Method and apparatus for controlling the movement of fluid to and from a syringe
First Claim
1. A method for aspirating and expelling fluid to and from a syringe comprising the steps of:
- providing an actuator having a cylinder-piston assembly and defining first and second chambers in said cylinder;
admitting a measured quantity of pressurized hydraulic medium to said first chamber in said actuator;
providing a syringe and coupling the motions of the piston of said syringe to the motions of the piston of said actuator;
admitting a quantity of liquifiable gas to said second chamber of said actuator;
whereby the saturated vapor pressure of said liquifiable gas exerts a counter-pressure on said piston in opposition to the pressure of said hydraulic medium.
0 Assignments
0 Petitions
Accused Products
Abstract
A syringe for injecting fluid into a body or for removing body fluids is coupled to move together with the piston of a double acting hydraulic actuator having two chambers. For the purpose of aspirating fluid into the syringe, the second chamber of the actuator has within it a liquifiable gas which exerts a constant pressure on the piston. The expulsion of fluid from the syringe is accomplished by the admission of a hydraulic medium under pressure to the first chamber of the actuator. The apparatus also includes a calibrating mechanism which preselects a quantity of hydraulic medium proportional to the quantity of fluid to be expelled from the syringe.
-
Citations
12 Claims
-
1. A method for aspirating and expelling fluid to and from a syringe comprising the steps of:
-
providing an actuator having a cylinder-piston assembly and defining first and second chambers in said cylinder; admitting a measured quantity of pressurized hydraulic medium to said first chamber in said actuator; providing a syringe and coupling the motions of the piston of said syringe to the motions of the piston of said actuator; admitting a quantity of liquifiable gas to said second chamber of said actuator;
whereby the saturated vapor pressure of said liquifiable gas exerts a counter-pressure on said piston in opposition to the pressure of said hydraulic medium. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An apparatus for aspirating and expelling fluid to and from a syringe, comprising:
-
a syringe;
including a piston moving within a cylinder;an actuator, including a piston moving within a cylinder and defining thereby a first chamber and a second chamber within said actuator; means for supplying a pressurized hydraulic medium to said first chamber of said actuator; means for admitting a quantity of liquifiable gas to said second chamber of said actuator; means for the preselection of the quantity of hydraulic medium admitted to said first chamber of said actuator; and flexible coupling means for providing fluid communication between said actuator and said means for preselection;
said piston of said syringe being coupled to said piston of said actuator to share the motion thereof;
whereby the pressure of the saturated vapor of said liquifiable gas exerts a counter-force on said piston of said actuator. - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
Specification