and downward annular flap. The method involves the molding of the body with the flap inclined upward. A tool is inserted into the open end of the body to fold the flap downward. In assembly, with the tool removed and the flap thus folded, the plunger moves past the flap so that the flap thereafter engages a shoulder on the plunger and forms an obstacle to the subsequent removal, accidental or otherwise, of the plunger.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 09/079,481 filed May 15, 1998 now U.S. Pat. No. 6,053,371. 
    
    
     FIELD OF THE INVENTION 
     This inventionl relates to a pump dispenser. More specifically, this invention relates to a pump dispenser in which a plunger reciprocates inside a hollow cylindrical body. The plunger includes a piston and an upward actuator defining a discharge spout. 
     BACKGROUND OF THE INVENTION 
     The U.S. Pat. 3,062,416 to Cooprider, issued Nov. 6, 1962, discloses a liquid dispenser comprising a hollow body and a one-piece plunger including an actuator/piston. The piston has an enlarged head at its lower end inside the hollow body. Inlet and outlet check valves are provided and a spring urges the plunger upward. 
     In assembly, after the Cooprider plunger is installed in the body, a tool is brought down against the upper end of the body. The lower end of the tool is so shaped as to cause the plastic of the body to be swaged inwardly thus providing a blocking flange to trap the plunger in the body. 
     SUMMARY OF THE INVENTION 
     The present invention is a pump dispenser and a method for making it. The dispenser comprises a hollow body having molded about the inside of its mouth an inward and downward annular flap. A dispenser plunger, which is biased upward by a spring, operates in the body and is held in by the flap. 
     The method involves the molding of the body with the flap extending inward and upward. A tool is inserted into the open end of the body so that it engages the flap and folds the flap to the inward and downward position. With the flap thus folded and the tool removed, the plunger is inserted into the body, engaging the flap and moving downward. The plunger is reduced in diameter above the lower end to define an annular upwardly facing shoulder. Once the shoulder has passed the flap, the flap, directed downwardly, forms an obstacle to the removal, accidental or otherwise, of the plunger. Thus, the plunger is retained in the body. 
     The molding of the flap and the step of folding it down makes unnecessary the swaging step to shape a blocking flange as disclosed, for instance, in the Cooprider patent. 
     The invention also includes plunger lock-down means comprising an outward pin on the actuator portion of the plunger and a bayonet slot in the upper wall of the cylinder body adapted to receive the pin and, after a turn of the plunger, hold the plunger down against the upward force of the spring. 
    
    
     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 an exploded sectional view of the plunger and the body of a dispenser embodying the invention; 
     FIG. 1A is an enlarged fragmentary sectional view of the area of the flap as shown in FIG. 1; 
     FIGS. 2,  3  and  4  are fragmentary progressive views of the insertion of the tool or mandrel into the body to fold the flap downward; 
     FIG. 5 is an enlarged sectional view of an assembled pump dispenser embodying the invention; 
     FIG. 5A is an enlarged fragmentary sectional view of a portion of FIG. 5; 
     FIG. 6 is a fragmentary sectional view taken on the line  6 — 6  of FIG. 5; and 
     FIG. 7 is a fragmentary exploded view showing the actuator portion of the plunger and the upper part of the body. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A pump dispenser embodying the invention is generally designated  10  in FIG.  5 . It comprises a hollow cylindrical body  12  and a cooperating one-piece plunger  14 . Rotatably surrounding the upper end of the body is the threaded closure  16 . 
     Referring more specifically to the body  12 , it is essentially cup-shaped including a bottom wall  18  which is centrally formed with an inlet opening  20  surrounded by a downward tubular connector  22  receiving a dip tube  21 . Above the opening  20  is formed an upward bevelled annular seat  24 . A cylindrical side wall  26  extends upward from the perimeter of bottom wall  18  and terminates in a circular mouth  26 A. 
     The sidewall  26  (FIG. 1) extends upward to include a vent opening  27  and a tapered zone  28  at which the wall flares slightly outward on the inside of the body at surface  30  (FIG. 5) and is thickened as the upper end of the body  12  is approached. Above the tapered zone  28  the side wall is formed on the inside of the body with an annular radial shoulder  32 . From the periphery of the shoulder the side wall extends upward in a cylindrical sleeve  34 . Outward from a midpoint of the sleeve portion extends an integral annular flange  36 , and spaced above the flange the cylindrical sleeve is formed with an outward peripheral bump  38 . 
     The closure  16  (FIG. 5) is a threaded cap comprising a sidewall  40  and a top wall  42  which is formed with an aperture  44  to receive the cylindrical sleeve  34  at the upper end of the body. In installation, there is sufficient “give” in the bump  38  and the margin of the aperture  44  to permit the top wall  42  to snap by the bump so that the cap is entrapped between the bump  38  and the flange  36 . 
