Description:DESCRIPTION
Technical Field
This disclosure relates generally to noise cancellation, and in particular to a noise reducing system for a vehicle, and a Heating, Ventilation, And Air Conditioning (HVAC) system with noise reducing functionality.

Background
Noise from Heating, Ventilation, and Air Conditioning (HVAC) system of a vehicle may stem from various components within the HVAC system and may manifest in different forms, including whistling, humming, rattling, or buzzing sounds. A common source of noise in vehicle HVAC systems is a blower fan which is responsible for circulating air within the HVAC system and may generate noise, particularly at higher speeds of rotation. Another cause of noise is airflow turbulence caused by obstructions, bends, or irregularities in the duct. Further, vibrations from components such as the blower motor, compressor, or duct may create audible noise. Loose or worn parts within these components can exacerbate vibration-related noise.
Addressing noise in the HVAC system contributes to a quieter and more comfortable driving experience for vehicle occupants. Therefore, there is a need for a mechanism for reducing noise in the HVAC system of the vehicle.

SUMMARY
In an embodiment, a system for a Heating, Ventilation, And Air Conditioning (HVAC) system for a vehicle is disclosed. The HVAC system may include a blower chamber housing an air blower generating an airflow to be released in a cabin of the vehicle. The HVAC system may include one or more air vents positioned in the cabin of the vehicle and fluidically coupled with the blower chamber via a duct. The one or more air vents may be configured to release the airflow generated in the blower chamber. The HVAC system may include at least one acoustic damper coupled to the duct leading from the blower chamber to the one or more air vents. Each of the at least one acoustic damper may be fluidically coupled with the duct via an associated opening formed on the duct. Further, each of the at least one acoustic damper cancels sound of an associated predetermined frequency range traveling through the duct.
In another embodiment, a sound reduction system is disclosed. The sound reduction system may include at least one acoustic damper positioned on the duct leading from a blower chamber to one or more air vents of a HVAC system. Each of the at least one acoustic damper may be fluidically coupled with the duct via an associated opening formed on the duct. Each of the at least one acoustic damper may be configured to cancel sound of an associated predetermined frequency range traveling through the duct. The sound reduction system may include a controller communicatively coupled with the at least one acoustic damper. The controller includes a processor and a memory communicatively coupled with the processor. The memory stores processor-executable instructions which, upon execution by the processor, cause the processor to receive an airflow rate of the air traveling through the duct, compare the airflow rate with a predefined threshold value, and switch ON the at least one acoustic damper, when the airflow rate is greater than the threshold value.
In yet another embodiment, a vehicle is disclosed. The vehicle may include a HVAC system that may include a blower chamber housing an air blower generating an airflow to be released in a cabin of the vehicle. The HVAC system may further include one or more air vents positioned in the cabin of the vehicle and fluidically coupled with the blower chamber via a duct. The one or more air vents may be configured to release the airflow generated in the blower chamber. The HVAC system may further include at least one acoustic damper coupled to the duct leading from the blower chamber to the one or more air vents. Each of the at least one acoustic damper may be fluidically coupled with the duct via an associated opening formed on the duct. Each of the at least one acoustic damper cancels sound of an associated predetermined frequency range traveling through the duct.

BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles.
FIG. 1 illustrates a schematic diagram of a Heating, Ventilation, And Air Conditioning (HVAC) system for a vehicle, in accordance with an embodiment of the present disclosure.
FIG. 2 illustrates a part of a schematic diagram of a HVAC system for a vehicle, in accordance with an embodiment.
FIG. 3 is a schematic diagram of an acoustic damper, in accordance with some embodiments.
FIG. 4 is a block diagram of a noise reducing system, in accordance with some embodiments.

