Abstract:
A head restraint assembly includes a locking mechanism that is electromagnetically actuated and is selectively moveable between a locked and an unlocked position, thereby allowing the head restraint to move between an upright and a folded position. The locked position comprises engagement of a first lock member with a second lock member to prevent rotation of the head restraint relative to a base portion of the head restraint and the unlocked position comprises disengagement of the first lock member from the second lock member to allow rotation of the head restraint relative to the base portion. An electromagnet is operatively connected to the head restraint and positioned to exert a magnetic force on the second lock member that urges the second lock member toward the unlocked position when the electromagnet is in an energized condition.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent application claims priority to U.S. Provisional Application No. 61/782,808, filed Mar. 14, 2013, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The subject matter disclosed herein relates to vehicle head restraints and, more particularly, to a vehicle head restraint with an electromagnetic release mechanism. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many vehicles, such as automobiles, include a headrest or head restraint atop an occupant&#39;s seatback and in a position adjacent the occupant&#39;s head. Head restraints are typically cushioned for comfort, are height adjustable, and most are commonly finished in the same material as the rest of the seat. Although head restraints provide desirable functionalities related to comfort and safety, the upward protrusion of the head restraints may partially obstruct sightlines for occupants of the vehicle. For example, head restraints associated with rear seats may reduce visibility for a driver during rearward movement of the vehicle. Such a situation is undesirable for a driver. As noted above, some head restraints are adjustable (e.g., rotatable, translatable) and/or removable, but the adjustments typically require a manual interaction with the head restraint. The adjustments may be cumbersome or impossible for a seated driver to perform. These are just a few drawbacks associated with current head restraints. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of the invention, a head restraint assembly includes a base portion mountable to a vehicle seat. Also included is a head restraint operatively coupled to the base portion and selectively rotatable with respect to the base portion about a first axis for movement between an upright position and a folded position. Further included is a locking mechanism including a first lock member mounted with respect to the base portion and a second lock member rotatably mounted with respect to the head restraint for movement between a locked position and an unlocked position, wherein the locked position comprises engagement of the first lock member with the second lock member to prevent rotation of the head restraint relative to the base portion, and wherein the unlocked position comprises disengagement of the first lock member from the second lock member to allow rotation of the head restraint relative to the base portion. Yet further included is an electromagnet operatively connected to the head restraint and positioned to exert a magnetic force on the second lock member that urges the second lock member toward the unlocked position when the electromagnet is in an energized condition. 
         [0005]    According to another aspect of the invention, a locking mechanism disposed within an interior portion of a head restraint includes a first lock member mounted within the head restraint. Also included is a second lock member mounted within the head restraint and rotatable about an axis between a locked position and an unlocked position, wherein the locked position comprises engagement of the first lock member with the second lock member to prevent rotation of the head restraint relative to the base portion, and wherein the unlocked position comprises disengagement of the first lock member from the second lock member to allow rotation of the head restraint relative to the base portion. Further included is a groove defined by the second lock member and a protuberance defined by the first lock member. Yet further included is a first stop surface and a second stop surface disposed within the groove, wherein the protuberance of the first member is inside the groove and simultaneously contacts both the first stop surface and the second stop surface when the second lock member is in the locked position, wherein the protuberance of the first member is externally located relative to the groove when the second lock member is in the unlocked position. Also included is an electromagnet mounted within the head restraint and positioned to exert a magnetic force on the second lock member that urges the second lock member toward the unlocked position when the electromagnet is in an energized condition, wherein the second lock member includes first and second protuberances that align with respective segments of the electromagnet when the second lock member is in the unlocked position. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0007]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0008]      FIG. 1  is a perspective, disassembled view of a head restraint assembly; 
           [0009]      FIG. 2  is a front elevational view of the head restraint assembly; 
           [0010]      FIG. 3  is a schematic, partial cut-away view of the head restraint assembly; 
           [0011]      FIG. 4  is a side, cross-sectional view of the head restraint assembly in an upright, locked position; 
           [0012]      FIG. 5  is a side, cross-sectional view of the head restraint assembly in an upright, unlocked position; 
           [0013]      FIG. 6  is a side view of the head restraint assembly in a folded position; and 
           [0014]      FIG. 7  is a schematic, cross-sectional, side view of a locking mechanism of the head restraint assembly. 
