Abstract:
A steering wheel includes a central portion connected to the steering column for rotation about an axis, and a rim extending around the central portion. A steering wheel includes a passageway extending through portions of the steering wheel. A plurality of spaced apart rings are disposed on the rim, and a plurality of N-type and P-type thermoelectric (“TE”) elements are disposed on the rings. The thermoelectric elements may comprise Peltier devices in the form of relatively thin plate-like units having generally planar opposite surfaces, and rectangular perimeters. An electrical conductor interconnects the P-type and N-type elements in series. The steering wheel includes first and second thermal conductors thermally connected to inner and outer surfaces of the thermoelectric elements. An air circulation device moves air through the passageway to cool the rim of the steering wheel.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to thermally-controlled steering wheels for vehicles, and more specifically to a heated and cooled steering wheel including a plurality of thermoelectric elements. 
       BACKGROUND OF THE INVENTION 
       [0002]    Thermal comfort of vehicle occupants is an important aspect of the driving experience. Vehicle touch surfaces can get hot after being exposed to the sun. Existing steering wheels may reach temperatures that are well above the ambient temperature. Because the steering wheel may be exposed to more direct sun than other controls necessary for driving (e.g. ignition switch, shifter, brake, accelerator, seat cushions etc.), the steering wheel may be too hot to touch, thus preventing the driver from driving the vehicle until it has cooled. Traditional methods of cooling a vehicle interior space by air circulation involve opening a door or opening one or more windows. These known cooling methods require a user to be present for security reasons while waiting for the steering wheel to cool. Although it may be possible to remotely actuate a vehicle&#39;s air conditioning system in some instances, this is typically a very inefficient way to cool the steering wheel, and the steering wheel may still be too hot to touch for some time even if the cabin air temperature is comfortable. In view of the above, a need exists for an improved way to cool vehicle steering wheels. 
         [0003]    Also, if a user begins to use a steering wheel after it has been exposed to cold temperatures, the user may experience discomfort upon contact with the cold wheel. Although heated steering wheels have been developed, known heated steering wheels may suffer from various drawbacks due to limits in the amount of heat available to heat the steering wheel. 
       SUMMARY OF THE INVENTION 
       [0004]    One aspect of the present invention is a steering wheel assembly for motor vehicles of the type having a steering column. The steering wheel includes a central portion connected to the steering column for rotation about an axis, and a rim extending around the central portion. The steering wheel includes a passageway extending through at least a portion of the rim, the central portion of the steering wheel. The passageway may also extend through the steering column. The rim defines an outer side portion facing away from the axis. The steering wheel further includes a plurality of spaced apart rings of material disposed on the rim. A plurality of N-type thermoelectric (“TE”) elements having inner and outer surfaces are disposed on at least one of the rings with the inner surface of the N-type TE element facing the rim. The steering wheel assembly further includes a plurality of P-type TE elements disposed on at least one of the rings with the inner surface of the TE element facing the rim. The N-type and P-type TE elements may be electrically connected to the rings upon which each of the thermoelectric elements is disposed. The N-type and P-type thermoelectric elements may comprise Peltier devices in the form of relatively thin plate-like units having generally planar opposite surfaces, and rectangular perimeters. An electrical conductor interconnects the P-type and N-type TE elements in series. The steering wheel assembly further includes a first thermal conductor thermally connected to the inner surfaces of the N-type and P-type TE elements, and a second thermal conductor that is thermally connected to the outer surfaces of the N-type and P-type TE elements, whereby the P and N type TE elements are thermally connected in parallel between the first and second thermal conductors. A powered air circulation device moves air through the passageway from the rim to the steering column to thereby cool the rim upon application of electrical power to the P-type and N-type elements. 
         [0005]    These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    In the drawings: 
           [0007]      FIG. 1  is a partially fragmentary isometric view of a portion of a vehicle interior including a heated/cooled thermoelectric steering wheel according to one aspect of the present invention; 
           [0008]      FIG. 2  is a cross-sectional view of the steering wheel of  FIG. 1 ; 
           [0009]      FIG. 3  is an enlarged cross-sectional view of the steering wheel of  FIG. 2 ; 
           [0010]      FIG. 4  is an isometric view of a ring including a plurality of thermoelectric elements; 
           [0011]      FIG. 5  is a partially schematic, fragmentary cross-sectional view of a steering wheel taken along the line V-V of  FIG. 1 ; 
           [0012]      FIG. 6  is a partially fragmentary, enlarged view of the steering wheel of  FIG. 1 ; 
           [0013]      FIG. 7  is a schematic view of the electrical components of a steering wheel according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0015]    With reference to  FIG. 1 , a motor vehicle  1  includes an interior space  2  including a steering wheel assembly  10  according to one aspect of the present invention. The steering wheel assembly includes a steering column  11 , a circular rim  12 , and a central portion or hub  13  that is connected to the steering column  11 . 
