Abstract:
A vehicle seat linkage assembly includes a rod. The linkage has a first link with an aperture and a second link adjacent but spaced from the first link and having a slot. Additionally, a drive nut is adjacent the rod. The drive nut has a body portion, one end, another end and an aperture engaging the rod. The one end is inserted into the slot and the another end is inserted into the aperture. When the nut is disposed into the slot and aperture, the nut is rotated to engage the slot and the aperture so that the nut cannot be disengaged from the first link and the second link.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of U.S. patent application Ser. No. 10/015,445, filed on Dec. 8, 2001 now abandoned. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     REFERENCE TO MICROFICHE APPENDIX 
     Not Applicable. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to a drive nut a drive screw for a seat adjuster and in particular to a nut and screw of a vehicle seat assembly that provides ease of assembly and low noise during operation. 
     Power seat adjuster are a popular option on many automotive vehicles and are frequently offered as standard equipment on higher priced vehicles. Such power seat adjusters are primarily used on the driver&#39;s seat and sometimes, on the front passenger seat of the vehicle to provide selective horizontal fore and aft and vertical movement of the seat as well to provide a comfortable seating position to suit each occupant&#39;s preference. 
     Such power seat adjusters typically carry a support frame, which supports the seat bottom and in some applications the seat back of the vehicle seat. The seat support frame is mounted on first and second, spaced track assemblies, each formed of an upper track, which is connected to the seat support frame and is slidably mounted on a lower track anchored to the vehicle floor. A drive mechanism typically includes a bi-directional electric motor, which rotates a pair of drive shafts extending outward from the motor to a gear assembly or box mounted on each upper track. In one arrangement, each gearbox rotates a lead screw extending longitudinally below each upper track. A drive block is fixedly mounted to each lower track and threadingly receives the lead screw to cause reciprocal, horizontal movement of the upper track and the attached seat support frame upon selective energization of the drive motor and the drive shafts. 
     Similar drive mechanisms are provided for vertical (up and down) adjustment of the seat support frame and, in a seat adjuster having a seat recliner adjustment mechanism, for angularly adjusting the position of the seat back with respect to the seat bottom. The vertical drive mechanism may also include separate front and rear edge seat adjustment drive mechanisms for selectively tilting the front rear edges of the seat bottom independent of each other as well as simultaneously to raise and lower the entire vehicle seat or, in some applications, only the seat bottom or cushion. 
     Each vertical and recliner drive mechanism also includes a drive motor having a rotatable output shaft connected to a gear assembly either directly in the case of the front and rear vertical drive mechanisms or by means of two shafts extending a from single motor to separate gear assemblies mounted on each upper track or on the seat support frame in the case of a seat recliner drive mechanism. 
     As the various drive motors are mounted between the track assemblies, the drive motor output shafts and drive shafts connected thereto are typically oriented perpendicular to the axis of the associated lead screw. In order to transmit rotation and drive force between the output shaft of the drive motor and the drive shaft connected thereto to the 90 degree offset lead screw, each gear assembly box typically includes a worm gear, which is insert molded on one end of the associated lead screw. A worm is rotatably mounted in the gear box housing in meshing engagement with the worm gear and is connected to either one of the drive motor output shafts or to one of the drive shafts so as to rotate the worm gear and thereby the lead screw upon bi-directional energization of the selective drive motor. Thus, each drive motor requires a separate gear assembly for each lead assembly for each lead screw driven by the drive motor. 
     The rigid connection between the gears in the gear assembly, the drive shaft motor output shaft, the drive shaft, the lead screw and drive block also leads to additional problems during assembly and operation of a power seat adjuster. It is inevitable in the manufacture assembly of a mechanical mechanism, such as power seat adjuster, that dimensional conditions, such as concentricity, TIR, and linear discrepancies from nominal design dimensions, can and typically do occur. These dimensional conditions, without correction, can cause various problems in the operation of the power seat adjuster, such as poor breakaway from a stop position, slow operation of the power seat adjuster in extreme temperatures, excessive wear of the components of the power seat adjuster, uneven operation of the power seat adjuster. 
