Device comprising an acoustic exhaust volume for an engine and a deflector structure

Abstract

A device, suitable for placement under the floor of a motor vehicle, comprising an acoustic volume (1) for attenuating engine exhaust noise, having an elongated envelope (10) closed at its upstream end by an upstream wall (3), and comprising a deflecting structure (2), characterized in that said deflecting structure is a component (2) located at least partially on the external face of said upstream wall of the acoustic volume, comprising at least one lower rounded deflecting portion (20) extending vertically at least over the lower portion (300) of the external surface of said upstream wall (3) and transversely to the longitudinal direction of the acoustic volume envelope, with its convexity facing in the opposite direction to said upstream wall. Figure to be published with the abbreviation: Fig. 1

Description

Description Title of the invention: Device comprising an acoustic volume engine exhaust and a deflecting structure

[0001] — The present invention relates to a device comprising an acoustic volume exhaust of an engine and a deflecting structure, for an exhaust line of a motor vehicle.

[0002] = A motor vehicle with an internal combustion engine conventionally comprises in its exhaust line under its floor, an acoustic volume which has the function main purpose of reducing the noise of the gases emitted by the engine. Classically a volume acoustics is presented in the form of a closed envelope, of an overall elongated shape, and having inlet and outlet ports. Said envelope is fitted inte- earlier to allow the gases from the exhaust circuit to pass between said orifices inlet and outlet. The inlet and outlet ports are respectively connected to an inlet pipe and one or more outlet pipes on the exhaust circuit.

[0003] Due to its shape and volume, the acoustic volume has a negative impact on the pe- vehicle's entry into the air and leads to excess fuel consumption, and therefore an increase in pollutant emissions, particularly carbon dioxide emissions CO.

[0004] — When the acoustic volume, located under the floor of the vehicle, is arranged longitudinally- dinally in the hollow part of the longitudinal central tunnel which includes the floor, the acoustic volume is particularly subject to air turbulence arriving under the vehicle so that its air resistance is increased. In addition, the acoustic volume is particularly exposed to obstacles passing under the vehicle in circulation, whether moving obstacles or fixed obstacles, which can deteriorate the acoustic volume and / or damage a larger part of the exhaust line or unhook the latter.

