SE542878C2 - Ventilation system for seat extension - Google Patents

Abstract

The present invention relates to an air ventilation system (1) for a vehicle seat (100) comprising a movable seat extension portion (120), the ventilation system comprising: an air channel unit (10) having an outlet opening (40) adapted to be fluidly connected to a fan unit (60), and an inlet opening (50) adapted to be mounted to the seat extension portion, wherein the air channel unit is deformable so that a longitudinal distance between the inlet opening (50) and the outlet opening (40), along a longitudinal axis (L1), may be adjusted, when in use, so as to allow ventilation of the movable seat extension portion (120).

Description

lt is desirable to ventilate cushions of a vehicle seat from smell,moisture or heat at regular intervals. One way of achieving ventilation is toequip vehicle seats with an air ventilation system. Such a system may use afan to facilitate transport of air from the seat cushion to an air flow opening. ln some adjustable car seats, the seats are configured to allow for seatlength adjustment function by moving an extension part relative the seatstructure. This brings some difficulties to the ventilation of such seats. Onesolution for such adjustable car seats, is to arrange a separate ventilationsystem in the extension part structure with its own fan and exhaust opening.This solution, however, increases cost and noise level.

Hence, considering the issues stated above, there is a need for animproved solution of air ventilation system for adjustable vehicle seats.

SUMMARY OF THE INVENTION ln view of the above-mentioned and other drawbacks of the prior art,the object of the present inventive concept is to at least alleviate abovementioned problems by providing an air ventilation system for a vehicle seatcomprising a movable seat extension portion, the air ventilation systemcomprising an air channel unit having an outlet opening adapted to be fluidlyconnected to a fan unit, and an inlet opening adapted to be mounted to theseat extension portion, wherein the air channel unit is adjustable in sitape so that a longitudinal distance between the inlet opening and theoutlet opening, along a longitudinal axis, may be adjusted, when in use, so asto allow ventilation of the movable seat extension portion. ln the context of this application, “fluidly connected” is to be interpretedas allowing air flow between the components that are fluidly connected. Thismay comprise one or several intermediate parts allowing air flow between thetwo parts. Further, in the context of this application “ventilation” should beinterpreted as moving air through cushions of a vehicle seat so as to removesmell, moisture or heat from the vehicle seat. Further, “ adåustablein shape” should be interpreted as bendable and/or shearable about, orexpandable/compressible along, the longitudinal axis.

Further, the fan unit may be a central fan unit configured to ventilatethe main seat cushion. The air channel unit may be arranged to fluidlyconnect the cushion of the moveable seat extension portion to the fan unit.

