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The present invention is directed to a reflective muffler, to an air-processing unit for a pneumatic system, to a pneumatic system and to a vehicle, in particular a passenger car, with a pneumatic suspension system.
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During an exhaust phase, air flows through an intake / exhaust line to the atmosphere, which causes noise. Dumpers or mufflers are integrated in the exhaust line to reduce the level of noise. Waves propagating inside an attenuator are repeatedly reflected by the internal walls and an attenuation effect is achieved.
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Document
WO 2018/033300 A1 presents a sound attenuator for a compressed-air system, in particular a pneumatic suspension system, for damping compressed-air discharge flows from the pneumatic compressed-air system proceeding from a pressure side to an atmospheric side. Said sound attenuator comprises a housing, wherein a multiplicity of flow-deflecting means is provided, each have at least one first lateral face and one second lateral face, wherein the first lateral face is oriented at a first angular value and the second lateral face is oriented at a second an angular value with respect to the compressed-air discharge direction.
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As electric vehicles are becoming more popular, customers' requirements regarding noise, and in particular exhaust noise, are higher. This is especially relevant for drivers and users of passenger cars, which are in general more sensitive to noises. Nevertheless, this is of relevance for vehicles in general. It would therefore be beneficial to improve the damping behavior of known reflective mufflers adapted for use in a vehicle, in particular a passenger car.
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This is where the invention comes in, the object thereof is to provide a muffler, an air-processing unit, a pneumatic system, and a vehicle, in particular a passenger car, which is improved regarding aspects of noise-reduction, in particular a reduction of exhaust noise.
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According to a first aspect of the invention the object is achieved by a muffler of claim 1.
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According to the first aspect of the invention, a reflective muffler for reducing noise level in an exhaust line of an air-processing unit, for a vehicle such as a passenger car, is presented. The reflective muffler comprises an input port that configured to be connected to an exhaust port of the air-processing unit. The reflective muffler also comprises an output port that is configured to be connected to an exhaust line for exhausting air to the atmosphere, i.e. to the environment surrounding the muffler. The reflective muffler also comprises a damping unit that is arranged between the input port and the output port. The damping unit comprising a damping chamber that includes at least one flow-deflection element that is configured to block a direct flow path between the input port and the output port, and an inlet chamber arranged between the input port and the damping chamber.
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In the reflective muffler of the first aspect of the invention, the inlet chamber is separated from the damping chamber by a first separation wall having a pneumatic orifice and wherein the inlet chamber has a cross sectional area value perpendicular to a longitudinal direction that increases in a flow direction from the input port to the damping section.
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The invention starts from the observation that the source of noise in an air-processing unit is not only the changes in pressure, but also the vibrations of air in the exhaust system. The inclusion of the dedicated inlet chamber, separated from the damping chamber by the separation wall having the pneumatic orifice, e.g. an orifice with a pneumatic function, such as a throttle orifice or a Helmholtz orifice for a Helmholtz resonator, and with a tampered shape, in particular with a conical like shape or a frustum like shape (i.e. truncated pyramid) where the cross sectional area value perpendicular to a longitudinal direction increases in the flow direction enhances the dispersion of the wave energy and provides a better acoustic performance of the muffler. The waves propagating inside the damping unit are repeatedly reflected by the muffler's internal walls and by the least one flow-deflection element that blocks the direct path between output and input port.
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The invention further starts from the recognition that current solutions do not match customers' requirements regarding noise level, in particular exhaust noise, especially for drivers and other users of vehicles such as passenger cars, which generally favor a low noise level while driving.
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Based on these observations and recognitions the invention has proposed to provide the damping chamber with the flow-deflection element to act as a Helmholtz resonator that can be advantageously dimensioned so that the waves reflected by the muffler cancel out given frequencies of sound in the exhaust line. The sound energy is dissipated more efficiently, the vibrations are reduced, and the noise levels are significantly reduced.
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In the following, developments of the reflective muffler of the first aspect of the invention will be presented.
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Throughout the description, reference will be made to air, compressed air, processed air, exhaust air, air-processing unit and the like. However, the reflective muffler can also be used in processing units that are not based on air, but instead are based on another gas or fluid.
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In a preferred development, the pneumatic orifice is the only orifice of the first separation wall, and preferably, the pneumatic orifice is substantially aligned with the input port, i.e., along a longitudinal direction corresponding to a flow direction between the input port and the pneumatic orifice.
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Preferably, and according to another development of the reflective muffler of the invention, the at least one flow-deflection element is arranged in the damping chamber such that there is at least a first peripheral passage and a second peripheral passage different from the first peripheral passage for the flow, between the input port and the output port. Peripheral passage refers here to a passage delimited by the flow-deflection element and an inner peripheral inner wall of the damping chamber.
