Exhaust silencer

Abstract

Exhaust silencer (1) of an internal combustion engine with a silencer housing (1.3) having an exhaust inlet (1.1) and an exhaust outlet (1.2) and with a first Helmholtz resonator (2), formed from a first housing section (2.2) defining a first Helmholtz volume (2.1) with a first coupling pipe (2.3), wherein at least one second Helmholtz resonator (3) is provided, formed from a second housing section (3.2) defining a second Helmholtz volume (3.1) with a second coupling pipe (3.3), via which the second Helmholtz volume (3.1) can be coupled to an exhaust flow A of the exhaust inlet (1.1), wherein the second coupling pipe (3.3) is arranged at least partially inside the first coupling pipe (2.3) and both coupling pipes (2.3, 3.3) define an annular gap R, through which the first Helmholtz volume (2.1) can be coupled to the exhaust gas flow A, wherein the exhaust gas inlet (1.1) is a type of exhaust gas inlet nozzle (1.1) is designed and the exhaust gas inlet nozzle (1.1) and the first coupling pipe (2.3) open into a third housing section (1.6), characterized in that the exhaust gas inlet nozzle (1.1) and the first coupling pipe (2.3) are arranged coaxially and wherein the outlet of the exhaust gas inlet nozzle (1.1) and the inlet of the first coupling pipe (2.3) have an identical diameter.

