WO2020029214A1

WO2020029214A1 - Automotive air ventilation unit with noise absorbing screen at interior air intake

Info

Publication number: WO2020029214A1
Application number: PCT/CN2018/099788
Authority: WO
Inventors: Lianfeng JIANG; Dupuy FREDERIC; Yunzhu WU; Jian Li; Huilian CHEN; Wenfeng SONG
Original assignee: Psa Automobiles Sa
Priority date: 2018-08-10
Filing date: 2018-08-10
Publication date: 2020-02-13
Also published as: EP3833560A1; CN112566804A; EP3833560A4

Abstract

An air ventilation unit (6) for the interior compartment of a vehicle (2), comprising an exterior air intake (8); an interior air intake (10) with an opening (10.2); a valve (12) for selectively opening the exterior air intake (8) or the interior air intake (10); a blower (14) for blowing the exterior or interior air towards the interior compartment; and a noise absorbing screen (26) arranged in front of the opening (10.2) of the interior air intake (10) and distally from the opening (10.2) so as to allow a lateral interior air intake flow between the screen (26) and the opening (10.2).

Description

AUTOMOTIVE AIR VENTILATION UNIT WITH NOISE ABSORBING SCREEN AT INTERIOR AIR INTAKE

FIELD OF TECHNOLOGY

The invention is directed to the field of vehicles, more particularly to the air ventilation of the passenger compartment of vehicles.

BACKGROUND

Prior art patent document published FR 3 012 374 A1 discloses a Heating Ventilation and Air-Conditioning (HVAC) unit for vehicles. The HVAC unit comprises a flap that selectively opens an exterior air intake or an interior air intake, depending on various conditions. The selected exterior or interior air is then moved by a blower in the unit for passing through an evaporator of an air-conditioning system and a heat exchanger of the cooling circuit of the engine of the vehicle, before being circulated inside the passenger compartment of the vehicle. This unit shows an actuator for moving the flap that is directly mounted on said flap.

Generally speaking, the air circulation generated by the blower of an HVAC unit can generate noise at various locations but in particular at air vents on the dashboard.

Prior art patent document EP 2 106 938 A1 discloses a cover flap for a ventilation air vent in a vehicle. The cover flap configured to be pivotally mounted in an air vent, i.e. at the exit of a ventilation channel in the vehicle, e.g. on the dashboard. The cover flap comprises a main part forming a shell, an interior part mounted on an inner face of the main part, a layer of noise absorbing material sandwiched between the main part and the interior part. The noise absorbing material is intended to reduce the noise generated by the air-conditioning compressor that can be propagated through the ventilation channels in the passenger compartment of the vehicle.

Noise generation issues remain however in HVAC units, in particular in relation with the blower of such units.

SUMMARY

Technical Problem

The invention has for technical problem to alleviate at least one of the drawbacks of the above cited prior art. More specifically, the invention has for technical problem to reduce the noise production of the air ventilation unit for the interior compartment of a vehicle.

Technical solution

The invention is directed to an air ventilation unit for the interior compartment of a vehicle, comprising an exterior air intake; an interior air intake with an opening; a valve for selectively opening the exterior air intake or the interior air intake; a blower for blowing the exterior or interior air towards the interior compartment; wherein the air ventilation unit further comprises a noise absorbing screen arranged in front of the opening of the interior air intake and distally from said opening so as to allow a lateral interior air intake flow between said screen and said opening.

According to a preferred embodiment, the noise absorbing screen comprises at least one layer of noise absorbing material and a support of said at least one layer.

According to a preferred embodiment, the support forms a grating to which the at least one layer of noise absorbing material is attached.

According to a preferred embodiment, the noise absorbing material is a fibrous or foam material.

According to a preferred embodiment, the noise absorbing material shows a sound absorbing coefficient that is greater than 0.8 for frequencies ranging from 800 to 10 000 Hz.

According to a preferred embodiment, the noise absorbing screen covers at least 40%of the cross-sectional surface of the opening of the interior air intake or of the surface of a projection on the screen of said opening along a main axis thereof.

According to a preferred embodiment, the noise absorbing screen has an inner main surface oriented towards the opening of the interior air intake, said inner surface being concave.

According to a preferred embodiment, the noise absorbing screen has a periphery with a portion thereof which is in contact with an edge of the opening of the interior air intake.

According to a preferred embodiment, the noise absorbing screen forms a curved and concave plate with regard to the interior air intake.

The invention is also directed to an automotive vehicle comprising an interior compartment and an air ventilation unit for said interior compartment; wherein the air ventilation unit is according to the invention.