         [0016]    As shown in  FIG. 2 , rim  12  generally comprises a tube  24  having a cylindrical inner surface  25 , a cylindrical outer surface  26 , and an internal passageway  27 . The outer surface  26  is generally in the shape of a toroid. The tube  24  may have a generally uniform wall thickness “T.” The tube  24  may be formed from a metal such as steel, or other materials having the required structural characteristics, and heat transfer capability. A plurality of N-type thermoelectric elements  28 , and a plurality of P-type thermoelectric elements  30  may be mounted on a conductive inner layer  32  disposed on outer surface  26  of tube  24 . Thermally insulating material  34  is disposed between adjacent TE elements  28  and  30  to thermally isolate adjacent P and N-type TE elements. An outer conductive layer  36  is disposed on, and interconnected with, outer surfaces  38  and  40  of N-type TE elements and P-type TE elements  28  and  30 , respectively. Inner surfaces  42  of N-type TE elements  28  and inner surfaces  44  of P-type TE elements  30  may be electrically connected to inner conductive layer  32 . 
         [0017]    The N-type and P-type TE elements  28  and  30 , respectively, may comprise Peltier elements wherein the N and P-type thermoelectric materials are stacked electrically in series, and thermally in parallel. The basic construction of Peltier elements is known, and the details of the materials and methods utilized to fabricate the N and P-type elements  28  and  30  will not therefore be described herein. In a preferred embodiment, the TE elements  28  and  30  comprise thin plate-like members having a quadrilateral or square perimeter and generally parallel, flat opposite side surfaces  38 ,  40 ,  42 , and  44 . The thickness divided by the cross-sectional area is generally in the range of 0.125, but it may be in the range of about 0.08 to about 0.20. It will be understood that the TE elements could have circular perimeters, oval perimeters, or other suitable shape. In a preferred embodiment, the TE elements  28  and  30  are about 2 mm×3 mm×0.5 mm thick. Although the inner surfaces  42  and  44  of the TE elements  28  and  30 , respectively, are planar, the curvature of outer surface  26  of tube  24  is sufficiently large relative to the size of the TE elements  28  and  30  so as to permit the use of solder to bridge both electrically and physically between the TE elements  28  and  30  and the tube  24 . 
         [0018]    With further reference to  FIG. 3 , an electrical insulating layer/thermoadhesive  46  is disposed on outer surface  26  of tube  24 . A layer  32  of flexible conductive material is disposed on layer  46 , and gaps or electrically insulating material  48  are disposed between adjacent electrical conductors  32 . Solder  50  and  52  is used to electrically secure the TE elements  28  and  30  to inner conductive layer  32 , and to outer conductive layer  36 . Gaps or insulating material  54  electrically isolate conductive layer  36  from adjacent conductive layers. Metalization and defusion layers  56  are disposed between the solder and the TE elements  28  and  30 . The electrically conductive layers  32  and  36  interconnect alternating N and P-type TE elements in series. However, the N and P-type TE elements are thermally connected in parallel due to the thermal conductivity of the materials other than thermally insulating material  34 . This provides for heat transfer directly between outer wheel cover or skin  58  and tube  24 . It will be understood that the TE elements  28  and  30  and other components are shown schematically in  FIG. 3  with increased thickness and reduced spacing for purposes of illustrating the arrangement of the various layers of material. 
         [0019]    With further reference to  FIG. 4 , TE elements  28  and  30  may be mounted to a ring  60  having an outer surface  62 , and an inner surface  64 . The TE elements  28  and  30  are electrically interconnected/insulated in substantially the same manner as described in more detail above. The TE elements  28  and  30  on ring  60 A may all comprise N-type TE elements  28 , and an adjacent ring  60 B having all P-type TE elements  30  may be positioned adjacent the ring  60 A. 
         [0020]    The total resistance of the network of TE elements  28  and  30  preferably has a resistance in the range of about 0.5 to 2.0 ohms. Thus, the rings  60  and TE elements  28  and  30  are attached in a parallel-series configuration. This is accomplished by using a “cut” (not shown) in each ring  60  with a dielectric separator (e.g. a piece of polymer material). Each ring  60  has at least one positive locator pin (not shown) to provide correct orientation of the ring and to enable electrical conduction from one ring  60  to one or more adjacent rings  60 . Each ring  60  is electrically isolated from tube  24  by a thermally conductive layer such as an electrodeposited metal oxide, a thin organic varnish, a powder coated paint, or other suitable material. 
