Syringe construction
BACKGROUND OF THE INVENTION 
     As it is well known, the spread of infection by hypodermic needles is a serious problem, especially as one using a hypodermic injector is very likely to touch the needle and be infected by contact. It is also noted that the sequential injection of contents while maintaining the contents separate is a problem not heretofore satisfactorily overcome. It is also noted that the present art of syringes with sealed off compartments within the syringe require prior functions before it can be used. 
     Applicant is aware of the below listed prior patents: 
     
         ______________________________________                                    
                 PATENT                                                   
NAME             NO.       DATE                                           
______________________________________                                    
FLETCHER         1,867,355 JULY 12, 1932                                  
WHITAKER ET AL   2,720,880 OCT. 18, 1955                                  
DEBAZ            2,829,643 APRIL 8, 1958                                  
McCONNAUGHEY ET AL                                                        
                 3,091,240 MAY 28, 1963                                   
STEVENS          3,911,916 OCT. 14, 1975                                  
ONG              3,976,069 AUG. 24, 1976                                  
BARTNER          4,394,863 JULY 26, 1983                                  
WHEELER          4,439,184 MARCH 27, 1984                                 
GAHWILER         4,465,476 AUG. 14, 1984                                  
KAMSTRA          4,496,344 JAN. 29, 1985                                  
MILLER ET AL     4,540,405 SEPT. 10, 1985                                 
BRUNET           4,643,721 FEB. 17, 1987                                  
______________________________________                                    
 
    
     SUMMARY OF THE INVENTION 
     Among the objects of the present invention is to provide a hypodermic injector wherein contents in one or more separate chambers may be reliably injected sequentially from the separate chambers. 
     It is a more particular object of the present invention to provide a closed chamber within a syringe to store the contents free from contact with external objects such as the metal needle. 
     It is a more particular object of the present invention to provide a closed chamber within a syringe and still be able to inject from the syringe without requiring activation of the syringe by motions other than those used in injections. 
     It is a more particular object of the present invention to provide a syringe for sequential injection of two or more materials wherein an intermediate free piston or pistons are slidable in a syringe tube having a circumferential surface in sealing engagement about the interior surface of the syringe tube to separate the contents and being changeable under differential pressure to automatically pass the second or successive contents to be injected. 
     It is a more particular object of the present invention to provide a hypodermic injector for injecting one or more sequential contents with a syringe holder by which the syringe is retained, used and discarded with little chance of coming in contact with the needle. 
     It is another object of the present invention to provide a hypodermic syringe in which the contents are confined by elements within the syringe and a needle cover of ample size and material to prevent accidental puncturing of the administrator. 
     Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings, which form a material part of this disclosure. 
     This invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, which will be exemplified in the construction hereinafter described, and of which the scope will be indicated by the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of a single chamber hypodermic ready for use. 
     FIG. 2 is a longitudinal sectional view of a single chamber hypodermic with the contents stored in an intermediate position in the syringe tube. 
     FIG. 3 is a longitudinal sectional view of a 2 chamber hypodermic ready for use taken along line 3--3 FIG. 10. 
     FIG. 4 is a longitudinal sectional view of a 3 chamber hypodermic ready for use. 
     FIG. 5 is a longitudinal sectional view of a 2 chamber hypodermic using a different configuration of chambers. 
     FIG. 6 is a view similar to FIG. 5 with the material in the one chamber discharged. 
     FIG. 7 is a view similar to FIG. 6 showing the contents of chamber 2 flowing past the free piston. 
     FIG. 8 is a perspective of one type of free piston. 
     FIG. 9 is a perspective of a second type of free piston. 
     FIG. 10 is a cross section of the second type of free piston. 
     FIG. 11 is a cross section generally along line 11--11 of FIG. 10. 
     FIG. 12 is a perspective of a holder for holding the syringe if the syringe is made without a finger flare. 
     FIG. 13 is a cross section generally along line 13--13 of FIG. 12. 
     FIG. 14 is a partial view showing the holder in open and closed position. 
     FIG. 15 is a partial view similar to FIG. 14 with a separate clip member for transferring the holder from its open position to its closed position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now more particularly to the drawings, and specifically to FIGS. 1-7, there is shown a hypodermic needle or syringe, generally designated 20 and including a generally cylindrical tube or cartridge 21, ordinarily of glass or plastic. The tube 21 has an open end 28, the upper end in FIGS. 1-7, open as by an out-turned lip or flange 22. The other, lower end of the cylindrical tube 21 is reduced, as by an end wall or shoulder 23 to a reduced outlet port 24. Thus, the interior of the reducing end wall 23 may provide an annular internal shoulder, as at 25. 
     Extending from the reduced outlet port 24 may be an injection needle 26 communicating with the interior of the tube 21 through a connector 27 or secured to the inside of nipple 24. 