[0005] …— Patent application FR3077094 describes a device comprising a volume acoustic which has a closed envelope including a thermal insulating screen mitically enveloping the external surface of the envelope of the acoustic volume and a portion of which is shaped into an aerodynamic deflector. This device aims to improve the aerodynamic performance of the volume acoustics while improving the thermal protection of the floor against heat clear at the level of acoustic volume, the device being installed under the floor of a motor vehicle, near the rear bumper, oriented substantially along the transverse direction of the vehicle. It is not intended to address problems with the obstacles. The invention aims to propose a solution meeting the need to improve aerodynamic performance and behavior in the face of obstacles at the level of an acoustic volume of an exhaust line, and in particular when the acoustic volume, located under the floor of the vehicle, is arranged in a longitudinal orientation of the vehicle, in particular in the tunnel part of the floor. To this end, the invention provides a device, suitable for being arranged under the floor of a motor vehicle, comprising an acoustic volume attenuating the noise of the engine exhaust gases, having an elongated envelope closed at its upstream end by an upstream wall, and said device comprising a deflecting structure. According to the invention, said deflecting structure is a part located at least in part on the external face of said upstream wall of the acoustic volume, comprising at least one rounded deflecting lower part. This rounded shape extends on the one hand in height at least on the lower part of the external surface of said upstream wall and on the other hand transversely to the longitudinal direction of the envelope of the acoustic volume, and is convex facing in the opposite direction to said upstream wall. Said part with a rounded deflecting lower part is thus capable of deflecting the air arriving at the acoustic volume and guiding it under the acoustic volume and / or avoiding obstacles by deflecting moving obstacles or by guiding the exhaust line above a fixed obstacle. The concept of "upstream" relative to the wall is defined in relation to the arrival of exhaust gases in the acoustic volume. This concept is also relative to the concept of "front" corresponding to the arrival of air on the device in place under the floor of the vehicle when moving forward, or in relation to the longitudinal direction and the front of the vehicle. In other words, the upstream wall corresponds to the front wall which closes the upstream end (also front end) of the envelope of the acoustic volume. The concept of "lower" is defined in relation to the usual position of the acoustic volume and / or the device placed under the floor of the vehicle, or in relation to the vertical direction of the vehicle in its usual position, resting on its wheels. The concept of "lower" also refers to the part of the device in use which is closest to the ground. Preferably, said part extends in height over at most the lower half of the external surface of said upstream wall. Preferably, said rounded part of the part is located in the lower half of the part (depending on the height of the part in use). Preferably, said rounded-shaped part has a radius of curvature greater than or equal to 20 millimeters, more preferably greater than or equal to 25 millimeters. In particular, said rounded part can be likened to a portion of sphere. Preferably, said part has a closed shape on the external surface of said upstream wall. Preferably, said deflecting part is formed of a shell attached to the external face of said upstream wall of said acoustic volume. Preferably, said part is a single-piece shell. Advantageously, said part is removably secured to said upstream wall. The invention also relates to a vehicle, in particular an internal combustion vehicle, equipped with a device comprising an acoustic volume as described above, said device being installed externally under the floor of the vehicle and oriented in the longitudinal direction of the vehicle so that the upstream wall of the acoustic volume is at the front of the acoustic volume. The upstream wall thus corresponds to the front wall which closes the front end of the envelope of the acoustic volume. In particular, said device is installed in the hollow part of the longitudinal central tunnel which comprises the floor of the vehicle. Other features and advantages of the invention will emerge from reading the description given below of a particular embodiment of the invention, given for informational purposes but not as a limitation, with reference to the appended drawings in which: [Fig.1] is a perspective view of a device comprising an acoustic exhaust volume of an engine and a deflector structure according to an embodiment of the invention, integrated into an exhaust line of a heat engine partially shown. [Fig.2] is a partial view from below of the device according to [Fig.1], integrated into an exhaust line and installed under the floor of a vehicle. [Fig.3] is a longitudinal sectional view in the vertical plane XZ of a part of the device illustrated in the preceding figures. [Fig.4] is an enlarged and longitudinal sectional view in the vertical plane XZ of a part of the device illustrated in the preceding figures. In the present description, the terms front, rear, upper, lower, refer to the usual directions of the vehicle resting on its wheels, and correspond to the directions of the device comprising an acoustic volume and a deflecting structure according to the invention mounted under the floor of the vehicle. The axes of the orthonormal trihedron X, Y, Z, correspond respectively to the longitudinal axis (oriented from front to rear), transverse (oriented towards the right of the vehicle) and vertical for a vehicle resting on its wheels (usual position). Figures 1 to 4 will be discussed together. [Fig.1] represents a device D comprising an acoustic volume exhaust of an engine and a deflector structure 2 according to one embodiment of the invention. This device is integrated into an exhaust line of a thermal engine, shown partially in transparency, comprising in addition to the acoustic volume 1, a depolluting member B connected upstream of the acoustic volume, to treat the exhaust gases leaving the engine. This part of the exhaust line comprising the device D is shown in a view from below in [Fig.2], installed under the floor P of the vehicle, in the hollow part of the central tunnel T which the floor comprises longitudinally. The device comprising the acoustic volume is thus arranged in the longitudinal direction (direction X) of the vehicle. The acoustic volume 1 comprises an external metallic envelope 10, which is shown transparently in the figures, in order to show the internal pipes in which the incoming and outgoing exhaust gases circulate. Said external envelope 10 has a volume shape and is generally elongated in the longitudinal direction of the vehicle. Each of its front and rear longitudinal ends is closed by walls, respectively upstream 3 and downstream 4, usually called respectively inlet cup and outlet cup with reference to the direction of circulation of the exhaust gases entering and leaving the acoustic volume. The upstream wall 3 thus corresponds to the front wall (or inlet cup) which closes the front end of the acoustic volume envelope. According to the example, the upstream wall 3 comprises an inlet orifice 30 receiving a pipe 5 for connection to the depolluting member B from which the gases which enter the acoustic volume arrive. The deflecting structure 2 of the device essentially comprises a part in the form of a shell, generally of rounded shape, which is fixed on the external face of the upstream wall 3, and in the lower part of this upstream wall. The shell 2 occupies a zone 300 of the upstream wall 3 extending in the vertical direction (Z direction) over a portion of height “h” of said upstream wall 3 starting from the lower edge of the envelope, and in the transverse direction (Y direction) over the entire width of said upstream wall. The lower part 20 of the hull, i.e. the lower part extending over approximately half the height of the hull, has a very rounded shape, and a convexity facing in the opposite direction to said upstream wall 3, in other words a convexity facing upstream (also the front) of the upstream wall 3. This very rounded shape of the hull has a radius of curvature of approximately 25 millimeters; it corresponds substantially to a portion of a sphere. This very rounded shape of the lower part of the part allows the deflector function. It allows the air flow (arrows A in [Fig.3]) to be diverted, arriving opposite the acoustic volume when the vehicle is moving forward, and allows it to be guided below the envelope 10 of the acoustic volume. This improves the vehicle's air penetration and therefore minimizes the impact of the acoustic volume on fuel consumption. In addition, this very rounded shape makes it possible to manage obstacles present under the vehicle and which could hit the exhaust line, in particular the acoustic volume which is the low point of the line, either by deflecting light moving obstacles under the floor, or by deflecting and guiding the exhaust line upwards (towards the floor P) when the acoustic volume of the vehicle encounters a fixed obstacle. Comparative tests have shown that it is preferable for the radius of curvature of the very rounded shape located in the lower part of the hull to be at least 20 millimeters to have an effective air deflecting effect and an effective anti-obstacle effect. The larger the radius of curvature, the greater the efficiency of the rounded shape. The larger value of the radius of curvature depends mainly on the space available for the hull. Without the part with this very rounded deflecting lower part, the acoustic volume, which corresponds to the lowest point of the vehicle and whose inlet cup is in particular very flat and very straight, in other words arranged at right angles to the longitudinal direction of the vehicle, would be particularly exposed to turbulence and moving or fixed obstacles appearing under the vehicle when the vehicle is moving forward. With this deflector part 2, the gain in aerodynamic coefficient SCX was for example dimensioned at 0.004m? and the gain in CO is 0.2 grams. According to the example illustrated, the lowest point of the shell corresponds to the lowest point of the acoustic volume, however it could, if the arrangement of the acoustic volume under the floor of the vehicle allows it without altering the ground clearance of the vehicle, to fix the shell overhanging this low point of the acoustic volume, the shell would pass (slightly) under the cup-envelope junction. Furthermore, the part 2 has a closed shape on the upstream wall 3, that is to say that the part is formed of a sheet metal wall open on the side of the upstream wall 3 of the acoustic volume, the latter completely closing said part 2. This closed shape on the upstream wall helps to minimize the whistling noises that could be generated by the air entering the room, and also helps to protect it from the entry of gravel. The room can also include an orifice to evacuate liquids that could enter it, this orifice being small in size to prevent the entry of stones for example. In addition, this closed shape of part 2 on the upstream wall allows for easy attachment of the part to the upstream wall, by providing docking zones along its entire length. perimeter. The part is made of sheet metal, and can be fixed by welding to the upstream wall 3. This deflector part being added, for example fixed in a removable manner, it can be put in place or not, or even replaced, depending on the needs of the vehicle by the car manufacturer or a garage. The invention makes it possible to minimize the impact relative to air penetration (aerodynamic coefficient SCx) while maintaining the necessary volume of the acoustic volume without complicating the inlet cup, and therefore to reduce the emission of pollutants. It also makes it possible to manage obstacles that may appear under the vehicle.