     Another aspect of a power seat adjuster, which is critical in the use of a power seat adjuster, particularly during excessive forces generated during a vehicle collision, is the requirement for seat integrity. As the occupant&#39;s seat belt is frequently attached by a seat belt buckle mounting bracket directly to one of the upper tracks of a power seat adjuster to enable the seat belt to move fore and aft with the upper track, any forces exerted on the occupant during a vehicle collision are transmitted directly though the seat belt buckle mounting bracket to the upper track. These forces cause the upper track to move upward with respect to the lower track and, in the event of excessive force, could lead to a complete pullout or separation of the upper track and the attached seat from the lower track. In order to prevent track separation, seat integrity requirements have necessitated the design of the components of a power seat adjuster to resist track separation. 
     Several attempts have been made to provide adapters that meet the above requirements. For example, in U.S. Pat. Nos. 5,172,601, 5,467,957, and 5,575,531, a drive nut with a pair of opposing flat sided legs with rounded edges that engages a bracket having wings with a pair of opposing open ended keyhole slots is disclosed. The slots have an arcuate portion in communication with a pair of opposing flat sides. The legs are inserted into slots and then rotated so that the rounded edges of the legs engage the arcuate portion of the slots. However, the load carrying capability of the wings is reduced because of the size of the opening in the slots required to insert the legs. As a result, these designs are not always able to resist separation forces on the seat and are prone to structural failure by allowing the slots to bend and the legs to separate from the slots causing separation of the seat. 
     Another attempt to solve the above problem is shown in U.S. Pat. No. 5,860,319. This design uses a round block drive device to fit into a housing. A resilient member is used to cushion or isolate the drive block from the housing. The resilient member co-acts with holes formed in the side walls of the housing to permit relative motion of the threaded interconnected lead screw and drive block with the housing. This design is expensive and difficult to assembly and has not been widely used in vehicle seat applications. 
     Thus, the vehicle seat assemblies and, in particular seat assemblies having power adjustment capability, it is desirable to provide an adjuster, which produces low noise, emissions during operation prevents seat separation and is simple and inexpensive to make. Furthermore, it is desirable to provide an adjuster that can be easily assembled to reduce assembly time and errors. 
     The present invention seeks to solve most of the above problems with a simple, quiet, easy to assemble drive nut that is structurally superior to known present designs. 
     A vehicle seat linkage assembly including a threaded rod defining a longitudinal axis. The linkage includes a first link having a portion forming an enclosed aperture. A second link is adjacent but spaced away from the first link. The second link having a portion forming a slot. The slot has a circular portion. The circular portion and the enclosed aperture define a lateral axis extending between the first link and the second link. Additionally, a drive nut threadably engages the rod. The drive nut has one lateral projection, another lateral projection opposite the one projection and a portion engaging the rod. The drive nut and rod are moveable so that the longitudinal axis is positioned relative to the lateral axis to insert the one projection into the slot and to position the another projection adjacent but spaced away from the aperture while the one lateral projection remains in the slot. The another projection has a width substantially the same as the base of the aperture. Thereafter moving the another projection relative to insert the another projection into the aperture while the one lateral projection remains in the slot. 
     The present invention is advantageous in that the drive nut engages a slot on one side and an aperture on the other side so that the drive nut is prevented from being withdrawn from the slot and the aperture. Furthermore, the drive nut is easy to assemble, inexpensive to make and produces law noise. 
