Exhaust air rail manifold

A dual wall, air gap exhaust manifold with an integral inlet connecting flange defining an elongated, internal, air injection passageway enclosed by an L-shaped plate welded over an elongated slot in the flange to form the elongated passageway, the L-shaped plate also being welded over a series of short channels which extend between the elongated passageway and the manifold inlet openings. The elongated passageway has an air inlet connector. The spaced dual walls of the manifold runners are joined together at the flange openings, just downstream of the channels.

BACKGROUND OF THE INVENTION 
This invention relates to exhaust gas manifolds for internal combustion 
engines, and particularly to a specialized dual wall exhaust manifold 
enabling rapid temperature rise of the catalytic converter by removing 
minimal thermal energy from the flow of hot combustion gases from the 
engine, but also by exothermic combustion in the manifold itself resulting 
from a special, relatively simple construction. 
The technology of internal combustion engines has for some years included 
knowledge that post engine combustion in the exhaust manifold of remaining 
combustible components in the exhaust gases reduces pollution from the 
ultimate exhaust gas discharge. Unfortunately, special manifold 
arrangements for accomplishing this have been technologically complex and 
expensive, usually involving a "nest" of hoses and/or tubes to the system, 
a complex louver system, or otherwise. The complexity not only involves an 
initial high cost, but also maintenance problems and expenses over the 
lifetime of the engine. 
SUMMARY OF THE INVENTION 
Ultimately, the invention herein was developed having a dual wall, air gap 
exhaust manifold with an integral inlet connecting flange defining an 
elongated internal passageway enclosed preferably by an L-shaped plate 
welded over an elongated slot in the flange to form the elongated 
passageway, the L-shaped plate also being welded over a series of short 
channels which extend between the elongated passageway and the manifold 
inlet openings. The elongated passageway has an air inlet connector. The 
spaced dual walls of the manifold runners are joined together at the 
flange openings, just downstream of the channels. The dual walls of the 
intake manifold body or log also join together at the outlet port. 
The novel structure provides a relatively simple manifold capable of mass 
production, effective in operation, and free of a series of extraneous 
tubes and hoses. The novel dual wall structure with the air inlets is 
capable of minimum heat sink for the inner liner, for optimum heat up and 
combustion of residual combustible gases, and rapid heating of a 
downstream catalytic converter. 
These and several other features, objects and advantages of the invention 
will become apparent to those in the art upon studying the following 
specification in conjunction with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The manifold assembly 10 comprises a main body 12 from which extend a 
plurality of spaced runners 14, an inlet connecting flange 16 for 
attachment of the manifold to an engine block, and an outlet or exhaust 
flange 18. 
The body or, as it is commonly called, "log" 12 of the manifold is an 
elongated member in flow communication with each of the several runners, 
here shown to be four in number. The illustrated manifold can, for 
example, be for one bank of cylinders of a V-8 engine, there being a 
mirror image duplicate of this manifold on the opposite side of the 
engine. 
The log 12 includes an outer jacket 20 and an inner liner 22. The jacket 
and liner are spaced from each other preferably a controlled amount of 
several millimeters in width to form a dead air space serving as a heat 
insulator between the jacket and liner. The liner will typically be of 
less thickness than the jacket, both preferably being of stainless steel 
or other corrosion resistant material. Integrally extending from log 12 
are the plurality of runners which continue the double wall construction, 
and are to receive exhaust gases from respective ones of the several 
engine cylinders. Connecting the individual runners to the inlet flange 
assembly 16 are individual sleeves 26 (FIGS. 1 and 3). The outer end of 
each sleeve 26 is welded to the two engaging walls of jacket 20 and liner 
22, while the inlet end of each sleeve 26 is welded to the peripheral wall 
of a corresponding through opening of connector plate 16. This sleeve 
arrangement is preferably made in accordance with the teachings in pending 
patent application Ser. No. 151,556, filed May 14, 1993, and entitled AIR 
GAP MANIFOLD PORT FLANGE CONNECTION, referred to above and incorporated by 
reference herein. As noted, jacket 20 and liner 22 are engaged with each 
other circumferentially where they are joined to sleeve 26. Likewise, the 
jacket and liner are engaged with each other where they join discharge 
flange 18. This flange 18 has suitable orifices 18a such as the three 
depicted in FIG. 2, for attachment to an exhaust pipe of conventional or 
air-gap type. 
Inlet flange 16 is an elongated component of substantial thickness, having 
a plurality of bolt-receiving openings 30 (FIG. 1) at spaced intervals 
along its length for attachment to the engine. Shown along its upper edge 
is the special air injection structure to enable ambient air to be 
injected for oxidation purposes into the exhaust gases as they flow from 
the engine to the exhaust manifold assembly. More specifically, an 
elongated passageway 36 extends along the length of flange 16 to be 
adjacent to and overlap all of the plurality of exhaust gas inlet openings 
38 (FIG. 2). This passageway is formed by an elongated slot or channel 40 
(FIG. 7) formed into the upper outer corner of flange 16 as by machining, 
casting or stamping, and terminating short of the opposite ends of the 
flange. A plurality of short channels 42 (FIG. 7) normal to channel 40, 
extend between elongated channel 40 and each of openings 38 so as to allow 
flow communication therebetween. Coveting both elongated channel 40 and 
the plurality of short channels 42 is an elongated, L-shaped cover plate 
50. The upper horizontal leg 50a of cover plate 50 extends over the top of 
channel 40 and is welded to the upper surface of connector plate 16. The 
vertical leg 50b of cover plate 50, which is normal to 50a, extends over 
the side of channel 40 as well as over short channels 42, and is welded to 
the side face of connector plate 16 as well as to the adjacent area of 
sleeves 26, thereby enclosing channels 40 and 42 from the ambient 
atmosphere. An air inlet conduit 60 having a threaded outer end 60a is 
welded to plate 16 at one end of passageway 36, so that oxygen-bearing air 
can be injected into passageway 36 and thus into the hot exhaust gases 
flowing through ports 38 into the exhaust manifold, where further 
combustion occurs, including conversion of carbon monoxide to carbon 
dioxide with the added oxygen, due to the maintained high temperature of 
the exhaust gas and the presence of the additional oxidizing gas, i.e., 
air. The combined heat of the exhaust gases flowing from the engine and 
the further combustion occurring in the exhaust manifold during start-up 
causes the inner liner 22 to rapidly heat to an elevated temperature while 
the outer jacket is thermally insulated by the air gap. The apparatus has 
been found very effective, simple to fabricate, relatively inexpensive, 
and highly effective to oxidize the noxious gases such as carbon monoxide 
and oxides of nitrogen and sulfur emitted from the engine. 
It is conceivable that certain minor variations may be made in the 
illustrated structure which is the preferred embodiment set forth as 
exemplary of the invention. Therefore, the invention is not intended to be 
limited to this specific embodiment, but only by the scope of the appended 
claims and the reasonably equivalent structures to those defined therein.