Description

The invention relates to an exhaust silencer for an internal combustion engine, comprising a silencer housing with an exhaust inlet and an exhaust outlet, and a first Helmholtz resonator formed from a first housing section defining a first Helmholtz volume and a first coupling pipe, wherein at least one second Helmholtz resonator is provided, formed from a second housing section defining a second Helmholtz volume and a second coupling pipe, via which the second Helmholtz volume can be coupled to an exhaust flow A of the exhaust inlet, wherein the second coupling pipe is arranged at least partially within the first coupling pipe and both coupling pipes define an annular gap R, via which the first Helmholtz volume can be coupled to the exhaust flow A, wherein the exhaust inlet is designed as an exhaust inlet nozzle and the exhaust inlet nozzle and the first coupling pipe open into a third housing section. An exhaust silencer with a Helmholtz resonator is already known from DE 102 54 631 B4. The Helmholtz resonator has a Helmholtz tube through which it is connected to an exhaust inlet. In addition, an exhaust pipe is provided, which is arranged coaxially with the Helmholtz tube and together with it defines an annular gap R through which the Helmholtz resonator is supplied. The exhaust pipe leads through the Helmholtz resonator to a reflection chamber connected to the Helmholtz resonator in the direction of flow, to which the outlet pipe is connected. According to DE 10 2005 054 002 A1, the exhaust gas flow is coupled directly to several Helmholtz resonators via the branched exhaust gas inlet pipe. According to US 4 501 341 A, the exhaust gas flow is directly coupled to a Helmholtz resonator via a branch of the exhaust gas inlet pipe. From WO 82 / 00 854 A1 it is known to couple an exhaust gas flow from 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 also known to couple an exhaust gas flow from the exhaust gas inlet to a Helmholtz resonator via a separate first coupling pipe arranged coaxially to the exhaust gas inlet. In addition, a second coupling pipe is provided, which is positioned parallel to the first coupling pipe, via which a second Helmholtz resonator is coupled. JP S60-30463 A discloses a device for noise reduction in which a resonator is placed in the engine intake port. FR 48791 E discloses a silencer for an internal combustion engine. Another motor vehicle silencer is known from US 2 357 792 A. US 2014 / 0034416A1 shows a resonator array with a base plate featuring a variety of wedge-shaped spacers. US Patent 4,759,423 A discloses a muffler comprising a pair of plates shaped to define an arrangement of pipes through which exhaust gases can flow. The arrangement of pipes includes at least one inlet that can be connected to at least one exhaust pipe of a vehicle and at least one outlet that can be connected to at least one exhaust pipe of a vehicle. US patent 3,613,830 A shows an exhaust silencer with two Helmholtz resonators connected via coupling pipes. One of the coupling pipes runs inside the other. The invention is based on the objective of designing and arranging an exhaust silencer with a Helmholtz resonator in such a way as to ensure improved frequency response. The problem is solved according to the invention by the fact that the exhaust gas inlet nozzle and the first coupling pipe are arranged coaxially and wherein the outlet of the exhaust gas inlet nozzle and the inlet of the first coupling pipe have an identical diameter. This allows at least two Helmholtz resonators, each operating in different frequency ranges, to be arranged in series and still directly blown upon. The resulting superimposed frequency response of both Helmholtz resonators covers a significantly wider frequency range, thus enabling a very broad overall attenuation of engine noise. The coupling tube can also be made up of multiple sections. A coupling tube with a varying diameter is also possible. It can also be advantageous if the second coupling tube is routed through the first housing section and both housing sections or both Helmholtz volumes are arranged sequentially with respect to one direction of the second coupling tube. This allows a double Helmholtz resonator to be realized in a small installation space. Furthermore, it can be advantageous if the annular gap R has an inlet opening E1 with a normal vector N1, wherein the normal vector N1 forms an angle α with a flow direction S of the exhaust gas inlet nozzle, with 90° < α ≤ 180° or 100° < α ≤ 180°. The inlet opening E1 is formed from both pipe ends or the respective pipe edges that define the annular gap R. It can also be advantageous if the second coupling pipe has an inlet opening E2 with a normal vector N2, where the normal vector N2 forms an angle b with a flow direction S of the exhaust inlet nozzle, with 0°<= b < 90°. As long as the exhaust gas flows parallel to the inlet opening E1, E2 from the flow direction S of the exhaust inlet nozzle, i.e., perpendicular to the normal vector N1, N2, and thus only flows over the inlet opening E1, E2, this is referred to as "flowing over" the Helmholtz resonator. Otherwise, if the flow direction S with respect to the inlet opening E1, E2 has a directional component perpendicular to it, i.e., parallel to the normal vector N1, N2, as claimed, this is referred to as "blowing" the Helmholtz resonator. The flow direction S can be arbitrarily configured upstream of the further shape of the exhaust inlet nozzle, regardless of this. It can be advantageously provided that at least one perforated resonator wall is included within the Helmholtz volume in at least one housing section. The respective Helmholtz volume can also be divided by a perforated resonator wall, with the different parts of this Helmholtz volume functionally belonging to the single Helmholtz resonator. This is to be distinguished from housing walls with a leakage opening, which are provided to separate different housing sections, as explained below. Of particular importance for the present invention is the following: if the first Helmholtz volume is bounded by housing walls inside the silencer housing, and a leakage opening is provided in at least one housing wall, and / or if the second Helmholtz volume is partially bounded by the housing wall and the leakage opening is provided in the housing wall. The respective Helmholtz volume is coupled to a volume of another housing section within the silencer housing via the leakage opening. The leakage opening can be designed as a recess or as a leakage tube, so that coupling with directly or indirectly adjacent housing sections is possible. A Helmholtz volume can therefore have an additional opening in the form of a leakage, besides the coupling tube, and does not need to be completely sealed off from adjacent chambers. However, the size of the leakage opening is limited, preferably to a value below 200 mm². Consequently, the leakage is limited to a fraction of the exhaust gas flow passing through the silencer, at most 2% to 5%. Such a design closely resembles a classic Helmholtz resonator, as it ensures acoustic behavior similar to that of a classic Helmholtz resonator. In connection with the design and arrangement according to the invention, it can be advantageous if the silencer housing has at least one further housing section or a further housing chamber with a housing wall, wherein the leakage opening connects or couples