     From the foregoing disclosure and the following more detailed description of the various preferred embodiments, it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of vehicle seat linkage assemblies. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side partial sectional view of a seat adjuster according to the present invention; 
         FIG. 2  is an exploded perspective view of the drive member; 
         FIG. 3  is a perspective view of the drive nut; 
         FIG. 3   a  is a side view of the drive nut; 
         FIG. 3   b  is a top view of the drive nut; 
         FIG. 4  is a perspective view similar to  FIG. 2 , showing the drive nut inserted into the slot in one support prior to insertion into the aperture in the other support; 
         FIG. 4   a  is a top view along  4   a - 4   a  in  FIG. 4 ; 
         FIG. 5  is a perspective view similar to  FIG. 4  in, which the drive nut is inserted into the slot in one support and the aperture in the other support; and 
         FIG. 6  is a perspective view similar to  FIG. 5  in, which the drive nut has been rotated to engage both supports in a fully assembled position. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the seat adjuster assembly as disclosed here, including, for example, specific dimensions of the drive nut and its associated bracket, will be determined in part by the particular intended application and use environment. Certain feature of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity of illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the drive member in the seat structure illustrated in the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The seat structure  10  shown in  FIG. 1  includes a seat adjuster with the drive nut and screw of the present invention in the seat adjuster. Seat structure  10  includes a lower rail or frame member  12  and an upper rail of frame member  14  that is slidably carried by the lower rail  12  to move the seat fore and aft relative to a motor vehicle in which the seat is mounted. Lower rail  12  includes a pair of support legs  16  that are adapted to mount seat structure  10  to a motor vehicle floor pan. A seat riser  18  is fastened to the upper rail. The seat cushion and seat back are mounted to the seat riser, which is moved by drive member  20 . 
     Referring to  FIGS. 2-6  drive member  20  includes electric drive motor  30  for drive rod spindle  40  and drive nut  50  in bracket  60 . Motor  30  is mounted to seat riser  18  by bracket  32 . Motor  30  is connected to transmission assembly  34  by a conventional fastening means. Optionally, a flexible cable is used to connect the motor  30  to transmission assembly  34 . Transmission assembly  34  includes a worm (not shown) that engages with the and drives a worm gear (not shown). The worm gear is molded onto and integral with the drive rod  40  that is preferably threaded. 
     As will be described in greater detail below, the drive rod  40  is engaged for relative movement with a drive nut  50 . Drive nut  50  is, in turn, mounted to bracket  60  that is fixed to the lower frame member, by conventional fastening means including welding. Rotation of the drive rod while drive nut  50  is held against rotation by bracket  60  produces an axial travel of drive nut  50  relative to the drive rod  40 . Drive rod  40  is coupled to the upper frame member  14  through the transmission assembly  34  and bracket  32  while drive nut  50  is carried by lower frame member  12 . Rotation of drive rod  40  thus results in movement of upper frame rail  14  relative to lower frame member  12 . This moves the seat assembly relative to the vehicle. 
     Drive nut  50  and bracket  60  contain specific features that result in improved ease of assembly of the seat adjuster, improved structural integrity of the joint and low noise. 
     Drive nut  50  has a main body with longitudinal axis  51 . Main body  52  has through passage  52  that is preferably a threaded aperture. Alternatively, passage  52  may be of any suitable configuration that is consistent with the teaching of the invention. A pair of ends  54  extend axially along longitudinal axis  51  from main body  52  in opposite directions. The bottom portion of main body  52  and the entire cross section of each of the ends  54  have a cross section  55  that is preferably circular. Alternatively, cross section  55  may be any shape consistent with the teachings of the invention. Main body  52  and each end  54  has two opposite sides  56  that are preferably flattened over its entire axial length. Alternatively, sides  56  may be partially arcuate. Preferably, drive nut  50  is made of vibration isolating material such as nylon. Alternatively, drive nut  50  can be made of any other suitable thermoplastic or thermostat plastic. 
