Exhaust flap means

Abstract

An exhaust flap means for motor vehicles comprises a housing (10) in which an exhaust flap (12) is arranged. The exhaust flap (12) is connected with a flap shaft (14) for pivoting the exhaust flap (12). The housing (10) comprises two passage openings (22) opposite each other for guiding through the flap shaft (14). Further, two bearing means (18,40) for supporting the flap shaft (14) are provided. To permit an evening out of an offset between the two passage openings (22), one bearing means (18) comprises a bearing body (24) of ceramics, which has a spherical configuration. The opposite bearing means (40) comprises a bearing sleeve of graphite.

Description

[0001] The present application claims priority to German Patent Application No. 10 2004 046 077.9, filed Sep. 23, 2004, which application is incorporated herein fully by this reference. BACKGROUND OF THE INVENTION [0002] The invention relates to an exhaust flap means. [0003] With bulky engines in particular, it is known to switch off individual cylinders in certain driving situations to save fuel. To further maintain the required counterpressure in the exhaust gas train, exhaust flaps are provided in individual exhaust pipes. Further, the provision of exhaust flaps serves the purpose of keeping the engine noise unchanged, if possible, even if some of the cylinders are switched off. [0004] The exhaust flap means for motor vehicles comprises a housing in which the exhaust flap is arranged. The particularly tubular housing is inserted into the exhaust gas train. Likewise, the housing can be part of the exhaust gas train. The exhaust flap is pivotably supported in the housing via a flap...

AI Technical Summary

Benefits of technology

[0005] It is the object of the invention to provide an exhaust flap means where the coaxiality differences can be evened out in a simple manner.

[0007] In a first solution according to the invention, each of the two bearing means comprises a spherically configured bearing body of ceramics or a comparable firm and heat-resistant material. In this case, at least a substantial portion of the bearing body is ceramics or the like. Using bearing bodies of ceramics has the advantage that they are very temperature-stable and corrosion-resistant. It is thus possible to provide the bearing means near the exhaust flap housing. Particularly, the bearing bodies can be received directly by bearing shells or the like formed in the housing.

[0008] Preferably, the spherically configured bearing bodies comprise a portion shaped like a spherical calotte. Because of this configuration, it is possible to slightly pivot the bearing bodies relative to the longitudinal axis of the bearing so that existing coaxiality differences can be evened out.

[0010] Although the provision of spherically configured bearing bodies of ceramics is advantageous in that a coaxiality compensation can be effected and bearing in the housing is possible, ceramic bearing bodies have the disadvantage that they are expensive components. The reasons therefor are the material as well as the relatively complicated production of a spherical bearing body which, if necessary, has to be finished.

[0011] According to a second invention, the flap shaft is supported by the two bearing means comprising a bearing sleeve of graphite. It is essential that the substantial components of the bearing sleeve consist of graphite or an eqivalent soft material with good slide characteristics. Providing such a bearing sleeve has the advantage that it consists of a soft material so that coaxiality differences can be evened out by a slight deformation of the bearing sleeve. Further, the graphite bearing sleeve can be a cylindrically configured bearing sleeve which thus is cost-effective as well.

[0012] Preferably, the graphite bearing sleeve is sealed. By sealing the graphite bearing sleeve, the service life of the bearing sleeve can be considerably extended since the graphite is damaged by the oxygen in the exhaust gases in connection with the high temperatures. In a particularly preferred embodiment, the graphite bearing sleeves are sealed outside the housing. This is particularly advantageous since sealing within the housing would impair the flow and sealing exactly at the housing border is difficult. Sealing outside the housing, e.g., by a particularly pot-shaped cover surrounding the graphite bearing sleeve, is sufficient in that an oxygen exchange does not happen since flowing through the bearing sleeve is avoided although the graphite bearing sleeve comes into contact with oxygen.

Problems solved by technology

With bulky engines in particular, it is known to switch off individual cylinders in certain driving situations to save fuel.

Because of manufacturing tolerances occurring, there exists the problem that the passage openings opposite each other are not exactly coaxial.

This may lead to a jamming of the shaft in operation or to damage to the bearing means.

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