Double acting stirling engine piston ring

• US 4,582,328 A
• Filed: 12/27/1983
• Issued: 04/15/1986
• Est. Priority Date: 03/02/1982
• Status: Expired due to Fees

• Current Assignee: Mechanical Technology Incorporated
• Original Assignee: Mechanical Technology Incorporated
• Inventors: Howarth, Roy B.
• Primary Examiner(s): Smith, Robert L.
• Application Number:
  US06/565,859
• Time in Patent Office: 840 Days
• Field of Search: 277/75, 277/216, 277/74, 277/27, 277/214
• US Class Current: 277/451
• CPC Class Codes: F16J 9/08 with expansion obtained by pressure of the medium
• CPC Class Codes: Y10S 277/902 Seal for sterling engine
• CPC Class Codes: Y10S 277/91 O-ring seal
• CPC Class Codes: Y10S 277/926 Seal including fluid pressure equalizing or balancing feature

Abstract

A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring'"'"'s surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

Claims

1. A pressure balanced piston ring for limiting the leakage of a high pressure region on one side of the piston ring to a region of low pressure on the opposite side of the piston ring along a cylinder wall, said piston ring apparatus comprising:

a piston ring of low elastic modulus material maintained in a circumferential groove in said reciprocating piston;

two elastomeric seals, positioned on opposite axial sides of said piston ring so as to isolate an inner surface from the high and low pressure regions;

means for balancing the pressure on said inner surface of the piston ring with the average pressure in a leak path between the piston ring and the cylinder wall, thereby rendering friction and wear of the piston ring independent of the high and low pressures; and

means for exerting a predetermined force on said piston ring to maintain contact with the cylinder wall and control the friction between the piston ring and the cylinder wall and leakage between the high and low pressure regions.

2. A pressure balanced piston sealing ring assembly for use in providing a seal between a piston and a cylinder in which is contained one variable pressure region on one side of the sealing ring assembly and an oppositely variable pressure region on the other side of the sealing ring assembly, comprising:

a piston sealing ring;

an inner and outer surface on said piston sealing ring;

a contact surface on said outer surface slidingly engageable with said cylinder;

a first sidewall on said sealing ring exposed to one variable pressure region;

a first elastomeric seal operatively associated with said first sidewall for isolating said inner surface from said one variable pressure region;

a second sidewall on said sealing ring exposed to the oppositely variable pressure region;

a second elastomeric seal operatively associated with said second sidewall for isolating said inner surface from said oppositely variable pressure region;

a leakage path between said oppositely variable pressure regions coupled to radial passageways through said sealing ring for communicating an average pressure to the inner surface of the piston sealing ring so as to balance pressure forces acting on the inner and outer surfaces; and

means for exerting a predetermined force on said sealing ring to maintain said contact surface in engagement with the cylinder so as to provide a seal therebetween.

3. The piston ring assembly of claim 2, further comprising a circumferential groove and two associated steps on said piston, said groove being of an appropriate depth to contain said exerting means and said piston sealing ring and said two steps being of a lesser depth, one elastomeric seal disposed in each step such that each elastomeric seal is maintained in sealing contact between said piston sealing ring and said piston so as to isolate said inner surface.

4. The piston ring assembly of claim 3, further comprising a cylindrical extension on each sidewall exposed to the variable pressure regions such that said sealing ring forms a T-shaped cross section so as to contain said elastomeric seals.