Patent Application
20170074133
The invention relates to an exhaust gas muffler of an internal combustion engine, comprising a muffler housing having an exhaust gas inlet and an exhaust gas outlet and comprising a first Helmholtz resonator, made of a first housing portion that delimits a first Helmholtz volume and that comprises a first coupling pipe, wherein at least one second Helmholtz resonator is provided made of a second housing portion that delimits a second Helmholtz volume and comprises a second coupling pipe, via which the second Helmholtz volume can be coupled to an exhaust gas flow A of the exhaust gas inlet.
An exhaust gas muffler with a Helmholtz resonator is already known from DE 10254631 B4. The Helmholtz resonator has a Helmholtz pipe, via which it is connected to an exhaust gas supply line. In addition, an exhaust gas pipe is provided that is arranged coaxially to the Helmholtz pipe and with this delimits an annular gap R, via which the Helmholtz resonator is supplied. The exhaust gas pipe passes through the Helmholtz resonator to a reflection chamber, connecting in the direction of flow to the Helmholtz resonator, to which the exhaust pipe connects.
According to DE 10 2005 054 002 A1 the exhaust gas flow is directly coupled via the branched exhaust gas inlet pipe to a plurality of Helmholtz resonators.
According to U.S. Pat. No. 4,501,341 A the exhaust gas flow is directly coupled via a branching of the exhaust gas inlet pipe to a Helmholtz resonator.
From WO 82 00 854 A1 it is known to couple an exhaust gas flow of the exhaust gas inlet to a Helmholtz resonator via a separate coupling pipe arranged coaxially to the exhaust gas inlet.
From EP 0 839 993 A2 it is similarly known to couple an exhaust gas flow of the exhaust gas inlet via a separate first coupling pipe arranged coaxially to the exhaust gas inlet, to a Helmholtz resonator. A second coupling pipe is also provided, positioned parallel to the first coupling pipe, via which a second Helmholtz resonator is coupled.
The object of the invention is to improve and arrange an exhaust gas muffler with Helmholtz resonator so that a better frequency response is guaranteed.
The object is achieved according to the invention in that the second coupling pipe is arranged at least partly within the first coupling pipe, and both coupling pipes delimit an annular gap R via which the first Helmholtz volume can be coupled to the exhaust gas flow A.
This allows at least two Helmholtz resonators, each working in different frequency ranges, to be arranged one behind the other and despite this to be directly blown against. Through the overlapping frequency responses of both Helmholtz resonators hereby achieved, a substantially greater frequency range is covered so that very extensive overall damping of the engine noise is possible.
The respective coupling pipe can also have a multi-piece construction. A coupling pipe with a varying diameter is also possible.
To this end it can also be advantageous if the second coupling pipe is passed through the first housing portion and both housing portions or both Helmholtz volumes are arranged one after another in relation to a direction RK of the second coupling pipe. This allows a twin Helmholtz resonator to be created in a small space.
It can also be advantageous if the annular gap R has an inlet opening E1 having a normal N1, wherein the normal N1, with a direction of flow S of the exhaust gas inlet nozzle, includes an angle a, with 90°<a<=180° or 100°<=a<=180°. The inlet opening E1 is formed by the two pipe ends or the respective pipe edges, delimiting the annular gap R.
It can also be advantageous if the second coupling pipe has an inlet opening E2 with a normal N2, wherein the normal N2, with a direction of flow S of the exhaust gas inlet nozzle, includes an angle b, with 0°<=b<90°.
While the exhaust gas coming from direction of flow S of the exhaust gas inlet nozzle runs parallel to the inlet opening E1, E2, and thus at right-angles to the normal N1, N2, and so just overflows the inlet opening E1, E2, this is referred to as “overflowing” of the Helmholtz resonator. Otherwise, if the direction of flow S in relation to the inlet opening E1, E2 has a directional component at right-angles thereto, and consequently parallel to the normal N1, N2, as claimed, then “blowing against” the Helmholtz resonator is referred to. Independently of this, upstream the direction of flow S can be formed as desired according to the further form of the exhaust gas inlet nozzle.
In doing so it can advantageously be provided that in at least one housing portion at least one perforated resonator wall is provided within the Helmholtz volume. The respective Helmholtz volume can also be divided by a perforated resonator wall, wherein the various parts of the Helmholtz volume functionally appertain to the one Helmholtz resonator. As explained below, a distinction should be made between these and housing walls with a leakage opening provided for the separation of various housing portions.
It can be of particular importance for the invention if the first Helmholtz volume is delimited by housing walls within the muffler housing, and in at least one housing wall a leakage opening is provided and/or if the second Helmholtz volume is partly delimited by the housing wall and the leakage opening is provided in the housing wall. Via the leakage opening a coupling takes place between the respective Helmholtz volume and a volume of another housing portion within the muffler housing. The leakage opening can take the form of a recess or the leakage pipe, so that a coupling with directly or indirectly adjoining portions is possible.
