Vehicle seat with serpentine air flow channel

A vehicle seat includes a thermal comfort system including an air duct in a foam cushion, a thermoelectric device, a heat sink extending inside the air duct from the thermoelectric device, and an air mover that causes air to flow from the passenger cabin, through the seating surface, along the air duct and heat sink, and back out of the seat. In a cooling mode, air flowing along air duct absorbs heat from one side of the thermoelectric device via the heat sink while the opposite side of the thermoelectric device absorbs heat from the trim cover via thermal conduction. The air duct can be shaped to position the thermoelectric device near the seating surface for enhanced conductive energy exchange without the need for uncomfortable rigid ductwork.

TECHNICAL FIELD

The present disclosure relates to a vehicle seat and, in particular, to a vehicle seat with a thermal comfort system.

BACKGROUND

Vehicle seats can be configured to provide a flow of air through the seating surface to enhance environmental comfort of the seat occupant by virtue of the movement of air in the vicinity of the seat occupant's physical contact with the seating surface, which is typically hotter or colder than the seat occupant desires, particularly when the seat occupant is initially seated on especially hot or cold days. Such ventilated vehicle seats may be configured to flow air past a heat exchanger in the seat to heat or cool the air before it is forced out of the seat through the seating surface as conditioned air to provide desired thermal comfort to the seat occupant.

For example, U.S. Pat. No. RE38,128 to Gallup et al. discloses a vehicle seat with a climate control system including individual heat pumps associated with the seat bottom and with the seat back. Dedicated fans blow air through each of the heat pumps, then along air channels inside the seat, and finally out of the seat through the seating surface. The seat back and seat bottom are separately controllable. The heat pumps may include thermoelectric modules that selectively heat or cool the air before it passes through the seating surface. Additional fans are provided to separately blow air along opposite sides of the thermoelectric modules. Heat energy is thus transferred to and from both opposite sides of the thermoelectric modules by forced convection only.

SUMMARY

In accordance with one or more embodiments, a vehicle seat includes a seat bottom and a seat back. At least one of the seat bottom or the seat back includes an air permeable trim cover including a seating surface, an air duct and a thermoelectric device underlying the trim cover, a heat sink attached to the thermoelectric device, and an air mover. The air duct defines an air flow channel in the seat, and the heat sink extends into the air flow channel. The air mover is operable to cause air to flow into the seat through the trim cover, along the air flow channel and heat sink, and out of the seat at a location away from the seating surface. The thermoelectric device is arranged to modulate the temperature of the trim cover by thermal conduction, and the air flow channel is shaped so that air flows in a direction toward the trim cover at an upstream side of the heat sink and in a direction away from the trim cover at a downstream side of the heat sink.

In some embodiments, an angle between the direction toward the trim cover and the direction away from the trim cover is greater than 90 degrees.

In some embodiments, the heat sink is attached to a first side of the thermoelectric device, and an opposite second side of the thermoelectric device is located outside the air flow channel.

In some embodiments, the vehicle seat includes a conductive layer attached to the thermoelectric device. The conductive layer extends along and is in contact with the trim cover.

In some embodiments, the vehicle seat includes a foam cushion underlying the trim cover. At least a portion of the air flow channel extends through the foam cushion.

In some embodiments, the vehicle seat includes at least one air intake channel having a first end in fluidic communication with the trim cover and a second end in fluidic communication with the air flow channel of the air duct at a location upstream from the heat sink. At least some of the air that flows into the seat through the trim cover flows along the air intake channel(s) before flowing along the heat sink and out of the seat.

In some embodiments, the vehicle seat includes at least one air intake channel having a first end in fluidic communication with the trim cover and a second end in fluidic communication with the air flow channel of the air duct at a location downstream from the heat sink. At least some of the air that flows into the seat through the trim cover flows along the air intake channel(s) and out of the seat without flowing along the heat sink.

In some embodiments, the vehicle seat includes a foam cushion underlying the trim cover. A foam portion of the air duct is defined by the foam cushion, and the heat sink extends into the air flow channel along the foam portion of the air duct.