DETAILED DESCRIPTION
Exemplary embodiments are described with reference to the accompanying drawings. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the spirit and scope of the disclosed embodiments. It is intended that the following detailed description be considered as exemplary only, with the true scope and spirit being indicated by the following claims. Additional illustrative embodiments are listed below.
The present disclosure relates to a noise reducing system. The noise reducing system implements at least one acoustic damper that may be coupled to a duct leading from a blower chamber to one or more air vents of a vehicle. The acoustic dampers may be coupled to the duct, in a branched manner. Sound (i.e. noise) may be generated in the duct from various sources at different frequencies. For example, the sound may be due to blower motor, blower impeller, or blower suction. The acoustic damper may reduce intensity (i.e. amplitude) of sound of a targeted frequency range to reduce an overall induced sound due to airflow. The acoustic damper may be operational only when the airflow reaches a predefined threshold to restrict the lag. For example, when the airflow rises above a threshold value, then a valve of the acoustic damper may open.
Referring now to FIG. 1, a schematic diagram of a HVAC system 100 for a vehicle is illustrated, in accordance with an embodiment of the present disclosure. The HVAC system 100 may include a blower chamber 102 that may house an air blower 104. The air blower 104 may generate an airflow to be released in a cabin of the vehicle. The HVAC system 100 may further include one or more air vents 106 that may be positioned in the cabin of the vehicle and fluidically coupled with the blower chamber 102 via a duct 108. The one or more air vents 106 may be configured to release the airflow generated in the blower chamber 102, into the cabin. For example, in some embodiments, the blower chamber 102 housing the air blower 104 may be positioned in a hood of the vehicle. Further, the one or more air vents 106 may be provided on a dashboard inside the cabin of the vehicle.
As will be appreciated by those skilled in the art, the duct 108 may be a conduit that may provide a channel for flow of the air from the blower chamber 102 to the one or more air vents 106. As such, the duct 108 may lead from the blower chamber 102 to the one or more air vents 106. The duct 108 may have a rectangular or a circular cross-section, and may be made of sheet metal, fiberglass, or other materials. Additionally, the duct 108 may be insulated to prevent heat loss or gain as air travels through it.
The HVAC system 100 may further include at least one acoustic damper 110 that may be coupled to the duct 108. As shown in FIG. 1, the acoustic damper 110 may be fluidically coupled to the duct 108 via an associated opening formed on the duct 108. The acoustic damper 110 may be coupled to the duct 108 in a branched-out manner. That is, the acoustic damper 110 may emerge from the duct 108 as a branch. For example, the acoustic damper 110 may be coupled to the duct 108 via a branch-duct 112 originating from the duct 108. For example, the branch-duct 112 may be a part of the acoustic damper 110 (i.e. formed into the acoustic damper 110), such that the acoustic damper 110 is coupled to the duct 108 by attaching the branch-duct 112 to the duct 108. In other examples, the branch-duct 112 may be a part of the duct 108 (i.e. formed into the duct 108), such that the acoustic damper 110 is coupled to the duct 108 by coupling the acoustic damper 110 to the branch-duct 112. Further, alternatively, the branch-duct 112 may be a separate component that may be attached to the duct 108, and the acoustic damper 110 may be coupled to the branch-duct 112. As such, the air travelling through the duct, upon encountering the branch-duct 112, may enter into the acoustic damper 110.
The acoustic damper 110 may be coupled to the duct 108 via the branch-duct 112 with an axis of the acoustic damper 110 perpendicular to an axis of the duct 108. For instance, the direction at which the air travels inside the duct 108 may be perpendicular to the direction at which the air enters or travels inside the branch-duct 112 and the acoustic damper 110.
As will be appreciated, the air travelling through the duct 108 may carry sounds of various frequency ranges, that may lead to unwanted noise in the cabin. The sound in the airflow may stem from various sources and may exhibit different frequencies. For example, the sound may be due to the air blower 104 (i.e. fan) responsible for circulating air within the HVAC system. The frequency of this sound may depend on the speed of the air blower 104. Higher speeds of the air blower 104 usually result in higher-frequency sound, while lower speeds produce lower-frequency sound. Further, the sound may be due to airflow turbulence emanating due to obstructions or irregularities in the airflow path. Turbulent airflow may produce a range of frequencies depending on the size and shape of the obstructions. Another example source of sound vibration of the components within the HVAC system, such as the motor of the air blower 104. These components may vibrate at certain frequencies, leading to audible sound. Furthermore, worn components may lead to increased sound levels. For example, worn bearings in the motor of the air blower 104 or loose duct connections can generate sound, often at irregular frequencies.
