Burner

An underfed burner has an elongated cylindrical body closed at both ends and a feed tube connected between the ends for feeding an air and gas fuel mixture into the burner through an entry portal. A pressure dispersing baffle is formed within the entry portal integral with the body of the burner and deflected downwardly into the interior of the burner. The baffle is in the form of two flaps supported by a rib integral with the body of the burner and extending across the entry portal. The baffle is formed by a die and a punch carried by the die. The die forms a depression about the opening created by the deflected baffles to define the portals and extends gradually longitudinally away from the flaps while the punch cuts the material to form the portal, the rib and the baffle flaps. A pair of mandrels enter the body of the burner from respective ends to provide support for the die and punch. One of the mandrels carries a pivotable support member which is pivoted into operative position by a cam carried by the other mandrel.

BACKGROUND OF THE INVENTION 
This invention relates to a gas burner of the type used extensively in gas 
fired fireplaces, in decorative gas logs used in fireplaces and in certain 
commercial dryers, and more particularly to a burner of this type having a 
unitary inlet baffle and a method for constructing a burner with such 
baffle. 
An underfed burner comprises a feed tube which provides a venturi to draw 
in air along with gas fuel, the feed tube being connected in communication 
with an elongated burner body intermediate closed ends of the body. The 
gas and air mix within the body and produce a flame which burns at outlet 
ports along the length of the body. A burner of this construction permits 
entrainment and mixing of the gas and air to occur totally within the 
burner body itself. Additional mixing space at either side of the burner 
is not required. The problem encountered with the conventional underfed 
burner design is that dynamic pressure is seen at the outlet of the feed 
tube, such pressure causing local disturbances and instability in the 
flame. The instability of the flame at the outlet of the feed tube can 
result in excessive carbon monoxide which is undesirable and, in the case 
of unvented gas fireplace logs, is particularly dangerous and undesirable. 
The prior art thus incorporated a baffle member positioned and welded 
within the burner body to disperse the pressure surge and reduce the 
carbon monoxide to acceptable levels. 
The baffles used in the prior art generally comprise a plate with 
apertures, the plate being positioned within the burner body at the 
location where the feed tube opens into the burner body and a small 
distance within the body in both directions from the opening. The baffle 
permits the gas and air entering into the burner to be dispersed to permit 
mixing in a controlled manner along the length of the baffle plate and 
beyond toward the ends of the burner and exit the burner body at the exit 
ports. The pressure surge at the outlet of the feed tube thereby is 
substantially reduced with a corresponding reduction in local flame 
disturbances. However, the process of locating and welding the baffle 
within the burner body is difficult, labor intensive, time consuming and 
costly. This may be readily understood from the fact that the baffle must 
be held within the body of a burner which has a substantially cylindrical 
configuration with a diameter in the order of approximately 1.25 inch and 
the baffle plate must extend across the body in the area of the entry into 
the body by a feed tube having a diameter also in the order of 
approximately 1.25 inches. Not only must the baffle be held but it also 
must be welded in position. Accordingly, this adds to the cost of the 
burner and also to performance inconsistencies from burner to burner. 
Additionally, welding of the feed tube to the burner body is also a 
difficult process and requires a special drilling operation to raise an 
edge to aid in locating the two tubes and an upstanding surface about 
which a 360 degree weld is made. 
SUMMARY OF THE INVENTION 
Consequently, it is a primary object of the present invention to provide an 
underfed burner having a pressure surge dispersing baffle in the burner 
body which is not required to be assembled into the burner. 
It is another object of the present invention to provide an underfed burner 
having a pressure surge dispersion baffle which is not welded to the body 
of the burner. 
It is a further object of the present invention to provide an underfed 
burner having a pressure surge dispersion baffle which is formed from and 
integral with the body of the burner, the baffle being a pair of wings or 
flaps deflected out of the surface and into the interior of the body. 
It is a still further object of the present invention to provide a method 
of forming a pressure dispersing baffle within the body of an underfed 
burner at the location of the attachment of the gas/air feed tube, the 
method requiring no separate attachment of the baffle to the burner. 
Accordingly, the present invention provides an underfed burner having an 
elongated body closed at each end and having a feed tube connected 
intermediate the closed ends for feeding air and gas fuel into the bumer, 
there being a pressure spreading or dispersing baffle disposed within the 
burner at the air and gas entrance, the baffle being deflected out of the 
body of the burner so that assembly and welding of a separate baffle, as 
in the prior art, is avoided. 