       
    
    
       [0015]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to the Figures, a head restraint assembly  10  is schematically depicted. The head restraint assembly  10  includes a base portion  14  that is mountable to a vehicle seat (not illustrated), and, more specifically, to the upper portion of the seatback of the vehicle seat. In the embodiment depicted, the base portion  14  includes two post members  18  that are mounted, or mountable, to the top of the seatback of the vehicle seat, as understood by those skilled in the art. Each of the post members  18  includes a respective elongated, straight portion  22 . Each of the straight portions  22  extends into a respective hole formed in the top of the seatback to attach the head restraint assembly  10  to the vehicle seat. The base portion  14  also includes a cross-member  26  that interconnects the two post members  18 . 
         [0017]    The head restraint assembly  10  further includes a head restraint  30  mounted with respect to the base portion  14 . In the embodiment depicted, the head restraint  30  includes a plastic frame  34  that provides rigid structure to the head restraint  30 . The head restraint  30  also includes cushion (not shown) and a head restraint cover (not shown) that are mounted with respect to the frame  34  for movement therewith. The head restraint cushion is comprised of a soft foam material or a like material to provide a cushion between the head of a human occupant of the vehicle seat and the head restraint frame  34 . The head restraint cover covers at least part of the cushion and the frame to enhance the aesthetics of the head restraint. Exemplary cover materials include cloth, vinyl, leather, etc. Other frame configurations may be employed within the scope of the claimed invention. 
         [0018]    The frame  34  is rotatably mounted with respect to the base portion  14  such that the frame  34  (and the rest of the head restraint  30 , including the cushion and cover) is selectively rotatable with respect to the base portion  14  about a first axis A 1 , and, therefore, is also selectively rotatable with respect to the seatback portion of the vehicle seat. More specifically, the head restraint  30  is mounted with respect to the base portion  14  and selectively rotatable with respect to the base portion  14  about a first axis A 1  for movement between an upright position ( FIGS. 2-5 ) and a folded position ( FIG. 6 ). 
         [0019]    A locking mechanism  38  includes a first lock member  42  mounted with respect to the base portion  14  and, more specifically, mounted to the cross-member  26 . The locking mechanism  38  also includes a second lock member  46  rotatably mounted with respect to the head restraint frame  34  for movement between a locked position ( FIG. 4 ) and an unlocked position ( FIG. 5 ). Bushing  48  extends through a hole in the second lock member  46  to rotatably support the second lock member  46 ; the second lock member  46  is rotatable about a second axis A 2  ( FIG. 7 ) between the locked and unlocked positions; the axis A 2  is coextensive with the bushing  48 . A rod  49  extends through a hole in the bushing  48  to support the bushing  48  relative to the frame  34 . 
         [0020]    The Figures illustrate an aperture in the head restraint assembly  10  that corresponds to a general location in which the locking mechanism  38  is located. It is to be appreciated that a cover layer of plastic or the like is disposed over the aperture to enclose the locking mechanism  38  within the head restraint assembly  10 . 
         [0021]    When the second lock member  46  is in the locked position, it is engaged with the first lock member  42  such that the interaction of the first and second lock members  42 ,  46  prevents rotation of the head restraint  30  relative to the base portion  14 . When the second lock member  46  is in the unlocked position, it is disengaged from the first lock member  42  such that the first and second lock members do not restrict rotation of the head restraint  30  relative to the base portion  14 . 
         [0022]    An electromagnet  50  is operatively connected to the head restraint  30  and positioned such that, when the electromagnet  50  is energized, the electromagnet  50  exerts a magnetic force on the second lock member  46  that urges the second lock member  46  toward the unlocked position. The electromagnet  50  includes a copper wire coil  54  around a ferromagnetic core  58 . The core  58  is generally U-shaped, with a first segment  62  extending through the coil  54  and having opposite ends  64 ,  66 . The core  58  also includes second and third segments  70 ,  74  extending from a respective one of the ends  64 ,  66  of the first segment  62  toward the second lock member  46 . 
         [0023]    The second lock member  46  includes first and second protuberances  78 ,  82  that align with the second and third segments  70 ,  74 , respectively, of the core  58  when the second lock member  46  is in the unlocked position. More specifically, when the second lock member  46  is in the locked position ( FIG. 4 ), the protuberances  78 ,  82  are not aligned with segments  70 ,  74 , respectively. When the electromagnet  50  is energized, i.e., when electrical current flows through the coil  54 , the electromagnet exerts a magnetic force on the second member  46  that draws the protuberances  78 ,  82  adjacent to, and into alignment with, the segments  70 ,  74 , thereby rotating the second lock member  46  into the unlocked position ( FIG. 5 ). 
