Power plants – Internal combustion engine with treatment or handling of... – Material from exhaust structure fed to engine intake
Reexamination Certificate
1999-03-16
2001-02-06
Jeffery, John A. (Department: 3742)
Power plants
Internal combustion engine with treatment or handling of...
Material from exhaust structure fed to engine intake
C060S300000, C060S302000
Reexamination Certificate
active
06182446
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a multi-cylinder internal combustion engine with at least two cylinder banks each of which includes an exhaust system with a catalytic converter wherein one of the cylinder banks can be made inoperative during partial load operation of the engine.
DE 196 11 363 C1 discloses a multi-cylinder internal combustion engine including two cylinder banks each having several cylinders wherein one of the cylinder banks is always operative while the other can be inactivated during partial load operation. Each cylinder bank is provided with an exhaust system including a catalytic converter. Downstream of the catalytic converters, the separate exhaust gas systems are joined in a common exhaust pipe section, which is then again split to feed two mufflers through which the exhaust gas is discharged to the atmosphere.
During partial load operation, a vacuum is generated in the exhaust system associated with the inactivated cylinder bank upstream of the respective catalytic converter so that the exhaust gas of the operational cylinder bank first flows through its associated catalytic converter. Then however it is returned, by way of the common exhaust pipe section and the catalytic converter of the inactivated cylinder bank, to the cylinders of the deactivated cylinder bank. In this way, the catalytic converter of the deactivated cylinder bank is maintained at operating temperature also during partial load operation so that the exhaust gas emissions are maintained at minimum level when the inactivated cylinder bank is reactivated.
It is the object of the present invention to reliably maintain the catalytic converter of the cylinder bank, while inactivated during partial load operation, at operation temperature in a simple manner, specifically without the need for generating a vacuum upstream of the catalytic converter of the inactivated cylinder bank.
SUMMARY OF THE INVENTION
In a multi-cylinder internal combustion engine having at least two cylinder banks each with an exhaust system including a catalytic converter, wherein one of the cylinder banks can be deactivated when the engine operates only under partial load, the exhaust systems are interconnected by a cross-over structure disposed upstream of the catalytic converters so that exhaust gas can flow also through the catalytic converter of the deactivated cylinder bank and a length compensating element is disposed in at least one of the exhaust pipe sections extending between the cylinder banks and the cross-over structure and the cross-over structure.
The cross-over structure interconnecting the exhaust systems of the different cylinder banks upstream of the catalytic converters provides for heating of all the catalytic converters also during partial load operation of the engine. Part of the exhaust gas of the operational cylinder bank or banks is diverted, by way of the cross-over structure, to the catalytic converter of the exhaust system of the deactivated cylinder bank. All catalytic converters are therefore maintained operational. As a result, exhaust emissions will not increase when the deactivated cylinder bank is reactivated.
The heating of the catalytic converter of the exhaust system of the deactivated cylinder bank is achieved without a need for vacuum generating means since the cross-over structure is arranged upstream of the catalytic converters. With this arrangement, a part of the exhaust gas flows automatically through the catalytic converter of the deactivated exhaust system simply because of the lower flow resistance of this parallel passage.
In order to accommodate thermally caused differential length changes of the exhaust pipes between the cylinder banks and the cross-over structure at least one of the exhaust pipe sections upstream of the catalytic converters includes a length compensating element. Different component temperatures and thermally caused differences in the component length can be accommodated by the length compensating element or elements. The high temperature exhaust gas flows through the exhaust pipe section of the operative cylinder bank upstream of the crossover pipe section and also through the cross-over pipe section so that these pipe structures are hot and thermally expanded. The upstream pipe section of the deactivated cylinder bank, however, assumes a substantially lower temperature. As a result, the different pipe sections expand to different degrees. The length difference between the pipe sections is accommodated by the length compensating element, so that cracks and breaks which could make the engine inoperational are avoided.
With the incorporation of a length compensating element in the cross-over pipe section interconnecting the exhaust systems, the cross-over structure may be arranged in close proximity to the engine upstream of the catalytic converters so that both catalytic converters are heated by the exhaust gas even when one cylinder bank is deactivated. The differential expansions of the exhaust pipes are accommodated by the length compensating element.
There may be only a single length compensating element arranged in one of the exhaust pipe sections between the cylinder banks and the cross-over pipe structure or in the cross-over pipe structure. However, preferably several such length compensating elements are provided, that is preferably one in each exhaust pipe section upstream of the cross-over pipe structure. The length compensating elements can accommodate pull (contraction) as well as push (expansion) forces on the pipes.
In one embodiment of the invention, there is additionally provided a vacuum generating means, preferably an exhaust gas re-circulation arrangement with a conduit extending between the exhaust pipe section of the deactivated cylinder bank and the intake duct of the operating cylinder bank. The exhaust gas re-circulation arrangement has the advantage that additional catalytic converters arranged close to the respective cylinder bank or oxygen sensors can be maintained at operating temperature by the re-circulated exhaust gas.
Another advantage of this arrangement is that thermal energy is drained from the re-circulated exhaust gas that is, the exhaust gas is cooled whereby the density of the re-circulated exhaust gas is increased and higher exhaust gas re-circulation rates and a reduction in exhaust gas emissions can be achieved.
Further advantages and embodiments will be described below on the basis of the accompanying drawings.
REFERENCES:
patent: 5782088 (1998-07-01), Gunther et al.
patent: 44 31 058 (1995-08-01), None
patent: 196 11 363 (1997-06-01), None
patent: 2 311 330 (1997-09-01), None
patent: 2 304 602 (1997-03-01), None
patent: 8-177472 (1996-07-01), None
patent: 9-112254 (1997-04-01), None
Gunther Josef
Klein Herbert
Langrock Dieter
Bach Klaus J.
Daimler-Chrysler A.G.
Jeffery John A.
LandOfFree
Internal combustion engine with at least two cylinder banks does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Internal combustion engine with at least two cylinder banks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Internal combustion engine with at least two cylinder banks will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591098