Disposable safety syringe having a retractable needle

• US 6,193,695 B1
• Filed: 01/14/2000
• Issued: 02/27/2001
• Est. Priority Date: 01/14/2000
• Status: Expired due to Fees

• Current Assignee: Wayland J. Rippstein Jr
• Original Assignee: Wayland J. Rippstein Jr
• Inventors: Rippstein, Wayland J. Jr.
• Primary Examiner(s): YASKO JR, JOHN D
• Application Number:
  US09/483,225
• Time in Patent Office: 410 Days
• Field of Search: 604/195, 604/192, 604/198, 604/187, 604/110, 604/263
• US Class Current: 604/195
• CPC Class Codes: A61M 2005/3121 via the proximal end of a syringe, i.e. syringe end opposite to needle cannula mounting end
• CPC Class Codes: A61M 2005/3123 having air entrapping or venting means, e.g. purging channels in pistons
• CPC Class Codes: A61M 2005/3231 Proximal end of needle captured or embedded inside piston head, e.g. by friction or hooks
• CPC Class Codes: A61M 2005/3235 triggered by radial deflection of the anchoring parts between needle mount and syringe barrel or needle housing, e.g. spreading of needle mount retaining hooks having slanted surfaces by engagement with correspondingly shaped surfaces on the piston at the end of an injection stroke
• CPC Class Codes: A61M 2005/3242 Needle retraction by vacuum
• CPC Class Codes: A61M 5/315 Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding
• CPC Class Codes: A61M 5/3234 Fully automatic needle retraction, i.e. in which triggering of the needle does not require a deliberate action by the user

Abstract

A disposable syringe assembly generally including a cylinder assembly 10, a needle assembly 20, a piston assembly 30, a seal cap assembly 40, a piston stem 50 and handle 60. The cylinder assembly 10 may be engaged with the needle assembly 20 substantially near the needle end of the cylinder assembly 10 and the cylinder assembly may be engaged with the seal cap assembly 40 near the seal cap end of the cylinder assembly 10. The cylinder assembly 10 may further including a fluid region 14 and an air region 15. As fluid is drawn into the fluid region 14 by movement of the piston assembly 30, air is displaced from the air region 15 through a one-way valve. As fluid is discharged from the cylinder assembly 10, a low pressure is created in the air region 15. When substantially all fluid is discharged from the cylinder assembly, a connector on the piston assembly 30 may engage a connector on the needle assembly 20, and the needle assembly 20 may be disengaged from the cylinder assembly 10 and the needle assembly 20 may be retracted into the cylinder assembly 10.

Claims

1. An improved syringe assembly, comprising:

a cylinder body having a needle end and a seal cap end, the cylinder body having a central axis and an internal through bore extending between the needle end and the seal cap end;

a retainer adjacent the needle end of the cylinder body;

a needle assembly including a hypodermic needle and needle support, the needle support being in scaled engagement with the needle and releasably retaining the needle assembly in sealed engagement with the cylinder body by the retainer;

a piston assembly having a needle end and a seal cap end and including a piston for coaxial telescopic movement of the piston assembly within the internal through bore, and one or more piston seals for effecting a pneumatic seal between the piston and an inner wall of the cylinder body;

a connector for selectively attaching the piston assembly to the needle assembly;

a piston stem having a piston end and a handle end with the piston end attached to the piston assembly for axially moving the piston assembly within the through bore of the cylinder body;

a handle attached to the handle end of the piston stem;

a seal cap assembly attached to the seal cap end of the cylinder body, the seal cap assembly including a seal cap having a piston side and a stem handle side, the seal cap being in pneumatic sealing engagement with the seal cap end of the cylinder body for effecting a pneumatically sealed chamber inside of the cylinder body between the piston assembly and the seal cap assembly, the seal cap assembly including a port for telescopic movement of the piston stem through the port, and including a seal for effecting a pneumatic seal between the seal cap and the piston stem; and

a one-way valve for evacuation of air from within the internal through bore between the piston assembly and the seal cap assembly while prohibiting the entry of air into the internal through bore of the cylinder body.

2. The syringe assembly as defined in claim 1, wherein the cylinder body further comprises:

a frustoconical closure portion having a through bore on the needle end of the cylinder body for supporting and stabilizing the needle assembly within the cylinder body.