     On a rod 30 extending into the open end 28 of the tube or cylinder 21 is a piston 31 in snug sliding engagement with the interior of the tube. The piston or enlarged head 31 on the rod 30 may be of rubber or other suitable sealing material, and the rod 30 may be provided on its outer end, exteriorly of the tube 21 with a head 32. 
     Interiorly of the tube 21, between the piston 31 and the shoulder 25, there is a free piston 33 also in snug sliding engagement with the interior of tube 21. 
     The free piston 33 may be of a flexible rubber like material and of a hollowed shaped configuration 48 facing toward the end wall 23. This hollowed shape 48 may be circular in shape as shown in FIGS. 5, 6, and 7 or it may be flat and narrow in shape as shown in FIGS. 9, 10 and 11. It may also be filled with a low strength compressible resilient material. More specifically, the free piston 33 includes a closed end 34 of less external diameter than the interior of the tube 21, and a peripheral side wall 35 extending from the closed end 34 obliquely outwardly to the interior of the tube 21. The oblique side wall 35 terminates at its larger end in a generally cylindrical peripheral sealing surface 36 in slideable conforming engagement with the interior of the cylindrical wall of tube 21. Further, free piston 33 has its large end of side wall 35 generally cylindrical, as sealing surface 36, for sealing engagement with the interior of tube 21. As shown in FIGS. 1-4, this sealing surface 36 may be two or more surfaces. The free piston side wall 35 may have external ribs 37 extending generally from the sealing surface 36 to the closed end 34 of the free piston 33. These ribs help to prevent tipping of the piston as it moves in the tube 21. Thus, the free piston 33 is generally hollow, with a generally flat closed end 34, and a flaring side wall 35 terminating in a sealing surface 36. 
     The hollow end 48 is provided with a plurality of lugs 40 as shown in FIG. 4 or a stopper movement inhibitor surface 40A 40A as shown in FIGS. 9 and 10. A path 39 for the contents of the syringe to flow through is generated by the lugs 40 or by the opening in the annular ring 40A. Stopper movement inhibitor surface array of lugs 40 or the stopper movement inhibitor surface 40A is engagable with the internal shoulder 25, the condition shown in FIGS. 1, 6, and 10. 
     As shown in FIGS. 1-4, the free piston 33 can be located in the syringe 20 in different positions to allow different uses of the syringe. FIG. 1 shows the free piston 33 located adjacent to internal shoulder 25. In this position the syringe has only 1 contents chamber 41. FIG. 2 also shows a one contents chamber 41 with the contents stored in the tube 20 still sealed by the inner wall of the tube 21, the piston 31, and the free piston 33. As shown in FIG. 3, two free pistons 33 are used in the syringe 20. The lower free piston 33 located adjacent the internal shoulder 25, the intermediate piston 33A, and the inner wall of tube 21, form the first contents chamber. The intermediate piston 33A, piston 31, and the inner wall of tube 21 forms a second contents chamber. As shown in FIG. 4, three (3) content chambers are shown. The lower or first content chamber is composed of the free piston 33, the needle seal 45, and the inner wall of tube 21. Chamber 2 comprises 2 free pistons 33 and 33A, and chamber 3 comprises a free piston 33A and piston 31. It is possible to add additional chambers therefore merely by adding additional free pistons 33. If a free piston were used as shown in FIG. 1 adjacent surface 25 in the syringe shown in FIG. 4, the lower chamber would be made up of two free pistons 33 and the inner wall of tube 21. In this arrangement the needle seal 45 would not be needed. FIG. 5 shows a two chamber syringe in which a needle seal 45 forms a part of the lower chamber. 
     As a result it has been shown that a free piston 33 can be used to provide a syringe with 1, 2, 3 or more content chambers. 
     In order to discharge the contents from the syringe, the needle seal 45 must be removed from the syringe filled with content as shown in FIGS. 4 and 5. If the syringes are filled as shown in FIGS. 1, 2, 3 it would only be necessary to remove a cover 45A similar to that shown in FIG. 2 if the syringe is a sterile application. If the syringe is not a sterile type application, no cover would be needed on the syringe output port since the contents are sealed inside the syringe. 
