US20110005856A1

US20110005856A1 - Exhaust silencer

Info

Publication number: US20110005856A1
Application number: US12/812,375
Authority: US
Inventors: Leif Larson
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2008-01-09
Filing date: 2009-01-02
Publication date: 2011-01-13

Abstract

An exhaust silencer of a combustion engine, comprising a housing (1) that is to be connected to an exhaust pipe, through which housing the exhaust gases are arranged to be conducted and which comprises a reactive part (2) and an absorbing part (3) in the flow direction of the exhaust gases. The reactive part (2) is mainly hollow and comprises, at the inlet thereof, a first exhaust pipe (5) for feeding the exhaust gases to the reactive part (2) and, at its outlet, a second exhaust pipe (6) for directing the exhaust gases from the reactive part (2) to the absorbing part (3), both exhaust pipes (5, 6) being arranged so as to essentially extend inside the reactive part (2) of the housing. The absorbing part (3) comprises an absorbing filling element (7), which essentially fills the absorbing part (3) of the housing and, at the inlet of the absorbing part (3), is shaped so as to direct the exhaust gases to the space (8) between the filling element (7) and the inner lining of the housing (1).

Description

The invention relates to an exhaust silencer according to the preamble of claim 1, comprising a housing that is to be connected to an exhaust pipe, exhaust gases being arranged to be conveyed through the housing that comprises a reactive part and an absorbing part in the flow direction of the exhaust gases.
Large combustion engines cause noises, one considerable source of which comprises the exhaust noise of the engine, which is mainly caused by pressure variations between the cylinders of the engine and outdoor air. Various silencers that are connected to the exhaust manifold or the exhaust pipe are already known. The problem is how to connect effective enough noise suppression with a relatively simple and cost-effective structure that would not cause an excessively high counterpressure in the exhaust system.
The purpose of the invention is to provide an improved solution to the above-mentioned problem that is related to the noise suppression of the exhaust gases of large combustion engines, in particular. In particular, the purpose of the invention is to provide an exhaust silencer, which eliminates various frequencies of acoustic noise in a structurally advantageous manner and as effectively as possible. A further purpose of the invention is to provide a silencer that is also capable of purifying the exhaust gases.
The objectives of the invention are mainly achieved in the manner that is described in detail in claim 1 and the other claims. According to the invention, the reactive part of the silencer is mainly hollow and comprises, at its inlet, a first exhaust pipe for feeding the exhaust gases to the reactive part and, at its outlet, a second exhaust pipe for conducting the exhaust gases from the reactive part to the absorbing part, both exhaust pipes being arranged to essentially extend inside the reactive part of the housing. The absorbing part comprises an absorbing filling element, which essentially fills the absorbing part of the housing and, at the inlet of the absorbing part, is formed so as to direct the exhaust gases to the space between the filling element and the inner lining of the housing.
While being as simple as possible, the structure according to the invention can be used to effectively suppress the low, medium and high frequencies of the exhaust noise of the engine. The solution is also advantageous regarding the total counterpressure caused by the exhaust system.
The said first and second exhaust pipes are preferably dimensioned so that they suppress the lowest frequencies of the exhaust noise by utilizing the mutual suppressive interference of sonic waves. In that case, the mouths of the said first and second exhaust pipes that are situated opposite each other are also arranged at a distance from each other. In practice, the said first exhaust pipe extends inside the reactive part for about one fourth of the total length of the reactive part. Correspondingly, the said second exhaust pipe extends inside the reactive part for about a half of the total length of the reactive part.
By arranging spark quenching means between the reactive part and the absorbing part, the soot particles in the exhaust gases can effectively be separated before the exhaust gases are released into the environment. In that case, besides purifying the exhaust gases as such, the purpose is also to prevent sparks from escaping out of the exhaust pipe and from possibly causing fire safety risks.
The spark quenching means preferably comprise a number of radially extending plate elements, which are formed so as to direct the exhaust gas flow into a rotating movement around the filling element of the absorbing part. In this way, the soot particles can effectively be directed onto the inner lining of the housing under the effect of centrifugal force. By arranging in the housing, in connection with the absorbing part and after the spark quenching means, a soot trap door in the longitudinal direction of the housing, the soot particles can then be recovered and, where necessary, easily removed from the housing.
By directing the exhaust gases towards the inner surface of the housing, the space between the housing and the filling element can be rendered relatively small compared to the diameter of the filling element. In that case, the total cross-sectional area of the space can be kept large enough, so that the arrangement does not increase the counterpressure of the exhaust silencer to a considerable extent. On the whole, the arrangement, for its part, also improves the suppression of medium and high-frequency noise.
To effectively direct the exhaust gases, the filling element on the side of the reactive part is preferably sharp-pointed, and most preferably conical.
The filling element preferably mainly consists of mineral wool, which is arranged inside a perforated plate, net or the like that is supported on the housing.
In an operating situation, the housing is preferably situated in the vertical direction, so that the exhaust gases are fed into the housing from below.