By achieving a ventilation system with the above mentioned design, asingle fan unit may be used for the entire seat cushion, which allows for acheaper solution than having a dedicated fan for the extension portion. ln one embodiment, the air channel unit comprises a tube fluidlyconnecting the inlet opening with the outlet opening, the tube adapted to bebendable about the longitudinal axis. ln one embodiment, the air channel unit comprises a first duct partprovided with the outlet opening, and a second duct part provided with theinlet opening. Further, the first and the second duct parts are mutuallyarranged to form an air channel extending through the first and second ductparts along the longitudinal axis from the inlet opening in the second duct partto the outlet opening in the first duct part. l\/loreover, the first duct part and thesecond duct part are configured to be, when in use, displaceable relativeeach other along the longitudinal axis. Hereby, the channel unit may alleviateany risk of having parts that may get tangled or crimped during movement, asthe two ducts may be rigid and allow the adjustment by means of relativemovement. ln one embodiment, one of the first and second duct parts is configuredto at least partly slide into, and out of, the other duct part, thereby defining aninner duct part and an outer duct part. ln one embodiment, the inner duct part and outer duct parts are formedto be tightly fitted together to be substantially air tight. Substantially air tight, inthe context of this application, means that air is kept from Ieaking through theair tight connection to the extent that the ventilation function is maintained. ln some embodiments, the air channel unit further comprise a sealingmeans arranged between the first and second duct part. Hereby, it is possibleto further decrease air leakage between the first and second duct parts. Thesealing means may be for example a flexible member of e.g. rubber or otherflexible material, with sealing abilities. ln yet one embodiment, one of the first and second duct part comprisesan engaging portion configured to engage with a slot arranged on the otherone of the duct parts. ln one embodiment the slot extends along thelongitudinal axis of the duct part. Hereby, the sliding movement direction maybe controlled to be along the longitudinal axis, which also contributes toavoiding any jamming drawer effect, i.e. that one of the ducts is rotatedrelative the other and thereby increases friction between the duct parts. ln one embodiment, the channel cross section of the air channel unitalong the longitudinal axis extends more along a lateral axis of the air channelunit than along a vertical axis of the air channel unit. Hereby, the duct will notoccupy so much height space under the seat, but still keep a good air flowcapacity, due to the total cross-sectional area of the duct. ln yet one embodiment, the inlet opening and/or the outlet openingis/are connected to a protrusion extending out from the air channel unit.Hereby, the protrusion on the inlet/outlet may easily be fluidly connected to afan duct and or a seat extension. ln one embodiment, one of the first or second duct part has a cut-outspace configured to allow air flow through said outlet opening or inlet openingof the other one of the first or second duct part when the first and second ductparts are in a retracted state. Hereby, the air flow is allowed even when thetwo duct parts are in the inner most retracted state. This design allowsincreased stroke length compared to a duct not having any cut-outs. The cut- out space on each duct part may be situated so that the cut out faces themating duct part inlet/outlet.ln yet one embodiment, the protrusion connecting the outlet opening isoffset along a lateral direction. Hereby, the connection to the fan unit may befacilitated, by offsetting the protrusion laterally towards the fan unit.ln one embodiment, the air ventilation system according furthercomprises a fan configured to move air through the channel of the air channelunit. ln one embodiment, the fan is a two-way fan, a one-way suction fan or aone-way blowing fan. The fan may be adapted to ventilate air from the seat orsupply the seat with air. The air may be conditioned, for instance temperatureor humidity conditioned. Due to the ability of alternating the air flow direction,one may preferably define the opening in the first part as a first opening, whilethe opening in the second part is defined as the second opening. The first andsecond opening then are referenced to as either an inlet or outlet openingdepending on the direction of the air flow through the air channel unit.According to another aspect of the invention a vehicle seat is providedwhich comprise a main seat structure, a seat extension displaceable relativethe main seat structure and a ventilation system according to any of theembodiments described above.ln one embodiment of the vehicle seat, the air channel unit of the ventilation system is arranged to the vehicle seat such that the first duct partis arranged to the main seat structure and fluidly connected to an exhaustopening, and the second duct part is arranged so that the inlet opening isfluidly connected to the seat extension, such that when the seat extension isdisplaced relative the main seat structure, the channel length along thelongitudinal axis of air channel unit is correspondingly adjusted. ln oneembodiment, the second duct part is also directly or indirectly mechanicallycoupled to the seat extension, so that the second duct part and the seat extension move in tandem.

The advantages of the method as defined above are largely analogousto the advantages of the vehicle arrangement as described above. That is,such a seat a||eviates the risk of having parts that may get tangled or crimpedduring movement of the seat extension and the single fan unit design allowsfor a cheaper solution. ln one embodiment of the vehicle seat, the mentioned ventilationsystem constitutes a first ventilation system arranged on a first lateral sideportion of the vehicle seat, and the vehicle seat comprises a secondventilation system according to any of the above-mentioned embodiments, onan opposing lateral side portion of the vehicle seat. Hereby, the vehicle seatextension may be ventilated by means of two ducts transporting air fromdifferent portions of the seat extension. ln other embodiments, there may bethree or more ventilation systems interconnected to further increase theventilation area of the seat.

Further features of, and advantages with, the present invention willbecome apparent when studying the appended claims and the followingdescription. The skilled addressee realize that different features of the presentinvention may be combined to create embodiments other than thosedescribed in the following, without departing from the scope of the presentinvention. The scope is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS The various aspects of the invention, including its particular featuresand advantages, will be readily understood from the following detaileddescription and the accompanying drawings, in which: Fig. 1a is a perspective view of a ventilation system in contracted stateaccording to an embodiment of the present invention; Fig. 1b is a perspective view of a ventilation system in expanded stateaccording to an embodiment of the present invention; Fig. 2a is a longitudinal side view of a ventilation system according to an embodiment of the present invention; Fig. 2b is a bottom view of a ventilation system according to anembodiment of the present invention; Fig. 2c is a transversal side view of a ventilation system according toan embodiment of the present invention; Fig. 2d is a transversal side view of a ventilation system according toan embodiment of the present invention; Fig. 2e is a top view of a ventilation system according to anembodiment of the present invention; Fig. 3a is a perspective view of a second duct part of a ventilationsystem according to an embodiment of the present invention; Fig. 3b is a perspective view of a first duct part of a ventilation systemaccording to an embodiment of the present invention; Fig. 4 is a cross-sectional side view of a vehicle seat comprising aventilation system according to an embodiment of the present invention; Fig. 5a is a cross-sectional side view of a vehicle seat comprising aventilation system according to an embodiment of the present invention; Fig. 5b is a cross-sectional side view of a vehicle seat comprising aventilation system according to an embodiment of the present invention; Fig. 6a is a cross-sectional side view of a vehicle seat comprising aventilation system according to an embodiment of the present invention; Fig. 6b is a cross-sectional side view of a vehicle seat comprising aventilation system according to an embodiment of the present invention.

