Exhaust pipes and assemblies

Details Exhaust pipes and assemblies Exhaust pipes and assemblies

2000-08-31

2002-06-04

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

Exhaust gas or exhaust system element heated, cooled, or...

C060S323000, C060S321000

Reexamination Certificate

active

06397589

ABSTRACT:

BACKGROUND
Internal combustion engines, both reciprocating and rotary engines, burn fuel to generate power. The combustion process produces an ongoing stream of hot combustion gases. The chemical composition of the stream of hot combustion gases is toxic to human ingestion. Under some conditions, the chemical composition of the hot combustion gases coming from an internal combustion engine is further combustible, and potentially explosive. The heat in the hot combustion gases must be removed from the engine on an ongoing basis in order to maintain a suitable operating environment in which the engine can operate.
To the extent the engine is mounted in an open air environment outside any enclosing structure, the exhaust gases can be vented into the open surroundings around the engine optionally through a scrubbing device and/or a sound attenuation device. However, in many applications, internal combustion engines are housed in relatively closed spaces, such as in engine compartments of land-based motor vehicles, in engine compartments of smaller watercraft, or in effectively totally enclosed quarters of e.g. ocean-going ships. Venting exhaust gases into the environment immediately surrounding the engine in such enclosing environments is unacceptable considering toxicity of such gases, considering combustibility of such gases, and considering heat content of such gases.
Accordingly, it is common practice to mount a ducted exhaust system to such engines, to duct the gases and heat away from the engine, to a safe location where the gases and heat can prudently be vented to the ambient open-air environment. Such ducted exhaust system can be as simple as a tubular pipe connected to an exhaust passage on the engine, leading to a safe venting location. In the alternative, the exhaust system can be quite elaborate in terms both of ducting of the gases and/or passing the gases through additional processes such as through a catalytic converter and/or through a muffler, before finally venting the resultant gases to the open air. Typically, the more sensitive the environment within which the engine is operating, or the more powerful the engine, the more elaborate and/or more sophisticated the exhaust system.
This invention relates to exhaust systems designed for high performance internal combustion engines, recognizing that the concepts utilized in the invention apply as well to exhausting hot gases generated by other sources. Accordingly, it is contemplated that the teachings here, and the claims which follow, will be construed as applying to such other heat sources to the extent the apparatus and methods disclosed here apply to such heat sources.
More specifically, this invention relates to exhaust systems, and especially to manifold pipe assemblies, and manifold pipe clusters in such exhaust manifold assemblies and exhaust systems. Such pipe assemblies, pipe clusters, manifold assemblies, and exhaust systems are used for collecting and disposing of heat and hot gases received from a source of heat and hot gases. Such heat and hot gases are commonly generated in large quantities by high performance internal combustion engines, for example engines capable of developing 350 or more horsepower, such as 1000 horsepower, 1500 horsepower, 2500 horsepower and more with which exhaust apparatus of the invention is suitably used.
Tubular metal manifold pipes are commonly mounted to exhaust passages on the engine to convey heat and exhaust gases away from the engine, and away from the engine compartment or other actual or functional enclosure in which the engine is disposed. Such manifold pipes receive the gases and heat expelled from the engine during exhaust cycles of the respective combustion chambers. Combustion gases and unburned fuel, along with the associated heat, are expelled from the engine through one or more exhaust passages. When a particular combustion chamber is in the exhaust stage of chamber operation, the piston or rotary vane, or other containment structure containing the combustion, forces the exhaust gases out of the combustion chamber through one or more such exhaust ports. Opening and closing of the exhaust ports may be regulated by, for example, exhaust valves in a four cycle engine. During an exhaust cycle of such four-cycle engine, the exhaust valves are lifted to open the exhaust ports through which the gases can escape. When a given exhaust cycle is finished, respective exhaust valves are returned to their closed positions.
Many engines contain or comprise multiple combustion chambers, namely cylinders, which may be aligned in one or more rows or other arrangements, each combustion chamber having its own exhaust requirements and corresponding exhaust apparatus for receiving, conveying, and treating exhaust gases. In high performance engines, individual exhaust manifold pipes are typically assigned to respective individual combustion chambers. Typically, the multiple manifold pipes, associated with multiple respective combustion chambers, are secured to each other at ends of the manifold pipes disposed away from the engine exhaust passages. The ends of the multiple manifold pipes are mounted to a manifold mounting bracket at the engine. The manifold mounting bracket has receiving apertures suitably sized, configured, and positioned to receive the respective manifold pipes in suitable orientation for alignment of the bracket receiving apertures and the manifold pipes with corresponding exhaust passages of the engine. Open pipe ends are, for example, inserted into the apertures in the manifold mounting bracket and are secured to the bracket such as by welding closed those portions of the apertures disposed outwardly of the manifold pipes.
The manifold mounting bracket is mounted securely to the engine by e.g. mounting bolts which extend through corresponding mounting holes in the mounting bracket, and which are turned into threaded holes in the engine. Such mounting brings the manifold bracket receiving apertures and the open ends of the manifold pipes into alignment with respective exhaust passages of the engine. Such alignment creates sealed continuous paths for flow of exhaust gases from the combustion chambers, through the exhaust passages of the engine, through the receiving apertures of the manifold bracket, and through the manifold pipes of the exhaust system, and thus away from the engine.
The engine exhaust passages are typically short, cylindrical apertures leading from respective combustion chambers, through respective exhaust ports, toward outside ambient environment.
The manifold bracket thus serves as an interface, mating the intake ends of the manifold pipes with the exhaust passages of the engine. The plurality of manifold pipes thus connected to the engine are sometimes referred to as a manifold pipe cluster.
In a multiple-cylinder engine, distal outlet ends of multiple ones of the manifold pipes may be received in common into an intake end of an exhaust pipe, which collects exhaust gases from two or more of the manifold pipes, and further conveys the exhaust gases and heat away from the engine. When so combined with an exhaust pipe downstream of the manifold pipe cluster, the combination assembly is generally referred to as an exhaust manifold assembly. Typically, a given multiple cylinder engine may have as few as one exhaust pipe, up to as many exhaust pipes as the engine has cylinders. The exhaust manifold assembly, in combination with any other components used therewith, such as catalytic converter, muffler, tail pipe, etc., defines the exhaust system.
Exhaust gas temperatures at the manifold mounting bracket can be greater than 1000 degrees Fahrenheit. High temperature of the exhaust gases is desirable for high power output from the engine, but places a high degree of stress on the manifold pipes. Namely, excessively high temperatures at especially the intake ends of the manifold pipes can lead to premature failure of conventional exhaust manifold assemblies, compromising the ability of the exhaust manifold assembly to remove the heat and exhaust gase

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