In the following, the invention is described by means of examples and with reference to the appended schematic drawings, in which

FIG. 1 shows an embodiment of the exhaust silencer according to the invention as a longitudinal section, and

FIG. 2 shows an axonometric illustration of the silencer of FIG. 1, with the housing of the silencer cut open and the absorbing material removed.

The reference number 1 refers to the housing of the exhaust silencer, which is attached to the exhaust pipe of a combustion engine to direct the exhaust gases through the silencer. The housing 1 comprises a reactive part 2 and an absorbing part 3, which are arranged sequentially in the flow direction. Between these, there are the spark quenching means 4.
The reactive part 2 is intended for suppressing low noises and it includes a first exhaust pipe 5, through which the exhaust gases are fed into the housing 1, and a second exhaust pipe 6, which is arranged at a distance from the first exhaust pipe 5 and through which the exhaust gases are directed, through the spark quenching means 4, to the absorbing part 3, wherein the suppression of medium and high-frequency exhaust noise, in turn, is provided before the exhaust gases are directed out of the silencer and into the environment.
For the absorption of low noises, the first exhaust pipe 5 extends inside the reactive part 2 for about one fourth of the total length of the reactive part 2. Correspondingly, the second exhaust pipe 6 extends inside the reactive part 2 for about a half of the total length of the reactive part 2. In this way, the low noises can effectively be suppressed by utilizing the mutual suppression interference of sonic waves. To improve the effectiveness of the noise suppression, the dimensioning should also take into consideration the sparking frequency of the combustion engine and the diameters of the silencer and the exhaust pipe of the engine, as well as the respective requirements made of noise suppression.
The absorbing part 3 contains a filling element 7, which preferably consists of mineral wool and is surrounded by a perforated plate material, wire mesh or the like, which is supported on the housing 1. At its end next to the reactive part 2, the filling element 7 is rendered conical, so that the exhaust gases are directed to the space 8 between the inner lining of the housing 1 and the filling element 7 to be further conducted outside.
The spark quenching means 4 include a number of radially extending plate elements 9, which are shaped so as to direct the exhaust gas flow into a rotating movement around the filling element 7 of the absorbing part. The rotating movement thus provided is tailor-made to direct the soot particles, which are heavier than the exhaust gases, towards the inner lining of the housing 1, where they can be easily recovered and removed from the housing through a longitudinal soot trap door 10.
The exhaust silencer according to the invention preferably has a rotationally symmetrical structure, and it can preferably be situated in the vertical direction, in so far as the application so requires. In this position, the soot door is also easy to open and empty.
The structure of the exhaust silencer according to the invention is advantageous regarding the total counterpressure inflicted on the exhaust system. Furthermore, the spark quenching means can easily be integrated into it, directing, for their part, the exhaust gases radially outwards towards the inner lining of the housing.
The invention is not limited to the above embodiment, but various modifications can be considered within the appended claims.

Claims

1. An exhaust silencer of a combustion engine, comprising a housing that is to be connected to an exhaust pipe, through which housing the exhaust gases are arranged to be conducted, the housing comprising a reactive part and an absorbing part in the flow direction of the exhaust gases, whereby the reactive part is mainly hollow and comprises, at the inlet thereof, a first exhaust pipe for feeding the exhaust gases to the reactive part and, at its outlet, a second exhaust pipe for directing the exhaust gases from the reactive part to the absorbing part, both the exhaust pipes being arranged to essentially extend inside the reactive part of the housing, wherein the absorbing part comprises an absorbing filling element, which essentially fills the absorbing part of the housing and, at the inlet of the absorbing part, is shaped so as to direct the exhaust gases from the central part of the housing to the space between the filling element and the inner lining of the housing.

2. The silencer according to claim 1, wherein the first and second exhaust pipes are dimensioned so as to suppress the lowest frequencies of the exhaust noise by utilizing the mutual suppression interference of sonic waves.

3. The silencer according to claim 1, wherein the mouths of first and second exhaust pipes, which are situated opposite each other, are arranged at a distance from each other.

4. The silencer according to claim 1, wherein the first exhaust pipe extends inside the reactive part for about a fourth of the total length of the reactive part.

5. The silencer according to claim 1, wherein the second exhaust pipe extends inside the reactive part for about a half of the total length of the reactive part.

6. The silencer according to any of the preceding claims, wherein between the reactive part and the absorbing part, there are spark quenching means.

7. The silencer according to claim 6, wherein the spark quenching means comprise a number of radially extending plate elements, which are shaped so as to direct the exhaust gas flow into a rotating movement around the filling element of the absorbing part.

8. The silencer according to claim 6, wherein the housing comprises, in connection with the absorbing part and after the spark quenching means, a soot trap door in the longitudinal direction of the housing for recovering the soot particles and, if required, removing them from the housing.

9. The silencer according to claim 1, wherein the filling element, on the side of the reactive part, is sharp-pointed.

10. The silencer according to claim 1, wherein the filling element mainly consists of mineral wool, which is arranged inside a perforated plate, net or the like, which is supported on the housing.

11. The silencer according to claim 1, wherein, in an operating situation, the housing is situated in the vertical direction, so that the exhaust gases are fed to the housing from below.

12. The silencer according to claim 9, wherein the filling element, on the side of the reactive part, is conical.