Exhaust gas muffler

Details Exhaust gas muffler Exhaust gas muffler

1999-10-25

2001-01-09

Dang, Khanh (Department: 2837)

Acoustics

Sound-modifying means

Muffler, fluid conducting type

C181S231000

Reexamination Certificate

active

06170604

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas muffler for an internal combustion engine, especially for a hand-held work tool such as a motor chain saw, especially comprising a muffler housing which has an inlet and an outlet for the exhaust gas. A partition within the housing comprises a damping element having multiple openings and being positioned in the flow path of the exhaust gas.
Exhaust gas mufflers are arranged in the exhaust gas flow of internal combustion engines and are supposed to smooth the exhaust gas pulsation so that the noise level is substantially reduced.
A German patent document 29 29 965 A1 shows an exhaust gas muffler which is arranged in the exhaust gas manifold of an internal combustion engine that drives a chain saw and whose exhaust gas muffler housing has an inlet positioned in the exhaust line for the exhaust gas. Within the exhaust gas muffler housing a partition is arranged which comprises a damping element with multiple openings positioned in the flow path of the exhaust gas. Upon entering the exhaust gas muffler housing, the pulsating exhaust gas flow, is forced through a plurality of holes with small flow cross-section that provide a dampening or muffling effect.
In the known exhaust gas muffler the damping element is embodied as a fixedly installed planar perforated plate which divides the interior of the exhaust gas muffler housing into two muffler compartments. The inlet and the outlet of the exhaust gas muffler for the exhaust gas are correlated with different compartments so that the exhaust gas of the engine passes through the inlet opening into the first exhaust gas muffler compartment and then flows through the perforated exhaust gas muffler plate as well as an additionally provided spark protector screen into the second exhaust gas muffler compartment.
The present invention has the object to improve the aforementioned exhaust gas muffler such that the manufacturing cost of the exhaust gas muffler can be lowered while the damping or muffling effect is increased.
SUMMARY OF THE INVENTION
This object is inventively solved with the following features. A housing having an inlet and an outlet for engine exhaust gas is provided. The housing has walls defining the interior of the housing. The housing is comprised of a first housing shell having a first connecting flange and a second housing shell having a second connecting flange. The first and second connecting flanges are fastened to one another in a common flange plane. The first housing shell has a first bottom and the second housing shell has a second bottom. A partition is mounted in the housing and divides the interior of the housing into two compartments. The two compartments are connected by flow connections that allow passage of the engine exhaust gas between the two compartments. The partition has opposed ends supported respectively on the first and second bottoms. The partition has two wall portions curved outwardly in opposite directions relative to a plane of the partition and has multiple openings. The wall portions define a damping element positioned in the flow path of the engine exhaust gas from the inlet to the outlet. The multiple openings allow passage of the engine exhaust gas therethrough. The wall portions have edges that are connected to the inlet and delimit a flow cross-section of the inlet.
The invention also relates to a method for manufacturing a partition for an exhaust gas muffler wherein the two sheet metal parts are first sized to a desired size. Multiple openings are formed in a first wall portion of each one of the two sheet metal parts. The first wall portions are shaped so as to curve out of a plane of the sheet metal parts. The two sheet metal parts are joined face-to-face in a joining plane such that the first wall portions are aligned with one another but project in opposite directions away from the joining plane of the two sheet metal parts. The first wall portions define a damping element. A second wall portion of each one of the sheet metal parts is shaped so as to curve out of the plane of the sheet metal parts. The second wall portions are aligned with one another but project in opposite directions away from the joining plane of the two sheet metal parts. The second wall portions define an outlet channel.
The exhaust gas muffler housing is comprised of two housing shells which are joined at a common flange plane. The partition is a separate component which is supported at the bottom of each housing shell after insertion into the exhaust gas muffler housing. The compartments on opposite sides of the partition are connected by flow connections so that flow of the exhaust gas between the compartments can take place without impairment. Expediently, the lateral sides of the partition are positioned with play relative to the neighboring walls of the exhaust gas muffler housing so that, on the one hand, a flow connection via the gap between the partition and the neighboring housing walls is provided and a common housing volume is thus created. On the other hand, when assembling the exhaust gas muffler, the partition can be inserted into the housing shells with minimal work expenditure. When placing the second housing shell onto the first housing shell and thus closing the exhaust gas muffler housing, the partition is fixed in its position within the muffler housing by its support locations at the bottoms of the housing shells with sufficient pre-tension. The housing shells each have a peripheral flange. In the assembled position the flanges rest on one another in a common flange plane. By crimping or folding or similar mechanical means, the flange edges of the housing shells are connected to one another so that the exhaust gas muffler housing is closed and sealed.
The damping element having multiple openings for providing exhaust gas flow is embodied as an exhaust gas “shower” within the partition, wherein the term shower is used to describe an element having multiple openings through which a fluid introduced into the element can exit the element. The exhaust gas shower is delimited by perforated wall portions which relative to the plane of the partition are positioned opposite one another. The free edges of the perforated wall portion delimit the inlet cross-section. In the assembled position of the partition inside the exhaust gas muffler housing, the inlet cross-section of the exhaust gas shower overlaps the inlet of the exhaust gas muffler housing. The exhaust gas discharged from the internal combustion engine flows through the inlet in the housing wall first into the interior of the exhaust gas shower and is then forced through the openings of the perforated wall portions into the interior of the muffler housing. The exhaust gas flows out of the exhaust gas shower on either side of the partition into both compartments. The damping action on the pressure pulsation of the exhaust gas flow is improved by the simultaneous flow into the entire interior (both compartments) of the housing. Return flow of the exhaust gas on the opposite side of the partition to the outlet on the other side of the partition improves the damping action further.
In a preferred configuration of the exhaust gas muffler, the partition has an outlet channel embodied therein which opens into the outlet of the exhaust gas muffler housing. An outlet window at the surface of the partition connects the outflow channel to the interior of the exhaust gas muffler housing. The exhaust gas can flow from the exhaust gas muffler housing via the outlet window at one side of the partition into the outflow channel. The position of the outlet window on the partition can be freely selected and can be optimized with respect to the muffling behavior of the muffler. The outlet window is advantageously provided with a spark protector screen. The exhaust gas exiting from the exhaust gas shower is very hot, but because of the inventive arrangement it will not directly impact the spark protector screen so that ash formation or especially burning of the spark protector screen

Affiliated with

Also associated with

Rating

Exhaust gas muffler does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Exhaust gas muffler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exhaust gas muffler will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2493513