DETAILED DESCRIPTION The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which currently preferredembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limited tothe embodiments set forth herein; rather, these embodiments are provided forthoroughness and completeness, and fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elementsthroughout. ln the following, references are made to top, bottom, front, back, etc.,and these directional references are to be interpreted to refer to sides asviewed in Fig. 1a, 1b. The air ventilation system 1 or its components, mainlythe air channel unit 10, are described with reference to a longitudinal axis L1,a lateral axis L2, and a vertical axis V, each axis being mutually perpendicularto each other, as seen in Figs. 1a, 1b.

Further, references are also made sometimes to a longitudinal plane,lateral plane, and a vertical plane. These are defined as follows.

A longitudinal plane is defined as a plane having a normal vectorparallel with the longitudinal axis.

A lateral plane is defined as a plane having a normal vector parallelwith the lateral axis.

A vertical plane is defined as a plane having a normal vector parallelwith the vertical axis. ln figure 1 the air ventilation system 1 is illustrated, and has an airchannel unit 10 comprising a first duct part 20 having an outlet opening 40adapted to be fluidly connected to a fan unit 60. The air channel unit furthercomprise a second duct part 30 having an inlet opening 50 adapted to bemounted to the seat extension portion 120. The first duct part 20 and thesecond duct part 30 are mutually arranged to form an air channel extendingthrough the first and second duct parts 20, 30 along a longitudinal axis L1 ofthe air channel unit 10 from the inlet opening 50 in the second duct part 30 tothe outlet opening 40 in the first duct part 20. Further, the first duct part 20and the second duct part 30 are configured to, when in use, be displaceablerelative each other along the longitudinal axis L1, such that the air channelextension of the air channel unit 10 along the longitudinal axis L1 isadjustable so as to allow air ventilation of the moveable seat extensionportion 120. ln Fig. 1a, the air channel unit 10 according to one embodiment of thepresent invention is illustrated. The air channel unit 10 is seen in a retractedstate, in which state the air channel extension of the air channel unit 10 alongthe longitudinal axis L1 is at a minimum. This state is adapted to be usedwhen the seat extension is in its inner position. ln Fig. 1b, the air channel unit 10 according to one embodiment of thepresent invention is illustrated. The air channel unit 10 is seen in an expandedstate, in which state the air channel extension of the air channel unit 10 alongthe longitudinal axis L1 is greater than the extension of the channel lengthwhen the air channel unit 10 is in a retracted state. This state is adapted to beused when the seat extension is in its outermost position. Further, anyposition between the one in Fig 1a and figure 1b may be used for positions ofthe seat extension being between the inner position and the outermostposition.

Each of the first and second duct parts 20, 30 have a portion thattogether is configured, when assembled together, to form an air channelextending along the first longitudinal axis L1. Each of these portions have ashape that substantially resembles a cuboid. Each of these portions extend ina dominant direction, which direction is along the first longitudinal direction L1when the first and the second duct part 20, 30 are assembled to form the airchannel Further, the channel cross section of the air channel unit 10 along thelongitudinal axis L1 extends more along a lateral axis L2 of the air channelunit than along a vertical axis V of the air channel unit. ln particular, the crosssection of the air channel along the longitudinal axis L1 is substantiallyquadrilateral, with the exception of some curved interior edges. These interioredges have a curvature of radius being smaller than the air channel width, i.e.the extension of the air channel along the lateral axis L2.