The baffle may be a pair of flaps or wings extending on opposite sides of a 
central portion of the surface of the burner body deflected into the body 
of the burner so that air entry passages are provided between the 
deflected wings and the surfaces from which deflected. 
The integral deflection wing overcomes the difficulties of the prior art 
deflecting baffle since the need for a separate plate positioned within 
and welded to the burner body is eliminated. The deflecting wings are 
formed by a punching operation utilizing a punch within an external die 
operating in conjunction with a mandrel internally positioned within the 
burner body prior to the closure of both ends of the burner. The die has a 
pair of sloped surfaces extending outwardly from a substantially 
cylindrical flattened surface forming the exterior of a housing within 
which the punch may slide, the punch having an inverted Vee cross 
sectional configuration with the central apex forming the undeflected 
portion of the burner body and the walls of the Vee together with the 
outer edge of the body of the punch acting to drive material out of the 
surface of the burner and into the body to form the wings. 
The die and punch act against an internal mandrel or smash bar which 
supports the burner against the forces of the punch and die.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, an underfed prior art burner 10 is illustrated 
in FIGS. 1 and 2, the burner comprising a burner body 12 having an 
elongated cylindrical configuration with the body closed at the ends by 
crimping the body adjacent the ends and forming flat mounting portions 14, 
16 extending from the crimping for attachment to apparatus using the 
burner to provide a flame. Connected to the burner intermediate the ends 
by welding is a fuel feed tube 18 which also has a cylindrical 
configuration, and generally has the same diameter as the burner body 12. 
The feed tube 18 at the end remote from the weldment with the burner has 
an inlet end 20 for receiving gas fuel and for drawing in air by venturi 
action through a plate 22 having a gas inlet orifice 24 as is 
conventional, and may include a conventional gas/air adjustment member 26. 
At the weldment end, the feed tube 18 is received within and welded to an 
outstanding annular edge 28 which is formed during a special drilling 
operation required by the prior art, the drilling operation known as "T" 
drilling. 
Disposed along the surface of the burner body generally diametrically 
remote from the fuel/air inlet is a multiplicity of outlet ports 30 which 
provide a flame front when the fuel mixture is ignited. As aforesaid, 
there is a dynamic pressure which occurs as the gas air mixture exits the 
feed tube and enters the burner body. This pressure distribution creates a 
flame instability at the flame front occurring at the outlet ports 30. 
Accordingly, the prior art provided a baffle in the form of a plate 32 
within the burner body at the disposition of the entry of the fuel tube 18 
and in either direction thereof, the plate having a plurality of apertures 
34 therethrough for dispersing the gas/air mixture as it enters the burner 
body to thereby reduce substantially the dynamic pressure disturbance. The 
baffle plate 32 is located and held within the body of the burner and 
welded in place and, of course, such procedures are difficult and labor 
intensive, and therefore relatively expensive to perform. Additionally, 
the assembly of the fuel feed tube to the burner body by utilizing the 
special drilling operation to assist the welding of the two tubes is also 
difficult and cost ineffective. 
Consequently, the present invention overcomes these problems of the prior 
art by providing an underfed burner having a pressure surge dispersing 
baffle in the burner body at the location of the connection therein by the 
feed tube, the baffle being formed integral with the body of the burner. 
To this end, as illustrated in FIGS. 4 through 6, a pair of wings or flaps 
36, 38 are deflected into the interior of the burner body 12 substantially 
intermediate the ends. It may be noted at this time that the burner 
illustrated in FIGS. 4 through 6 is the same as that illustrated in FIG. 1 
except for the baffle construction and therefore the same reference 
numerals are used, and that the bottom view of the burner of FIGS. 4 
through 6, as in the prior art, is illustrated in FIG. 3. The wings 36, 
38, have respective creases 40, 41, and are formed below the bottom of a 
depression formed by an internally bulging surface 42, 44 extending 
gradually from the outer surface of the burner body longitudinally a small 
distance to the edge of the body from where the wings are deflected, that 
is the portion of the arcuate opening created by the deflection of the 
wings. By the wings or flaps being deflected down into the hollow of the 
burner body 12, the openings define respective fuel mixture entry portal 
46, 48 formed by the space between the upper surface of the respective 
wings or flaps 36, 38 and the lower adjacent edge of the burner body from 
where the wings are deflected, as illustrated in FIG. 6, the wings having 
a rib 45 therebetween. 