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In another development, the at least one flow-deflection element is configured as a V-shaped flow-deflection element arranged such that a leading edge of the flow-deflection element is pointed towards the input port and there is a respective passage for air-flow, namely the first peripheral passage and the second peripheral passage, between each respective end point of the V-shaped flow-deflection element and the inner peripheral wall of the damping section.
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Preferably, in a development, the damping section comprises a plurality of V-shaped flow-deflection elements, in particular between two and ten, preferably three, V-shaped flow-deflection elements. It is preferred that the leading edges of the V-shaped flow-deflection elements are aligned along the longitudinal direction of the reflective muffler.
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In yet another development that comprises a plurality of aligned V-shaped flow deflection elements, a distance between the end points of each V-shaped flow-deflection element decreases as a distance between leading edges and the input port increases. This means that the size or wingspan of the V-shaped flow deflection elements decreases as the distance to the input port increases.
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In another development, which may include any combination of the technical features described above, the damping unit further comprises an outlet chamber that is arranged between the damping chamber and the output port. In particular, the outlet chamber has a cross sectional area value determined perpendicular to the longitudinal direction that decreases in a direction of flow from the damping chamber to the output port. Also preferably, a development of the reflective muffler further comprises a second separation wall that is arranged between the damping chamber and the outlet chamber. The second separation wall includes a second pneumatic orifice, which is preferably the only orifice of the second separation wall and/or is substantially aligned with the output port.
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In a preferred development, the reflective muffler is made of plastic, in particular using injection molding or blow molding or extrusion or polymer casting or 3D printing techniques.
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According to a second aspect of the invention the object is achieved by an air-processing unit of claim 11, the air-processing unit is adapted for processing compressed air.
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The air-processing unit, also referred to as APU, comprises an air input port, for receiving compressed air, in particular from an external compressed air supply unit such as a compressor, which can be a pneumatically controlled compressor or an electrically controlled compressor. The APU also comprises an air output port, for providing processed compressed air to an external pneumatic unit, in particular via a main pressure delivery line. The APU also comprises an exhaust port for exhausting compressed air to the atmosphere, in particular via a dedicated exhaust line. According to the second aspect of the present invention, the air-processing unit further comprises a reflective muffler in accordance with the first aspect of the invention. The APU thus shares the advantages of the inventive reflective muffler or of any of its developments. The reflective muffler is arranged in the exhaust line, with the input port of the reflective muffler connected to the exhaust port and the output port of the reflective connected to the atmosphere, in particular via an outlet port of the exhaust line.
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The APU is configured to provide processed compressed air to a pneumatic system and typically comprises an air-drying unit, which can be operated in delivery phase, where dried (processed) air is provided via the air output port to the pneumatic unit. The APU can also be operable in a regeneration phase, in which dried air from a reservoir or from other pneumatic units is used to regenerate the desiccant material in the air-drying unit. The air used in the regeneration phase is then exhausted via the exhaust line and the reflective muffler. Further, if the pressure at the air-drying unit is above a predetermined value, the compressed air can also be exhausted via the exhaust line and the reflective muffler. The use of the inventive reflective muffler in the APU enables a reduction of the noise level, in particular during exhaustion.
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According to a third aspect the object is achieved by a pneumatic system of claim 12.
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The pneumatic system comprises a compressed air supply unit, in particular a compressor, for generating compressed air. The inventive pneumatic system also comprises an air-processing unit in accordance with the second aspect of the present invention, wherein the air input port is connected to the compressed air supply unit. The pneumatic system of the third aspect also comprises a pneumatic unit configured to receive the processed compressed air from the APU for operation of the pneumatic unit.
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The pneumatic system of the third aspect thus shares the advantages of the APU of the second aspect of the invention.
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In the following, developments of the pneumatic system of the third aspect will be described.
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In a preferred development, the pneumatic system is configured as a pneumatic suspension system, wherein the pneumatic unit comprises two or more air bellows. Optionally, the pneumatic system comprises a compressed air reservoir arranged between the air output port of the APU and the air bellows and/or a compressed air distribution valve unit for controlling provision of processed compressed air to the two or more air bellows.
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In another development, the pneumatic system alternatively or additionally comprises an electronic control unit for controlling operation of the air-processing unit and, optionally, for controlling operation of the compressed air reservoir and/or of the compressed air distribution valve unit.
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According to a fourth aspect the object is achieved by a vehicle, in particular a passenger car, of claim 15.