3. The syringe assembly as defined in claim 1, wherein the connector includes a male connector and a female connector.

4. The syringe assembly as defined in claim 3, wherein the male connector is secured to the piston and the female connector is secured to the needle assembly.

5. The syringe assembly as defined in claim 1, wherein the one-way valve forms a seal between the seal cap and the piston stem.

6. The syringe assembly as defined in claim 1, wherein the one-way valve is positioned within the seal cap assembly.

7. The syringe assembly as defined in claim 1, wherein the piston stem includes a weakened portion for breaking off the piston stem near the piston end.

8. The syringe assembly as defined in claim 1, further comprising:

a stop-lever substantially adjacent the seal cap, wherein the stop level selectively engages the piston stem for temporarily fixing the axial position of the piston relative to the cylinder body.

9. An improved syringe assembly, comprising:

a cylinder body having a needle end and a seal cap end, the cylinder body having a central axis and an internal through bore extending between the needle end and the seal cap end;

a needle assembly including a hypodermic needle and needle support, the needle support being in sealed engagement with the needle and releasably retained within the needle end of the cylinder body;

a piston assembly having a needle end and a seal cap end and including a piston for coaxial telescopic movement of the piston assembly within the internal through bore, and one or more piston seals for effecting a pneumatic seal between the piston and an inner wall of the cylinder body;

a piston connector mechanically attached to the piston assembly;

a needle connector mechanically attached to the needle assembly and selectively attachable to the piston connector;

a piston stem having a piston end and a handle end with the piston end attached to the piston assembly for axially moving the piston assembly within the through bore of the cylinder body along the central axis;

a seal cap assembly including a seal cap having a piston side and a stem handle side, the seal cap being in pneumatic sealing engagement with the seal cap end of the cylinder body for effecting a pneumatically sealed chamber inside of the cylinder body between the piston assembly and the seal cap assembly, the seal cap assembly including a port for telescopic movement of the piston stem through the port, and the seal cap assembly including a seal for effecting a pneumatic seal between the port and the piston stem; and

a one-way valve for evacuation of air from within the internal through bore between the piston assembly and the seal cap assembly and to prohibit the entry of air into the internal through bore of the cylinder body.

10. The syringe assembly as defined in claim 9, wherein the cylinder body further comprises:

a frustoconical closure portion having a through bore on the needle end of the cylinder body for supporting and stabilizing the needle assembly within the cylinder body.

11. The syringe assembly as defined in claim 9, wherein the connector includes a male connector and a female connector.

12. A method of operating a hypodermic needle inside of a cylinder body having a through bore, a needle end and a seal cap end, the method comprising:

positioning a needle assembly including a hypodermic needle, a needle support and a needle connector within the needle end of the cylinder body;

positioning a piston assembly within the cylinder body, the piston assembly including a piston, one or more piston seals, a piston stem and a piston connector;

inserting the hypodermic needle into a source of fluid;

moving the piston assembly from the needle end of the cylinder body toward the seal cap end of the cylinder body, thereby drawing fluid through the needle assembly into a fluid region inside of the cylinder body and simultaneously displacing air from an air region in the cylinder body through a one-way valve assembly;

inserting the hypodermic needle with the drawn fluid within the cylinder body into a fluid repository;

applying a force upon the piston stem to move the piston assembly toward the needle end of the cylinder body, thereby displacing fluid from within the fluid region in the cylinder body and simultaneously expanding the volume of the air region in the cylinder body without permitting the entry of substantially any air into the air region of the cylinder body, thereby lowering the air pressure in the air region of the cylinder body;

connecting the needle connector to the piston connector;

releasing the needle assembly from its position in the cylinder body; and

reducing the applied axial force upon the piston stem to allow the piston assembly and connected needle assembly to move from the needle end of the cylinder body toward the seal cap end of the cylinder body, thereby retracting the needle assembly into the cylinder body.

13. The method defined in claim 12, wherein releasing the needle assembly from the cylinder body includes shearing a retainer which connected the needle assembly to the cylinder body.

14. The method defined in claim 12, wherein releasing the needle assembly from the cylinder assembly includes breaking a friction fit between the needle assembly and the cylinder body.

15. The method defined in claim 12, wherein retracting the needle assembly further comprises applying a force to the piston stem to fully retract the needle assembly into the cylinder body.

16. The method as defined in claim 12, further comprising:

breaking the piston stem after use of the syringe.