Hypodermic needle retractor

Claim 2

A syringe, comprising: a tubular body defining a chamber, said tubular body being open at one end to receive a plunger; a needle mounting at the other end of said tubular body; a needle means removably supported by said needle mounting and projecting from said needle mounting away from said tubular body, said needle means having an inner end within said chamber, said inner end being provided with a head means; said piston means connected to said plunger, said piston means being axially movable within said chamber, said piston means including an engaging means at a forward end thereof, said engaging means engaging shoulder means of said needle means located behind said head means when said piston means is moved within said chamber to said other end of said tubular body whereby to grip said needle means so that subsequent movement of said piston means towards said one end draws said needle means into said chamber; and a frangible diaphragm means on said piston means, said head means further including a piercing end to rupture said diaphragm means upon engagement of said engaging means with said head means.

Claim 3

The syringe according to claim 1 wherein said needle means includes a needle housing having a substantially axial passageway extending partway along said needle housing from one end thereof and a hollow needle secured in said axial passageway, and at least one hole in said needle housing wall communicating with said axial passageway.

Claim 4

The syringe according to claim 2 wherein said head means comprises a tapered head on the other end of said needle housing defining a substantially radially outwardly extending, annular shoulder.

Claim 5

The syringe according to claim 1 wherein said needle means comprises a hollow needle removably carried in said needle mounting, said needle having an inner end portion formed with an enlarged head, said inner end portion being mounted on said needle.

Claim 6

The syringe according to claim 1 wherein said engaging means comprises a tubular extension on said piston means, said tubular extension having a radial abutment surface and a tapered opening which engages over said needle head means.

Claim 7

The syringe according to claim 1 wherein said plunger includes a needle receiving housing open at a forward end through said piston to communicate with said engaging means.

Claim 8

The syringe according to claim 6 wherein said housing is open to atmosphere external of said chamber.

Claim 9

The syringe according to claim 6 wherein said housing comprises a substantially cylindrical wall substantially coaxial with said body, a length greater than the length of said needle means and an inner diameter to freely receive said needle means.

Claim 10

The syringe according to claim 1 wherein said frangible diaphragm is formed by a central portion of a cap engaged on said piston means, said cap also constituting a seal member between said piston means and the wall of said chamber.

Claim 11

A hypodermic syringe comprising: a body having a cylindrical wall terminating at one end with a needle mounting, said body providing a chamber to receive a liquid to be injected; a needle movably mounted in said mounting and having a terminal end located in said chamber, said terminal end having a head means; a piston slidably and sealingly located within said chamber and longitudinally movable so as to vary the volume of said chamber; operator manipulable means extending from said piston to enable a user to reciprocate said piston; wherein said piston includes gripping means to engage said terminal end of said needle when said chamber provides a minimum volume, so that subsequent movement of said piston to increase the volume of said chamber draws said needle into said chamber; and housing means in said manipulable means to receive said needle drawn into said chamber.

Claim 12

A hypodermic syringe comprising: a body having a cylindrical wall terminating at one end with a needle mounting, said body providing a chamber to receive a liquid to be injected; a needle movably mounted in said mounting and having a terminal end located in said chamber, said terminal end having a head means; a piston slidably and sealingly located within said chamber and longitudinally movable so as to vary the volume of said chamber; operator manipulable means extending from said piston to enable a user to reciprocate said piston; wherein said piston includes gripping means to engage said terminal end of said needle when said chamber provides a minimum volume, so that subsequent movement of said piston to increase the volume of said chamber draws said needle into said chamber; and housing means in said manipulable means to receive said needle drawn into said chamber.

Claim 13

The syringe of claim 10 wherein said head means includes a head with an abutment surface, said gripping means includes a co-acting abutment surface to engage said abutment surface of said head.

Claim 14

The syringe of claim 10 wherein said piston includes a seal member which slidably and sealingly engages said cylinder wall, said seal member including a frangible diaphragm extending across said gripping means and which is ruptured by said head means when said gripping means is moved into engaging contact with said head means.