In some embodiments, the heat sink is supported and biased toward the trim cover by the foam cushion.

In some embodiments, the air duct includes an intake portion upstream from the foam portion such that air flows along the intake portion before flowing along the heat sink. The intake portion of the air duct may be formed at least in part by an intake housing formed separately from and attached to the foam cushion.

In some embodiments, the air duct includes an exhaust portion downstream from the foam portion such that air flows along the exhaust portion before exiting the seat. The exhaust portion of the air duct may be formed at least in part by an exhaust housing formed separately from and attached to the foam cushion.

In some embodiments, the vehicle seat includes a duct housing that includes the intake housing and the exhaust housing formed together as a single piece attached to the foam cushion.

In some embodiments, the foam portion of the air duct is formed in the foam cushion and extends between opposite first and second ends located and spaced apart along a surface of the foam cushion facing away from the trim cover. The heat sink extends into the air flow channel at an apex of the foam portion of the air duct positioned between the trim cover and this surface of the foam cushion.

In some embodiments, the vehicle seat includes a foam cushion underlying the trim cover. The foam cushion has a first side facing the trim cover and an opposite second side. The heat sink is located along a U-shaped portion of the air duct that is formed in the foam cushion with opposite first and second ends spaced apart along the second side of the foam cushion.

In some embodiments, the vehicle seat includes a housing and a plurality of air intake channels. The housing is formed separately from the foam cushion and is attached to the second side of the foam cushion. The housing at least partly defines an intake portion of the air duct upstream from the foam portion. The air intake channels are formed in the foam cushion separately from foam portion of the air duct and extend from the first side to the second side of the foam cushion. The intake portion fluidly connects at least one of the air intake channels to the foam portion of the duct such that air flows along a serpentine-shaped path while in the seat. Air flows away from the trim cover in the air intake channel(s) before flowing toward the trim cover to reach the heat sink and then flowing away from the trim cover away again before exiting the seat.

Various aspects, embodiments, examples, features and alternatives set forth in the preceding paragraphs, in the claims, and/or in the following description and drawings may be taken independently or in any combination thereof. For example, features disclosed in connection with one embodiment are applicable to all embodiments in the absence of incompatibility of features.

DETAILED DESCRIPTION

The vehicle seat described below uses a thermoelectric device (TED) to help provide thermal comfort to a seat occupant by heating or cooling the seating surface with the TED via thermal conduction. In a cooling mode, air from the passenger cabin of the vehicle can be drawn through the seating surface by an air mover to provide a localized cooling sensation to the seat occupant and to remove heat from the hot side of the thermoelectric device. This air movement through the seating surface can also contribute to modulating the temperature of the seating surface via convective heat transfer. An air duct within the seat can be shaped to position the TED near the seating surface for enhanced conductive energy exchange without the need for uncomfortable rigid ductwork.

FIG. 1illustrates an exemplary vehicle seat10adapted for installation in the passenger cabin of a vehicle via rails along the underside of the seat or other suitable attachment features. The seat10includes a seat bottom12that supports the majority of the weight of a seat occupant when in use and a seat back14extending from the seat bottom. The seat back14includes a head rest16in this example. Forward (F) and rearward (R) directions are designated inFIG. 1and may be referred to as longitudinal directions. Upward (U) and downward (D) directions may be referred to as vertical directions, while left and right may be referred to as transverse directions. These directions are with respect to the seat10and not necessarily with the vehicle in which the seat is installed. The seat10presents a seating surface18in the form of an exterior surface of a trim cover20. Each of the seat bottom12and the seat back14includes a portion of the seating surface18, which is in contact with the seat occupant in use. As used herein, the terms “underlying” and “overlying” are in relation to a reference frame in which the seating surface18is the topmost surface. For example, an underlying layer in the seat back14is generally located rearward of the portion of the seating surface18provided by the seat back, and an underlying layer in the seat bottom12is generally located beneath the portion of the seating surface provided by the seat bottom.

