Flexible piston rod

• US 20050251097A1
• Filed: 06/21/2005
• Published: 11/10/2005
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: Insulet Corporation, M2 Medical Group Holdings, Inc.
• Original Assignee: M2 Medical A/S
• Inventors: Mernoe, Morten
• Granted Patent: US 7,220,248 B2
• Time in Patent Office: Days
• US Class Current: 604/221
• CPC Class Codes: A61M 2005/31518 designed to reduce the overall size of an injection device, e.g. using flexible or pivotally connected chain-like rod members
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/14546 Front-loading type injectors
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump

Abstract

A flexible piston rod includes a piston and a row of elements, each having top, bottom, and lateral surfaces, the top surface of one element being connected to the bottom surface of an adjacent element by a hinge that allows the two adjacent elements to pivot from a first position, where a portion of the top surface of one element abuts a corresponding portion of the bottom surface of the adjacent element and corresponding to a rectilinear, relatively stiff configuration of the piston rod, to a second position wherein the top surface of one element is spaced from the bottom surface of the adjacent element and corresponding to a curved configuration of the piston rod. The lateral surface of each element has first and second mutually-opposed cylindrical surface portions incorporating a thread for meshing with a corresponding thread of an actuator for displacing the piston rod longitudinally.

Claims

1. A flexible piston rod, particularly for use in medicine dispensing devices, comprising a row of elements each having a top surface and a bottom surface as well as a lateral surface, the top surface of one element being connected to the bottom surface of the adjacent element by a hinge means located and adapted to allow the two adjacent elements to pivot from a first position where at least a portion of a top surface of one element abuts a corresponding portion of the bottom surface of the adjacent element, said first position corresponding to a rectilinear, relatively stiff configuration of the piston rod, to a second position wherein said top surface of one element is spaced from said bottom surface of the adjacent element corresponding to a curved configuration of said flexible piston rod.

2. A piston rod according to claim 1, wherein said lateral surface has a first and a second mutually opposed circular cylindrical surface portions incorporating a screw thread for meshing with a corresponding screw thread of an actuator for displacing the piston rod in the longitudinal direction thereof.

3. A piston rod according to claim 2, wherein at least one surface portion disposed between said first and second surface portion is a plane so as to allow co-operation with means to prevent rotation of the piston rod around the longitudinal axis thereof when said screw threads on the lateral surface of said elements are engaged by said actuator screw threads.

4. A piston rod according to claim 1, wherein said portions of said top and bottom surfaces are spaced from said hinge.

5. A piston rod according to claim 1, wherein said elements and said hinges form an integrally molded piston rod molded in one piece from a moldable plastic material.

8. A piston rod according to claim 2, wherein said portions of said top and bottom surfaces are spaced from said hinge.

9. A piston rod according to claim 3, wherein said portions of said top and bottom surfaces are spaced from said hinge.

10. A piston rod according to claim 2, wherein said elements and said hinges form an integrally molded piston rod molded in one piece from a moldable plastic material.

11. A piston rod according to claim 3, wherein said elements and said hinges form an integrally molded piston rod molded in one piece from a moldable plastic material.

12. A piston rod according to claim 4, wherein said elements and said hinges form an integrally molded piston rod molded in one piece from a moldable plastic material.

6. A flexible piston rod comprising a strip of relatively stiff and resilient material having in the relaxed state an arcuate cross section taken transversely to the longitudinal direction of said strip, a longitudinal row of evenly space apertures being provided along the length of said strip for receiving projections of an actuator for displacing said strip in the longitudinal direction thereof.

7. A piston rod according to claim 6 wherein a major portion of the said strip is rolled into a roll when the piston rod is in a least extended condition.