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Injection apparatus

  • US 3,977,401 A
  • Filed: 03/25/1975
  • Issued: 08/31/1976
  • Est. Priority Date: 03/25/1975
  • Status: Expired due to Term
First Claim
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1. A disposable automatically operated hypodermic syringe for injecting medication into a patient comprising:

  • a. a unitary elongated tubular housing having a first end and a second end, said housing first end having a cylindrical shaped relief in the inner wall thereof extending from the end of the housing to a shoulder formed by the unrelieved adjacent portion of the housing, and the second end of the tubular housing being the injecting end and being provided with a transverse end wall having a centrally located axial aperture therethrough, air escape port means penetrating the side wall of the housing proximate the said second end;

    b. a hypodermic needle supporting piston slidably supported in an intermediate portion of said housing, a hypodermic needle axially supported in and hermetically affixed to the needle supporting piston, and having a sharpened end protruding from a first face of the needle supporting piston in the direction of the first end of the housing, and an elongated stem with sharpened end projecting from a second face of the needle supporting piston in the direction of the second end of the housing, at least one shearable tab affixed to the inner wall of the housing to abut against the second face of the needle supporting piston to maintain the elongated stem of the hypodermic needle retracted within said tubular housing until said syringe is operated,c. an elongated hollow medication cartridge slidably supported in said tubular housing adjacent to and upstream of the needle supporting piston in the direction of the first end of the tubular housing, said medication cartridge having a puncturable transverse end closure in proximity to the needle sharpened end protruding from the first face of the needle supporting piston and a transverse end wall with an aperture therethrough affixed to its other end, a medication cartridge piston slidably supported inside the medication cartridge and positioned adjacent the said other end of the medication cartridge, said medication cartridge being adapted to be filled throughout its remaining interior space with fluid medication;

    d. an internal annular valve recess in the interior wall of said housing at a position distant from the internal surface of the transverse wall at the second end of the housing equal approximately to the combined axial lengths of the needle supporting piston and the medication cartridge,e. a compressed gas cartridge slidably supported in hermetically sealed relation in the housing first end relief, an annular axially compressable spring member supported in said relief between the compressed gas cartridge and the shoulder of the relief, said compressed gas cartridge having a puncturable end closure facing the interior of the housing,f. a cylindrical slidable valve member having a transverse substantially rigid end closure facing the compressed gas cartridge, a pointed penetrator affixed to the end closure with the point proximate the compressed gas cartridge puncturable end closure, at least one port aperture penetrating the slidable valve member cylindrical side wall, the open end of the slidable valve member abutting the medication cartridge,g. a disc shaped depressible closure member affixed to the first end of the housing proximate the adjacent wall of the compressed gas cartridge and adapted when depressed to force the cartridge against the pointed penetrator to release the compressed gas, whereby gas pressure against the slidable valve member urges the medication cartridge into rupturable contact and communication with the hypodermic needle, and whereby said gas pressure forces the needle supporting piston to shear the at least one retaining tab, and to move the needle supporting piston, the needle, the medication cartridge and the slidable valve member together toward the second end of the housing at which position the stem of the hypodermic needle has been inserted into the patient and the slidable valve member is in the internal annular recess in the housing, whereby gas pressure passes into the interior of the slidable valve member and into the medication cartridge to force the medication piston along the length of the medication cartridge thereby injecting the medication into the patient.

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