The seat10is a ventilated seat configured to provide air flow (A) through the seating surface18when an underlying seat component is pressurized or depressurized, such as via an internal or external fan or blower. The air flow may include air discharged into the passenger cabin through the seating surface in a positive-ventilation or “push” configuration, or it may include ambient air from the vehicle passenger cabin pulled through the seating surface18in the illustrated negative-ventilation or “pull” configuration. Positive and negative ventilation may also be combined, with positive ventilation of the seat bottom12and negative ventilation of the seat back14, or vice versa. Or the seat bottom and/or the seat back can each have positive and negative ventilated portions. As noted above, air exiting the seat through the seating surface may be heated or cooled by a heat exchanger prior to exit. The embodiments of the thermal comfort system illustrated in the figures are configured particularly for a pull system, but many of the disclosed advantages may be realized if reconfigured as a push system.

Air flow through the seating surface18is enabled in part by at least a portion of the trim cover20being air permeable. Perforated leather is one example of an air permeable trim cover20. Certain woven or knit fabrics are also air permeable. Polymeric materials such as polyvinyl chloride (PVC) or polyurethane can also be used in the trim cover20and can be made air permeable via perforations or other suitable means. Different types of materials may also be combined to form the trim cover, so long as it is air permeable at the desired locations. The trim cover20may also be a multi-layer material including a plurality of different air permeable materials laminated or otherwise attached together. In the illustrated example, the air flow includes air drawn into the seat10along a central portion22of both the seat bottom12and the seat back14, which is located between bolster portions24,26located along opposite left and right sides of the seat10. An exemplary thermal comfort region28of the seat bottom12is illustrated in broken lines inFIG. 1representing a region of the seat where air flow may be provided through the trim cover and/or where localized modulation of the temperature of the trim cover via thermal conduction may be provided. In this particular example, the thermal comfort region is generally U-shaped and corresponds to the typical location of the legs and pelvis of the seat occupant. Other configurations are possible. The following description and illustrations are with respect to the seat bottom12but are applicable to the seat back14as well.

FIG. 2is a top view of the seat bottom12with the trim cover20omitted, andFIG. 3is a cross-sectional side view of the seat bottom taken along the thermal comfort region28. As illustrated inFIG. 2, the seat bottom12includes a foam cushion30with a plurality of air intake channels32that open along a first or top side34of the cushion and extend at least partially therethrough. A thermally conductive layer36is disposed over at least a portion of the foam cushion30. In this example, the conductive layer36is in the form of a pair of thermally conductive strips each with opposite lengthwise ends38,40spaced apart in the longitudinal direction. Between the opposite ends38,40, each strip extends beneath a cushion insert42and has a central portion44attached to an underlying thermoelectric device46(FIG. 3). The thermal comfort region28is defined as a region in which the thermally conductive layer36and the air intake channels32are located. In this case, the air intake channels32open along opposite lengthwise edges of each of the strips of the conductive layer36. Other arrangements are possible.

FIG. 3is a side cross-sectional view of the seat bottom12illustrating an example of a serpentine-shaped air flow path along which the air flow changes direction multiple times. In addition to the components illustrated inFIG. 2,FIG. 3illustrates the thermoelectric device46, an air duct48, a duct housing50, a heat sink52, and an air mover54. The air mover54is a fan, blower, pump, or other suitable device operable to cause air to flow into the seat through the air permeable trim cover20, along the air duct48and heat sink52, and then back out of the seat. The illustrated duct housing50is arranged along a second or bottom side56of the foam cushion30and, together with the foam cushion, defines the air duct48. An air flow channel58is defined by and within the air duct48. The illustrated air duct48includes an intake portion60, a foam portion62, and an exhaust portion64. The foam portion62of the air duct48is formed in the foam cushion30, and the intake and exhaust portions60,62are formed at least in part by the duct housing50. Air flows through the trim cover20, into and along the air intake channels32, along at least a portion of the air duct48, then back out of the seat. At least some of the air drawn into the seat under operation of the air mover54is routed to flow along the heat sink52to exchange thermal energy with the thermoelectric device46, an opposite side of which exchanges thermal energy with the trim cover20along a thermally conductive path provided by the conductive layer36.

