[0001] The present subject matter described herein, relates to a system and method for air circulation in a vehicle. More particularly, the present subject matter described herein relates to a system and method for providing clean and fresh air inside the passenger compartment of a vehicle. The present subject matter ensures that the passenger is not exposed to health related issues pertaining to inhaling air with high CO2 concentration.
BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] In extreme condition i.e. too hot or too cold outside the vehicle, user operate air conditioning system in recirculation mode to maintain cooling performance and also to avoid entry of pollutants and bad smell from external environment. Because of the recirculation mode, oxygen concentration inside vehicle is reduced and the level of C02 concentration inside vehicle increases beyond permissible limits which may have harmful effects on the occupant and may affect his ability to concentrate while driving.
[0004] Quality of air is important discussion nowadays mainly because of health concern associated with poor air quality. In closed volume system like passenger vehicle, the level of C02 concentration is main reason of poor air quality.
[0005] The main source of CO2 is passengers in closed cabin when no outside air (mainly exhaust air) enters the vehicle cabin. It was measured that levels of

CO2 increases rapidly when fraction of fresh air is low inside the cabin. In addition to that there are several other parameters which affect the level of CO2 like vehicle speed, blower speed and cabin volume.
[0006] Generally, air circulation system of a vehicle operates in two modes i.e. fresh air mode and recirculation mode. The system works in recirculation mode by recirculating the air already present in the passenger compartment of the vehicle. A sensor is provided in the compartment of the vehicle to measure its carbon dioxide (CO2) concentration. When the CO2 concentration of the compartment increase above a predetermined limit, the system switch to fresh air mode and fresh air is introduced into the compartment through heating, ventilation and air conditioning (HVAC) unit.
[0007] Referring to Fig. 1 illustrating a schematic diagram of existing air circulation system in a vehicle. As per the system, during recirculation mode, the fresh air opening of the air circulation system is closed. The system recirculates air already present in the passenger compartment of the vehicle. The sensor, present in the compartment, measures the concentration of CO2. When the concentration of CO2 increases above 2500 ppm, the system switches from recirculation mode to fresh air mode. During fresh air mode, the fresh air opening of the air circulation system is opened and fresh air is introduced in the compartment of the vehicle through heating, ventilation and air conditioning unit. With the introduction of fresh air in the compartment of the vehicle, the concentration of CO2 decreases and the system switch to recirculation mode again.
[0008] A problem frequently faced by the passengers of the vehicle is that during fresh air mode, the fresh air brings bad smell, dust particles and other pollutants and it further ingress other harmful gases from the environment. This creates discomfort to the passengers of the vehicle. Further, the heating, ventilation and air condition unit put a lot of load on the engine which reduces fuel economy of vehicle.

[0009] To overcome the drawbacks of existing air circulation system, the present subject matter discloses a system and a method for circulating clean and fresh air in a recirculation mode in a vehicle.
OBJECTS OF THE DISCLOSURE
[0010] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0011] The principal object of the present invention is to provide a system and a method for circulation clean and fresh air in a recirculation mode in a vehicle.
[0012] Another object of the present invention is to provide a system and a method for circulating clean and fresh air to maintain temperature in the compartment of a vehicle as per user requirement.
[0013] Another object of the present invention is to provide a system and a method for circulating clean and fresh air to keep the CO2 concentration, in a compartment of a vehicle, in control.
[0014] Another object of the present invention is to provide a system and a method for circulating clean and fresh air through which load on the engine is reduced.
[0015] These and other objects and advantages will become more apparent when reference is made to the following description and accompanying drawings.
SUMMARY
[0016] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
[0017] The present invention discloses a system and method for circulating clean and fresh air in a vehicle. According to the preferred embodiment, the system for circulating clean and fresh air in a vehicle, the system comprises of a