Further, as can be seen in Figs. 1a, 1b, the first duct part 20 hasslightly smaller dimensions than the second duct part 30, so that the first ductpart 20 can move at least partly into the cavity of the second duct part 30. ln particular, the first duct part 20 is configured to at least partly slide into andout of the second duct part 30. Hence, in this case, one may define the twoduct parts 20, 30 as the first duct part 20 being the inner duct part 20, and thesecond duct part 30 being the outer duct part 30. Naturally, anyone of the firstand second duct parts 20, 30 may be designed to have the role of the outerduct part. ln the following, for the sake of clarity, the first duct part 20 and thesecond duct part 30 are referred to as the inner duct part 20 and the outerduct part 30, respectively.

The inner duct part 20 and outer duct part 30 are configured such thatthe inner duct part 20 tightly fits into the second duct part 30. This helps toprevent any air flow leakage in between the contacting regions of the innerand outer duct parts 20, 30. Further, while not shown, the air channel unit 10may comprise a sealing member between the first duct part 20 and thesecond duct part 30. The sealing member may for instance be arranged alongthe circumference of the opening of the inner duct part 20, which opening isconfigured to open into the interior of the outer duct part 30.

The outer duct part 30 comprises an engaging portion 32 configured toengage with a slot 22 arranged on the inner duct part 20. The slot 22 isarranged on a top side of the inner duct part 20. The slot 22 extends alongthe top side of the inner duct part 20, in a direction parallel to the longitudinalaxis L1. The slot 22 is provided as a cylindrically shaped recess, whosesymmetry axis runs parallel to the longitudinal axis L1 but is offsetperpendicularly from the outer surface of the inner duct part 20 on which theslot 22 is arranged. The engaging portion 32 has a shape suitable for residinginside slot 22, and suitable for sliding in said slot 22. The engaging portion 32is configured to guide the air channel unit as it moves between an expandedstate and a contracted state. Further, it helps to prevent a relativedisplacement of the inner and outer duct part in a lateral direction L2.

Figs. 1a, 1b also show the air channel unit 10 according to oneembodiment wherein both the inlet opening and the outlet opening are bounded by protrusions, an inlet protrusion 31 and an outlet protrusion 21, respectively. The inlet protrusion 31 is arranged on a top side of the outerduct part 30. The outlet protrusion 21 is arranged on a bottom side of theinner duct part 20. Both the inlet protrusion 31 and the outlet protrusion 21extend a distance along a direction parallel to the vertical axis V. Each of theinlet protrusion 31 and the outlet protrusion 21 constitute tube sections havinga substantially quadrilateral cross section along the vertical axis V. Bothprotrusions 31, 21 define a section of the air channel, each of which extendsalong the vertical axis V. ln Figs. 2a - 2e, the air channel unit 10 according to one embodimentof the present invention is illustrated as seen from different views. Fig. 2aillustrate a side view of the air channel unit 10. Fig. 2b illustrate a bottom viewof the air channel unit 10. Figs. 2c and 2d illustrate the air channel unit 10 asseen from the left and the right relative Fig. 2a, respectively. Fig. 2e illustratea top view of the air channel unit 10.

The inlet protrusion 31 has a substantially quadrilateral cross sectionalong the vertical axis V, as can be seen in Fig. 2e. Further, the channelsection defined by the inlet protrusion 31 has a substantially quadrilateralcross section along the vertical axis V, with the exception of inner edgesbeing slightly curved.

The outlet protrusion 21 has a substantially quadrilateral cross sectionalong the vertical axis V, as can be seen in Fig. 2b. Further, the channelsection defined by the outlet protrusion 21 has a substantially quadrilateralcross section along the vertical axis V, with the exception of inner edgesbeing slightly curved.

Further, the outlet protrusion 21 is arranged on the inner duct part 20such that a central line of the channel section is at an offset along the lateralaxis L2 relative the longitudinal plane. ln Figs. 3a-3b, the air channel unit 10 according to one embodiment ofthe present invention is illustrated as seen when taken apart. Specifically, Fig.3a illustrate a perspective view of the outer duct part 30, while Fig. 3billustrate a perspective view of the inner duct part 20. 11 As can be seen in Figs. 3a, 3b, each of the of the inner duct part 20and the outer duct part 30 has a cut-out space 23, 33, respectively, which cut-out spaces are configured to allow further retraction of the air channel unit 10in a retracted state without blocking the air flow through the air channel unit10.

The bottom portion of the outer duct part is cut so as to form said cut-out space 33. The bottom portion is cut so that the boundary of the cut-outspace 33 at least partly reflects the shape of the exterior surface of the outletprotrusion 21. Hence, when the air channel unit 10 is fully retracted, the outletprotrusion 21 of the inner part 20 is placed in said cut-out space 33.