As such, sounds of various different frequencies and corresponding sound intensities may be generated in a HVAC system of a vehicle. Further, sounds with certain frequencies may generate relatively higher sound intensity. For example, sounds with frequencies around 160 Hz (i.e. in the range of 140 to 180 Hz) may generate a relatively higher sound intensity, and therefore may contribute more to an overall noise from the HVAC system 100.
In order to eliminate or reduce the noise from the HVAC system 100, the acoustic damper 110 may be coupled to the duct 108 of the HVAC system 100. The acoustic damper 110 cancels a sound of an associated frequency travelling through the duct 108. Therefore, the acoustic damper 110 tuned at the above frequency range (i.e. around 160 Hz or the range of 140 to 180 Hz) cancels that sound, thereby leading to substantial reduction of sound traveling through the duct 108.
In some embodiments, the acoustic damper 110 may be configured to be switched ON and OFF, based on an airflow rate of the air travelling through the duct 108. For example, the airflow rate of the air traveling through the duct 108 may be detected based on a speed setting of an air blower 104. As will be understood, the sound intensity may increase as the flow rate of the air flowing through the duct 108 increases. To this end, a user (for example, a user of the vehicle) may operate a button (not shown in FIG. 1) to switch ON or OFF the acoustic damper 110, to thereby turn ON or turn OFF the noise cancelling function of the acoustic damper 110. Alternatively, a controller (not shown in FIG. 1) may switch ON or OFF the acoustic damper 110 based on the speed setting of the air blower 104.
In some embodiments, the system 100 may include multiple acoustic dampers 110, each of which may be capable of cancelling only sounds belonging to a predetermined frequency range associated with that acoustic damper 110. As will be understood, for high intensity of sound comprising of multiple different ranges of frequencies, a single acoustic damper 110 may not be able to create a substantial noise reduction. Therefore, to address sounds of the multiple ranges of frequencies, multiple acoustic dampers 110 may be installed in the HVAC system 100, each of which is capable of cancelling major noise-causing frequency range. This is explained in detail in conjunction with FIG. 3.
Referring now to FIG. 2, a part of a schematic diagram of a HVAC system 200 (corresponding to the HVAC system 100) for a vehicle is illustrated, in accordance with an embodiment of the present disclosure. Similar to the HVAC system 100, the HVAC system 200 may include a blower chamber that may house the air blower (not shown in FIG. 2), and one or more air vents (not shown in FIG. 2) that may be positioned in the cabin of the vehicle and fluidically coupled with the blower chamber 102 via a duct 202 (corresponding to the duct 108).
As mentioned above, in order to address noises caused by multiple ranges of frequencies in the airflow through the duct 202, multiple acoustic dampers may be installed in the HVAC system 200. For example, the HVAC system 200 may include a plurality of acoustic dampers 204A, 204B, 204C, 204D (hereinafter, collectively referred to as plurality of acoustic dampers 204 (corresponding to the acoustic damper 110). Each of the plurality of acoustic dampers 204 may be coupled to the duct 202 via associated branch-ducts 206A, 206B, 206C, 206D with an axis of the acoustic damper 204 perpendicular to an axis of the duct 202. As such, the direction at which the air travels inside the duct 202 may be perpendicular to the direction at which the air enters or travels inside the branch-duct and the acoustic damper 204.
As mentioned above, each of the plurality of acoustic dampers 204 cancels sound of an associated predetermined frequency range traveling through the duct 202. For example, the acoustic damper 204A may be tuned to cancel the sounds in a frequency range of 140 to 180 Hz (around 160 Hz), the acoustic damper 204B may be tuned to cancel the sounds in a frequency range of 110 to 140 Hz (around 125 Hz), and so on. As such, the plurality of acoustic dampers 204 may be used to cancel sounds of plurality of frequency ranges with highest sound intensity. As will be understood, the number of the acoustic dampers 204 may be increased or decreased to achieve optimal sound level of the HVAC system 100.
Referring now to FIG. 3, a schematic diagram of an acoustic damper 300 (corresponding to the acoustic dampers 110, 204) is illustrated, in accordance with some embodiments. In some embodiments, the acoustic damper 300 may work on the Helmholtz frequency principle. Further, it should be noted that one or more parameters associated with the acoustic damper 300 may determine the frequency of the sound that the acoustic damper 300 may be tuned to cancel. For example, as shown in FIG. 3, the one or more parameters may include a volume (V) of an air chamber 306, a cross-section area (S) of a branch-duct 308, and a length (L) of the branch-duct 308. Accordingly, the frequency (fH) to be cancelled for the acoustic damper 300 may be calculated as below:
fH=\frac{c}{2\pi}\sqrt{\frac{S}{LV}}
… Equation (1)