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The vehicle, in particular a passenger car, comprises a pneumatic system in accordance with the third aspect and which, therefore, also shares its advantages.
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It shall be understood that a preferred embodiment of the present invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.
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These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
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The embodiments of the invention are described in the following on the basis of the drawings in comparison with the state of the art, which is also partly illustrated. The latter is not necessarily intended to represent the embodiments to scale. Drawings are, where useful for explanation, shown in schematized and/or slightly distorted form. With regards to additions to the lessons immediately recognizable from the drawings, reference is made to the relevant state of the art. It should be borne in mind that numerous modifications and changes can be made to the form and detail of an embodiment without deviating from the general idea of the invention. The features of the invention disclosed in the description, in the drawings and in the claims may be essential for the further development of the invention, either individually or in any combination.
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In addition, all combinations of at least two of the features disclosed in the description, drawings and/or claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below or to an object which would be limited in comparison to the object claimed in the claims. For specified design ranges, values within the specified limits are also disclosed as limit values and thus arbitrarily applicable and claimable.
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The following drawings show in:
- Fig. 1
- a view of a reflective muffler according to an embodiment of the invention;
- Fig. 2
- an internal view of a reflective muffler according to an embodiment of the invention;
- Fig. 3
- a detailed view of V-shape flow-deflection elements used in the reflective muffler of Fig. 2;
- Fig. 4
- a view of two halves of a reflective muffler that can be brought together for forming a reflective muffler according to an embodiment of the invent tion;
- Fig. 5
- a schematic block diagram of an embodiment of a pneumatic system comprising an air-processing unit according to an embodiment of the in vention; and
- Fig. 6
- a schematic block diagram of a passenger car according to an embody ment of the invention.
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Fig. 1 shows an external view of an embodiment of a reflective muffler 100 according to the invention. The reflective muffler 100 includes an input port 102 configured to be connected to an exhaust port 3 of an air-processing unit 200 (see Fig. 5). The reflective muffler also includes an output port 104 that is configured to be connected to an exhaust line 30 (see Fig. 5) for exhausting exhaust air 106b to the atmosphere A. The reflective muffler 100 includes a damping unit 107 that is arranged between the input port 102 and the output port 104. The exhaust air 106b is configured to flow from the input port 102 to the output port 104 following a flow direction F that is substantially identical to the longitudinal direction L. Fig. 1 shows the external housing 105 of the reflective muffler 100, where optionally an arrow points towards the outlet port 104 and has been included to facilitate the correct inclusion of muffler 100 in the exhaust line.
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Fig. 2 shows an internal view of a reflective muffler according to the invention, in particular, but not necessarily, of the reflective muffler 100 of Fig. 1. Identical reference numbers are used for those technical features having an identical or similar function and the following discussion will thus be focused on the technical features shown in Fig. 2 that are not shown in Fig. 1. In particular, the reflective muffler 100 of Fig. 2 comprises a damping chamber 108 that includes at least one, and in particular three, as exemplarily shown in Fig. 2, flow-deflection elements 110 that are configured to block a direct flow path 112 between the input port 102 and the output port 104. The direct flow path corresponds to the flow path that the air would follow from the input port 102 to the output port 104, and an inlet chamber 114 arranged between the input port 102 and the damping chamber 108. The inlet chamber 114 is separated from the damping chamber 108 by a first separation wall 122 that includes a pneumatic orifice 124. The pneumatic orifice is an orifice that significantly determines the pneumatic behavior of the reflective muffler 100, for instance acting as a throttle orifice or being an orifice of a Helmholtz resonator, for example formed by the damping chamber 108. The inlet chamber 114 has a cross sectional area value CS1 determined in a plane that is perpendicular to the longitudinal direction L that increases in a flow direction L from the input port 102 to the damping section 108. The cross-sectional value CS1 shown in Fig. 1, perpendicular to the longitudinal direction L, increases strictly, whereas in other embodiments, the cross-sectional value of the inlet chamber increases monotonically, such that there are some sub-regions which have a substantially constant cross-sectional value.
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In this particular embodiment of a reflective muffler 100 shown in Fig. 2 the pneumatic orifice 124 is the only orifice of the first separation wall 122. Further, the pneumatic orifice 124 is substantially aligned with the input port 102, along the longitudinal direction L.
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Further, the at least one flow-deflection element 110 is arranged in the damping chamber 108 such that there is at least a first peripheral passage P1 and a second peripheral passage P2, different from the first peripheral passage P1, for the flow between the input port 102 and the output port 104. The first peripheral passage P1 is delimited by an inner peripheral wall 120 of the housing 105 and a first end section of the flow-deflection element 110. The second peripheral passage P2 is delimited by the inner peripheral wall 120 of the housing 105 and a second end section of the flow-deflection element 110.