both Helmholtz volumes to each other and / or at least one Helmholtz volume to the housing section. Thus, a substantially acoustic coupling of the Helmholtz volume with a further volume is ensured. This results in a particular acoustic behavior. Furthermore, it can be advantageous if the leakage opening of a housing wall has a total cross-sectional area L of 0 ≤ L ≤ 500 mm², or 0 ≤ L ≤ 200 mm², or 0 ≤ L ≤ 100 mm², or 0 ≤ L ≤ 50 mm². With a total cross-sectional area L, the leakage opening is sufficiently small to ensure its function as a Helmholtz volume or Helmholtz resonator. Further advantages and details of the invention are explained in the claims and the description and illustrated in the figures. These show: Fig. 1 a schematic diagram of an exhaust silencer with two Helmholtz resonators; Fig. 2 a schematic diagram of an exhaust system; Fig. 3 a schematic diagram of Fig. 1 with a leakage pipe. An exhaust silencer 1 according to Fig. 1 has a silencer housing 1.3, which serves to accommodate an exhaust inlet nozzle 1.1 and an exhaust outlet nozzle 1.2. The silencer housing 1.3 also has two further housing walls 1.4, 2.4, so that a total of three housing sections 3.2, 2.2, 1.6 are formed. While the inlet nozzle 1.1 and the outlet nozzle 1.2 for connecting the exhaust system 4 shown in Fig. 2 open into the third housing section 1.6, which is designed as a reflection chamber, the first and second housing sections 3.2, 2.2 each define a Helmholtz volume 2.1, 3.1 as part of a first and second Helmholtz resonator 2, 3. The first Helmholtz volume 2.1 is supplied with flow via a coupling pipe 2.3, which, like the inlet nozzle 1.1, opens within the third housing section 1.6, so that the exhaust gas flow A entering through the inlet nozzle 1.1 meets the first coupling pipe 2.3 in an axial direction.Within the first coupling tube 2.3, a second coupling tube 3.3 is arranged, which terminates in the second Helmholtz volume 3.1. The second coupling tube 3.3 has an inlet opening E2, which is also located directly upstream of the exhaust gas inlet 1.1, so that the exhaust gas flow A encounters the inlet opening E2 as it exits the exhaust gas inlet 1.1. The two coupling tubes 2.3, 3.3 are axially offset such that the second coupling tube 3.3 is positioned inwards within the first coupling tube 2.3 with respect to direction RK. An annular gap R is thus formed between the first coupling tube 2.3 and the second coupling tube 3.3, through which the first Helmholtz volume 2.1 is coupled to the exhaust gas inlet 1.1. The annular gap R also has an inlet opening E1, which is limited by the respective end face of the first and second coupling tubes 2.3 and 3.3, respectively, whereby in the case of the first coupling tube 2.3 is about the inner front edge and in the case of the second coupling tube 3.3 it is about the outer front edge. The inlet opening E1 is assigned a normal vector N1, which forms an angle α with the flow direction S of the exhaust gas stream A. To ensure direct blowing of the first Helmholtz volume 2.1 via the first coupling pipe 2.3, the angle α should be greater than 90°. An angle α of 90° would mean that the exhaust gas stream A, or rather its flow direction S, runs perpendicular to the inlet opening E1; the inlet opening would only be overflowed. At 180°, complete blowing occurs. In principle, an angle α of less than 90° is also conceivable. In this case, the second coupling pipe 3.3 projects beyond the end face of the first coupling pipe 2.3 in the direction of the exhaust gas inlet 1.1, so that the inlet opening E1, like the inlet opening E2, has a normal vector N1, N2 that runs parallel to the flow direction S. As already mentioned, the normal vector N2 of the inlet opening E2 forms an angle b of 0° with the flow direction S, i.e., the flow direction S runs parallel to the normal vector N2. Depending on the cross-section of the second coupling tube 3.3, the position of the inlet opening E2 can change so that the normal vector N2 forms an angle b > 0 with the flow direction S; however, the angle b should not reach 90° so that direct blowing via the second coupling tube 3.3 is possible. The angle values ​​mentioned above refer to the magnitude of the respective angle a, b. Similarly, 0° and 180° are to be considered equivalent. The above nomenclature is based solely on the assumed flow directions S of the exhaust gas on the one hand, and the normal vectors N1, N2 on the other. Within the second Helmholtz volume 3.1, a resonator wall 3.4 is provided, which is designed as a perforated partition. It has a certain dividing effect on the Helmholtz volume 3.1, but does not lead to a complete separation of the Helmholtz volume 3.1, so that the Helmholtz volume 3.1 together with the coupling tube 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 partition between the first Helmholtz volume 2.1 and the second Helmholtz volume 3.1, a leakage opening 1.5 is provided, which ensures leakage or overflow between the two Helmholtz volumes 2.1, 3.1. The leakage opening has a size L of approximately 80 mm². Likewise, in the housing wall 2.4, which forms a partition to the third housing section 1.6, a leakage opening in the form of a double leakage opening 2.5 of size L is provided, through which the first Helmholtz volume 2.1 can communicate with the third housing section 1.6 or the exhaust gas outlet port 1.2 and / or the exhaust gas inlet port 1.1. The third housing section 1.6, or the reflection chamber thus formed, can also be designed in multiple parts, such that the exhaust gas inlet 1.1 or the exhaust gas outlet 1.2, as well as the respective coupling pipes 2.3, 3.3, open into the same or adjacent chamber sections of the third housing section 1.6. In this case, the corresponding volumes would be coupled to each other via corresponding openings. In the embodiment shown in Fig. 2, the exhaust silencer 1 is coupled to an exhaust system 4 of a motor vehicle, wherein a catalyst 4.1 is provided in an inlet pipe 4a of the exhaust system, which is connected to the exhaust inlet nozzle 1.1, while a rear silencer 4.2 is provided in an outlet pipe 4b of the exhaust system 4. According to the embodiment shown in Fig. 3, the leakage opening 1.5 of the second Helmholtz volume 3.1 is designed as a tube and connects the second Helmholtz volume 3.1 directly to the third housing section 1.6, while the first Helmholtz volume 2.1 is also coupled to the housing section 1.6 via the leakage opening 2.5. Thus, the two Helmholtz volumes 2.1 and 3.1 are not directly coupled to each other. In principle, the leakage opening of the respective Helmholtz volume 2.1, 3.1 can also be omitted entirely. Reference symbol list 1 Exhaust silencer 1.1 Exhaust inlet, nozzle 1.2 Exhaust outlet, nozzle 1.3 Silencer housing 1.4 Housing wall, partition 1.5 Leakage opening, recess, leakage pipe 1.6 Third housing section, reflection chamber 2 First Helmholtz resonator 2.1 First Helmholtz volume 2.2 First housing section, housing wall 2.3 First coupling pipe 2.4 Housing wall 2.5 Leakage opening, recess 3 Second Helmholtz resonator 3.1 Second Helmholtz volume 3.2 Second housing section, housing wall 3.3 Second coupling pipe 3.4 Resonator wall 4 Exhaust system 4a Inlet pipe 4b Exhaust pipe 4.1 Catalyst 4.2 Rear silencer A Exhaust flow a Angle b Angle E1 Inlet opening E2 Inlet opening N1 Normal vector N2 Normal vector R Annular gap RK Direction S Flow direction L Total cross-section, size

