Medicinal syringe with piston stopper withdrawal and rotation-limiting means
View Patent ↗The syringe is formed according to DIN ISO 11040 and has a syringe barrel ( 1 ) with a syringe head ( 1 a ) formed on one end and a grip plate ( 4 ) formed at the other open end. An elastomeric piston stopper ( 6 ) is insertable in this open end, which is movable back and forth and which has a cruciform-cross-sectioned piston rod ( 7 ) screwed into it. A stop element, which reduces the interior diameter of the syringe barrel, is provided at the open end of the syringe barrel to perform a back-stop function, i.e. to prevent unintended withdrawal of the piston stopper. For this purpose a plastic part ( 2 ) connected to the grip plate ( 4 ) is provided with snap catches ( 3 ), which snap onto the inner side of the syringe barrel ( 1 ). These snap-catches ( 3 ) prevent the piston rod ( 7 ) from being rotated out of the piston stopper and the piston stopper ( 6 ) from being withdrawn from the syringe barrel. At the same time the finger support is enlarged.
1. A medicinal syringe comprising:
a cylindrical syringe barrel ( 1 ) made of glass or plastic, said cylindrical syringe barrel including a syringe head ( 1 a ) at one end of the cylindrical syringe barrel and a grip plate ( 4 ) at another open end of the syringe barrel, said another open end being remote from said one end of the cylindrical syringe barrel, said syringe head ( 1 a ) having a Luer connection cone or a hollow syringe needle integratable therein, said grip plate ( 4 ) being formed as a small strip with a width and a length;
an elastomeric piston stopper ( 6 ) and a piston rod ( 7 ), said piston stopper being insertable in the cylindrical syringe barrel ( 1 ) and provided with a threaded blind hole ( 8 ) for screw connection with said piston rod, said piston rod having a cruciform cross-section; and
a plastic part ( 2 ) fitting with said grip plate ( 4 ) at said open end remote from said syringe head ( 1 a ), said plastic part ( 2 ) comprising a retaining section ( 2 a ), a hood-shaped section ( 2 b ) that fits on said grip plate ( 4 ), and two one-piece snap catches ( 3 ) on opposite long sides of the hood-shaped section ( 2 b ) and in one piece therewith;
in which said retaining section ( 2 a ) is provided with a through-going central passage having a cylindrical inner surface ( 2 i ), said hood-shaped section ( 2 b ) fits on said grip plate ( 4 ) so that said hood-shaped section ( 2 b ) protrudes and extends laterally and outwardly beyond said grip plate ( 4 ) to form an enlarged finger support together with said grip plate ( 4 ), said enlarged finger support having a length (I) that is larger than said length of said grip plate ( 4 );
so that, when said plastic part ( 2 ) is placed on said grip plate ( 4 ), said retaining section ( 2 a ) extends from said open end remote from said syringe head ( 1 a ) toward said syringe head with said cylindrical inner surface ( 2 i ) bearing on an outer surface ( 1 o ) of the cylindrical syringe barrel ( 1 ) and said snap catches ( 3 ) engage over straight sides of said grip plate ( 4 ) and snap on an inner side of the syringe barrel ( 1 );
whereby said plastic part ( 2 ) prevents unintended withdrawal of the piston stopper and rotation of the piston rod through an angle of more than 90° while at the same time providing the enlarged finger support.
2. The medicinal syringe as defined in claim 1 , wherein said grip plate ( 4 ) is formed according to DIN ISO 11040.
3. The medicinal syringe as defined in claim 1 , wherein said grip plate ( 4 ) has a width (w) that is equal to that of the hood-shaped section ( 2 b ) of the plastic part ( 2 ).
4. The medicinal syringe as defined in claim 1 , wherein opposite ends of the hood-shaped section ( 2 b ), which extend beyond said grip plate ( 4 ), are rounded.
5. The medicinal syringe as defined in claim 1 , wherein said plastic part ( 2 ) is formed in one piece as an injection molded part.
6. The medicinal syringe as defined in claim 1 , wherein said plastic part ( 2 ) comprises separate components that are connected with each other.
7. The medicinal syringe as defined in claim 6 , wherein said separate components are injection molded parts.
8. The medicinal syringe as defined in claim 1 , wherein said enlarged finger support has a width (w) equal to said width of said grip plate ( 4 ).