Abstract:
A vehicle seat recliner that includes a load bearing cam and an anti-chucking cam that act upon a plurality of latches to lock the recliner in a selected position. The load bearing cam is connected to the anti-chucking cam with a lost motion connection.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national phase of PCT Application No. PCT/US2012/040119 filed on May 31, 2012, which claims foreign priority benefits under 35 U.S.C. §119(a)-(d) to DE 10 2011 078 216.8, filed Jun. 28, 2011, the disclosures of which are incorporated in their entirety by reference herein. 
     TECHNICAL FIELD 
     This development relates to a vehicle seat reclining mechanism. 
     BACKGROUND 
     Vehicle seats are provided with reclining mechanisms that, among other functions, permit the seatback of the vehicle seat to be moved to different angular orientations relative to the seat base and retained at a selected position. Without making any representation as to the scope or content of the prior art, applicants acknowledge that the following patents were considered in conjunction with the preparation of this application: U.S. Pat. Nos. 5,681,086; 6,312,053; 5,779,313; 7,150,502; 7,828,386; 7,669,931; 7,677,666; and 7.828,385. 
     SUMMARY 
     A recliner for a vehicle seat has a load bearing cam that provides robustness for the recliner mechanism and an anti-chucking cam that resists noise and vibration in the vehicle seat. 
     The recliner includes a stationary plate that is secured to either the seat bottom or the seatback and a pivotal plate that is secured to the other part of the seat. The pivotal plate is pivotally connected to the stationary plate about a pivot axis. The pivotal plate has a set of radially inwardly extending gear teeth. A plurality of latches are provided that are pivotally connected to the pivotal plate. Pivot connectors are provided that are received in pivot recesses formed in the latches. The latches are provided with a set of radially outwardly extending gear teeth that are selectively engaged with the teeth of the pivotal plate. The load bearing cam and anti-chucking cam together prevent disengagement of the teeth of the latches from the radially inwardly extending gear teeth of the pivotal plate. The load bearing cam resists disengagement of the teeth and backs up the latches in the event a crash load is applied to the seat that is greater than a normal load. The anti-chucking cam operatively engages the latches to resist chucking movement of the seatback. The anti-chucking cam clamps the latches into a locked position in which the teeth of the latches engage the teeth of the pivotal plate. The angle inclination of the seatback relative to the seat base is adjusted by pivoting the load bearing cam and the anti-chucking cam until the gear teeth of the latches disengage the gear teeth of the pivotal plate. 
     The anti-chucking cam may include a plurality of slots that each receive a protrusion that extends axially from the backup cam to provide a lost motion connection between the load bearing cam and the anti-chucking cam. The load bearing cam has a plurality of backup lobes that each shift into a cutout in one of the latches. The backup lobes engage a finger formed on each of the cutouts that drive the latches into a retracted position in conjunction with the protrusion engaging end of the slot to shift a set of first contact surfaces of the anti-chucking cam away from a set of second contact surfaces on the anti-chucking cam. 
     The anti-chucking cam may further include a plurality of tangs extending in an axial direction that are each engaged by a spring that biases the anti-chucking cam into engagement with the latches. The anti-chucking cam may also include a plurality of lobes that have first contact surfaces that are oriented at an angle of more than 4°, and for example between 12° and 14°, relative to a circumference of the recliner. The first contact surfaces each contact a second contact surface that is oriented at a complimentary angle relative to the circumference of the recliner on one of the latches to drive the latch into engagement with the teeth of the pivotal plate. 
     The load bearing cam may have a plurality of load receiving lobes that are spaced to provide clearance relative to the latches when the load bearing cam is in the position in which it backs up the latches. The load bearing cam may also have a plurality of load receiving lobes that have a backup surface that is oriented at an angle that is normal to the surface of the latches that are backed up by the load bearing cam. In addition, the load bearing cam may define at least two slots that each receive a helically wound spring that biases the load bearing cam toward the locked position in engagement with the latches. 
     To provide easy entry, an arcuate surface feature is provided inside the stationary plate that engages at least one protrusion formed on one of the latches. The latch is held in the refracted position by the protrusion that follows the arcuate feature through a range of motion except for a range of motion corresponding to a comfort adjustment area. 
     The vehicle seat recliner also provides improved energy absorption. The pivot connector may include a bearing surface that may be deformed to absorb energy in the event of a crash. The pivotal plate also defines integral end stops that confine the latches in an opening direction and in a closing direction. The end stops have guide surfaces that limit movement of each of the latches until a crash load is applied and may be deformed to absorb energy in response to application of a crash load. 
