Exhaust collector with primary tube

Details Exhaust collector with primary tube Exhaust collector with primary tube

1996-01-19

1998-03-24

Hart, Douglas

Power plants

Internal combustion engine with treatment or handling of...

By means producing a chemical reaction of a component of the...

60313, 60323, F01N 710

Patent

active

057299730

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention refers to an exhaust collector with primary tubes for collecting exhaust gases from a multiple cylinder combustion engine of the piston-type to a common flow.


BACKGROUND OF THE INVENTION

The most important component in the system for purifying an exhaust gas of a combustion engine is the three-way catalytic converter. It has to convert nitrogen oxides, hydrocarbons and carbon monoxide into nitrogen, water and carbon dioxide. This conversion does not start before the catalytic converter has reached its working temperature of approximately 300.degree. C. To ensure a quick start of the catalytic converter, it is usually placed as near as possible to the engine, considering that it should not be damaged by too high temperatures or gas speeds. This implies that the length of the exhaust tubes between the engine exhaust ports and the exhaust tube collector becomes relatively short.
Through these considerations of the catalytic converter working conditions, it is not possible to optimize the length of the exhaust pipes to exploit a decompression wave of the first order, so that the engine output ratio can be adapted to a suitable range of power and revolutions. If the primary tubes are made as long as desired, this can lead to that it takes an unacceptable long time before the catalytic converter reaches its working temperature. The primary reason why it takes such a long time is the large pipe wall mass and heat exposed surface that must be heated during cold starting.
The demands for a catalytic purification of combustion engines to function optimally within a broad working range has led to different kinds of added equipment being tested for the catalytic converter to reach up to a full working temperature within a reasonable time, specially during cool weather and when the engine is run on low strain.
Consequently, it is known to achieve a reduction of the exhaust dumping at cold starting by using two tandem coupled catalytic converters, one of which is comparatively small and therefore can be warmed up quickly. When the exhaust gases have acquired their normal working temperature, a switching is done from the start converter to the main catalytic converter. Different variants of systems with start and main catalytic converters are known, for example through U.S. Pat. No. 3,44,817, U.S. Pat. No. 4,444,012 and U.S. Pat. No. 4,817,385.
SE 9101125-4 further shows a system where the catalytic converter and the exhaust silencer are dimensioned for low strain. If an increased exhaust resistance is detected, which occurs during a transfer to a higher performance range, a passage past the catalytic converter is opened by means of a valve and the exhaust system is adapted for the high performance area.
However, the solutions described above, using a start and a main catalytic converter as well as valves for switching from one control mode to another, imply price rises and risks for function disturbances in the exhaust purification system.


OBJECT OF THE INVENTION

One object of the present invention is therefore to produce an exhaust collector with primary tubes that is long enough to be able to exploit gas dynamic effects, without the collector system becoming space and material consuming, heavy and prone to extending the warm-up time of the catalytic converter to working temperature.


SUMMARY OF THE INVENTION

This object is achieved, according to the invention, in that the primary tubes are tangentially wound around the collector, and that the primary tube walls nearest to the collector, at least to a substantial part form the peripheral walls of the collector. By having the primary tubes integrated with the collector in this way, the tubes may be given a length advantageous for gas dynamics, without having to take complicated measures to reduce the time that is needed before a catalytic converter connected to the collector system reaches its working temperature.
According to an advantageous variant of the invention, the collector forms an oblong cylindrical chamber to whi

REFERENCES:
patent: 3791144 (1974-02-01), Lang
patent: 3927525 (1975-12-01), Jacobs
patent: 5293744 (1994-03-01), Imagawa

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