Claims

Exhaust silencer (1) of an internal combustion engine with a silencer housing (1.3) having an exhaust inlet (1.1) and an exhaust outlet (1.2) and with a first Helmholtz resonator (2), formed from a first housing section (2.2) defining a first Helmholtz volume (2.1) with a first coupling pipe (2.3), wherein at least one second Helmholtz resonator (3) is provided, formed from a second housing section (3.2) defining a second Helmholtz volume (3.1) with a second coupling pipe (3.3), via which the second Helmholtz volume (3.1) can be coupled to an exhaust flow A of the exhaust inlet (1.1), wherein the second coupling pipe (3.3) is arranged at least partially inside the first coupling pipe (2.3) and both coupling pipes (2.3, 3.3) define an annular gap R, through which the first Helmholtz volume (2.1) can be coupled to the exhaust gas flow A, wherein the exhaust gas inlet (1.1) is a type of exhaust gas inlet nozzle (1.1) is designed and the exhaust gas inlet nozzle (1.1) and the first coupling pipe (2.3) open into a third housing section (1.6), characterized in that the exhaust gas inlet nozzle (1.1) and the first coupling pipe (2.3) are arranged coaxially and wherein the outlet of the exhaust gas inlet nozzle (1.1) and the inlet of the first coupling pipe (2.3) have an identical diameter. Exhaust silencer (1) according to claim 1, characterized in that the second coupling tube (3.3) is guided through the first housing section (2.2) and both housing sections (2.2, 3.2) or both Helmholtz volumes (2.1, 3.1) are arranged one after the other with reference to a direction RK of the second coupling tube (3.3). Exhaust silencer (1) according to claim 1 or 2, characterized in that the annular gap R has an inlet opening E1 with a normal vector N1, wherein the normal vector N1 encloses an angle a with a flow direction S of the exhaust inlet nozzle (1.1), with 90° < a <= 180° or 100° <= a <= 180°. Exhaust silencer (1) according to one of the preceding claims, characterized in that the second coupling pipe (3.3) has an inlet opening E2 with a normal vector N2, wherein the normal vector N2 forms an angle b with a flow direction S of the exhaust inlet nozzle (1.1), with 0°<= b < 90°. Exhaust silencer (1) according to one of the preceding claims, characterized in that a perforated resonator wall (3.4) is provided in at least one housing section (3.2) within the Helmholtz volume (3.1). Exhaust silencer (1) according to one of the preceding claims, characterized in that the first Helmholtz volume (2.1) is limited by housing walls (1.4, 2.4) and a leakage opening (1.5, 2.5) is provided in at least one housing wall (1.4, 2.4) and / or that the second Helmholtz volume (3.1) is partially limited by the housing wall (1.4) and the leakage opening (1.5) is provided in the housing wall (1.4). Exhaust silencer (1) according to claim 6, characterized in that the silencer housing (1.3) has at least one further housing section (1.6) into which at least the outlet nozzle (1.2) and / or the inlet nozzle (1.1) opens, wherein the leakage opening (1.5, 2.5) connects both Helmholtz volumes (2.1, 3.1) to each other and / or at least one Helmholtz volume (2.1, 3.1) to the housing section (1.6). Exhaust silencer (1) according to one of claims 6 or 7, characterized in that the leakage opening (1.5, 2.5) of a housing wall (1.4, 2.4) has a total cross-sectional area L with 0 <= L <= 500 mm2 or 0 <= L <= 200 mm2 or 0 <= L <= 100 mm2 or 0 <= L <= 50 mm2. System consisting of an exhaust system (4) for an internal combustion engine with an exhaust silencer (1) according to one of the preceding claims.

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