     The features of the vehicle seat recliner summarized above will be better understood in view of the attached drawings and the following detailed description of the illustrated embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle seat recliner made according to one embodiment of the present invention; 
         FIG. 2  is a side elevation view of the outer side of the vehicle seat recliner; 
         FIG. 3  is an exploded perspective view from the inner side of the vehicle seat recliner; 
         FIG. 4  is an exploded perspective view from the outer side of the vehicle seat recliner; 
         FIG. 5  is an inner side partially assembled view of some of the component parts of the vehicle seat recliner assembled to a stationary case plate; and 
         FIG. 6  is an inner side view of a vehicle seat recliner with the rotary case plate removed with all component parts assembled to the stationary case plate. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of the illustrated embodiments of the present invention are provided below. The disclosed embodiments are examples of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale. Some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed in this application are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to practice the invention. 
     Referring to  FIG. 1 , a vehicle seat recliner  10  is shown to include a rotary case plate  12  that is rotatable relative to a stationary case plate  14 . The rotary case plate  12  is normally attached to the vehicle seatback frame. The stationary case plate  14  is normally attached to the vehicle seat base (not shown). An adjustment lever  16  may be used to engage and disengage the recliner mechanism  10  to change the angle of orientation of the seatback relative to the seat base. Other types of actuating elements may be used, such as a motor or control cable. A plurality of weld flats  18  are provided on the outside of the rotary case plate  12  that are used to weld the recliner  10  to a vehicle seatback. 
     A circular groove is formed in the rotary case plate  12  that is interrupted by a notch  22 . The circular groove  20  is used to provide an easy entry function for the recliner  10  by holding the latches disengaged during rotation of the plates except in the comfort adjustment area. 
     Referring to  FIG. 2 , the outer side of the stationary case plate  14  is shown assembled to the rotary case plate  12  of the vehicle seat recliner  10 . The adjustment lever  16  is shown in solid lines and also in phantom lines to illustrate that the lever  16  may be moved as little as 23° from its engaged to disengaged position thereby greatly reducing the amount of travel required to operate the vehicle seat recliner. A hub  26  extends through the vehicle seat recliner and may be used to transmit displacement of the lever  16  to the internal components of the vehicle seat recliner  10 . Alternatively, the hub  26  could be eliminated by providing a direct drive connection. Weld flats  28  are provided at three spaced locations on the stationary case plate  14  that are used to weld the vehicle seat recliner  10  to the seat base (not shown). 
     Referring to  FIGS. 3 and 4 , the rotary case plate  12  is shown separated from the stationary case plate  14 . A master latch  30  and slave latches  32  are received on the stationary case plate  14  at approximately 120° spacing. The master latch  30  and slave latches  32  are each received on a pivot post  36 . The latches  30 ,  32  each include a recess  38  in which the pivot post  36  is received. The recess is generally cylindrical in shape, but may be somewhat oval to reduce the contact between the recess  38  and pivot post  36  to two lines of contact. The latches  30 ,  32  have latch teeth  40  that engage inner teeth  42 , shown in  FIG. 4 . The latch teeth  40  engage the inner gear teeth  42  to lock the rotary case plate  12  and stationary case plate  14  together when engaged. A refraction notch  46  is also provided on the latches  30 ,  32  and is used to disengage the latches  30 ,  32  from the inner gear teeth  42 . 
     The latches  30 ,  32  are disengaged by rotation of a load cam  48 . In the illustrated embodiment, the load cam  48  is rotated by manipulating the adjustment lever  16  or other actuator. The load cam  48  includes a retraction protrusion  50  that is received in the retraction notch  46  when the adjustment lever  16  is rotated. A cam connecting pin  52  extends axially from the retraction protrusion  50 . A pair of helical springs  56  are received in an arcuate recess  58  defined in the inner diameter of the load cam  48 . Helical springs  56  bias the load cam  48  into its engaged position. The helical springs also engage a stake  60 . 
     Actuator keys  62  are provided on the hub  26  and adjustment lever  16  assembly that is received in keyways  64  formed in the load cam  48 . 
     An anti-chucking cam  68  includes cam locks  70  that define a clamping edge  72 . The cam locks  70  define the clamping edges  72  that engage axial protrusion  74  formed on each of the latches  30 ,  32 . The axial protrusion  74  on the master latch  30  is triangular in shape to cooperate with the circular groove  20  and notch  22  formed in rotary case plate (not shown in  FIG. 3 ). The anti-chucking cam  68  defines three lost motion slots  76 . The cam connecting pin  52  extending from the load cam  48  are received in the lost motion slots  76 . The lost motion slots  76  permit the load cam  48  to be rotated relative to the anti-chucking cam  68  to a limited extent. 
     A spring tang  78  is provided on the anti-chucking cam  68  that will be described more specifically with reference to  FIGS. 5 and 6  below. 