Claims

Claims

1. Device (D), suitable for being arranged under the floor of a vehicle engine, comprising an acoustic volume (1) attenuating the noise of the engine exhaust gas which has a shaped envelope elongated (10) closed at its upstream end by an upstream wall (3), and comprising a deflecting structure (2), characterized in that said deflector structure is a part (2) located at least partly on the external face of said upstream wall of the acoustic volume, comprising at at least one rounded-shaped deflecting lower portion (20) extending on the one hand in height at least on the lower part (300) of the external surface of said upstream wall (3) and on the other hand transversely to the longitudinal direction of the envelope of the acoustic volume, and convexity facing in the opposite direction to said upstream wall.

2. Device according to claim 1, characterized in that said part de- deflector (2) extends in height over at most the lower half of the external surface of said upstream wall (3).

3. Device according to one of claims 1 to 2, characterized in that said rounded-shaped part (20) of the part (2) is located in the lower half of the room.

4. Device according to one of claims 1 to 3, characterized in that said rounded-shaped portion (20) has a radius of curvature greater than or equal to 20 millimeters.

5. Device according to one of claims 1 to 4, characterized in that said part (2) has a closed shape on the upstream wall (3).

6. Device according to one of claims 1 to 5, characterized in that said part (2) is formed of a shell attached to the external face of said upstream wall (3) of the acoustic volume.

7. Device according to one of claims 1 to 6, characterized in that said part (2) is a single-piece shell.

8. Device according to any one of claims 1 to 7, characterized in that said part (2) is removably secured to said upstream wall (3).

9. Motor vehicle with motor, in particular with internal combustion, equipped with a device (D) comprising an acoustic volume (1) and a deflector structure (2) according to any one of claims 1 to 8, said device (D) being installed externally under the floor (P) of said vehicle and oriented in the longitudinal direction of the vehicle of so that the upstream wall {3) of the acoustic volume is in front of the acoustic volume.

10. Motor vehicle according to claim 9, characterized in that that the said device is installed in the hollow part of the central tunnel longitudinal (T) which includes the vehicle floor.