         [0024]    The second lock member  46  defines a groove  90 , and the first lock member  42  defines a protuberance  94 . Referring specifically to  FIG. 7 , the groove  90  includes a first stop surface  98  and a second stop surface  102 . The protuberance  94  of the first lock member  42  is inside the groove  90  and simultaneously contacts both the first stop surface  98  and the second stop surface  102  when the second lock member  46  is in the locked position ( FIGS. 4 and 7 ). The protuberance  94  of the first lock member  42  does not extend inside the groove  90  when the second lock member  46  is in the unlocked position. The interaction between the protuberance  94  and the stop surfaces  98 ,  102  when the protuberance  94  is inside the groove  90  prevents rotation of the head restraint  30  relative to the base portion  14 . The first stop surface  98  and the second stop surface  102  are substantially parallel to one another. 
         [0025]    The protuberance  94  of the first lock member  42  includes a first surface  106  and a second surface  108  that are parallel to one another. The first surface  106  contacts the first stop surface  98  when the second lock member  46  is in the locked position, and the second surface  108  contacts the second stop surface  102  when the second lock member  46  is in the locked position. 
         [0026]    The first stop surface  98  is a circle segment, i.e., an arc of a circle  110  having a first center point  114 . The second stop surface  102  is a circle segment, i.e., an arc of a circle  118  having a second center point  122 . The axis A 2  and the first center point  114  form an angle  126  that is between about 3 and about 5 degrees. That is, if a first line  130  is drawn from a point on the first stop surface  98  to the axis A 2 , and a second line  132  is drawn from the point on the first stop surface  98  to the first center point  114 , the first and second lines  130 ,  132  will form an angle  126  therebetween that is between about 3 and about 5 degrees. In the embodiment depicted, the angle  126  is 3.829 degrees. 
         [0027]    The axis A 2  and the second center point  122  form an angle  136  that is between about 3 and about 5 degrees. That is, if a first line  140  is drawn from a point on the second stop surface  102  to the axis A 2 , and a second line  142  is drawn from the point on the second stop surface  102  to the second center point  122 , the first and second lines  140 ,  142  will form an angle  136  therebetween that is between about 3 and about 5 degrees. In the embodiment depicted, the angle  136  is 3.908 degrees. 
         [0028]    Referring to  FIGS. 1 ,  4 ,  5  and  7 , insulating members  143  separate the coil  54  from other components, including the core  58 . The rod  49 , which is mounted to the frame  34 , supports the insulating members  143  and the coil  54  via brackets  144 . A torsion spring  148  is coiled around the rod  49 , and operatively interconnects the second lock member  46  and the frame  34  such that the spring  148  biases the second lock member  46  toward its locked position. Other torsion springs  152  operatively interconnect the frame  34  and the base portion  14  such that the torsion springs  152  bias the head restraint  30  toward its folded position. 
         [0029]    Accordingly, when the head restraint  30  is in the upright position and the electromagnet  50  is not energized, as shown in  FIG. 4 , the spring  148  maintains the second lock member  46  in the locked position, and the head restraint  30  is not rotatable about axis Al because of the interaction between the surfaces of the protuberance  94  and the groove  90 . When a vehicle user desires the head restraint  30  to move to the folded position ( FIG. 6 ), the user may cause electrical current to flow through the coil  54 , which creates a magnetic field and thereby causes the second lock member  46  to overcome the bias of spring  148  and rotate about axis A 2  to the unlocked position ( FIG. 5 ). With the protuberance  94  outside of the groove  90 , there is nothing to prevent the rotation of the head restraint  30  about axis A 1 , and the springs  152  cause the head restraint  30  to rotate about axis A 1  to the folded position. 
         [0030]    When a vehicle user desires to move the head restraint  30  from the folded position back to the upright position, the user may manually rotate the head restraint  30  back to the upright position; with the electromagnet not energized, the spring  148  will automatically move the second lock member  42  to the locked position so that the head restraint  30  will remain in the upright position. 
         [0031]    The coil  54  is in electrical communication with a source of electrical energy, such as the vehicle&#39;s battery, via wires that extend from the coil  54 , through one or both post members  18 , and through the seat back portion of the vehicle seat. A switch to control current flow from the battery to the coil  54  may be manually operated by the vehicle user, or may, for example, be controllable remotely such as via a wireless key fob. Additionally, the coil  54  may be controlled via voice commands enabled with an audible detection system configured to receive a voice command from the user to activate the electromagnet into the energized condition. Furthermore, the coil  54  may be configured to detect whether an occupant is seated in the seat that the head restraint  30  is connected to. This is accomplished with one or more sensors in the seat and/or seatback. In the event the seat is empty, the coil  54  may be energized to release the latch that controls the position of the head restraint  30 . 
         [0032]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.