FR2509787A3 - Silencer for IC-engine - has apertures in intermediate walls of perforated pipe allowing partial axial flow - Google Patents

Abstract

The exhaust silencer for an ic-engine comprises a pipe (1) perforated between its inlet (2) and outlet (3) and containing intermediate walls (12,13,14), enclosed by a gastight housing (4,5,6) in which there are partitions (10,11), to form damping chambers (7,8,9) between housing and pipe. The gases flow to and fro between the pipe and the damping chambers. Each intermediate wall has apertures (15,16), so that some gas can flow in the axial direction of the pipe. The distance between the walls can be arranged to increase progressively in the axial flow direction.

Description

Exhaust silencer.

 The present invention relates to a silencer for the exhaust gases of internal combustion engines, comprising a perforated pipe having an inlet and an outlet; intermediate walls arranged inside this pipe and connecting to the inside wall of the latter; and an impermeable casing surrounding this pipe so as to form a space between the pipe and the casing, this space being divided into several damping chambers by means of partitions which terminate at the pipe and at the casing and which are housed between the intermediate walls.

It has been found that when such exhaust silencers, which are described for example in the patent
United States 2,072,372, are correctly sized, they very effectively muffle the noise of exhaust gases. However, these silencers are relatively bulky and, due to the high pulsation forces produced by the pressure peaks in the exhaust gases, they place relatively high demands on the engine power.

 Therefore, the first object is to provide a muffler of the type mentioned above, which is less bulky than the known muffler, while retaining the same noise damping capacity, or while having an improved noise damping capacity. noise and which places less demands on engine power.

 This first object is achieved mainly by providing each intermediate wall with several passage openings to allow the exhaust gas to flow in the axial direction of the perforated pipe.

 The exhaust gases which pass through the perforated pipe, coming from a damping chamber will meet and mix with the exhaust gas flowing axially, which will also distribute the pressure peaks and will effectively reduce the noise produced by the exhaust gases, making it possible to reduce the volume of the damping chambers. There will also be less resistance to the flow of exhaust gases through the muffler or muffler, with a corresponding decrease in engine power losses.

The invention is now described in more detail with reference to the accompanying drawing, in which
FIG. 1 is an axial section view of a silencer according to the invention, and
Figure 2 is a view taken on the line -11-II of Figure 1.

 The drawing illustrates a perforated pipe 1 constructed from a sheet of steel or other suitable material. The pipe 1 has an inlet 2 for the exhaust gases coming from a combustion engine and an outlet 3. Around the perforated pipe 1 and spaced from it is a gas-tight casing 4 having end walls 5, 6 which are hermetically welded against the external surface of the pipe 1.

Between the perforated part of the pipe 1 and the casing 4 is housed a noise-absorbing or sound-absorbing space which is divided into several damping chambers 7, 8, 9 by means of partitions 10, 11. The damping chambers 7, 8 , .9 communicate with each other through the perforated pipe 11
The interior of the perforated pipe 1 is divided by means of the intermediate walls 12, 13, 14 which, in the illustrated embodiment, are oblique to the longitudinal axis of the pipe 1, but which could also develop at right angles with respect to this axis. As can be seen, each of the partitions 10, 11 is situated approximately in the center, respectively between the pairs of walls 12, 13 and 13, 14. Each intermediate wall is provided with through orifices, for example the orifices 15 and 16 shown in Figure 2.

 The exhaust gas under pulsating pressure, fed into the silencer by the inlet 2 will flow in a known manner, through the perforated pipe 1, into a surrounding damping chamber, as shown in FIG. 1 with the curved arrows - and from there they go back into the pipe 1. The exhaust gas flow coming from this damping chamber takes place before or in front of a partition, as shown, since the pressure is higher in front of this partition than behind it, while the influx of exhaust gas takes place consecutively behind a partition.

 Because each intermediate wall 12, 13, 14 is provided with through orifices, for example 15 and 16, an exhaust gas flow is created which is directed axially through the interior of the pipe 1. This axial flow of exhaust gas which is pulsating, mixes with the exhaust gases flowing into the interior of the pipe 1, coming from the damping chambers 7, 8, 9, from which it follows that the pressure differences inside the pipe 1 are effectively evenly distributed and the flow resistance is reduced.

 As can be seen from FIG. 1, the length of the respective damping chambers increases successively starting from the inlet 2, in order to obtain a consecutive expansion of the gas and with this the best possible noise damping effect .

Claims (2)

Claims.  1 - A silencer for exhaust gases from combustion engines, comprising a pipe (1) which is perforated along its wall and provided with an inlet (2) and an outlet (3) and at the the interior of which there are intermediate walls (12, 13, 14) connecting to the interior surface of the pipe (1) which is surrounded by a gas-impermeable casing (4, 5, 6) forming therebetween m8me and the pipe a space divided by partitions (10, 11) leading to the casing and to the pipe, several damping chambers (7, 8, 9), these partitions being housed between the intermediate walls, allowing the exhaust gases to flow out of the pipe, opposite an intermediate wall and into an adjacent damping chamber and from there to return into the pipe behind this intermediate wall, characterized in that each intermediate wall (12, 13, 14) is provided with several passage openings (15, 16) so as to create a flow of exhaust gas in the axial direction of the perforated pipe, which meets the flow of gas arriving opposite this intermediate wall.  2 - A silencer according to claim 1, characterized in that the distance between the partitions (12,13, 14) increases successively in the axial direction of the flow.