Afterburner for a fuel-burning heater and method of construction

An afterburner for a fuel-burning heater having a combustion chamber and wherein the combustion chamber includes a discharge end through which products of combustion exit the combustion chamber, the afterburner comprising:

• a ring portion generally perpendicular to the movement of combustion products and securable to the remainder of the heater for maintaining the afterburner adjacent the discharge end of the combustion chamber and having a central opening;
• a nose cone portion attached to first inner edge sections of the ring portion so as to be positioned substantially in registry with the central opening thereof and including peripheral edge portions, and the ring portion having second inner edge sections adjacent the central opening which are spaced longitudinally from the peripheral edge portions of the nose cone portion so that the spacings provided between the second inner edge sections and the peripheral edge portion of the nose cone portion provide passage ways through which products of combustion move through the afterburner;
• the peripheral edge portions and the second inner edge portions are in overlapping relationship so that the flow of combustion products exiting the discharge of the combustion chamber is changed in direction as the flow moves through the passageway-providing spacings of the afterburner;
• and
• the ring portion and nose cone portion are constructed as a unit of a single piece of material.

An afterburner positionable adjacent the discharge end of the fuel-burning heater through which products of combustion exit the heater, said afterburner comprising:

• a nose cone portion having a nose and a skirt extending about the nose and terminating in peripheral edge portions, the nose cone portion being arranged substantially centrally of the discharge end of the heater and oriented so that the nose of the nose cone portion is directed in a downstream direction relative to the flow of combustion products through the discharge end and adjacent the discharge end;
• a ring portion generally perpendicular to the movement of combustion products and securable to the remainder of the heater for maintaining the afterburner in position adjacent the discharge end and attached to the heater so as to support the nose cone portion centrally of the discharge end as aforesaid, the ring portion including a central opening and inner edge sections adjacent the central opening, the inner edge sections being disposed upstream of the nose cone portion when the ring portion is secured to the remainder of the heater, the ring portion including a plurality of spokes integrally formed with and joined to the nose cone portion so that the peripheral edge portions of the nose portion and the inner edge sections are spaced longitudinally from one another so that the spacings therebetween provide passageways through which products of combustion are directed as the combustion products exit the heater, the peripheral edge portions and the inner edge sections disposed in an overlapping relationship as the afterburner is viewed in a direction corresponding with the downstream direction of flow of combustion products through the discharge end.

An afterburner for use with a fuel-burning heater having a combustion chamber assembly having an inner shell providing a combustion chamber for the heater and having a discharge end and an outer shell positioned about the inner shell and provided with preformed openings adjacent the discharge end of the inner shell, the afterburner comprising:

• a ring portion generally perpendicular to the movement of combustion products and having a central opening;
• a nose cone portion attached to first inner edge sections of the ring portion so as to be positioned in registry with the central opening thereof and including peripheral edge sections;
• the ring portion having second inner edge sections adjacent the central opening which are spaced longitudinally from the peripheral edge portions of the nose cone portion so that the spacings provided between the second inner edge sections and the peripheral edge portions of the nose cone portion provide passage ways through which products of combustion exit the combustion chamber;
• and
• the ring portion including a plurality of tabs associated with the inner edge sections so as to extend radially outwardly therefrom and cooperable with the inner shell and outer shell so that when the afterburner is disposed in an operative position adjacent the discharge end of the inner shell, each tab is received by a corresponding one of the preformed openings provided in the outer shell and so that as the inner shell lengthens and contracts relative to the outer shell in response to a change in temperature of the inner shell, each tab of the ring portion is permitted to move within its corresponding preformed opening to accommodate a change in position of the afterburner longitudinally of the outer shell.

A combustion chamber assembly for a fuel-burning heater comprising:

• an inner shell providing a combustion chamber for the heater and including an inlet end through which fuel and air enter the chamber for ignition and an opposite discharge end through which products of combustion exit the combustion chamber;
• an outer shell supported in a spaced relation about the inner shell and having means disposed adjacent the discharge end of the inner shell providing at least one preformed opening;
• an afterburner including:
• (a) a ring portion generally perpendicular to the movement of combustion products and positioned adjacent the discharge end of the inner shell and having a central opening;
• and
• (b) a nose cone portion attached to first inner edge sections of the ring portion and supported in registry with the discharge end of the inner shell, the ring portion having second inner edge sections adjacent the central opening which are spaced longitudinally from the peripheral edge portions of the nose cone portion so that the spacings provided between the second inner edge sections and the peripheral edge portions of the nose cone portion provide passageways through which products of combustion exit the combustion chamber;
• and
• the ring portion including at least one tab joined thereto so as to extend radially outwardly from the inner edge sections and wherein each tab is accepted by a corresponding preformed opening provided in the outer shell, the ring portion cooperating with the inner shell and outer shell so that as the inner shell lengthens and contracts relative to the outer shell in response to a change in temperature of the inner shell, each tab of the ring portion is permitted to shift within its corresponding preformed opening to accommodate a shift in position of the afterburner along the length of the outer shell.

A method of making an afterburner for the combustion chamber of a fuel-burning heater wherein the afterburner is to include a ring portion securable to the remainder of the heater and a nose cone portion and wherein the ring portion is to include a central opening and inner edge sections adjacent the central opening and the nose cone portion is to include peripheral edge portions which are spaced from the inner edge sections of the ring portion, the method including the steps of:

• providing a blank of sheet metal;
• forming the blank in a first press operation to shape the ring portion and the nose of the nose cone portion;
• lancing the blank to sever the inner edge sections of the ring portion from the remainder of the blank along preselected paths so that the peripheral edge portions of the nose cone portion are disposed on the side of each preselected path opposite the corresponding inner edge section;
• forming the blank in a second press operation so that the peripheral edge portions of the nose cone portion are moved in a direction having a component oriented substantially normal to the radial plane of the ring portion to space the peripheral edge portions of the nose cone portion from the inner edge sections.