Abstract:
An apparatus for evacuating liquid condensation from pipe systems which is particularly applicable to exhaust pipe systems in high efficiency furnaces. The apparatus forms a junction sleeve between two pipes and has drainage channels which prevent condensate liquid from flowing from one pipe into the other pipe. A thermoplastic rubber composition of the apparatus dampens noise and vibration in the pipe system. External grooves provide locating features for mounting clamps.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is based on and claims priority to U.S. Provisional Application No. 60/175,522, filed on Jan. 11, 2000. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to pipe systems and more particularly to furnace pipe systems and more particularly to liquid evacuation devices for furnace pipe systems. 
     Drainage of water condensation from furnace exhaust pipes in typical heating systems accumulates in undesirable areas and causes deterioration or damage to heating system components. Water condenses from the atmosphere onto the exhaust pipe walls because the hot gasses which travel in the exhaust pipe contact the exhaust pipe walls which are often much cooler. The difference between the temperature of the hot gasses and the temperature of the exhaust pipe walls causes water condensation to form on the exhaust pipe walls because the quantity of water vapor which may be contained in a volume gas decreases as the gas temperature decreases. When the temperature of a gas is decreased by contact with a cooler surface the gas may become saturated with water vapor so that water will condense out of the gas and onto the cool surface as liquid. Water condensation typically drains along the exhaust pipe walls and accumulates in pools on any horizontal surface. It is desirable to prevent such accumulation of water and thereby extend the useful live of heating system components. 
     U.S. Pat. No. 5,620,302 teaches that drainage holes which are provided in a furnace blower housing allow water to drain out of a furnace blower. However, drainage holes in a blower housing do not prevent water from first entering the blower. The presence of water within the blower may cause deterioration or damage to blower components before the water eventually flows through the blower drainage holes. 
     SUMMARY OF THE INVENTION 
     Accordingly, the invention described and claimed herein relates to a sleeve which provides a junction between a furnace blower pipe and a heating system pipe and which provides means for water condensation drainage away from a furnace blower. The sleeve comprises two generally concentric cylinders, an outer cylinder and an inner cylinder, which are joined by an annular wall. A blower pipe cavity which is formed between the two cylinders on one side of the annular wall is sized to mate with an end of a blower pipe. An exhaust pipe cavity which is formed between the two cylinders on an opposite side of the annular wall is sized to fit an end of a heating system exhaust pipe. The exhaust pipe cavity also serves as a condensate reservoir. At least one protrusion from the annular wall or the outside cylinder into the exhaust pipe cavity forms a pipe-stop which prevents the exhaust pipe from abutting the annular wall thereby providing a space between the annular wall and the exhaust pipe for water condensate to flow. At least one hole through the outer cylinder and into the exhaust pipe cavity provides a condensate exit port from the exhaust pipe cavity. It is a primary advantage of the invention to provide means to drain water from the inner exhaust pipe walls away from the blower and thereby prevent or significantly reduce the flow of water into a furnace blower. 
     It is a further primary advantage of the invention to provide a drainage outlet for water condensation that does not interfere with the operation of a furnace blower. It is still another primary advantage of the invention to provide a condensate evacuation apparatus which is adapted for use on horizontally, vertically or diagonally mounted pipe systems. 
     Those skilled in the art will recognize that the invention is not limited to furnace pipe applications. The apparatus of the invention may be used to evacuate water condensation from a pipe at any number of similar pipe junctions. It is an advantage of the invention to provide a condensation drainage apparatus that can accommodate a wide variety of pipe sizes. These and other objects of the invention will be made apparent in the drawings and in the following detailed description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a bottom perspective view of an exhaust drain sleeve in accordance with one embodiment of the invention. 
     FIG. 2 is a top view of an exhaust drain sleeve in accordance with one embodiment of the invention. 
     FIG. 3 is a bottom view of an exhaust drain sleeve in accordance with one embodiment of the invention. 
     FIG.  4 . is a side view of an exhaust drain sleeve in accordance with one embodiment of the invention. 