first microcontroller to receive speed input from a vehicle speed sensor and CO2 concentration from a CO2 concentration measuring sensor and a sub-assembly to receive fresh air from a fresh air opening on cowl upper of the vehicle, when the speed input is more than a predefined speed and the CO2 concentration is more than a predefined PPM level.
[0018] In an aspect, the system further comprises of a second microcontroller to receive outside air temperature from a temperature sensor and to open a conditioned air door flap when the outside air temperature is beyond a predefined range and the fresh air is received from the fresh air opening.
[0019] In an aspect of the present invention, the fresh air opening on cowl upper of the vehicle is connected to the sub-assembly through a first conduit.
[0020] In an aspect of the present invention, the sub-assembly comprises of a fan and an air filter.
[0021] In an aspect of the present invention, the conditioned air door flap is placed inside a second conduit which connects heating, ventilation and air conditioning (HVAC) unit to a mixing chamber. A conditioned air from the HVAC unit is passed to the mixing chamber when the conditioned air door flap is opened.
[0022] In an aspect of the present invention, the clean and fresh air from the sub-assembly and the conditioned air from the heating ventilation and air conditioning (HVAC) unit mix with each other in the mixing chamber.
[0023] In an aspect of the present invention, the air filter includes but not limited to a HEPA filter, activated carbon filter and restricts the ingress of pollutant and smell into vehicle cabin.
[0024] In an aspect, the method comprises the steps of receiving, speed input from a vehicle speed sensor and C02 concentration from a C02 concentration measuring sensor, by a first microcontroller; receiving fresh air from a fresh air opening on cowl upper of the vehicle, when the speed input is above a predefined speed and the C02 concentration is above a predefined PPM level; sending the

fresh air to a sub-assembly, through a first conduit, using a fan in the sub-
assembly; cleaning, in the sub-assembly, the fresh air using an air filter to get rid
of pollutants, smell particles and other harmful gases; sending fresh and clean air
to a mixing chamber through a second conduit; receiving ambient air temperature
5 from a temperature sensor, by a second microcontroller; opening a conditioned air
door flap when the ambient air temperature is out of a predefined cut-off range
and the fresh air is received from the fresh air opening; sending conditioned air
from heating ventilation and air conditioning (HVAC) unit to the mixing chamber
through a third conduit; mixing the fresh and clean air with the conditioned air in
10 the mixing chamber to receive cool/hot fresh and clean air and sending the
cool/hot fresh and clean air to vehicle cabin through a fourth conduit. However, if the ambient air temperature is within the predefined cut-off range, the conditioned air door flap is closed and only the fresh and clean air is sent to the vehicle cabin through the fourth conduit.
15 [0025] In an aspect of the present invention, the predefined speed is 10 km/h.
[0026] In an aspect of the present invention, the predefined CO2 concentration
is 2500 ppm.
[0027] In an aspect of the present invention, the predefined cut-off range of
the ambient air temperature is between 15 degrees to 30 degrees Celsius.
20 [0028] In an aspect of the present invention, the air filter includes but not
limited to a HEPA filter, activated carbon filter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The illustrated embodiments of the subject matter will be best
25 understood by reference to the drawings, wherein like parts are designated by like
numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
6

[0030] Fig. 1 illustrates a schematic diagram of existing air circulation system
in a vehicle;
[0031] Fig. 2 illustrates a system for circulating clean and fresh air according
to the preferred embodiment of present subject matter;
5 [0032] Fig. 3 illustrates block diagram of a system for circulating clean and
fresh air according to one of the embodiment of present subject matter; and
[0033] Fig. 4 illustrates method for circulating clean and fresh air according to
one of the embodiment of present subject matter.
[0034] The figures depict embodiments of the present subject matter for the
10 purposes of illustration only. A person skilled in the art will easily recognize from
the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
15 [0035] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the
20 contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the scope of the present disclosure as defined by the appended claims.
[0036] It is also to be understood that various arrangements may be devised
that, although not explicitly described or shown herein, embody the principles of
25 the present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0037] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. As
7