     A hub retainer  80  retains the component parts of the vehicle seat recliner  10  on the hub  26 . It should be understood that the hub  26  may be replaced with a different type of operator if desired to reduce part count. Three clock springs  82  are secured to spring retainer  84  that are integrally formed on the stationary case plate  14 . The clock springs  82 , or power springs, exert a biasing force on the spring tang  78  of the anti-chucking cam  68 . A first set of end stops  86  and a second set of end stops  88  are embossed or otherwise provided by the stationary case plate  14 . The end stops guide movement of the latches  30 ,  32 . The end stops  86 ,  88  also provide energy absorption that may be formed under crash load and increase energy absorption in the seat recliner mechanism. 
     Referring to  FIG. 5 , the stationary case plate  14  is shown partially assembled with the load cam  48  holding the master latch  30  and slave latches  32  in their engaged position in which the latch teeth  40  would be in engagement with the inner gear teeth  42  shown in  FIG. 4 . The load cam  48  is biased into this orientation by helical spring  56 , shown in  FIGS. 3 and 4 , but not visible in  FIG. 5 . 
     When the adjustment lever  16  is moved, the hub  26  rotates the load cam  48  in a counter-clockwise direction (as shown in  FIG. 5 ) into the refraction notch  46 . The refraction notch  46  includes a finger  47  that is engaged by the retraction protrusion  50  that positively engages the latches  30 ,  32  to pull the latch teeth  40  out of engagement with inner gear teeth  42  (shown in  FIG. 4 ). The latches  30 ,  32  pivot about one of the pivot posts  36  that is received in the respective recesses  38 . 
     The end stops  86  and  88  guide pivotal movement of the latches  30 ,  32 . End stop  86  also engages retraction protrusion  50  to limit its rotation in one direction. End stop  88  limits the pivoting motion of the latches  30 ,  32  by engaging the finger  47  when the latches  30 ,  32  are rotated by the retraction protrusion  50 . 
     Referring to  FIG. 6 , the anti-chucking cam  68  is shown installed over the load cam  48 . The anti-chucking cam includes cam locks  70  that define a clamping edge  72 . Clamping edge  72  engages axial protrusion  74  to drive the latches  30 ,  32  into a firm anti-chucking relationship with the teeth  40  engaging inner gear teeth  42  (shown in  FIGS. 3 and 4 ). The cam locks  70  force the clamping edge  72  into full engagement with the axial protrusion  74  and may create a small amount of spacing between the retraction protrusions  50  and the latches  30 ,  32 . The amount of spacing is very limited and may be on the order of 1/10 th  of a millimeter. 
     The anti-chucking cam  78  is biased by the clock springs  82  that engage a spring tang  78  formed on the anti-chucking cam  68 . The clock springs  82  drive the cam locks  70  and their associated clamping edge  72  into engagement with the axial protrusions  74 . 
     Release of the recliner will be described with reference to  FIGS. 5 and 6 . When it is desired to release the recliner, the adjustment lever  16  is rotated in a counter-clockwise direction, as shown in  FIGS. 5 and 6 . The motion is transmitted by the hub  26  initially to the load cam  48  by means of the actuator key  62  and keyway  64  shown in  FIGS. 3 and 4 . The load cam  48  is rotated in a counter-clockwise direction while the anti-chucking cam  68  remains stationary as a result of the lost motion connection. The limited spacing between the protrusion  50  and latches  30 ,  32  eliminates or minimizes any friction thereby reducing the force required to release the recliner. The lost motion connection is provided by the cam connecting pins  52  that are received in the lost motion slot  76 . Rotation of the load cam  48  continues until the cam connecting pins  52  engage the opposite end of the lost motion slot  76 . When the cam connecting pins  52  reach the opposite end of the lost motion slot  76 , the anti-chucking cam  68  begins to also rotate in a counter-clockwise direction disengaging the clamping edge  72  from axial protrusion  74  as the refraction protrusions  50  are received in the refraction notches  46  and engage the fingers  47 . Engagement of the fingers  47  causes the teeth  40  to disengage the inner gear teeth  42  (shown in  FIGS. 3 and 4 ) thereby releasing the rotary case plate  12  for rotation relative to the stationary case plate  14 . 
     Disengagement of the seat recliner is facilitated by the slight spacing between the refraction protrusion  50  of the load cam  58  and the latches  30 ,  32 . At this point, the rotation of the adjustment lever  16  is opposed by the helical springs  56  shown in  FIGS. 3 and 4 . As the release movement continues at the end of the lost motion, the biasing force exerted by the clock springs  82  must be overcome in addition to the biasing force exerted by the helical springs  56 . However, due to the spacing, there is little or no frictional resistance between the load cam  48  and latches  30 ,  32 . 
     Easy entry is provided by the recliner by the axial protrusions  74  that are held in a coordinated retracted condition as a result of engagement with the circular groove  20  and notch  22  that are formed in rotary case plate  12 . When the rotary case plate  12  is rotated, the latches  30 ,  32  are held by the groove  20  in a disengaged position until the seatback is returned to its normal position. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.