         [0021]    With further reference to  FIGS. 5 and 6 , rings  60 A and  60 B may be positioned adjacent the 3 o&#39;clock and 9 o&#39;clock positions  66  and  68 , respectively of rim  12 , and the 12 o&#39;clock position  70  and 6 o&#39;clock position  72  may be configured without rings  60 A or  60   b.  In this way, the heating and cooling effects of the rings  60 A and  60 B can be directed to the 9 o&#39;clock and 12 o&#39;clock regions of the steering wheel rim  12  to provide heating or cooling in the areas of the rim  12  where a user&#39;s hand is most likely to be placed. Although the rings  60 A and  60 B could be positioned around the entire rim  12 , positioning of the rings  60 A and  60 B only at the 3 o&#39;clock and 9 o&#39;clock regions reduces the total cost and complexity of the steering wheel assembly  10 . A plurality of conductors  74  may extend between adjacent rings  60 A and  60 B to electrically interconnect the rings  60 A and  60 B. A temperature sensor  76  may be positioned on the central portion or hub  13  of the steering wheel  10 . As discussed below in more detail in connection with  FIG. 7 , the temperature sensor  76  and rings  60 A and  60 B are electrically connected to a controller and to the vehicle power supply. 
         [0022]    The steering wheel assembly  10  also includes one or more spokes  15 A- 15 D that extend from the central portion  13  to the rim  12  (see also  FIG. 6 ). The spokes  15 A- 15 D include passageways  16 A- 16 D extending between rim  12  and central portion or hub  13  of the steering wheel assembly  10 . A fan  19  may be positioned in central portion/hub  13  to provide air draw up through parts  17 A and  17 B on an underneath side of central portion/hub  13 . Alternately, the passageways  16 A- 16 D may be fluidly connected to passageways  18 A and  18 B extending through steering column  11 . A fan  19 A may be utilized to circulate the air through passageways  16 A- 16 D and passageways  18 A and  18 B. Passageways  18 A and B may vent directly into the interior space  2  of the vehicle, or the passageways  18 A or  18 B may be fluidly connected to passageways  20  of the vehicle heating and air conditioning system  21 . 
         [0023]    With further reference to  FIG. 7 , the steering wheel rim and hub  13  include the N and P-type TE elements  28  and  30 . The temperature sensor  76  illustrated in  FIG. 7  comprises a thermister  76 . Also, a conventional electrical heater element  80  may also be disposed on rim  12  to provide heating of the rim  12 . A clock spring  82  in a steering column module  78  includes a first 10-way ribbon  84 , a second 10-way ribbon  86 , and 1-way ribbons  88  and  89  that operably interconnect the TE elements  28  and  30 , thermister  76 , and heater element  80  to a steering wheel climate control module  90  through steering column  11 . The steering wheel climate control module  90  includes a mid-speed controller area network (“MS-CAN”) unit  92  that is connected to the MS-CAN bus  94  of a vehicle. 
         [0024]    In use, the controller  90  determines if the steering wheel rim needs to be heated or cooled. If the steering wheel rim  12  needs to be heated, the controller  90  supplies electrical power to resistance heater  80 . If, however, the rim  12  needs to be cooled, the controller  90  supplies electrical power to the TE elements  28  and  30 , causing heat to transfer from the outer surface of the steering wheel to the inner surface  25  of tube  24 . Circulation of air through the internal passageway  26  of rim  12  due to fan  19  thereby transfers the heat out of the rim  12  and into the passageways  18 A and  18 B in steering column  11 . Incoming air  99  is drawn into passageway  18 B in column  11 , and heated air  98  exits through internal passageway  18 A. As discussed above, the passageways  18 A and  18 B may open into the vehicle interior space  2 , or the passageways  18 A and  18 B may be connected to one or more passageways  20  of a vehicle heating and air conditioning system  20 . 
         [0025]    Controller  90  may be operably connected to a wireless communication device such as a cell phone (not shown) to provide for remote actuation/control of the system. Controller  90  may also be operably connected to a remote start fob or to a conventional remote keyless entry or remote start fob to provide for actuation/control of the system prior to vehicle entry by a user. Also, controller  90  may be operably connected to a “door open” switch whereby the system is actuated upon opening of the vehicle door. Still further, the system may be configured to periodically monitor the vehicle cabin temperature and sun load (applied heat) utilizing sensors. Cooling (or heating) of the steering wheel may be controlled based on predefined criteria based or measured temperature or other parameters. 
         [0026]    It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.