Vacuum insulated exhaust system
OwnerDavid Johnsoninventor
Life of this patent
Estimating the term…
Abstract
A double-walled exhaust pipe is used with an internal combustion engine and includes a first elongate outer tube and a second elongate inner tube positioned concentrically within the outer tube and affixed at the ends. A chamber is created between the inner and outer tubes which extends substantially their entire length and is sealed against the atmosphere by welding at the ends of the tubes. A one-way valve is affixed to the outer tube and in fluid communication with the chamber so that a vacuum having a negative pressure at least 20 inches of mercury can be drawn. The outer tube preferably has a greater wall thickness than the inner tube.
Claims16
A double-walled exhaust pipe for use with an internal combustion engine, comprising:
- a first elongate outer tube;
- a second elongate inner tube positioned concentrically within said outer tube and affixed thereto only at first and second opposite ends thereof;
- a chamber between said inner and outer tubes extending substantially their entire length and being sealed against the atmosphere;
- and
- wherein said chamber has a negative pressure of at least 20 inches of mercury.
The method of constructing a double-walled exhaust pipe, comprising the steps of:
- providing a first elongate outer tube;
- providing a second elongate inner tube positioned concentrically within said outer tube;
- affixing said inner tube and outer tube only at first and second ends thereof, there being no points of contact between the tubes;
- creating a chamber sealed against the atmosphere in a space between said inner and outer tubes;
- and
- drawing a vacuum in said chamber to a negative pressure of at least 20 inches of mercury.
The method of constructing a double-walled exhaust pipe, comprising the steps of:
- providing a first elongate outer tube;
- providing a second elongate inner tube positioned concentrically within said outer tube;
- aligning the tubes axially;
- joining the inner tube to the outer tube at a first end of the pipe by swaging;
- welding said tubes together at said first end along said swaged joint;
- orienting said tubes vertically with the first end at the bottom;
- introducing sand into the space between the tubes through a second end of the pipe as the tubes are vibrated;
- joining the tubes at the second end by swaging and welding them along said swaged joint;
- bending the sand-filled double tube;
- cutting off the welded second end;
- removing sand from the space between the tubes through the second end;
- joining the inner tube to the outer tube at the second end by swaging and welding them along said swaged joint;
- and
- welding one-way valves into the outer tube, one at each end of the pipe, each of said valves being in fluid communication between the space between the tubes and the surrounding atmosphere.
Dependencies are inferred from the claim text.