     Since accidental puncturing of the administrator of the contents of the syringe is becoming more serious, as an example, administering a medicine to a patient with a serious or contageous disease, a needle cover 45A which helps prevent this accidental puncture is shown in FIG. 2. As previously described, the contents to be injected is contained in the chamber inside the syringe. As a result the needle cover 45A does not have to seal the syringe, but has to keep the needle clean and sterile. This can be accomplished by a cover which employs the principle of &#34;tortous path;&#34; that is, there cannot be a straight path to the item to remain sterilized. As a result tube 21 is provided with a lip 42 with a locking corner 43. The cover 40 is provided with a mating locking corner 44 as well as tapered assembly surface 46. In storage, or prior to use, the cover 40 is assembled to the tube 21 with the tapered assembly surface 45 engaging the lip 42, thus retaining it in position. In using the syringe, the administrator removes the cover 45A by sliding it off the lip 42. The cover 45A is designed to have enough yield at this point to allow for the circumferential stretch. After the needle is used, the needle can be very contageous. As a result the cover 45A or seal 45 must be replaced. As can be seen in FIGS. 2 and 4, the target area to reinsert the needle 26 is much larger in FIG. 2 than in FIGS. 4 and 5. Since the seal 45 shown in FIG. 4 also must be sealable against the needle 26, the material normally used for this function is a rubber or rubber like material. As a result it is possible for the needle even though it has entered the target hole to pierce the material of the seal and puncture the administrator. Besides having a larger target, the cover 45A shown in FIG. 2 can be made of a solid plastic material which cannot be punctured by the needle. In order to prevent the needle from ever becoming reexposed, the cover is reinserted onto tube 21, a greater distance than from which it was removed. Moving this further distance engages locking corner 44 of the cover with locking 43 of the tube 21 thus locking the cover to the tube. An additional flange or shield 47 can be added to cover 45a for further protection as well as aid in reassembly of the cover. 
     After the needle 45 has been removed, pressure applied to head 32 is transmitted to piston 31 and then onto the contents of the chamber adjacent piston 31. If the syringe contents are filled as shown in FIG. 2, this pressure will move the contents and the free piston toward the outlet 24 until the movement inhibitor surface 40a of free piston 33 comes into contact with internal shoulder 25. If the syringe contents are filled as shown in FIGS. 4 and 5 moving of free piston towards the outlet 24 will push the contents 41 to the outlet. 
     Although the free piston 33 is in sealing engagement with the inside of tube 21, due to the resilience of the material of free piston 33 and the interference fit between them, pressure on piston 31, onto contents 41A could have a tendency to push the contents past the seal and mix it with the contents in chamber 41. In order to prevent this, movement of free piston 33 builds up pressure in chamber 41 since the area of the discharge port and the needle 26 is much less than the area of the inside of tube 21. This build up of pressure, causes the free piston 33 to move which not only forces the fluid through the needle 26, but the reactive force of the contents in chamber 41 applies equal and opposite forces to the internal surface 48a of hollow shape 48 of free piston 33. Since fluids under pressure produce equal forces in all directions, the contouring of the internal surface 48 produces additional radial forces to side wall 35 and sealing surface or surfaces 36. 
     As a result the more force applied to the head 32, the higher the sealing force if there is contents in the adjacent chamber, thus preventing the passage of the contents of chamber 41 entering chamber 41A or the contents of chamber 41A entering chamber 41 when contents are in chamber 41. When the contents in chamber 41 is exhausted, no further additional sealing forces are generated. 
     When no further additional sealing forces exist, the sealing force still generated by the resilence of the material and the interference fit still exists. In order to allow the contents of the next chamber to flow to the outlet port 24; the free piston 33 is provided with a method for the content to bypass the free piston when the free piston 33 has engaged internal shoulder 25. 
     The forces generated on the contents by piston 31 when the pressure is applied to head 32 will move the free piston or pistons 21 axially in the tube 33. When the free piston 33 is against the end surface 25, the forces on the contents on the side wall 35 will overcome the resilient material sealing forces of free piston 33. Over coming the resilient material sealing force will cause the side wall 35 to collapse inwardly, since the resilient material sealing forces are lower than the forces related to those provided by piston 31. The circumferential position of the collapsing of the wall 35 of free piston 33 will be indeterminate on free piston designs shown in FIG. 8. In FIGS. 9-10 and 11 and 12, the circumferential position is controlled by the thin wall location in the design. The thinner the wall the weaker the resilient sealing force: as a result the force at which the wall will collapse or move inwardly is controlled by the design of the wall. 
     As shown in FIG. 7, when wall 35 collapses, the contents moves past the wall 35 and into the spaces generated by lugs 40. In FIG. 11 collapse of the thinner wall 35 will allow the contents to flow past the free piston 33 and into the path 39 to the output port 14 and needle 26. 
     Thus in preparation for the dispensation of contents, from a syringe as shown in FIG. 5, a first content is introduced, as at 41, into the tube 21, being located between the tube end 23 and the free piston 33. A second content 41a is contained in the space between the free piston 33 and the piston 31. As the sealing surface 36 of the free piston 33 engages about its periphery in sealing engagement with the interior of the tube 21, the contents 41 and 41a are normally maintained separate and apart. 
     Movement of plunger 31 into the cylinder 21 displaces the fluid 41 out of the cylinder and moves the free piston 33 to a position with the lugs 40 movement inhibitor surface 40a just engaging the surface 25 of the tube end wall 23. 