Thermal comfort is thereby provided to the seat occupant through combined conductive and convective thermal energy transfer. In a cooling mode, the seat occupant experiences a cooling sensation provided in part by the TED46extracting thermal energy through the trim cover20via the conductive layer36and in part by the air movement in the vicinity of their body and the associated evaporation of perspiration. Some of the same air that moves past the seat occupant's body at the seating surface18also flows along the heat sink52and absorbs thermal energy from the waste side of the TED, thereby maintaining its capacity to absorb thermal energy from the seating surface. In a heating mode, the polarity of the voltage and the direction of current flow through the TED46is reversed so that the seat occupant experiences a heating sensation provided at least in part by the TED transferring thermal energy through the trim cover20. The air mover54may be optionally operated in the heating mode to allow the TED to absorb available thermal energy from the air flow via the heat sink52to help maintain the capacity of the TED to provide thermal energy at the opposite side.

Referring again toFIG. 3, the air duct48and the thermoelectric device46underlie the trim cover20. The heat sink52is attached to the thermoelectric device46and extends into the air flow channel58defined in the seat by the air duct48. The air mover54is operable to cause air to flow into the seat through the trim cover20, along the air flow channel58and heat sink52, and out of the seat at a location away from the seating surface18. The air flow channel58is shaped so that air flows in a direction toward the trim cover20at an upstream side66of the heat sink52and in a direction away from the trim cover at a downstream side68of the heat sink. In this example, the air flows in an upward direction to reach the heat sink52and in a downward direction when flowing away from the heat sink. With the foam portion62of the air duct48in the illustrated U-shape, the directional change of the air flow from the upstream side66to the downstream side68is through an angle of 180 degrees. Perfectly parallel portions of the air flow channel58are not required, however. The angle between the directions of airflow at the respective upstream and downstream sides66,68of the heat sink52may be just over 90 degrees, for example, but may preferably be closer to 180 degrees. When oriented in the direction of the load applied by the seated passenger (e.g., vertically downward inFIG. 3), the air flow channel in the foam portion62of the air duct is less likely to collapse or be pinched together. The cushion30may be a single continuous piece of molded foam or may be constructed from multiple pieces.

The heat sink52is attached to a first side70of the thermoelectric device46, and an opposite second side72of the thermoelectric device is located outside the air flow channel58. This prevents any inadvertent heat exchange between the second side72of the TED46and the air flowing through any part of the thermal comfort system and helps minimize thermal losses due to convective heat transfer at the second side of the TED. The second side72of the thermoelectric device46is arranged to modulate the temperature of the trim cover20by thermal conduction. This means that there is a continuous path of solid material between the second side72of the TED46and an inner surface of the trim cover20. The solid materials along this path preferably have a high thermal conductivity on the order of metallic materials, which is generally greater than 10 W/m-K and preferably greater than 100 W/m-K. Copper, aluminum, or graphite foils or layers are some examples of materials that may be included in the path of solid material between the second side of the TED and the trim cover. In another manner of describing this thermal conduction type of temperature control and thermal energy exchange, there is an absence of air or other fluid flow between the second side of the TED and the trim cover—i.e., there is substantially no forced convection or other convective heat transfer between the second side of the TED and the trim cover.

In the illustrated embodiment, the conductive heat exchange between the TED46and the trim cover20is facilitated by the thermally conductive layer36, which has its central portion44attached to the second side72of the TED and extends to opposite ends along the inner surface of the trim cover20between the trim cover and foam cushion30. The conductive layer36may include one or more flexible strips of graphite or multi-layer graphene. In a more particular example, each flexible strip includes graphite pressed and laminated between protective carrier films, such as metal foils or polymer films that are sufficiently thin to minimize thermal losses. Such strips may be about 0.5 mm to 2.0 mm thick, with the majority of the thickness provided by the graphite. The conductive layer36serves to selectively locate areas of high thermal energy exchange wherever desired along the seating surface18—i.e., without the conductive layer, heating and cooling by the TED via thermal conduction is limited to the relatively small area at the second side of the TED.