A Helmholtz volume can therefore in addition to the coupling pipe have a further opening in the form of a leakage and does not have to be fully compartmentalised from adjoining chambers. The size of the leakage opening is however limited, preferably to a value of less than 200 mm2. Consequently, the leakage is restricted to a fraction of the exhaust gas flow passing through the exhaust gas muffler of a maximum 2% to 5%. Such a design is very similar to a conventional Helmholtz resonator, for it guarantees an acoustic performance similar to that of a conventional Helmholtz resonator.
In connection with the improvement and arrangement according to the invention it can be advantageous if the muffler housing has at least one further housing portion or one further housing chamber with a housing wall, wherein the leakage opening couples both Helmholtz volumes with one another and/or at least one Helmholtz volume with the housing portion. Consequently, a substantially acoustic coupling of the Helmholtz volume with a further volume is guaranteed. Thus, this is accompanied by a particular acoustic performance.
It can also be advantageous if the leakage opening of a housing wall has an overall cross-section L with 0<=L<=500 mm2 or 0<=L<=200 mm2 or 0<=L<=100 mm2 or 0<=L<=50 mm2. The leakage opening with an overall cross-section L is sufficiently small to guarantee the effect as a Helmholtz volume or Helmholtz resonator.
Further advantages and details of the invention are described in the claims and in the description and illustrated in the Figures. These show as follows:
An exhaust gas muffler 1 according to
The inlet opening E1 is associated with a normal N1, which with a direction of flow S of the exhaust gas flow A includes an angle a. In this way direct blowing against the first Helmholtz volume 2.1 via the first coupling pipe 2.3 is guaranteed, should the angle a be greater than 90°. An angle a of 90° would mean that the exhaust gas flow A or its direction of flow S was running at right-angles to the inlet opening E1, and the inlet opening was only being overflowed. At 180° full blowing occurs. Essentially, an angle a of less than 90° is also conceivable. In this case the second coupling pipe 3.3 overhangs the end face of the first coupling pipe 2.3 in the direction of the exhaust gas inlet nozzle 1.1, so that the inlet opening E1, in the same manner as the inlet opening E2, has a normal N1, N2, running parallel to the direction of flow S.
As already stated the normal N2 of the inlet opening E2 with the direction of flow S includes an angle b of 0°, e.g. the direction of flow S runs parallel to the normal N2. Depending on the chamfer of the second coupling pipe 3.3 the position of the inlet opening E2 may vary, so that the normal N2 includes an angle b>0 to the direction of flow S; the angle b should not reach 90°, however, so that direct blowing via the second coupling pipe 3.3 is possible.
With the abovementioned angles the values given for a and b respectively, can be assumed. Similarly, 0° can be equated to 180°. The abovementioned nomenclature results simply on the basis of the assumed directions of flow S of the exhaust gas on the one hand and the normal N1, N2 on the other.
Inside the second Helmholtz volume 3.1 a resonator wall 3.4 is provided, in the form of a perforated dividing wall. It has a certain dividing effect on the Helmholtz volume 3.1, but does not lead to a total separation of the Helmholtz volume 3.1, so that the Helmholtz volume 3.1 together with the coupling pipe 3.3 forms the second Helmholtz resonator 3 as an independent functional unit.
In the housing wall 1.4, which in this embodiment forms the dividing wall between the first Helmholtz volume 2.1 and the second Helmholtz volume 3.1, a leakage opening 1.5 is provided, which guarantees a leakage or overflow between both Helmholtz volumes 2.1, 3.1. Here the leakage opening has a dimension L of approximately 80 mm2. Similarly, in the housing wall 2.4, forming a dividing wall with the third housing portion 1.6, a leakage in the form of a double leakage opening 2.5 of dimension L is provided, via which the first Helmholtz volume 2.1 can communicate with the third housing portion 1.6 or the exhaust gas outlet nozzle 1.2 and/or the exhaust gas inlet nozzle.
The third housing portion 1.6 or the reflection chamber thus formed can also have a multi-piece construction, so that the exhaust gas inlet nozzle 1.1 or the exhaust gas outlet nozzle 1.2 and the respective coupling pipe 2.3, 3.3 discharge in the same or adjoining chamber parts of the third housing portion 1.6. In this case the corresponding volumes would be coupled together via corresponding openings.
In the embodiment of
According to the exemplary embodiment of
Essentially, the leakage opening of the respective Helmholtz volume 2.1, 3.1 can also be fully dispensed with.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 103 054.0 | Mar 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/054312 | 3/2/2015 | WO | 00 |