     The cap is loosely enough disposed on the sleeve  34  so that it can spin as it is screwed onto the finish (not shown) of a container. The flange  36  will, of course, sit on the top of the finish and be be sealingly compressed thereagainst when the cap is screwed tight. 
     The plunger  14  comprises an elongate tubular piston  50 . The piston  50  is defined by a stem  51  and an enlarged tubular piston head  52 . Intermediate the head and the stem there is formed a narrow annular upward shoulder  54 . The lower end of the head is formed with an annular seal  56  sealingly engaging the inside of the side wall  26  of the body  12 . Inside, above the seal  56 , the head presents an annular downward face  58 . 
     As stated, the plunger  14  is tubular, formed with an axial passage  64  which may be provided with integral inward ribs  66 . 
     At the upper end of the plunger  14  and unitary therewith is the actuator  70 . The plunger  14  is formed therein with a check valve compartment  72  (FIG. 5A) at the lower end of which is an annular lip  74 . A central ball stop  76  extends downward from the actuator head into the upper portion of the compartment  72 . A laterally extending portion of the actuator  70  forms the spout  78  (FIG. 5) having a discharge passage  80 . 
     Both the body  12  and the plunger  14  are molded of a plastic, such as high density polyethylene, which is resilient in thin sections and rigid in thick section. The resilience in thin sections is used to advantage in the lip  74 , piston seal  56  and in the flap  100  adjacent the sidewall  26 , to be explained. 
     The upper end of the plunger  14  and sleeve  34  are formed with interfitting lockdown means. This comprises the diametrically opposed outward pins  110  (FIG. 6) on the plunger  14  and the bayonet grooves  112  in the upper end of the pump body  12 . As shown in FIGS. 6 and 7, the lower locking portion of the grooves is preferably a radial opening  112 A. 
     The valving for the dispenser comprises the inlet check ball  81  which seats on seat  24  at the lower end of the body  12 , and the discharge check ball  82  which seats on the inward lip  74  at the upper end of the plunger. In assembly, the ball  82  is installed by being forcibly inserted through the lip  74  from below. A spring  84  is compressively disposed between the annular face  58  and the bottom wall  18  of the body and urges the plunger upward. 
     The operation of the pump dispenser is as well known in the art exemplified by the Cooprider patent. 
     Attention is now directed to the method by which the dispenser of the invention is made. In the molding of the body  12  an annular inward and upward retaining flap  100  is formed unitary with the body  12  inward from the annular shoulder  32  and at the lower end of the cylindrical sleeve  34 . 
     As shown in FIG. 1A, the annular flap  100  has straight sides and is unitary with the body  12  and as molded extends upward from a juncture  101  at the inward edge of the shoulder  32  and inclines inwardly at a turn  102  at the juncture as shown. The flap  100  extends inward from the turn  102  at an angle of approximately 45° to the horizontal to an inward distal edge  104 . Between the distal edge  104  and the turn  102  the flap  100  tapers slightly, narrowing toward the turn  102 . By having the narrowest width of the flap at the turn  102 , the fold of the flap at the turn during the shaping of the pump body is facilitated. 
     In the preparation of the body  12  (FIG. 2) a tool or mandrel M is inserted into the body. As the lower end of the mandrel M enters the body, it engages the flap  100  (FIG. 3) and deflects the flap to horizontal (FIG.  3 ). Further insertion of the mandrel bends the flap down (FIG.  4 ). The shape thus formed is a downward incline of the flap which could not be molded given the closed lower end of the body  12 . 
     The mandrel M is removed. 
     In the assembly of the pump (FIG. 1) the plunger  14  is inserted into the body  12 . The lower end of the piston head  52  engages the inner side of flap  100 . Further insertion spreads the flap, and as the shoulder  54  (FIG. 1) of the piston passes the flap  100 , the flap  100  snaps inwardly toward the side of the stem  51  of the piston. Any attempt at retraction of the plunger for that matter, will be stopped as the shoulder  54  on the piston engages the distal edge  104  of the flap  100 . The flap thus becomes a lock, entrapping the plunger in the body. 
     The hold-down means shown in FIGS. 6 and 7 is engaged by depressing the plunger  14  while the pins  110  are in line with the vertical portion of the bayonet grooves  112 . The pins  110  bottom out in the bottom of the grooves. The plunger is then turned clockwise to trap the pins  110  in the horizontal runs of the grooves  112  in line with the radial openings  112 A. 
     The present invention provides a low-cost pump dispenser. An important aspect is the structure and method by which the plunger  14  is held in the body  12 . This includes the flap  100 , and the method of shaping the flap as described is also part of the invention. In contrast to what the art shows, this lock involves no additional parts and no special tools or swaging steps. 
     Variations in the product and method invention are possible. Thus, while the invention has been shown in only one embodiment and method, 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.