Single use disposable syringe
First Claim
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1. A syringe comprising a tubular housing having an entrance for a plunger at one end and an outlet for fluid at the other end, a plunger disposed in said housing and movable relative to the housing between a rear position and a forward position, and means for preventing the plunger from drawing liquid into the syringe once it has been pushed to said forward position;
- wherein said plunger comprises a piston and piston rod releasably coupled to one another, and means for releasably coupling said piston to said piston rod when initially drawing fluid into said syringe as said plunger is moved to said rear position and for disengaging said piston from said piston rod when ejecting fluid from said syringe as said plunger is pushed toward said forward position so that the piston rod cannot pull the piston back to draw more fluid into the syringe, said means for releasably coupling said piston to said piston rod including a spring washer circumferentially disposed about said piston rod and engaging said piston and piston rod when under radial compression and releasing said piston from said piston rod when the radial compression of the washer is released, and means for radially compressing said washer when initially drawing fluid into said syringe as said plunger is moved to said rear position and releasing the radial compression of said washer as said plunger is moved toward said forward position.
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Abstract
A syringe comprising means making it possible to make the plunger integral with the end of the plunger stem during the first filling, and to cause the disconnection between these element during a refilling attempt.
140 Citations
12 Claims
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1. A syringe comprising a tubular housing having an entrance for a plunger at one end and an outlet for fluid at the other end, a plunger disposed in said housing and movable relative to the housing between a rear position and a forward position, and means for preventing the plunger from drawing liquid into the syringe once it has been pushed to said forward position;
wherein said plunger comprises a piston and piston rod releasably coupled to one another, and means for releasably coupling said piston to said piston rod when initially drawing fluid into said syringe as said plunger is moved to said rear position and for disengaging said piston from said piston rod when ejecting fluid from said syringe as said plunger is pushed toward said forward position so that the piston rod cannot pull the piston back to draw more fluid into the syringe, said means for releasably coupling said piston to said piston rod including a spring washer circumferentially disposed about said piston rod and engaging said piston and piston rod when under radial compression and releasing said piston from said piston rod when the radial compression of the washer is released, and means for radially compressing said washer when initially drawing fluid into said syringe as said plunger is moved to said rear position and releasing the radial compression of said washer as said plunger is moved toward said forward position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A syringe comprising a tubular housing with forward and rear compartments, said forward compartment having a smaller inside diameter than said rear compartment, said housing having an entrance for a plunger at the rear end thereof and an outlet for fluid at the forward end thereof, a plunger disposed in said housing and movable relative to the housing between a rear position and a forward position, and means for preventing the plunger from drawing liquid into the syringe once it has been pushed to said forward position;
- wherein said plunger comprises a piston and piston rod releasably coupled to one another, and means for releasably coupling said piston to said piston rod when initially drawing fluid into said syringe as said plunger is moved to said rear position and for disengaging said piston from said piston rod when ejecting fluid from said syringe as said plunger is pushed toward said forward position so that the piston rod cannot pull the piston back to draw more fluid into the syringe, said means for releasably coupling said piston to said piston rod comprising;
(a) first and second legs attached to said piston in spaced relation to the forward end of said piston rod so that said legs are movable between a first position wherein said legs extend parallel to one another and to the longitudinal axis of said piston rod, and a second position wherein said legs extend toward one another transversely to the longitudinal axis of said piston rod; (b) engagement means attached to said forward end of said piston rod for engaging said first and second legs so as to couple said piston rod to said legs only when said legs are in said first position; and
,(c) a spring washer circumferentially disposed about said first and second legs so as to define a central aperture wherein said central aperture has a first inside dimension when said spring washer is in the rear compartment of said housing, said first inside dimension being of a size sufficient to permit said legs to remain in said first position while positioned in said central aperture and a second inside dimension when said spring washer is in the forward compartment of said housing, said second inside dimension being of a size sufficient to accommodate said legs in said central aperture only when said legs are in said second position.
- wherein said plunger comprises a piston and piston rod releasably coupled to one another, and means for releasably coupling said piston to said piston rod when initially drawing fluid into said syringe as said plunger is moved to said rear position and for disengaging said piston from said piston rod when ejecting fluid from said syringe as said plunger is pushed toward said forward position so that the piston rod cannot pull the piston back to draw more fluid into the syringe, said means for releasably coupling said piston to said piston rod comprising;
Specification