used herein, the singular forms “a”, “an” and “the” are intended to include the
plural forms as well, unless the context clearly indicates otherwise. It will be
further understood that the terms “comprises,” “comprising,” “includes” and/or
“including,” when used herein, specify the presence of stated features, integers,
5 steps, operations, elements and/or components, but do not preclude the presence
or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0038] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example,
10 two figures shown in succession may, in fact, be executed concurrently or may
sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0039] In addition, the descriptions of "first", "second", and the like in the
present invention are used for the purpose of description only, and are not to be
15 construed as indicating or implying their relative importance or implicitly
indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
[0040] Unless otherwise defined, all terms (including technical and scientific
20 terms) used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which example embodiments belong. It will be further
understood that terms, e.g., those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their meaning in the
context of the relevant art and will not be interpreted in an idealized or overly
25 formal sense unless expressly so defined herein.
[0041] These and other advantages of the present subject matter would be
described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise
8

various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0042] The main objective of the present invention is to provide a system 300
and a method 400 for circulating clean and fresh air in a vehicle 200.
5 [0043] The system 300 for circulating clean and fresh air in a vehicle 200,
according to the preferred embodiment comprises a first microcontroller 302, a
second microcontroller 316, a vehicle speed sensor 303, a CO2 concentration
measuring sensor 304, a temperature sensor 317, a mixing chamber 310, a fresh
air opening on cowl upper 301, a cut-out on instrument panel 315 of the vehicle
10 200, an air door flap 312, a sub assembly 306, a fan 307, an air filter 308, four
conduits 305, 309, 311, 314 and a heating ventilating and air conditioning unit (HVAC) 313.
[0044] Referring to figures 2 and 3 illustrating a system 300 for circulating
clean and fresh air in a vehicle 200, according to the preferred embodiment of
15 present subject matter. The first microcontroller 302 is configured to receive
speed input and CO2 concentration of the passenger compartment of the vehicle 200. A vehicle speed sensor 303 measures the speed of the vehicle 200 and sends the measured speed as input to the first microcontroller 302. The CO2 concentration measuring sensor 304 is provided on the instrument panel of the
20 vehicle and measures the instant CO2 concentration of the passenger compartment
of the vehicle 200. The CO2 concentration measuring sensor 304 sends the measured CO2 concentration as an input to the first microcontroller 302. Based on the received speed and CO2 concentration inputs, the first microcontroller 302 actuates a fan 307 in a sub-assembly 306 to receive fresh air from outside of the
25 vehicle 200 through a fresh air opening 301 of cowl upper of the vehicle 200
when the speed input is above a predefined speed and the CO2 concentration is above a predefined PPM level. For example, according to the preferred embodiment, the threshold cut-off value of speed of the vehicle 200 is 10 Km/h and for CO2 concentration is 2500 ppm. The speed cut-off value ensures that
30 vehicle 200 is not in traffic, where the probability of entering of CO2 and other
9

harmful gases is high. The CO2 concentration is measured to ensure that the passenger is not exposed to health related issues pertaining to inhaling air with
high CO2 concentration.
[0045] . The fresh air opening 301 on the cowl upper introduces fresh air into
5 the sub-assembly 306 through a first conduit 305. The sub-assembly 306
comprises the fan 307 and an air filter 308. The fan 307 in the sub-assembly 306
facilitates suction of air from the fresh air opening 301 on the cowl upper of the
vehicle 200. The freshly introduced air in the sub-assembly 306 is polluted and
may contain smell particles and other harmful gases. To clean the freshly
10 introduced air, the air filter 308 is provided in the sub-assembly 306 which
includes but not limited to a High-efficiency particulate air (HEPA) filter and/or activated carbon filter.
[0046] Fresh and clean air from the sub-assembly 306 is then introduced in
the mixing chamber 310 through a second conduit 309. The mixing chamber 310
15 has two inputs and one output. First input of the mixing chamber 310 is connected
with the sub-assembly 306 through the second conduit 309. The second input is connected to the heating ventilation and air conditioning (HVAC) unit 313 through a third conduit 311. The opening and closing of the second input depends on the second microcontroller 316. The second microcontroller 316 is configured
20 to receive the temperature input from the ambient temperature sensor 317. The
ambient temperature sensor 317 measures the ambient temperature and sends the measured value to the second microcontroller 316. Based on the received temperature input and when the fresh air is received from the fresh air opening 301, the second microcontroller 316 opens the second input by opening the air
25 door flap 312. The second microcontroller 316 is configured to open the air door
flap 312, based on the predefined threshold cut-off range of the ambient temperature, vehicle speed, and PPM level of CO2 concentration inside vehicle cabin. For example, according to the preferred embodiment, the threshold cut-off range of temperature is either greater than 30o C or less than 15o C, vehicle speed
30 is more than 10 km/h, and CO2 concentration is more than 2500 PPM.
10