Furthermore, the cut-out space 23 of the interior duct part 20 isconfigured such that the air flow channel is not closed off when the airchannel unit 10 is put into a retracted state. The cut-out space 23 isconfigured with dimensions along the longitudinal axis L1 and the lateral axisL2 corresponding to the channel cross section of the inlet protrusion 21. ln Fig. 4, a ventilation system according to the present invention isillustrated when mounted in a vehicle seat 100. Specifically, Fig. 4 illustrates across section of the vehicle seat 100 as viewed from the side. The vehicleseat 100 comprises a main seat structure 110. The vehicle seat 100comprises a seat extension 120 configured to be adjustably displaceablerelative the main seat structure 110, and a ventilation system 1. The airchannel unit 10 of the ventilation system 1 is arranged to the vehicle seat 100such that the first duct part 20 is arranged to the main seat structure 110 andfluidly connected to an exhaust opening 70, and the second duct 30 part isarranged to the seat extension 120 such that the inlet opening 50 is fluidlyconnected to a duct in the seat extension. Hereby, when the seat extension isdisplaced relative the main seat structure, the channel length along thelongitudinal axis L1 of air channel unit 10 is correspondingly adjusted. Theinner duct part 20 and the outer duct part 30 of the air channel unit 10 aremutually configured to allow the air channel unit 10 to expand or retract asnecessary whenever the seat extension portion 120 moves relative the main 12 seat structure 110. ln figure 4 only one cross-sectional view is illustrated, it ispossible to have several air channel units laterally distributed along the lateralaxis, so as to provide an increased ventilation capacity.

The vehicle seat 100 comprises a main seat cushion 111 arranged tothe main seat structure 110, and a seat extension cushion 121 arranged tothe seat extension structure 120. The vehicle seat 100 may comprise ductsextending throughout each respective seat structure, the seat extensionstructure 120 and the main seat structure 110 toward each respectivecushion. The ducts may have multiple inlets for drawing air from multipleregions beneath the cushions. Further, both the seat extension cushion 121and the main seat cushion 111 may be enclosed in a material through whichventilation of said cushions is facilitated. The material enclosure of thecushions may be a textile material. The material enclosure may be perforatedso as to facilitate ventilation of the seat cushion. Further, the seat cushionsmay be adapted to have ventilation holes and/or channels.

The material of the air channel unit 10 may be provided, wholly orpartly, in a polymer, for instance plastic polymer. The air channel unit 10 maybe provided, wholly or partly, in rubber, for instance natural rubber.

Further, a fan unit 60 is arranged in an exhaust fan chamber. Theducts of the vehicle seat are in fluid connection with the exhaust fan chamber.The fan unit 60 can therefore, during operation, draw air through the ductsand move the air through the exhaust opening 70. The fan unit 60 isconfigured to ventilate the air in the seat cushions 111, 121, by creating anairflow through ducts, in particular ventilating the cushion 121 arranged on theseat extension structure 120 via the air channel unit 10. The fan unit 60establishes an air flow from the seat extension cushion 121 through the airchannel established by the air channel unit 10, and guides the air flowthrough the exhaust opening. The exhaust opening 70 is located under theseat, and the air flow is consequently exhausted in a downward directionrelative the vehicle seat 100. This is in some situations favorable, due to the 13 enhanced convenience, as the air flow diffuses before reaching any eventualpassengers in any eventual back seats of the vehicle.

As the ventilating system 1 is configured to be attached to the vehicleseat 100, the vehicle seat 100 may be adjusted relative the car withoutimpacting the configuration of the air channel unit 10, since the air channelunit 10 works independently with respect to the seat structure position relativethe vehicle. ln Figs. 5a, 5b, and with Figs. 6a, 6b, the working principle of thepresent invention is illustrated schematically. Figs. 6a, 6b, however, illustratean embodiment of the ventilation system 1 where the first duct part 20 isslidable into and out of the second duct part 30. ln Figs. 5a, 5b, an embodiment of the ventilation system 1 is shownwhere the first air channel unit 20 does not slide into or out of the second airchannel unit 30. Rather, in this embodiment, the second duct part 30 isslidable along the top portion of the first duct part 20.