Using the above equation, for a target frequency, the dimensions of the damper may be adjusted.
In some embodiments, acoustic damper 300 may include a valve 302, through which acoustic damper 300 can be switched ON and OFF. In particular, to switch ON the acoustic damper 300, the valve 302 may be opened to thereby fluidically couple the acoustic damper 300 with the airflow in the duct 108. To switch OFF the acoustic damper 300, the valve 302 may be closed to thereby fluidically cut-off the acoustic damper 300 from the airflow in the duct 108. It should be noted that the acoustic damper 300 may be switched ON when an airflow rate in the duct 108 is high (e.g. higher than a threshold value) and due to which the resulting noise is higher. The airflow rate of the air traveling through the duct 108 may be detected based on a speed setting of an air blower 104.
Therefore, the valve 302 may be operated, for example, based on the speed setting of the blower. For instance, the valve 302 may be operated when the blower speed setting is five or higher. The blower setting may be manually set by a user, such as a driver of the vehicle, or automatically by the HVAC system. In another example, the valve 302 may be opened to switch ON the acoustic damper 300 based on an airflow sensed by an airflow sensor, as explained via FIG. 4. For instance, when the airflow sensed by the airflow sensor exceeds a threshold, the valve 302 may be opened.
Referring now to FIG. 4, a block diagram of a noise reducing system 400 is illustrated in accordance with some embodiments. The noise reduction system 400 may be capable of automatically operating an acoustic damper for switching ON and OFF the noise reducing function, based on airflow rate.
The noise reducing system 400 may include the at least one acoustic damper 110 that may be coupled to the duct 108 leading from the blower chamber 102 to one or more air vents 106 of the HVAC system (for example, HVAC system 100, as explained in FIG.1). The at least one acoustic damper 110 may be coupled to the duct 108 via the branch-duct 112 originating from the duct 108, with an axis of the acoustic damper 110 perpendicular to an axis of the duct 108. Each of the at least one acoustic damper 110 may be fluidically coupled with the duct 108 via an associated opening formed on the duct 108. Each of the at least one acoustic damper 110 may be configured to cancel sound of an associated predetermined frequency range traveling through the duct 108.
In some embodiments, the noise reducing system 400 may include an airflow sensor 402 that may be positioned in the duct 108. The airflow sensor 402 may be configured to detect an airflow rate of the air traveling through the duct 108. The noise reducing system 400 may further include a controller 404 that may be communicatively coupled with the at least one acoustic damper 110 and the airflow sensor 402. The controller may include a processor 404A and a memory 404B communicatively coupled with the processor 404A. The memory stores processor-executable instructions which, upon execution by the processor, cause the processor 404A to one or more operations. For example, the processor 404A may receive, from the airflow sensor 402, an airflow rate of the air traveling through the duct 108 as detected by the airflow sensor 402. The processor 404A may further compare the airflow rate detected by the airflow sensor 402 with a predefined threshold value. In some embodiments, the comparison may include comparison of the speed setting of the blower with a preset blower setting. For example, the preset speed setting of the blower may be 4; therefore, when the blower speed setting is increased to 5, the blower may be turned on. In other words, the predefined threshold value may be the preset blower setting. As will be understood, a (detected) airflow rate greater than the predefined threshold value may lead to higher sound intensity output from the HVAC system. As such, the processor 404A may switch ON the at least one acoustic damper 110, when the airflow rate detected by the airflow sensor 402 is greater than the threshold value.
For example, switching ON the acoustic damper 110 may include opening the valve 302 (refer FIG. 3) associated with the acoustic damper 110, that may fluidically couple the acoustic damper 110 with the airflow in the duct 108.
It should be noted that the above HVAC system 100 and the noise reducing system 400 may be implemented in a vehicle, for example, a four-wheeled vehicle, such as a passenger vehicle or a commercial vehicle. In some embodiments, the vehicle may include the HVAC system 100 that may include the blower chamber 102 housing the air blower 104 generating an airflow to be released in a cabin of the vehicle. As already explained above in conjunction with the HVAC system 100, the vehicle may further include the one or more air vents 106 positioned in the cabin of the vehicle and fluidically coupled with the blower chamber 102 via the duct 108. The one or more air vents 106 may be configured to release the airflow generated in the blower chamber 102. The vehicle may further include at least one acoustic damper 110 that may be coupled to the duct 108 leading from the blower chamber 102 to the one or more air vents 106. Each of the at least one acoustic damper 110 may be fluidically coupled with the duct 108 via an associated opening formed on the duct 108. Each of the at least one acoustic damper 110 cancels sound of an associated predetermined frequency range traveling through the duct 108. In some embodiments, the acoustic damper 110 may be coupled to the duct 108 via the branch-duct 112 originating from the duct 108, with an axis of the acoustic damper 110 perpendicular to an axis of the duct 108. In some embodiments, the at least one acoustic damper 110 may be configured to be switched ON and OFF, based on an airflow rate of the air travelling through the duct 108.
One or more techniques are described above for reducing noise in the HVAC system of the vehicle. The techniques provide for careful positioning of acoustic dampers that are tuned for cancelling sounds of certain frequency range. Multiple acoustic dampers may be used for cancelling sounds of multiple frequency ranges. The acoustic dampers may be easily fitted on the duct, to thereby address the sounds emanating in and propagating via the duct. The acoustic dampers may also be retrofitted on existing duct of the vehicle.
It is intended that the disclosure and examples be considered as exemplary only, with a true scope and spirit of disclosed embodiments being indicated by the following claims.
, Claims:
We claim:
1. A Heating, Ventilation, And Air Conditioning (HVAC) system (100) for a vehicle, the HVAC system (100) comprising:
a blower chamber (102) housing an air blower (104) generating an airflow to be released in a cabin of the vehicle;
one or more air vents (106) positioned in the cabin of the vehicle and fluidically coupled with the blower chamber (102) via a duct (108), the one or more air vents (106) configured to release the airflow generated in the blower chamber (102); and
at least one acoustic damper (110) coupled to the duct (108) leading from the blower chamber (102) to the one or more air vents (106), each of the at least one acoustic damper (110) fluidically coupled with the duct (108) via an associated opening formed on the duct (108),
wherein each of the at least one acoustic damper (110) cancels sound of an associated predetermined frequency range traveling through the duct (108).