[0047] In case, the temperature falls out of the threshold cut-off range and the
fresh air is received from the fresh air opening, the second microcontroller 316
opens the second input through which hot or cold air enters into the mixing
chamber 310 and is mixed with the fresh and clean air from the sub-assembly 306.
5 The hot or cold air from the heating ventilation and air conditioning (HVAC) unit
313 depends on the user input from the controls provided on the instrument panel.
[0048] The output of the mixing chamber 310 is connected with the cut-out
315 on the instrument panel through a fourth conduit 314. The hot/cold clean and
fresh air from the mixing chamber 310 is then introduced in the passenger
10 component of the vehicle 200 through the cut-out 315 on the instrument panel.
[0049] In case, the temperature falls in the threshold cut-off range, the second
microcontroller 316 keeps the second input closed by not opening the air door flap
312 and the clean and fresh air from the sub-assembly 306 is directly introduced
in the passenger compartment through the cut-out 315 on the instrument panel.
15 The air door flap 312 is closed because fresh air from outside the vehicle with
temperature between 15o-30oC need not to be conditioned and does not affect the comfort level of passenger. Further, level of CO2 concentration inside the vehicle cabin is also reduced rapidly without mixing outside fresh air with recirculated conditioned air.
20 [0050] Referring to figure 4, illustrating method 400 for circulating air in a
vehicle 200, according to one of the embodiment of present subject matter. At step 401, speed input from the vehicle speed sensor 303 and CO2 concentration from the CO2 concentration measuring sensor 304 is received by the first microcontroller 302. The CO2 concentration measuring sensor 304 measures CO2
25 level inside passenger compartment of the vehicle 200. Further, the speed of the
vehicle 200 is measured to restrict the entrance of fresh air from the surrounding of the vehicle 200, in case, the vehicle 200 is not moving or in traffic. During traffic or at red lights, the air surrounding the vehicle is more polluted due to emission of harmful gases from the nearby vehicle.
11

[0051] At step 402, fresh air from a fresh air opening (301) on cowl upper of
the vehicle (200) is received only when the speed input from the vehicle speed sensor 303 is more than a predefined speed and CO2 concentration of the passenger compartment of the vehicle is more than a predefined concentration.
5 [0052] At step 403, the fresh air is sent in the sub-assembly 306 through the
first conduit 305. The sub-assembly 306 has the fan 307 which draws the fresh air from the fresh air opening 301 on the upper cowl into the sub-assembly 306. The fresh air contains pollutants, smell particles and other harmful gases.
[0053] At step 404, the fresh air introduced in the sub-assembly 306,
10 containing pollutants, smell particles and other harmful gases, is filtered or
cleaned through the air filter 308 provided in the sub-assembly .306. The air filter 308 includes but not limited to a High-efficiency particulate air (HEPA) filter and/or activated carbon filter.
[0054] At step 405, the fresh and clean air is introduced in the mixing
15 chamber 310. The clean and fresh air is introduced in the mixing chamber 310
through first input wherein the mixing chamber 310 is connected with the sub-assembly 306 through the second conduit 309. The mixing chamber 310 has in total two inputs and one output.
[0055] At step 406, the ambient temperature of the vehicle 200 is received by
20 the second microcontroller 316.
[0056] At step 407, based on the received ambient temperature input and
when the fresh air is received from the fresh air opening 301, the second
microcontroller 316 opens the second input by opening the conditioned air door
flap 312. The second microcontroller 316 is configured to open the conditioned
25 air door flap 312, when the ambient air temperature is out of a predefined cut-off
range, vehicle speed is more than the predefined speed and CO2 concentration of the passenger compartment of the vehicle is more than the predefined concentration.
12