Both sets of figures, Figs. 5a, 5b, and Figs. 6a, 6b illustrate the airchannel unit 10 in the retracted state and the expanded state, respectively.Regardless whether the air channel unit is in an expanded or a retractedstate, the air flow channel defined by the two duct parts communicativelyconnects a duct in the seat extension structure 120 to the exhaust opening70. The air from the seat extension cushion 121 is ventilated actively bymeans of an exhaust fan 60 arranged to the main seat structure 110, onwhich the main seat cushion 111 is attached. Further, in Figs. 5a - 6b, theexhaust opening 70 opens toward the back of the vehicle seat. Hence, the airflow is directed toward the back of the vehicle seat. However, the exhaustopening may just as well be open to the bottom of the vehicle seat.

Claims (10)

1. 4 CLAIIVIS 1. An air ventilation system (1) for a vehicle seat (100) comprising amovable seat extension portion (120) and a fan unit (60), theventilation system comprising: an air channel unit (10) having an outlet opening (40) adapted tobe fluidly connected to said fan unit (60), and an inlet opening (50)adapted to be mounted to the seat extension portion, wherein the airchannel unit is adiiistabâe in shape so that a longitudinaldistance between the inlet opening (50) and the outlet opening (40),along a longitudinal axis (L1), may be adjusted, when in use, so asto allow ventilation of the movable seat extension portion (120), vtfherein the air ctaannei unit (tíši cornprises a first duct pan (20) provided vvitit the outlet opening (40). and a second duct part (30) proxfided with the inlet opening (50).

2. An air ventilation system (1) according to claim 1, A I _ .i u.. k... e... . A a :whereinthe first and the second duct parts (20, 30) are mutually arranged toform an air channel extending through the first and second duct parts(20, 30) along the longitudinal axis (L1) from the inlet opening (50) inthe second duct part (30) to the outlet opening (40) in the first duct part(20), wherein the first duct part (20) and the second duct part (30) areconfigured to be, when in use, displaceable relative each other along the longitudinal axis (L1).

3. Air ventilation system (1) according to any of claims 1 or 2, wherein one of the first and second duct parts (20, 30) is configured to at leastpartly slide into and out of the other duct part (20, 30), thereby definingan inner duct part (20) and an outer duct part (30). _ Air ventilation system (1) according to eèair-a-Banyf of the preceding gjgfrgg, wherein one (30) of the first and second duct part (20, 30)comprises an engaging portion (32) configured to engage with a slot(22) arranged on the other duct part (20) of said first and second ductpart (30, 20), wherein said slot extends along the longitudinal axis (L1)of said duct part (20). _ Air ventilation system (1) according to efaimàany of the greceding claisns wherein the channel cross section of the air channel unit (10) along the longitudinal axis (L1) extends more along a lateral axis (L2)of the air channel unit (10) than along a vertical axis (V) of the airchannel unit (10). _ Air ventilation system (1) according to any of the precedind claámsßlairrt~1~ wherein the inlet opening (50) and/or the outlet opening(40) is/are connected to a protrusion (31, 21) extending out from the airchannel unit (10). 7. Air ventilation system (1) according to anv of the precedind clairnseiaim 2, wherein one of the first and second duct part (20, 30) has a cut-outspace (23, 33) configured to allow air flow through said outlet opening(40) or inlet opening (50) of the other one of the first or second ductpart (20, 30) when the first and second duct parts (20, 30) are in aretracted state. (110), 16 Air ventilation system (1) according to anv of the precedind claimseiai-r-n 4 wherein said fan unit (60) i_§_configured to moveair through the channel of the air channel unit (10). A vehicle seat (100) comprising a main seat structure (110), a seat extension (120) displaceable relative the main seat structureand a ventilation system (1) according to any of claims 21-8, wherein the air channel unit (10) of the ventilation system is arranged to the vehicle seat such that the first duct part (20) isarranged to the main seat structure (â-Qïjg) and fluidly connected to anexhaust opening (70), and the second duct (30) part is arranged so thatthe inlet opening (50) is fluidly connected to the seat extension, suchthat when the seat extension (120) is displaced relative the main seatstructure (110), the channel length along the longitudinal axis (L1) of airchannel unit (10) is correspondingly adjusted. 10. A vehicle seat (100) according to claim 9, wherein the ventilation system (1) constitutes a first ventilation system arranged on a firstlateral side portion of the vehicle seat, and wherein the vehicle seatcomprises a second ventilation system (1) according to any of claims 1-_8_~ï~'- arranged on an opposing lateral side portion of the vehicle seat.