Supercritical fluid recirculating system for a precision inertial instrument parts cleaner

• US 5,505,219 A
• Filed: 11/23/1994
• Issued: 04/09/1996
• Est. Priority Date: 11/23/1994
• Status: Expired due to Fees

• Current Assignee: James F. Kirk
• Original Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Inventors: Lansberry, Don D., Council, Thomas G.
• Primary Examiner(s): Stinson, Frankie L.
• Application Number:
  US08/344,031
• Time in Patent Office: 503 Days
• Field of Search: 134/195, 134/196, 134/197, 134/111, 134/902, 134/198, 134/200, 134/105, 417/400, 417/401
• US Class Current: 134/105
• CPC Class Codes: B08B 7/0021 by liquid gases or supercritical fluids

Abstract

Fluid cleaning apparatus for precision parts, comprising in combination, a chamber, having a fluid inlet and a fluid outlet, for holding parts to be cleaned and a fluid tight recirculating flow system including the chamber. The fluid tight system directs supercritical carbon dioxide fluid flow across the parts being cleaned. A fluid recirculating cylinder has a first fluid port and a second fluid port connected in the flow system. A fluid piston is in the cylinder between said ports. A pneumatic cylinder has a further piston between a first pneumatic port and a second pneumatic port. A driving member is connected between the pistons for reciprocal movement caused by air from a source alternately introduced to the pneumatic ports to cause the fluid piston to pump fluid through the chamber and back to the recirculating cylinder. A shuttle valve is connected between the air source and the pneumatic ports. Two actuators are responsive to different positions of the driving member for switching the shuttle valve alternately to direct air from the supply to the pneumatic ports and exhaust used air. A plurality of one way valves are in the system to insure that the fluid pumped by the piston exhibits unidirectional flow through the chamber. A filter is connected in the fluid flow system upstream of the chamber.

Claims

1. Precision parts cleaning apparatus using supercritical carbon dioxide fluid for cleaning precision parts, comprising, in combination:

a chamber for holding said parts to be cleaned and having a fluid inlet and a fluid outlet;

a fluid tight recirculator flow system, including said chamber, for directing fluid flow across said parts to be cleaned;

a source of carbon dioxide gas;

pressure pump means and heater means connected to the source to change the gas to supercritical fluid and introduce the fluid to the recirculator flow system for movement by said system;

a recirculating cylinder having a first fluid port and a second fluid port connected in said flow system;

a piston in said cylinder;

a driving member connected to said piston;

a pneumatic motor for moving the driving member and said piston back and forth;

one way valves in said fluid flow system to insure that fluid is driven from the cylinder ports through the chamber unidirectionally to clean said parts, and back to the cylinder ports; and

,

a filter connected in the fluid flow system upstream of the chamber.

2. The apparatus of claim 1 wherein:

said motor comprises a pneumatic cylinder and piston with said piston rigidly connected to the recirculating piston by said driving member whereby pressures of about 3000 pounds per square inch are introduced into and moved through the flow system to even clean in cracks in said parts.

3. The apparatus of claim 2 further comprising:

nozzles for the fluid entering said parts chamber for establishing turbulence in the chamber to improve cleaning of the parts.

4. The apparatus of claim 3 further comprising:

a two position air valve shuttle for directing air against one side of the pneumatic piston for one stroke and against the other side of the piston for the successive stroke; and

means responsive to the position of said driving member to switch said shuttle to reverse the driving member direction.

5. Fluid cleaning apparatus for precision parts, comprising in combination:

a chamber, having a fluid inlet and a fluid outlet, for holding parts to be cleaned;

a fluid tight recirculating flow system including said chamber for directing supercritical carbon dioxide fluid flow across the parts being cleaned;

a source of carbon dioxide gas;

pressure pump means and heater means connected to the source to change the gas to supercritical fluid at about 3000 pounds per square inch and introduce the fluid to the recirculating flow system for movement by said system;

a fluid recirculating cylinder having a first fluid port and a second fluid port connected in said flow system;

a fluid piston in said cylinder between said ports;

a pneumatic cylinder having a further piston between a first pneumatic port and a second pneumatic port;

a driving member connected between said pistons for reciprocal movement caused by air from a source alternately introduced to said pneumatic ports to cause the fluid piston to pump fluid through said chamber due to the driving member and back to the recirculating cylinder;

a shuttle valve connected between the air source and pneumatic ports;

actuators responsive to different positions of the driving member for switching the shuttle valve alternately to direct air from the supply to the pneumatic ports alternately and exhaust used air;

a plurality of one way valves in the system to insure that the fluid pumped by said piston exhibits unidirectional flow through the chamber; and

,

a filter connected in the fluid flow system upstream of the chamber.

6. The apparatus of claim 5, further comprising:

at least one spray nozzle in said chamber connected to receive supercritical carbon dioxide fluid from the recirculating cylinder via the filter and spray it across said parts.

7. The apparatus of claim 5 wherein:

a first fluid path of said system extends from the first fluid port of the recirculating cylinder through a first one way valve to the filter;

a second fluid path of said system extends from the chamber outlet through a second one way valve to the second fluid port of the recirculating cylinder;

a third fluid path of the system extends from the second fluid port of the recirculating cylinder through a third one way valve to the filter; and

a fourth fluid path of the system extends from the chamber outlet through a fourth one way valve to the first fluid port of the recirculating cylinder.

8. The apparatus of claim 7 wherein:

the recirculating cylinder has a first stroke when the piston thereof is moved toward the first fluid port and a second stroke when the piston thereof is moved toward the second fluid port;

said first and second fluid paths establishing circulation of the fluid through the system during the first stroke, and said third and fourth fluid paths establishing circulation of the fluid through said system during the second stroke.

9. The apparatus of claim 8 wherein:

an extractor is connected to receive output fluid from said chamber converted into gas by a pressure drop in order to remove contaminants and solvents from said system.

10. Fluid cleaning apparatus for precision parts, comprising in combination:

a chamber, having a fluid inlet and a fluid outlet, for holding parts to be cleaned;

a spray nozzle in the chamber to receive said fluid;

a fluid tight recirculating flow system including said chamber and nozzle for directing supercritical carbon dioxide fluid flow across the parts being cleaned;

a source of carbon dioxide gas;

pressure pump means and heater means connected to the source to change the gas to supercritical fluid at about 3000 pounds per square inch and introduce the fluid to the flow system for movement by said system;

a fluid recirculating cylinder having a first fluid port and a second fluid port connected in said flow system;

a fluid piston in said cylinder between said ports;

a pneumatic cylinder having a further piston between a first pneumatic port and a second pneumatic port;

a driving member connected between said pistons for reciprocal movement caused by air from a source alternately introduced to said pneumatic ports to cause the fluid piston to pump fluid through said chamber and back to the recirculating cylinder;

a shuttle valve connected between the air source and pneumatic ports;

actuators responsive to different positions of the driving member for switching the shuttle valve alternately to direct air from the supply to the pneumatic ports alternately and exhaust used air;

a plurality of one way valves in the system to insure that the fluid pumped by said piston exhibits unidirectional flow through the chamber; and

,

a filter connected in the fluid flow system upstream of the chamber.