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HYPODERMIC INJECTION DEVICE WITH SHOCK ABSORBING SPRING

  • US 3,797,489 A
  • Filed: 02/10/1972
  • Issued: 03/19/1974
  • Est. Priority Date: 02/10/1972
  • Status: Expired due to Term
First Claim
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1. In a hypodermic injection device comprising a gun, a cartridge holder having a closed end and in operative relationship to the gun, a cartridge within the holder, said gun comprising a sleeve open at one end thereof, a plunger positioned within the sleeve, spring power means acting on said plunger tending to move it out the open end of the sleeve, restraining means cooperating with said plunger to prevent plunger movement, safety means acting on said restraining means to render it inoperative, said cartridge holder comprising a hollow shell acting as a prolongation of the gun sleeve, a puncturable seal closing off the end of the holder remote from the gun, said cartridge including an ampoule comprising a hollow cylindrical sleeve, a piston slidably positioned in one end thereof and means mounting a cannula extending from and closing off the other end, a fluid within the cylindrical sleeve between the piston and the cannula, the cartridge fitting within the cartridge holder with the free end of the cannula within the closed end of the holder, the improvement comprising:

  • shock absorbing and retracting spring means interposed between the cannula end of the cartridge and the closed end of the cartridge holder, said shock absorbing and retracting spring means being sized whereby it is compressed by the cartridge and acts as a shock absorber as said cartridge moves under the force of the spring power means until the cannula is fully projected into the patient, the shock absorbing and retracting spring means being further characterized by having a compressed spring force when the cannula is fully projected into the patient and injection begins under the continuing expansion of the spring power means to overcome the force of the spring power means and retract the cannula while injection continues and is completed.

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