2. The HVAC system (100) as claimed in claim 1, wherein the acoustic damper (110) is coupled to the duct (108) via a branch-duct (112) originating from the duct (108).

3. The HVAC system (100) as claimed in claim 2, wherein the acoustic damper (110) is coupled to the duct (108) via the branch-duct (112) with an axis of the acoustic damper (110) perpendicular to an axis of the duct (108).

4. The HVAC system (100) as claimed in claim 1, wherein the at least one acoustic damper (110) is configured to be switched ON and OFF, based on an airflow rate of the air travelling through the duct (108).

5. The HVAC system (100) as claimed in claim 4, wherein the at least one acoustic damper (110) comprises a valve (302) configured to open and close,
wherein the at least one acoustic damper (110) is switched ON upon opening of the valve 302 to fluidically couple the acoustic damper (100) with the airflow in the duct (108), and
wherein the at least one acoustic damper (110) is switched OFF upon closing of the valve (302) to fluidically cut-off the acoustic damper (110) from the airflow in the duct (108).

6. A noise reducing system (500) comprising:
at least one acoustic damper (110) positioned on the duct (108) leading from a blower chamber (102) to one or more air vents (106) of a Heating, Ventilation, And Air Conditioning (HVAC) system, each of the at least one acoustic damper (110) fluidically coupled with the duct (108) via an associated opening formed on the duct (108),
wherein each of the at least one acoustic damper (110) cancels sound of an associated predetermined frequency range traveling through the duct (108);
a controller communicatively coupled with the at least one acoustic damper (110), the controller comprising:
a processor; and
a memory communicatively coupled with the processor, the memory storing processor-executable instructions which, upon execution by the processor, cause the processor to:
receive an airflow rate of the air traveling through the duct (108);
compare the airflow rate with a predefined threshold value; and
switch ON the at least one acoustic damper (110), when the airflow rate is greater than the threshold value.

7. The noise reducing system (500) as claimed in claim 6, wherein the airflow rate of the air traveling through the duct (108) is detected based on a speed setting of an air blower (104).

8. The noise reducing system (500) as claimed in claim 6, wherein the acoustic damper (110) is positioned at the duct (108) via a branch-duct (112) originating from the duct (108), with an axis of the acoustic damper (110) perpendicular to an axis of the duct (108).

9. A vehicle comprising:
a Heating, Ventilation, And Air Conditioning (HVAC) system comprising:
a blower chamber (102) housing an air blower (104) generating an airflow to be released in a cabin of the vehicle; and
one or more air vents (106) positioned in the cabin of the vehicle and fluidically coupled with the blower chamber (102) via a duct (108), the one or more air vents (106) configured to release the airflow generated in the blower chamber (102); and
at least one acoustic damper (110) coupled to the duct (108) leading from the blower chamber (102) to the one or more air vents (106), each of the at least one acoustic damper (110) fluidically coupled with the duct (108) via an associated opening formed on the duct (108),
wherein each of the at least one acoustic damper (110) cancels sound of an associated predetermined frequency range traveling through the duct (108).

10. The vehicle as claimed in claim 9, wherein the acoustic damper (110) is coupled to the duct (108) via a branch-duct (112) originating from the duct (108), with an axis of the acoustic damper (110) perpendicular to an axis of the duct (108).