     Continued movement of the plunger 31, and thus the fluid 41a will create the pressure differential on opposite sides of the free piston 33. As the pressure of fluid 41a is increased on the wall 35 of the free piston 33, the wall 35 will be displaced inwardly, as in FIG. 7, to pass fluid 41a around the plunger 33 and through the interlug spaces 45, as seen in the condition of FIG. 7 for ejection through needle 26. 
     In preparation for the dispensation of contents from a syringe as shown in FIG. 1, a content to be injected is introduced as at 41. Movement of piston 31 inwardly into the tube seats the movement inhibitor surface 40a of the free piston 33 adjacent the surface 25 of tube end 23. Further inward movement of piston 31 causes the flow of the contents past the free piston 33 similarly described above. 
     In preparation for dispensation of contents from a syringe as in FIG. 4, contents are introduced as at 41, 41A and 41B. Movement of piston 31 inwardly into the tube ejects the contents of chamber 41 until movement inhibitor surface 40a free piston 33 is adjacent the surface 25 of tube end 23. Further movement of piston 31 into the chamber moves the contents of chambers 41A past the free piston 33 by the movement of free piston 33A moving the contents out of chamber 41A until the movement inhibitor surface 40a  free piston 33A is adjacent the closed end 34 of free piston 33. Still further movement of piston 31 moves the contents from chamber 41B past the collapsed free piston 33A and collapsed free piston 33 to the outlet port 24 in surface 25. 
     FIGS. 12-13 illustrate a holder constructed in accordance with instant invention. A holder is generally designated 50, as in FIGS. 12 and 13, serves to hold a hypodermic syringe cartridge 51. The hypodermic syringe cartridge 51 is basically the same as the syringe 20 shown in FIGS. 1-7 except that the flange 22 is eliminated. The hypodermic syringe cartridge 51 is shown in longitudinal section in FIG. 13, and in phantom in FIG. 12. The holder 50 may be molded of plastic, or otherwise suitably formed, and includes a transversely enlarged upper end portion or head 52 having a central opening 53 from which extend laterally outwardly a pair of finger holds 54. 
     Depending from respective finger holds 54, spaced inwardly from the ends thereof, are a pair of side members 56 which converge in the downward direction away from the enlarged head 52. The elongated side members 56 extend longitudinally of each other away from the enlargement or head 52. A pair of cross-pieces or transverse members 57 extends between the elongated side members 56 in the region adjacent to the head 52. Thus, the elongated members 56 are free to swing toward and away from each other from the crosspieces 57 to their free ends 58. Advantageously a snap hook 59 is provided adjacent to one end of one elongated side member 56 for a selective holding engagement with the other side member 56. Upon opening of the snap hook 59, the elongated side members 56 spread apart for receiving there between the tube 51 of an ejection device. 
     Further, the tube 51 of the ejection device has its forward end 23 in bearing engagement with inturned ends 60, FIGS. 13 and 14 on the lower ends elongated side members 56. That is, the inturned elements 60 on the ends of the elongated side members 56, serve to retain the tube 51 in position within the carrier or holder 50. 
     More specifically, entering from opposite finger holds 54 of the head 52 partially into the space 53 are a pair of resilient fingers 62. That is, the resilient fingers 62 extend inwardly from opposite side members 54 into the space 53, there terminating short of each other for resilient bearing engagement of the members with the end of tube 51 to position the latter longitudinally in the holder 50. 
     As a result, the tube 51 is held longitudinally between the inturned ends 60 and the resilient fingers 62, while the tube is held laterally with its upper region engaging crossmembers 57 and its lower region held by the elongated side members 56 removeably secured by the snap clip 59. 
     The lower ends of elongated side members 56 of holder 50 are releaseably retained snugly against the tube 51, with the inturned ends 60 engaging about the end 23 of the tube 51, FIGS. 13 and 14. The latch 59 may be opened to release the elongated side members 56, FIG. 14 for movement away from the tube 51, whereby the tube is released for outward swinging movement beyond inturned ends 60 and dropped from the holder 50. 
     A guide member 67 on the upper end of head 52, is provided with a through hole 68 for guiding and retaining rod 30. 
     Thus, an ejector without the flange 22, may be carried by a holder 50 in the manner described above, and a rod 30 with a head 32 applied thereto. 
     FIG. 15 illustrates a slightly modified embodiment wherein elongated side members 56 have a portion of the leg adjacent the inturned ends 60 modified to retain a clip 71 slideable to shift the inturned ends 60 to the holding position with respect to the tube 51 as shown by the solid lines. 
     From the foregoing, it is seen that the present invention provides a syringe for hypodermic injection of contents from a single closed chamber closed by several methods, of sequential contents from separate closed chambers and a holder for the injection device, if desired, all of which are extremely simple in construction and accomplish their intended objects without departing from the spirit of the present invention.