In order to form the baffle wings 36, 38, and to deform the wings into the 
burner body to create the burner inlet portals 46, 48, the present 
invention provides a method of punching the burner body at the location of 
the fuel mixture inlet by means of a punch and die apparatus. Thus, as 
illustrated in FIG. 7, the burner body 12 may be supported longitudally by 
a cradle (not illustrated) which is mounted on a table 50, the cradle 
having a cross sectional configuration conforming to an elongated segment 
of the external cylindrical configuration of the burner body so as to 
support the same. The burner body, while the ends are still open, receives 
a respective mandrel 52, 54 through each end for providing a support in 
the area about the location where the baffle wings are to be formed. Each 
mandrel is moved into and out of the burner body by power drive means such 
as, preferably, hydraulic cylinders (not illustrated). 
Mounted above the table 50 is a die assembly including a die member 56 
which may be vertically driven into and out of contact with the burner 
body positioned on the cradle and supported internally by the mandrels 52 
and 54. Movably mounted within a cylindrical cavity 58 forming a guide 
chamber within the die member 56 is a punch 60 having a substantially 
circular cross section and formed at its center with a recess 62 and 
having a pair of cutting and forming portions or prongs 64, 66 extending 
therefrom to complement the upper surface shape of the wings 36, 38 and 
the central rib 45. Preferably, both the die member 56 and the punch 60 
are hydraulically driven vertically. 
The mandrel 52 has a step 68 extending from the main portion thereof, the 
step being a vertically reduced portion of the mandrel and facing in the 
direction of the other mandrel 54. Pivotally mounted in a cut-out in the 
step portion 68 is a support member 70, the support member 70 having a cam 
edge 72 space from the pivot journal 74 and having a configuration for 
complementing and supporting the lower surface shape of the rib 45 an 
adjacent portion of the wings. The support member 70 has a complementary 
shape to that of the recess 62 of the punch and adjacent portions of the 
cutting and forming portions 64, 66. 
The mandrel 54 also has a step configuration with a step 74 extending from 
the main portion facing toward the mandrel 52. At the leading edge of the 
step there is a cam 76 mounted within a slot 78, the cam 76 being adopted 
to contact the cam edge 72 of the support member 70 and cam or force it up 
as the cam 76 forces the member 70 to pivot. The shape of the leading edge 
80 of the cam 76 complements the back 82 of the support member 70. Mounted 
within an inclined channel 84 within the mandrel 54 is a small reset 
spring 86. 
In operation, the mandrel 52 is driven into the burner body 12 and while it 
is moving the mandrel 54 is driven into the burner body also. As the 
mandrel 52 stops its inward movement, the cam 76 engages the cam edge 72 
and begins to force the support member upwardly about the pivot 74 until 
the outer portion is positioned beneath the material which forms the rib 
45. The die member 56 also is driven downwardly as the two mandrels are 
driven inwardly, the die member having forming surfaces 88 which engage 
the burner body 12 form the portions 42 and 44 and the remainder of the 
connecting depression. The punch 60 is activated and acts against the 
burner body in cooperation with the edges 90, 92 at the steps of the 
respective mandrel 52, 54 to cut the openings 46, 48 as the recess 62 and 
the support member 70 support the material which forms the rib 45. As the 
punch, die and mandrels recede from the now formed burner body, the 
support member 70 pivots downwardly and, as the cam recedes into the slot 
78, due to the release of pressure on it, the spring 86 nudges it and 
resets the cam. Thus, it may be seen that a two-piece mandrel operating 
with a die and an internal punch, is utilized the form the burner body and 
may be removed after the baffle portion of the burner is formed. 
Thereafter the ends of the burner body are closed by conventional means. 
With the construction of a baffle according to the present invention, it 
has been found in tests that carbon monoxide levels have been reduced even 
further than the levels provided by the prior art separate baffle plate 
designs. It also appears that results are more consistent, and this 
appears to be the result of the precise control, accuracy and 
repeatability of forming the entry portals 46, 48 as the baffles are 
formed. Thus, the control, accuracy and repeatability of the method of 
forming the baffles and the entry portals is superior to the prior art 
method of locating and welding a separate baffle within the burner body. 
Numerous alterations of the structure herein disclosed will suggest 
themselves to those skilled in the art. However, it is to be understood 
that the present disclosure relates to the preferred embodiment of the 
invention which is for purposes of illustration only and not to be 
construed as a limitation of the invention. All such modifications which 
do not depart from the spirit of the invention are intended to be included 
within the scope of the appended claims.