     FIG.  5 . is a side sectional view of an exhaust drain sleeve in accordance with one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In one embodiment, the invention comprises an outer cylinder  10  concentric to an inner cylinder  12 . The inner cylinder  12  is attached to the outer cylinder  10  by an annular wall  14 . Each cylinder  10 ,  12  has a blower end  16 ,  18  and an exhaust end  20 ,  22 . The inner cylinder  12  is tapered so that it becomes narrower toward its exhaust end  20 . Thus the inner cylinder  20  is not really a cylindrical but rather frusto-conical in shape. The exhaust end  20  of the inner cylinder  12  protrudes from the exhaust end  22  of the outer cylinder  10 . Conversely, the blower end  18  of the outer cylinder  10  extends over the blower end  16  of the inner cylinder  12 . In a preferred embodiment, the annular wall  14  is proximate to the blower ends  16 ,  18  of the inner and outer cylinders  10 ,  12 . 
     A blower pipe cavity  34  is formed by an inner surface  28  of the blower end  18  of the outer cylinder  10 , the blower side  30  of the annular wall  14  and an outer surface  32  of the blower end  16  of the inner cylinder  12 . The blower pipe cavity  34  is sized to mate with a blower pipe (not shown) so that the inner cylinder  12  fits inside the blower pipe, the outer cylinder  10  fits outside the blower pipe and the annular wall  14  abuts the blower pipe. 
     An exhaust pipe cavity  36  is formed by an inner surface  38  of the exhaust end  22  of the outer cylinder  10 , the exhaust side  26  of the annular wall  14  and an outer surface  40  of the exhaust end  20  of the inner cylinder  12 . The exhaust pipe cavity  36  is sized to mate with an exhaust pipe (not shown) so that the outer cylinder  10  fits outside the exhaust pipe. 
     At least one boss  42  is provided in the exhaust pipe cavity to prevent the exhaust pipe from abutting the exhaust side  26  of the annular wall  14 . The space thus provided between an end of an exhaust pipe and the annular wall  14  is an essential space to provide for the flow of condensate water. In a preferred embodiment, four about equally spaced bosses  42  protrude from an intersection of an exhaust side  26  of the annular wall  14  and the inner surface  38  of the exhaust end  22  of the outer cylinder  10 . 
     The invention provides a plurality, preferably six, of evenly spaced ribs  46  which protrude from the outside surface  40  of the exhaust end  20  of the inner cylinder  12 . The ribs  50  are oriented generally parallel to the axis  52  of the outer and inner cylinders  10 ,  12  and are tapered counter to the taper of the inner cylinder  12  so that rib height decreases toward the annular wall  14 . A short opposite taper  50  of the ribs  46  at the exhaust end  20  of the inner cylinder provides a lead-in shape to allow easy installation of an exhaust pipe. The ribs  46  provide a space  48  between the outer surface  40  of the exhaust end  20  of the inner cylinder  12 . The space  48  between the ribs  46  thus provides for the drainage of condensate water along the exhaust pipe toward the annular wall  14 . As illustrated, the ribs  46  do not completely obstruct an axial space adjacent to the exhaust side  26  if the annular wall  14  because that space is necessary to provide a condensate drainage path. 
     At least one drain hole  54  is provided through the outer cylinder  10  into the exhaust pipe cavity  36  proximate to the intersection between the outer cylinder  10  and the exhaust side  26  of the annular wall  14 . The at least one hole  54  provides a space for condensate water to flow out of the exhaust pipe cavity  36 . In a preferred embodiment, two drain holes  54  are provided and are located as mirror images of each other relative to a plane which bisects the cylinders  10 ,  12  through their central axis  52 . The apparatus may thereby be oriented to function as a condensate drain for horizontally, vertically or diagonally mounted pipe systems. 
     In a preferred embodiment, drain tubes  56  protrude from the outer cylinder  10  so that the drain tube walls surround the drain holes  54  thereby providing drain channels away from the blower pipe. 
     In a preferred embodiment of the invention, four annular rings  58  protrude from an outside surface  60  of the outer cylinder to form two clamp grooves  62  whereby one grove is proximate to each end  18 ,  22  of the outer cylinder  10 . The clamp groves  62  provide for installation of clamping devices so that the clamping devices will not migrate along the outside surface  60  of the outer cylinder  10  in response to system vibrations or other disturbances. Clamping devices are typically used to secure a junction apparatus to a pipe. 
     A preferred embodiment of the invention is a molded of thermoplastic rubber material so that the invention provides a resilient mount between a furnace blower and a heating system exhaust pipe. The use of thermoplastic rubber material also dampens noise and vibration of the heating system. A preferred material is a thermoplastic rubber that is known in the art to be used in 90+ furnace applications. 
     In a preferred embodiment graphic symbols or text  64  are molded into the outer surface  60  of the outer cylinder  10  to indicate the proper orientation for installation of the invention.