The thermally conductive layer36also allows the TED to be spaced away from the trim cover20as illustrated to make it less noticeable or unnoticeable to the seat occupant. In the illustrated embodiment, the cushion insert42separates the second side72of the TED46from the trim cover20. The cushion insert42may be formed from a similar type of foam material as the foam cushion30and fills a space between the TED46and the trim cover ranging from about 5 mm to about 25 mm. Depending on the particular materials and TED location, a spacing between about 10 mm and about 20 mm, or about 15 mm may be sufficient to make the TED virtually undetectable to the seat occupant with use of the cushion insert42. It is however contemplated that TEDs could be configured with relatively flexible thermally conductive plates along their opposite sides to place the TED closer to the trim cover.

The illustrated seat bottom12includes a plurality of air intake channels32. Each air intake channel32has a first end74along the top side34of the foam cushion30in fluidic communication with the trim cover20and a second end76in fluidic communication with the air flow channel58of the air duct48. Some of the air flow channels have their second ends76connected with the air duct48at a location upstream from the heat sink52, and some of the air flow channels have their second ends connected with the air duct at a location downstream from the heat sink52. At least some of the air that flows into the seat through the trim cover20thus flows along one or more of the air intake channels32before flowing along the heat sink52and out of the seat. In the example ofFIG. 3, at least some of the air that flows into the seat through the trim cover20flows along one or more air intake channels32and out of the seat without flowing along the heat sink52. The foam portion62of the air duct48and the heat sink52may in some cases be located so that all of the air drawn into the seat flows along the heat sink before exiting the seat.

With the heat sink52extending into the air flow channel58along the foam portion62of the air duct, the heat sink may be supported by the flexible and elastically deformable material of the foam cushion30, as illustrated inFIG. 3. Whether located in the seat bottom12as shown, or in the seat back, the foam material of the foam cushion30can thus serve to support the heat sink52and the TED46in a flexible manner, allowing this relatively rigid component of the system to move with the compressible foam material and thereby make it less noticeable to the seat occupant even though it is relatively close to the seating surface. The portion of the foam cushion beneath the heat sink52inFIG. 3, for example, acts as a sort of spring that biases the TED and heat sink toward the trim cover, allowing it to be displaced within the interior of the seat when the seat is occupied and returning it to its original position when the seat is not occupied.

The duct housing52may include an intake housing78that defines at least a portion of the intake portion60of the duct48, and/or an exhaust housing80that defines at least a portion of the exhaust portion64of the duct. These intake and exhaust housings78,80may be formed together as the duct housing50in a single piece attached to the foam cushion30as illustrated, or they may be formed as separate housings attached to the foam cushion30respectively upstream and downstream from the foam portion62of the air duct48. The duct housing52may be made from a material having a higher stiffness than the foam material of the cushion30, such as a rigid or semi-rigid thermoplastic or other suitable material. The duct housing50location, away from the seating surface, permits use of a more rigid material, which is sometimes useful to support the weight of the air mover and/or to form parts of the air duct with air flow channels perpendicular to the load direction (e.g., horizontal portions of the air flow channel58inFIG. 3) to prevent collapse or pinching of the air flow channel. The duct housing50serves to fluidly connect the air intake channels32, which are separate and distinct from the air duct48and air flow channel58, with the foam portion62of the air duct.

The foam portion62of the air duct48is formed in the foam cushion30and extends between opposite first and second ends82,84located and spaced apart along the second side56of the cushion, which is facing away from the trim cover20in this example. The heat sink52extends into the air flow channel58at an apex86of the foam portion62of the air duct, laterally between the two ends of the foam portion of the duct and vertically between the trim cover and the second side56of the foam cushion30. The illustrated foam portion62of the duct48has an inverted U-shape with vertical portions extending away from the heat sink52. For purposes of this disclosure, a U-shape does not necessarily include perfectly parallel opposite sides, nor is the U-shape necessarily rounded at the apex86. Any continuous air flow channel with first and second ends along the same side of the foam cushion with an apex along the flow channel is considered U-shaped.

