LONG-STROKE ROLLING DIAPHRAGM CYLINDER AND METHODS OF MAKING SAME

• US 20200132067A1
• Filed: 08/26/2019
• Published: 04/30/2020
• Est. Priority Date: 08/27/2018
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Hashemi, Saeed, Durfee, William Keith
• Granted Patent: US 11,300,116 B2
• Time in Patent Office: Days
• CPC Class Codes: B29C 66/432 for making tubular articles or closed loops, e.g. by joining several sheets B29C66/547 takes precedence; bending and joining sheets at right angles to the longitudinal axis of the article being formed and joining the edges B29C53/38; for making hollow articles or hollow preforms
• CPC Class Codes: F03C 1/002 details; components parts
• CPC Class Codes: F03C 1/013 with single cylinder, single-acting piston
• CPC Class Codes: F04B 45/0736 the actuating fluid being controlled by one or more valves
• CPC Class Codes: F04B 53/02 Packing the free space between cylinders and pistons
• CPC Class Codes: F04B 53/143 Sealing provided on the piston
• CPC Class Codes: F15B 15/10 the motor being of diaphragm type
• CPC Class Codes: F15B 2215/305 characterised by the use of special materials
• CPC Class Codes: F16J 3/02 Diaphragms
• CPC Class Codes: Y10T 29/49877 of flexible wall, expansible chamber devices [e.g., bellows]

Abstract

Hydraulic cylinders and methods of fabricating hydraulic cylinders, including long-stroke rolling diaphragm cylinders with any stroke length. In some embodiments, the cylinders are manufactured to have a stroke length to bore diameter (“stroke-to-bore”) ratio optionally greater than 1:1. Various embodiments are suitable for use in a passive hydraulic body-powered wearable robot, for example.

Claims

1. A hydraulic cylinder including:

a body defining a bore having a diameter;

a diaphragm positioned within the body; and

a piston secured to a rod and positioned within the diaphragm;

wherein the diaphragm defines a stroke length of the piston;

wherein the hydraulic cylinder has a stroke length to bore diameter ratio greater than 1;

1.

2. The hydraulic cylinder of claim 1, wherein the diaphragm includes a base material having a coating.

3. The hydraulic cylinder of claim 2, wherein the coating is an elastomer.

4. The hydraulic cylinder of claim 2, wherein the base material is fabric.

5. The hydraulic cylinder of claim 2, wherein the base material is polyurethane.

6. The hydraulic cylinder of claim 1, wherein the diaphragm includes an end enclosed with epoxy.

7. A method of manufacturing a diaphragm comprising:

providing a sheet of base material;

securing the sheet of base material into a cylindrical configuration having a first end, a second end and defining a center axis;

forming slits in the first end to form a plurality of flaps in the base material;

folding the flaps in an overlapping fashion toward the center axis;

securing the flaps in the overlapping fashion;

applying an elastomer to the base material in a vacuum chamber;

curing the elastomer; and

applying an epoxy proximate the flaps.

8. The method of claim 7, wherein the base material is fabric.

9. The method of claim 7, wherein the base material is polyurethane.

10. The method of claim 7, wherein the step of curing includes curing at a temperature between 80 and 85 degrees F.

11. The method of claim 7, wherein the step of curing includes curing for a period of time between 8 and 12 hours.

12. The method of claim 7, further comprising providing a first mold and rolling the sheet of base material around the first mold to form the cylindrical configuration.

13. The method of claim 12, further comprising positioning the first mold and the cylindrical configuration into a mold holder.

14. The method of claim 12, further comprising taping the base material to secure the base material in the cylindrical configuration.

15. The method of claim 14, further comprising drawing a line along the tape at a seam formed by the base material in the cylindrical configuration.

16. The method of claim 15, further comprising tracing the line with a hot knife.

17. The method of claim 12, further comprising removing the first mold from the cylindrical configuration after the base material is secured in the cylindrical configuration.

18. The method of claim 17, further comprising inserting a second mold into the cylindrical configuration;

wherein the first mold has a length greater than a length of the second mold.

19. The method of claim 7, wherein the flaps are secured in overlapping fashion with adhesive.

20. The method of claim 7, wherein the step of forming slits in the first end to form a plurality of flaps in the base material is conducted prior to the step of securing the sheet of base material into a cylindrical configuration.