Advantages of the invention

The invention is particularly interesting in that it substantially reduces the noise level in the recycling mode. The noise generated in that mode, even though limited compared with other noise sources (like wind noise, engine noise, etc. ) is becoming nowadays important and noticeable due to the general reduction of the other noise sources. This is particularly true for electric vehicle where the noise of the engine is not present anymore. In other words, the noise generated by the air circulation in a vehicle is generally becoming more annoying and the invention provides a solution for reducing the increased noise level of an air circulation unit when functioning the recycling mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic sectional view of a HVAC unit of a vehicle, according to the prior art and according to the invention (in the enlarged view) .

Figure 2 is a schematic sectional view of an air ventilation unit according to the invention.

Figure 3 is a perspective view of the interior air intake of an air ventilation unit, provided with a support for a noise absorbing layer according to the invention.

Figure 4 corresponds to figure 3 where the layer of noise absorbing layer is placed on the support, thereby forming a noise absorbing screen in accordance with the invention.

Figure 5 is a graphs showing the noise measured at the vicinity of the interior art intake of the air ventilation unit of figures 2 to 4 with and without the noise absorbing screen.

DETAILED DESCRIPTION

Figure 1 is a schematic section view of a Heating Ventilation and Air-Conditioning (HVAC) unit in a vehicle, according to the prior art. As this apparent, the vehicle 2 comprises a HVAC unit 4 located between the passenger compartment and the engine compartment at the front, approximatively below the windshield.

The HVAC unit 4 comprises an air ventilation unit or sub-unit 6. The latter comprises essentially an exterior air intake 8, an interior air intake 10, a flap 12 forming a valve for selecting one of the exterior and

interior air intakes

8 and 10, and a blower 14.

The HVAC unit 4 further houses an evaporator 16 fluidly connected to, and part of the air-conditioning system (not represented) of the vehicle and a heat exchanger 18 fluidly connected to, and part of a cooling circuit of the engine (also not represented) of the vehicle. A flap 20 allows the air to bypass the heat exchanger 18. The HVAC unit 4 comprises also a series of air vents 22 equipped with flaps 24 for closing or opening an air passage through these vents.

In usual functioning conditions, the flap 12 is positioned so as to open the exterior air intake 8 and close the interior air intake 10, so that the exterior air is drawn by the blower 14 inside the unit through the evaporator 16 and the heat exchanger 18 for reaching the air vents 22. The air circulates along the passenger compartment and reaches the trunk where exit flaps (not represented) are provided. These functioning conditions correspond to a fresh mode, i.e. a mode where the air in the compartment is renewed with fresh air from outside the vehicle.

In certain conditions, like when the exterior air is polluted or when the vehicle was stopped for a longer period in sunny conditions so that the interior temperature is particularly high, the flap 12 is switched so as to close the exterior air intake 8 and open the interior air intake 10. The interior air then drawn by the blower 14 and circulated in closed loop. These functioning conditions correspond to a recycling mode, i.e. a mode where the air in the compartment is recycled.

It has been detected by the inventors that in the recycling mode, the noise generated by the HVAC unit, more particularly by the air ventilation unit, is more important. The reason is that the noise generated by the blower is directly propagated to the passenger compartment through the intake channel, in a direction opposite to the intake air flow. To overcome that problem, the invention provides a noise absorbing screen 26 in front of the interior air intake 10. That screen 26 is represented very schematically in the enlarged view of the exterior and

interior air intakes

8 and 10 respectively. The screen is configured not to obstruct the intake 10 but rather arranged in front of the opening of the interior air intake and distally from said opening so as to allow a lateral interior air intake flow between said at least one layer and said opening.

Figure 2 is a schematic sectional view of an air ventilation unit according to the invention. As this is apparent, the flap 12 shows a closing surface 12.1 that is pivoting around the axis 12.2. The flap 12 is represented in a first position with continuous line, corresponding to a recycling mode, i.e. where air from the interior is drawn through the interior air intake 10; and in a second position with dashed line, corresponding to the fresh mode, i.e. where air from outside is drawn through the exterior air intake 8.

As this is apparent, the noise absorbing screen 26 is curved so as not to interfere with the flap 12 when the latter is rotating. The noise absorbing screen 26 consists for instance of a support 26.1 attached to the housing of the air ventilation unit 6 and one or several layers 26.2 of noise absorbing material arranged on said support. As least some portions of the noise absorbing screen 26 are distant from the edge or opening 10.1 of the interior air intake 10 so as to leave a passage for the air flow, meaning that the noise absorbing screen 26 does not work as an air filter but only as a noise absorbing means.

Figures 3 and 4 are perspective views of a more concrete embodiment of the invention, in line with the schematic view of figure 2, showing an air ventilation unit 6 equipped with a noise absorbing screen 26.

