NOISE DAMPER, IN PARTICULAR FOR AN AIR CONDITIONING SYSTEM OF A RAILWAY VEHICLE

Abstract

The noise damper includes a casing delimiting an air passage, the casing having walls each includes an acoustic insulation layer. The noise damper includes: at least one baffle arranged in the air passage to separate the air passage in several channels, each channel extending substantially parallel to a longitudinal direction, and a helical deflector arranged in each channel, extending parallel to the longitudinal direction.

Claims

1. A noise damper, comprising a casing delimiting an air passage, the casing having walls each comprising an acoustic insulation layer, wherein the noise damper comprises: at least one baffle arranged in the air passage to separate the air passage in several channels, each channel extending substantially parallel to a longitudinal direction; and a helical deflector arranged in each channel, extending parallel to the longitudinal direction.

2. The noise damper according to claim 1, wherein the casing is made of metal.

3. The noise damper according to claim 1, wherein the casing is made of aluminum.

4. The noise damper according to claim 1, having a length, in the longitudinal direction, substantially equal to 1 meter.

5. The noise damper according to claim 1, wherein said at least one baffle is inclined in regard to the longitudinal direction, so that the channels have not a constant cross section along the longitudinal direction.

6. The noise damper according to claim 1, wherein each baffle comprises an acoustic insulation layer on its faces.

7. The noise damper according to claim 1, wherein each helical deflector has a helical surface extending around a central axis and extending radially from the central axis to an inner surface delimiting a corresponding channel.

8. An air conditioning system, comprising the noise damper according to claim 1.

9. A railway vehicle, comprising the air conditioning system according to claim 8.

10. The railway vehicle according to claim 9, wherein the railway vehicle is an underground train.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Several aspects and advantages of the present disclosure will be enlightened in the following disclosure, given only as an example and made in reference to the attached FIGURE, in which:

[0022] FIG. 1 is an open view from above of a noise damper according to an example of embodiment of the present disclosure.

[0023] FIG. 1 shows a noise damper 10, according to an example of embodiment of the present disclosure. The noise damper 10 is intended to equip an air conditioning system, in particular in a railway vehicle. The railway vehicle is for example an underground train.

DETAILED DESCRIPTION

[0024] In an underground train, the air conditioning system is generally formed by an HVAC (Heat Ventilation Air Conditioning) unit arranged on a roof structure and one air duct system on the top of a ceiling. The air is blown from outlets placed on each side of the ceiling.

[0025] The main noise source inside the railway vehicle is fans of the HVAC unit. The critical point in term of noise level is the area just below diffuser closest to HVAC Unit. Thus, the noise damper 10 is arranged between an upstream duct 12 coming from the air conditioning system and a downstream duct 14 intended to distribute conditioned air towards a passenger area of the railway vehicle. The downstream duct 14 usually comprises outlets leading to the passenger area.

[0026] The function of this noise damper 10 is to reduce the noise coming from the fans of the HVAC unit.

[0027] The noise damper 10 comprises a casing 16 comprising walls 18 delimiting an air passage extending in a longitudinal direction X between the upstream duct 12 and the downstream duct 14. The casing 16 is preferentially metallic, advantageously made of aluminum.

[0028] Preferentially, the noise damper 10 has a length of about 1 meter in the longitudinal direction X. A longer noise damper (2 or 3 m) would be better for the acoustic but not acceptable for the passenger in term of temperature comfort. On contrary, with a smaller noise damper or without any noise damper, the aeraulic comfort would be better but it would be noisier for the passenger. Thus, a length of about 1 meter is optimal.

[0029] Each wall 18 comprises at least one acoustic insulation layer, intended to absorb noise of the airflow circulating in contact of this acoustic insulation layer, in a manner known.

[0030] The noise damper 10 according to the present disclosure also comprises at least one baffle 20 arranged in the air passage to separate the air passage in several channels. Each channel extends substantially parallel to the longitudinal direction X. In the example shown, the noise damper 10 comprises three baffles 20, separating the air passage into four channels.

[0031] Preferentially, at least one of the baffles 20 is inclined in regard to the longitudinal direction X, so that the channels have not a constant cross section along the longitudinal direction X. On the example shown, the two central channels are narrow on the side of the upstream duct 12, and wide on the side of the downstream duct 14, whereas the lateral channels are wide on the side of the upstream duct 12, and narrow on the side of the downstream duct 14.

[0032] Preferentially, each baffle 20 comprises an acoustic insulation layer 22 on its faces, so that each channel is transversally delimited between two acoustic insulation layers 22.

[0033] Each acoustic insulation layer 22 preferentially has a thickness of 20 mm.

[0034] Each channel also comprises acoustic insulation layers on its bottom wall and on its upper wall.

[0035] The noise damping depends on the surface of acoustic insulation in contact with the air. The global surface of insulation in contact with the air is increased by adding baffles inside the noise damper, thus the baffles 20 allow reducing noise.

[0036] Besides, the baffles 20 improve the air guiding, avoiding turbulences.

[0037] The noise damper 10 also comprises, in each channel, a helical deflector 24, extending substantially parallel to the longitudinal direction, i.e. in the direction of the airflow.

[0038] Each helical deflector 24 has a helical surface extending around a central axis. The helical surface extends radially from the central axis to an inner surface of the acoustic insulation layers delimiting the channel. Consequently, the air necessarily flows between the helical surface and the acoustic insulation layers 22, along the helical surface.

[0039] In other words, because of the helical deflector 24, the airflow necessarily encounters the acoustic insulation layers 22 delimiting the channel, and the helical deflector blocks the direct acoustic waves coming from the upstream duct 12.