As illustrated, at least some of the air that flows into the seat through the trim cover20may flow along a serpentine-shaped path while in the seat. In particular, air flows through the trim cover20and into the air intake channels32located upstream from the heat sink52, then away from the trim cover and through the air intake channels to the intake portion60of the duct38. From the intake portion60of the duct38, the air flows into the foam portion62of the duct and turns toward the heat sink52and TED46in the direction of the trim cover20. While in the foam portion62of the duct, the air flows along the heat sink52and changes direction to again flow in a direction away from the trim cover20. After exiting the foam portion62of the duct38, the air continues along the exhaust portion64of the duct, where additional air from different air intake channels may join the air flow, and is discharged from the seat. In this case, the air is discharged beneath the seat bottom12through the air mover54, which is located along a rear bottom portion of the seat bottom. The air mover54could alternatively be located anywhere along and/or inside the duct or be one of a plurality of air movers.

The thermoelectric device46is a solid-state electrically powered heat pump including particular dissimilar semi-conducting materials arranged between electrodes and/or thermally conductive plates and that produce a temperature differential across the conductive plates when a voltage is applied thereacross. Reversing the polarity of the applied voltage reverses the direction of the temperature differential and, thereby, the heat flux through the TED46. In this example, one thermally conductive plate (i.e., the bottom plate) of the TED46provides the first side70of the TED to which the heat sink52is affixed, and another thermally conductive plate (i.e., the top plate) provides the second side72of the TED to which the conductive layer36is attached. As noted above, the illustrated thermally conductive layer36may be in the form of two thin and flexible strips comprising a thermally conductive material. Each strip has its central portion44attached to the second side72of one of the TEDs46, and each strip extends in opposite frontward and rearward directions from the central portion44. The illustrated conductive layer36is non-limiting and may take on a variety of different shapes and be placed in conductive contact with the TED anywhere along the conductive layer and/or may be in some other non-strip form.

The illustrated configuration places the TED46relatively close to the seating surface, away from the relatively rigid duct portions60,64and thereby reduces thermal losses along the thermally conductive layer36and reduces the amount of bending required for the conductive layer to reach from the trim cover20to the TED. For example, if the TED46is located along the second side of the foam cushion30with the other portions of the duct38, the conductive layer36would have to extend vertically through the foam cushion30to a greater extent, and the required bending angle of the conductive layer would be much greater than illustrated inFIG. 3—i.e., closer to 90 degrees. Such sharp bends can have a negative effect on the thermal conductivity of the conductive layer, especially when the conductor is a relatively brittle material such as graphite. Bending a graphite-containing layer to high angles can cause a thermally “open” condition, analogous to breaking a wire in an electrical connection.

Also, there are thermal losses along the length of the thermally conductive layer36, analogous to resistive electrical losses along an electrical cable, such that the longer the conductive layer, the less efficient is the thermal energy transfer between the TED and the desired locations of the trim cover. Also, thermally conductive materials can be relatively expensive compared to other materials of the seat bottom, such as foam and other polymeric materials. The ability to place the TED closer to the trim cover reduces the amount of thermally conductive material necessary in the thermally conductive layer, or it allows a thicker and more conductive layer to be made with the same amount of material in a longer thinner layer.

Additionally, placement of the second side72of the TED46outside the air flow channel48avoids inadvertent heating or cooling of the second side of the TED and/or the conductive layer36, which would also reduce TED performance. The illustrated construction with a path of solid material that limits the heat transfer mode to conduction while avoiding convection optimizes TED performance.

The vehicle seat may include other components and/or layers that are not explicitly illustrated in the figures, such as a reticulated foam or3D-mesh layer between the foam cushion30and trim cover20, or additional air channels formed along the first side of the foam cushion and/or in non-vertical orientations. Resistance-type heating elements could be included to supplement or to be the primary source of heating in a heating mode, and the disclosed arrangements do not preclude the use of circulatory fluid cooling systems. While described above primarily as part of the seat bottom12, at least certain features of the disclosed thermal comfort system may also be employed for occupant comfort control along the seat back. For instance, the air flow channel58may be defined in the seat back14(FIG. 1) such that the air flows toward and away from the trim cover as it flows along the heat sink and exits the seat at along a rear lower portion of the seat back.