Exhaust gas muffler

Abstract

An exhaust gas muffler for an engine, the exhaust gas muffler having a body, at least one inlet for the exhaust gas from the engine on the body, a baffled chamber in the body to receive exhaust gas from the at least one exhaust gas inlet, at least one exhaust gas outlet from the baffled chamber to vent the exhaust gas from the baffled chamber, at least one fresh-air inlet on the body, a heat exchange conduit extending into the baffled chamber between the fresh air inlet and the at least one exhaust gas outlet, the heat exchange conduit being sized and shaped to permit heat exchange between the fresh air and the exhaust gas in the baffled chamber, and a fresh air outlet on the heat exchange conduit, the fresh air outlet being sized, shaped and located relative to the exhaust gas outlet to permit the fresh air to mix with exhaust gases being vented from the baffled chamber to lower an exit temperature of the exhaust gases.

Description

FIELD OF THE INVENTION [0001] This invention relates to the general field of exhaust systems, and more particularly to mufflers used with internal combustion engines. BACKGROUND OF THE INVENTION [0002] Internal combustion engines generate by products of combustion often referred to as exhaust gases. Typically, for noise control the exhaust gases pass through a muffler and tailpipe before being released. Such engines and their associated exhaust systems are ubiquitous, being used to power all types of motor vehicles as well as smaller, more specialized vehicles and devices such as, for example, golf carts, ATV's, lawn tractors, power generators, and other turf and industrial equipment. [0003] The exhaust gases from an internal combustion engine can be very hot, for example, over 1000° F. Such high temperatures can affect muffler components, in particular causing mufflers to wear out and require replacement faster than otherwise. Another problem is that the high exhaust temperature ma...

AI Technical Summary

Benefits of technology

[0008] Preferably, the operating temperature inside the muffler will be reduced, so that the muffler components are subjected to less heat stress and thereby achieve enhanced durability. The temperature of the exhaust gas output from the muffler will preferably also be reduced, producing a corresponding reduction in the risk of ignition of foreign materials and of back firing. It would be preferable as well if a heat shield or other bulky external device is not required, so that the muffler may be made as small as possible and thus more easily integrated into the existing motor compartments of the various internal combustion engine vehicles and devices.

Problems solved by technology

The exhaust gases from an internal combustion engine can be very hot, for example, over 1000° F. Such high temperatures can affect muffler components, in particular causing mufflers to wear out and require replacement faster than otherwise.

Another problem is that the high exhaust temperature may cause“after bang” or “back firing” when unburnt or semi-burnt hydrocarbons, which may be contained in the flow are ignited upon contact with hot muffler components.

High exhaust temperatures therefore are a potential safety hazard.

Also, since the motor compartment in smaller vehicles is more crowded, the heat emanating from a very hot muffler is more likely to have an adverse affect on the performance or durability of neighbouring components.

Thus, problems of high temperature exhaust gases can be more acute in smaller vehicles and motors.

As such, the muffler, if it gets very hot, becomes a safety hazard to users of the motorized device.

However, the outer insulation in this type of muffler also magnifies the problem of high internal and tailpipe exit temperature for the exhaust gases.

While these devices produce some cooling, the effect is limited since the cool air only passes past the outer skin of the muffler.

Further, the external heat shield adds bulk to the muffler, which can be a problem particularly in smaller vehicles where the space is not available.

This may force a costly redesign of the motor compartment and lead to a larger overall device.

Also the external heat shield adds weight and expense to the muffler, and is not that easy to fabricate.

Accordingly, in the absence of a more effective solution the durability and safety problems inherent to mufflers operating with high temperature exhaust are likely to continue.

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