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Optionally, as it is shown in Fig. 2, the damping unit 107 comprises an outlet chamber 126 that is arranged between the damping chamber 108 and the output port 104. The outlet chamber 126 shown in Fig. 2 has a cross sectional area value CS2 determined in a plane perpendicular to the longitudinal direction L that decreases in the direction of flow L from the damping chamber 108 to the output port 104. In the embodiment of the reflective muffler 100 shown in Fig. 2 the rate of increase of the cross sectional are value CS1 of the inlet chamber 114 is substantially identical to the rate of decrease of the cross sectional area value CS2 of the outlet chamber 126 such that the outer shape of the muffler has a plane of symmetry perpendicular to the longitudinal direction at a middle position of the damping chamber 108, which has a substantially constant cross sectional area value (not taking into account the at least one flow-deflection element 110.
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In particular the reflective muffler 100 shown in Fig. 2 further comprises a second separation wall 128 arranged between the damping chamber 108 and the outlet chamber 126, the second separation wall 128 having a second pneumatic orifice 130, substantially aligned with the output port 104.
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The particular and exemplary configuration of the flow-deflection element 110 of the reflective muffler 100 of Fig. 2 will be described in detail with reference to Fig. 3, which shows a detailed view of V-shape flow-deflection elements used in the reflective muffler of Fig. 2. The reflective muffler 100 includes three flow-deflection elements that are configured as a V-shaped flow- deflection elements 110, 110a, 110b. These are arranged such that a respective leading edge 116, 116a, 116b, of each of the flow- deflection elements 110, 110a, 110b is pointed towards the input port 102 (see Fig. 2). There is a respective first and second peripheral passage P1, P2 for airflow between each of the first and second end points 118, 118b, 118c and, 119, 119b, 119c respectively of the first, second and third V-shaped flow- deflection elements 110, 110a, 110b and an inner peripheral wall 120 of the damping section 108.
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In particular, the respective leading edges 116, 116a, 116b of the first, second and third V-shaped flow- deflection elements 110, 110a, 110b are aligned along the longitudinal direction L, and preferably, a respective distance d1, d2, d3 between the first and second end points 118, 119; 118b, 119b; 118c, 119c, of each of the first, second and third V-shaped flow- deflection elements 110, 110a, 110b decreases as a distance between the respective leading edge 116, 116a, 116b and the input port 102 increases.
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Fig. 4 shows a view of two halves 100a, 100b of a reflective muffler 100 that can be brought together for forming a reflective muffler according to the invention. The halves are preferably identical in shape. Alternatively, one half includes half of the housing 105 and the complete flow-deflection element and the remaining half only includes the remaining half of the housing 105. One or both of the halves are preferably made of plastic by means of a suitable forming process such as 3D-printing, CNC machining, polymer casting, rotational molding, also referred to as roto-moulding, vacuum forming or thermoforming, injection molding, extrusion, blow molding, or any other suitable process.
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Fig. 5 shows a schematic block diagram of an embodiment of a pneumatic system 300 comprising an air-processing unit 200 according to the invention. The pneumatic system 300 comprises a compressed air supply unit 302, in particular in the form of a compressor, in this particular example an electrically controlled compressor 302, for generating compressed air 106. The compressor 302 has an intake port 0 for taking air, for instance from the environment, and is configured to compress the air. The pneumatic system comprises an air-processing unit 200 for processing the compressed air 106 and for providing processed compressed air 106a. The processing of the air includes for example filtering and/or drying the compressed air 106. The air-processing unit 200 includes an air input port 1, which is connected to the compressed air supply unit 302, for receiving the compressed air 106 from the compressed air supply unit 302, an air output port 2, for providing processed compressed air 106a to a pneumatic unit 305, and an exhaust port 3 for exhausting exhaust air 106b to the atmosphere A, in particular via an exhaust line 30. The air-processing unit 200 further comprises a reflective muffler 100 arranged in the exhaust line 30, with the input port 102 connected to the exhaust port 3 and the output port 104 connected to the atmosphere A, in particular via an outlet port 3a.
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The pneumatic system 300 also comprises a pneumatic unit 305 that configured to receive the processed compressed air 106a for operation of the pneumatic unit 305. For example, in the pneumatic system 300, the pneumatic unit 305 comprises two or more air bellows 308, and optionally comprises a compressed air reservoir 306 and/or a compressed air distribution valve unit 310 for controlling provision of processed compressed air 106a to the two or more air bellows 308.