Figure 3 shows the interior air intake 10 of the air ventilation unit 6, where said intake 10 is delimited by a wall 10.1 that shows an edge 10.2 forming the opening of the intake. The support 26.1 of the noise absorbing screen 26 extends over the interior air intake 10 and is attached to the body. The support 26.1 is advantageously made of plastic. It comprises a wall that advantageously forms a grate, i.e. a wall with a series of openings 26.1.1. It can comprise a series of fastening means 26.1.2 for fastening one or several layers of noise absorbing material. These means are for instance shaped as hooks extending from the outer surface of the support. The latter comprises also fastening means 26.1.3 and 26.1.4 to the housing of the air ventilation unit 6. For instance, a first fastening means 26.1.3 is shaped as a tongue that engages in a corresponding slot 10.3 on the outer edge 10.2 of the wall 10.1 of the interior air intake 10. Two second fastening means 26.1.4 are provided at a side of the support 26.1 that is opposite to the first fastening means 26.1.3. They extend from the wall of the support 26.1 and have a free end in contact with and attached to the housing of the air ventilation unit 6. They keep therefore that side of the wall (for instance the right side) distant from the edge 10.2 of the intake 10, thereby allowing the air to flow laterally to the intake 10. The fastening means 26.1.4 form each a hollow post with a bottom end. A screw is inserted through the hollow post and through a hole in the bottom end for engaging with the housing of the air ventilation unit 6 and thereby pressing the bottom end against said housing.

The distance between the side of the support 26.1 that shows the second fastening means 26.1.4 and the opening is essentially determined by the height of these means. This height can be greater than 20mm and/or less than 50mm.

Figure 4 shows the noise absorbing screen 26 in a complete configuration, i.e. with a layer of absorbing material 26.2 applied against the support 26.1. The material can be fibrous or a foam. The material shows advantageously a sound absorbing coefficient that is greater than 0.8 for frequencies ranging from 800 to 10 000 Hz. The layer is advantageously a mat or a panel. More than one layer can be applied in a superimposed manner.

Still with reference with figures 3 and 4, the noise absorbing screen covers at least 50%of the surface of the opening in order to be able to absorb a substantial portion of the noise propagating back from the blower through the air ventilation unit.

Figure 5 illustrates the level of noise at various frequencies produced by an air ventilation unit according to the above when functioning in recycling mode. A test microphone has been placed at a transversally central position at a distance of 1m from the defrost exit and at the height of the front air vents (at a height of about 0.5m from the floor) . The upper continuous line shows the noise measured in the absence of a noise absorbing screen whereas the two lower lines (bold and dashed) show the noise measures in the presence of a noise absorbing screen, i.e. with a single layer of noise absorbing material (bold line) and with two layers thereof (dashed line) , respectively. It is apparent that the presence of the noise absorbing screen achieves a substantial noise reduction in the frequency range of 2 500 Hz to 10 000 Hz, of up to about 6dB (with the two layers at a frequency of about 7 500-8 000 Hz) .

Claims

Air ventilation unit (6) for the interior compartment of a vehicle (2) , comprising:

an exterior air intake (8) ;

an interior air intake (10) with an opening (10.2) ;

a valve (12) for selectively opening the exterior air intake (8) or the interior air intake (10) ;

a blower (14) for blowing the exterior or interior air towards the interior compartment;

characterized in that the air ventilation unit (6) further comprises:

a noise absorbing screen (26) arranged in front of the opening (10.2) of the interior air intake (10) and distally from said opening so as to allow a lateral interior air intake flow between said screen and said opening.
Air ventilation unit (6) according to claim 1, wherein the noise absorbing screen (26) comprises at least one layer (26.2) of noise absorbing material and a support (26.1) of said at least one layer.
Air ventilation unit (6) according to claim 2, wherein the support (26.1) forms a grating to which the at least one layer (26.2) of noise absorbing material is attached.
Air ventilation unit (6) according to one of claims 2 and 3, wherein the noise absorbing material is a fibrous or foam material.
Air ventilation unit (6) according to any one of claims 2 to 4, wherein the noise absorbing material shows a sound absorbing coefficient that is greater than 0.8 for frequencies ranging from 800 to 10 000 Hz.
Air ventilation unit (6) according to any one of claims 1 to 5, wherein the noise absorbing screen (26) covers at least 40%of the cross-sectional surface of the opening (10.2) of the interior air intake (10) or of the surface of a projection on the noise absorbing screen (26) of said opening along a main axis thereof.
Air ventilation unit (6) according to any one of claims 1 to 6, wherein the noise absorbing screen (26) has an inner main surface oriented towards the opening of the interior air intake (10) , said inner surface being concave.
Air ventilation unit (6) according to any one of claims 1 to 6, wherein the noise absorbing screen (26) has a periphery with a portion thereof which is in contact with an edge (10.2) of the opening of the interior air intake (10) .
Air ventilation unit (6) according to claim 8, wherein the noise absorbing screen (26) forms a curved and concave plate with regard to the interior air intake (10) .
Automotive vehicle (2) comprising an interior compartment and an air ventilation unit (6) for said interior compartment; characterized in that the air ventilation unit is according to any one of claims 1 to 9.