Claim 15

A syringe, comprising: a tubular body defining a chamber, said tubular body being open at one end to receive a plunger; a needle mounting at the other end of said tubular body; a needle means removably supported by said needle mounting and projecting from said needle mounting away from said tubular body, said needle means being carried by a needle support removably attached to said needle mounting, said needle support including shoulder means to engage corresponding shoulder means on said needle means preventing movement of said needle means axially with respect to said needle support and away from said tubular body, said needle means having an inner end within said chamber, said inner end being provided with a head means; piston means connected to said plunger and axially movable within said chamber, said piston means including engaging means for engaging shoulder means of said needle means located behind said head means when said piston means is moved within said chamber to said other end of said body whereby subsequent movement of said piston means towards said one end draws said needle means to draw said needle means into said chamber; and a frangible diaphragm means on said piston means, said head means further including a piercing end to rupture said diaphragm means on engagement of said engaging means with said head means.

Claim 16

A syringe, comprising: a tubular body defining a chamber, said tubular body being open at one end to receive a plunger; a needle mounting at the other end of said tubular body; a needle means removably supported by said needle mounting and projecting from said needle mounting away from said tubular body, said needle means being carried by a needle support removably attached to said needle mounting, said needle support including shoulder means to engage corresponding shoulder means on said needle means preventing movement of said needle means axially with respect to said needle support and away from said tubular body, said needle means having an inner end within said chamber, said inner end being provided with a head means; piston means connected to said plunger and axially movable within said chamber, said piston means including engaging means for engaging shoulder means of said needle means located behind said head means when said piston means is moved within said chamber to said other end of said body whereby subsequent movement of said piston means towards said one end draws said needle means to draw said needle means into said chamber; and a frangible diaphragm means on said piston means, said head means further including a piercing end to rupture said diaphragm means on engagement of said engaging means with said head means.

Claim 17

The syringe according to claim 13 wherein said needle means engages within an axial bore in said needle support, the bore diameter and length being such as to frictionally hold said needle means in assembled position for use.

Claim 18

The syringe according to claim 13 wherein said needle means is provided with an enlargement which engages a corresponding groove in said needle support to hold said needle means in assembled position for use.

Claim 19

A hypodermic syringe, comprising: a body having a cylindrical wall terminating at one end and providing a chamber to receive a liquid to be injected; a needle assembly mounted in said one end of said chamber and incorporating a needle; a needle housing within which said needle is secured, said needle housing being provided with head means; a support to which said needle housing is removably attached, with said needle support being attached to a needle support mounting, said needle being movable in said needle support mounting; a piston slidably and sealingly located within said chamber and longitudinally movable by operator manipulable means extending from sa id piston to enable a user to reciprocate said piston so as to vary the volume of said chamber; said piston including gripping means to engage said needle when said chamber provides a minimum volume, so that subsequent movement of said piston to increase the volume of said chamber draws said needle into said chamber; and housing means in said manipulable means to receive the needle drawn into said chamber.

Claim 20

A hypodermic syringe, comprising: a body having a cylindrical wall terminating at one end and providing a chamber to receive a liquid to be injected; a needle assembly mounted in said one end of said chamber and incorporating a needle; a needle housing within which said needle is secured, said needle housing being provided with head means; a support to which said needle housing is removably attached, with said needle support being attached to a needle support mounting, said needle being movable in said needle support mounting; a piston slidably and sealingly located within said chamber and longitudinally movable by operator manipulable means extending from sa id piston to enable a user to reciprocate said piston so as to vary the volume of said chamber; said piston including gripping means to engage said needle when said chamber provides a minimum volume, so that subsequent movement of said piston to increase the volume of said chamber draws said needle into said chamber; and housing means in said manipulable means to receive the needle drawn into said chamber.

Claim 21

The syringe of claim 16 wherein said needle housing is secured to said support by friction, which friction is overcome when said gripping means draws said needle into said chamber.

Claim 22

The syringe of claim 16 wherein said needle housing is mounted in said support by an interengaging annular rib and groove.