# US 2018/0023849 A1 · Cryogenic expander with collar bumper for reduced noise and vibration characteristics > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0023849 A1 - Document ID: US20180023849A1 - Status: Published application - Kind: A1 - Application number: 15/654,150 - Filed: 2017-07-19 - Published: 2018-01-25 - Earliest claimed: 2016-07-25 - Assignees: Sumitomo (SHI) Cryogenics of America, Inc. - Applicants: Sumitomo (SHI) Cryogenics of America, Inc. - Inventors: Ralph C. Longsworth - Web page: https://patentgrep.com/patent/US20180023849A1 ## CPC - F25B 9/14: characterised by the cycle used, e.g. Stirling cycle - F25B 2500/12: Sound - F25B 2500/13: Vibrations - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract A cryogenic expander maximizes the energy absorbing capacity of bumpers that prevent the displacer or piston in a pneumatically driven expander from hitting the cold or warm end of a cylinder. A collar at the warm end of the piston which has the same outside diameter as the piston and a lip at the warm end that engages an “O” ring before the piston hits the cold end or bottom of the cylinder. The warm end of the collar also engages an “O” ring before the pistons hits the warm end or top of the cylinder. Having “O” rings that are near the maximum diameter of the cylinder maximizes the amount of energy they can absorb, and thus permits quiet operation of larger size expanders than prior designs. ## Claims ### Claim 1 A cryogenic expander with reduced noise and vibration characteristics, the cryogenic expander comprising: a cylinder; a pneumatically driven reciprocating piston in the cylinder, the piston having a warm piston end and a cold piston end, the piston reciprocating between a warm cylinder end and a cold cylinder end, a distance of travel of the piston in the cylinder between the warm cylinder end and a cold cylinder end being defined as a stroke; a seal at the warm piston end between the piston and said cylinder; a bumper in the cylinder; a collar comprising a lip on a top of the collar, the collar being disposed at the warm piston end, the collar having a length, between the seal and the lip, that is at least as long as the stroke, the collar having an outside diameter that is the same as a diameter of the piston; wherein the lip engages the bumper to prevent the piston from touching the cold cylinder end to reduce noise and vibration characteristics. ### Claim 2 (depends on 1) A cryogenic expander in accordance with claim 1, wherein the lip is either inside or outside of the collar. ### Claim 3 (depends on 1) A cryogenic expander in accordance with claim 1, wherein the lip engages a bumper that prevents the piston from touching the warm end of the cylinder. ### Claim 4 (depends on 1) A cryogenic expander in accordance with claim 1, wherein the cryogenic expander operates on a GM cycle or a Brayton cycle. ### Claim 5 (depends on 1) A cryogenic expander in accordance with claim 1, further comprising a drive stem disposed on an axis of the piston at the warm piston end. ### Claim 6 A cryogenic expander having a pneumatically driven reciprocating piston in a cylinder comprising: a cylinder; a pneumatically driven reciprocating piston in the cylinder, the piston having a warm piston end and a cold piston end, the piston reciprocating between a warm cylinder end and a cold cylinder end, a distance of travel of the piston in the cylinder between the warm cylinder end and a cold cylinder end being defined as a stroke; a piston seal at the warm piston end between the piston and said cylinder; a bumper in the cylinder; a collar comprising a lip on a top of the collar, the collar being disposed at the warm piston end, the collar having a length, between the seal and the lip, that is at least as long as the stroke, the collar having an inside diameter that is at least 90% of the outside diameter; wherein the warm cylinder end comprises a cylinder head with a neck that extends inside the collar, the neck having a neck seal between the neck and the inside of the collar, wherein the lip engages the bumper that prevents the piston from touching the cold cylinder end to reduce noise and vibration characteristics. ### Claim 7 (depends on 6) A cryogenic expander in accordance with claim 6, wherein the lip is either inside or outside the collar. ### Claim 8 (depends on 6) A cryogenic expander in accordance with claim 6, wherein the lip also engages a bumper that prevents the piston from touching the warm end of the cylinder. ### Claim 9 (depends on 6) A cryogenic expander in accordance with claim 6, wherein the cryogenic expander operates on a GM cycle or a Brayton cycle. ### Claim 10 (depends on 6) A cryogenic expander in accordance with claim 6, wherein a pneumatic force that causes the piston to reciprocate acts on the collar. ### Claim 11 A cryogenic expander with reduced noise and vibration characteristics, the cryogenic expander comprising: a cylinder; a pneumatically driven reciprocating piston in the cylinder, the piston having a warm piston end and a cold piston end, the piston reciprocating between a warm cylinder end and a cold cylinder end, a distance of travel of the piston in the cylinder between the warm cylinder end and a cold cylinder end being defined as a stroke; a seal at the warm piston end between the piston and said cylinder; a bumper in the cylinder; a collar comprising a lip on a top of the collar, the collar being disposed at the warm piston end, the collar having a length, between the seal and the lip, that is at least as long as the stroke, the collar having an outside diameter that is less than a diameter of the piston, the collar having a cross sectional area that is less than 20% the cross section area of the piston; wherein the lip engages the bumper that prevents the piston from touching the cold cylinder end to reduce noise and vibration characteristics. ### Claim 12 (depends on 11) A cryogenic expander in accordance with claim 11, wherein the lip is either inside or outside the collar. ### Claim 13 (depends on 11) A cryogenic expander in accordance with claim 11, wherein the lip also engages a bumper that prevents the piston from touching the warm cylinder end. ### Claim 14 (depends on 11) A cryogenic expander in accordance with claim 11, wherein the cryogenic expander operates on a GM cycle or a Brayton cycle. ### Claim 15 (depends on 11) A cryogenic expander in accordance with claim 11, wherein a pneumatic force that causes the piston to reciprocate acts on the collar.