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The pneumatic system 300 also optionally comprises an electronic control unit 304 for controlling operation of the air-processing unit 200 and, optionally, for controlling operation of the compressed air reservoir 306 and/or of the compressed air distribution valve unit 310 and/or of the air bellows 308.
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The air-processing unit 200 in combination with the compressed-air supply unit 302 forms a so-called air-supply unit 250. The reflective muffler 100 can be applied to exhaust lines of any air supply unit to reduce exhaust noise.
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Fig. 6 shows a schematic block diagram of a vehicle, in particular a passenger car 400 according to the invention. The following discussion will be focused on those technical features that have not yet been described, in particular with reference to the reflective muffler 100 of Figs. 1 to 4 and to the air-processing unit 200 and the pneumatic system 300 of Fig. 5. Those technical features having an identical or similar function are referred to using the same reference numbers and the reader is referred to the discussion of the previous figures. The passenger car 400 includes a pneumatic system 300, including a compressor 302, an air-processing unit 200 that includes a reflective muffler 100 and a pneumatic unit that comprises air bellows 308 of a suspension system and, if applicable, a pneumatic braking unit 312 for applying a braking force to the wheels 402 of the passenger vehicle 400.
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In summary, the invention is directed to a reflective muffler for reducing noise level in an exhaust line of an air-processing unit. The muffler comprises an input port and an output port for exhausting exhaust air. A damping unit is arranged between the input port and the output port and comprises a damping chamber including at least one flow-deflection element that is configured to block a direct flow path between the input port and the output port, and an inlet chamber arranged between the input port and the damping chamber. The inlet chamber is separated from the damping chamber by a first separation wall having a pneumatic orifice. The inlet chamber has a cross sectional area value perpendicular to a longitudinal direction that increases in a flow direction from the input port to the damping section.
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Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
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In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.
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A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
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Any reference signs in the claims should not be construed as limiting the scope.
Reference numbers (Part of the description)
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- 0
- Intake port of compressed air supply unit
- 1
- Air input port of air-processing unit
- 2
- Air output port of air-processing unit
- 3
- Exhaust port of air-processing unit
- 3a
- Outlet port of air-processing unit
- 30
- Exhaust line of air-processing unit
- 100
- Reflective muffler
- 100a
- First half of reflective muffler
- 100b
- Second half of reflective muffler
- 102
- Input port of reflective muffler
- 104
- Output port of reflective muffler
- 105
- Housing of reflective muffler
- 106
- Compressed air
- 106a
- Processed compressed air
- 106b
- Exhaust air
- 107
- Damping unit
- 108
- Damping chamber
- 110
- First V-shaped flow-deflection element
- 110a
- Second V-shaped flow-deflection element
- 110b
- Third V-shaped flow-deflection element
- 112
- Direct flow path
- 114
- Inlet chamber
- 116
- Leading edge of first V-shaped flow-deflection element
- 116a
- Leading edge of second V-shaped flow-deflection element
- 116b
- Leading edge of third V-shaped flow-deflection element
- 118
- First end point of first V-shaped flow-deflection element
- 118b
- First end point of second V-shaped flow-deflection element
- 118c
- First end point of third V-shaped flow-deflection element
- 119
- Second end point of first V-shaped flow-deflection element
- 119b
- Second end point of second V-shaped flow-deflection element
- 119c
- Second end point of third V-shaped flow-deflection element
- 120
- Inner peripheral wall of housing
- 122
- First separation wall
- 124
- Pneumatic orifice at first separation wall
- 126
- Outlet chamber
- 128
- Second separation wall
- 130
- Pneumatic orifice at second separation wall
- 200
- Air-processing unit
- 250
- Air supply unit
- 300
- Pneumatic system
- 302
- Compressed air supply unit; compressor
- 304
- Electronic control unit
- 305
- Pneumatic unit
- 306
- Compressed air reservoir
- 308
- Air bellows
- 310
- Compressed air distribution valve unit
- 312
- Pneumatic braking unit
- 400
- Vehicle, in particular passenger car
- 402
- Wheels
- A
- Atmosphere
- CS1
- Cross sectional area value of inlet chamber
- CS2
- Cross sectional area value of outlet chamber
- d1
- Distance between end sections of first flow-deflection element
- d2
- Distance between end sections of second flow-deflection element
- d3
- Distance between end sections of third flow-deflection element
- F
- Flow direction from input port to output port of reflective muffler
- L
- Longitudinal direction of reflective muffler
- P1
- First peripheral passage
- P2
- Second peripheral passage