[0057] At step 408, conditioned air from the heating, ventilation and air
conditioning (HVAC) unit 313 is introduced in the mixing chamber 310 by
opening of the air door flap 312 through a third conduit 311. The nature of air i.e.
hot or cold is based on the user input from the controls provided on the instrument
5 panel. The temperature of the clean and fresh air is altered or retained according
to predefined threshold cut-off range of the ambient temperature.
[0058] At step 409, the fresh and clean air from the sub-assembly 306 and
cool/hot air from the heating, ventilation and air condition unit 313 is mixed in the
mixing chamber 310. Mixing of the fresh and clean air from the sub-assembly 306
10 and cool/hot air from the heating, ventilation and air condition (HVAC) unit 313
ensures that temperature of the resultant air inside the passenger compartment is as per the user requirement.
[0059] At step 410, the air resultant from the mixing of the fresh and clean air
from the sub-assembly 306 and cool/hot air from the heating, ventilation and air
15 condition (HVAC) unit 313 is introduced into the passenger compartment of the
vehicle 200 through the cut-out 315 on the instrument panel. The output from the mixing chamber 310 is connected with the cut-out 315 on the instrument panel through the fourth conduit 314.
[0060] However, at step 411, when the ambient air temperature is within a
20 predefined cut-off range, the conditioned air door flap 312 is kept closed. Further,
at step 412, only the fresh and clean air from the mixing chamber (310) is sent to the vehicle cabin through a fourth conduit (314).
[0061] The advantages of present system and method are manifold. The
system 300 and method 400 ensures that the passenger is not exposed to health
25 related issues pertaining to inhaling air of high CO2 concentration. Further, the
system 300 and method 400 restrict the entrance of fresh air from the surrounding of the vehicle, in case, the vehicle is not moving or in traffic because during traffic or at red lights, the air surrounding the vehicle is more polluted due to emission of harmful gases from the nearby vehicle. Furthermore, the system 300
30 and method 400 ensures that the fresh air from vehicle outside is mixed with the
13

hot/cold air from heating, ventilation and air condition (HVAC) unit 313 to
provide resultant air as per user requirement inside the vehicle cabin. For
example, if the temperature outside the vehicle is too hot or too cold and if the
fresh air received from outside the vehicle is directly supplied to vehicle cabin
5 then temperature inside vehicle cabin will also be too hot or too cold, which is not
desired by user. To avoid such issue, the fresh air received from outside the vehicle is mixed with cold/hot air from HVAC unit to provide resultant air as per user requirement. Thus, the present invention not only reduces CO2 concentration inside vehicle cabin by providing fresh and clean air to the user but also takes care
10 of outside temperature and provides mixed air as per user requirement. This
reduces the extra load on the engine and also no compromise in passenger comfort. However, if the ambient air temperature is within the predefined cut-off range i.e. less than 30o C and more than 15o C, the air door flap 312 is closed and only the fresh and clean air from the sub-assembly 306 is sent to the vehicle cabin
15 through the fourth conduit 314. The air door flap 312 is closed because fresh air
from outside the vehicle with temperature between 15o-30oC need not to be conditioned and does not affect the comfort level of passenger. Further, level of CO2 concentration inside the vehicle cabin is also reduced rapidly without mixing outside fresh air with recirculated conditioned air.
20 [0062] It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as
25 “includes but is not limited to,” etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least
30 one” and “one or more” to introduce claim recitations. However, the use of such
phrases should not be construed to imply that the introduction of a claim recitation
14

by the indefinite articles “a” or “an” limits any particular claim containing such
introduced claim recitation to inventions containing only one such recitation, even
when the same claim includes the introductory phrases “one or more” or “at least
one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should
5 typically be interpreted to mean “at least one” or “one or more”); the same holds
true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two
10 recitations,” without other modifiers, typically means at least two recitations, or
two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include
15 but not be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least
20 one of A, B, or C” would include but not be limited to systems that have A alone,
B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to
25 contemplate the possibilities of including one of the terms, either of the terms, or
both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0063] While the foregoing describes various embodiments of the invention,
other and further embodiments of the invention may be devised without departing
30 from the basic scope thereof. The scope of the invention is determined by the
claims that follow. The invention is not limited to the described embodiments,
15

versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

We Claim:

A system (300) for circulating air in a vehicle (200), the system (300) comprising:
a first microcontroller (302) to receive speed input from a vehicle speed sensor (303) and CO2 concentration from a CO2 concentration measuring sensor (304); and
a sub-assembly (306) to receive fresh air from a fresh air opening (301) on cowl upper of the vehicle (200), when the speed input is more than a predefined speed and the CO2 concentration is more than a predefined PPM level.
The system (300) as claimed in claim 1, wherein the system (300) further comprises of
a second microcontroller (316) to receive outside air temperature from a temperature sensor (317) and to open a conditioned air door flap (312) when the outside air temperature is beyond a predefined range and the fresh air is received from the fresh air opening 301.
The system (300) as claimed in claim 2, wherein the sub-assembly (306) comprises of a fan (307) and an air filter (308) which cleans the fresh air to provide clean and fresh air.
The system (300) as claimed in claim 3, wherein the conditioned air door flap (312) is placed inside a third conduit (311) which connects heating ventilation and air conditioning (HVAC) unit (313) to a mixing chamber (310).
The system (300) as claimed in claim 4, wherein the clean and fresh air from the sub-assembly (306) and the conditioned air from the heating ventilation and air conditioning (HVAC) unit (313) mix with each other in

the mixing chamber (310) to form hot/cold clean and fresh air which is provided to vehicle cabin through a fourth conduit (314).
A method (400) for circulating air in a vehicle (200), the method (400)
comprising the steps of:
receiving (401), speed input from a vehicle speed sensor (303) and C02
concentration from a CO2 concentration measuring sensor (304), by a first
microcontroller (302);
receiving (402) fresh air from a fresh air opening (301) on cowl upper of
the vehicle (200), when the speed input is above a predefined speed and
the C02 concentration is above a predefined PPM level;
sending (403) fresh air to a sub-assembly (306), through a first conduit
(305), using a fan (307) in the sub-assembly (306);
cleaning (404), in the sub-assembly (306), the fresh air using an air filter
(308) to get rid of pollutants, smell particles and other harmful gases; and
sending (405) clean and fresh air to a mixing chamber (310) through a
second conduit (309).
The method (400) as claimed in claim 6, wherein the method further
comprises the step of:
receiving (406) ambient air temperature from a temperature sensor (317).
The method (400) as claimed in claim 7, wherein the method further comprises the step of:
opening (407), by a second microcontroller (316), a conditioned air door flap (312) when the ambient air temperature is out of a predefined cut-off range and the fresh air is received from the fresh air opening (301); sending (408) conditioned air from heating ventilation and air conditioning (HVAC) unit (313) to a mixing chamber (310) through a third conduit
(3H);

mixing (409) the fresh and clean air with the conditioned air in the mixing chamber (310) to receive cool/hot fresh and clean air; and sending (410) the cool/hot fresh and clean air to vehicle cabin through a fourth conduit (314).
The method (400) as claimed in claim 7, wherein the method further comprises the step of:
sending (412) only the fresh and clean air from the mixing chamber (310) to the vehicle cabin through a fourth conduit (314) when the ambient air temperature is within a predefined cut-off range (411).