     Bracket  60  is formed in a shape of a pair of transversely spaced apart legs  62 ,  66  respectively fixed to the lower frame member by conventional fastening means including fasteners and welding. Bracket  60  has first leg  62  and second leg  66 , which is adjacent but spaced away at a first width  61  from first leg  62 . Bracket  60  is mounted to a tubular member  15  that is rotatably mounted to frame rail  14  by a U-shaped member  17 . Optionally, leg  62  is connected to leg  66  by means of a bridge to form a U-shaped member, which positioned adjacent to frame member  12  and fastened conventionally thereto. Seat riser  18  is connected to bracket  60 . Leg  62  has a slot  63  at its free end. Slot  63  has a pair of opposing flattened sides to form guide portion  64  that extends from its free end to interior arcuate portion  65 . Preferably, slot  63  resembles a keyhole shape. Alternatively, slot  63  may take any form consistent with the teachings of the invention. The shape of interior arcuate portion  65  is preferably a diameter that is larger than the width of guide portion  64 . Alternatively, the arcuate portion  65  is at least 85% of the inner surface of the aperture or further alternately the arcuate portion  65  is at least 90% of the interior surface. Second leg  66  has an aperture  68  near its free end. Guide portion  64  is preferably has opposing flattened surfaces but alternatively may be opposing slightly arcuate shapes or any other opposing shapes that permit drive nut  50  to pass through slot  63 . The interior arcuate portion  65  defines a plane with a first axis of rotation. Aperture  68  has a second axis of rotation formed on a plane. A transverse axis  69  extends from the first axis of rotation to the second axis of rotation. 
     As shown in  FIGS. 3 ,  3   a ,  3   b , and  FIGS. 4 and 4   a , cross section  55  of drive nut  50  has a shape that is complimentary with key slot  63  and aperture  68 . The largest width of main body  52  as measured between opposing sides  56 , as shown in  FIG. 3   a , is sized to permit main body  52  and another of the ends  54   a  to pass through opposing sides of guide portion  64  of slot  63 . One of the ends  54  is sized to fit into aperture  68 . The main body of the drive nut  50  has a longitudinal axis  51  that defines a second width  57 . One of the ends  54  extends from the main body  52  of the drive nut  50  along the longitudinal axis  51  and has a third width  58  that extends from the junction at the periphery of the main body to the tip of one of the ends  54  that fits into aperture  68 . The second width  57  and the third width  58 , when combined, are less than the first width  61  as shown in  FIG. 4   a  When the another end  54   a  extending from drive nut  50  is inserted into slot  63  and the another end  54   a  is disposed in arcuate portion  65  of leg  62 , main body  52  is translated on the transverse axis  69  until one of the ends  54  is disposed in aperture  68  of leg  66  and the another of the ends  54   a  remains disposed in arcuate portion  65  of leg  62  as shown in progression from  FIG. 4  to  FIG. 5 . One of the ends  54  has a shoulder portion that is larger in width than the width of the aperture to limit axial movement toward slot  63 . After another of the ends  54   a  is disposed in arcuate portion  65  and the one of the ends  54  is disposed in aperture  68 , drive nut  50  is rotated 90 degrees as shown in the progression from  FIG. 5  to  FIG. 6 . When drive nut  50  is rotated, about its longitudinal axis  51  so that circular portion of one end  54  remains disposed in aperture  68  of leg  66  and the other circular portion of another end  54   a  is disposed in the arcuate portion  65  of leg  62 , to prevent disengagement of lock drive nut  50  out of bracket  60 . Furthermore, the aperture  68  on leg  66  captures the one end  54  and restricts the movement of the another end  54   a  out of slot  63 . 
     With structure of bracket  60 , that is with slot  63  extending inwardly from the free end of first leg  62 , and aperture  68  in alignment with arcuate portion  65 , drive nut  50  is assembled with bracket  60  after drive rod  40  has been engaged with drive nut  50 . The open ends of bracket  60  avoid any obstacle to drive rod  40  during assembly after drive nut  50  has been mounted to bracket  60 , drive rod  50  is further rotated to a position in, which end  42  of drive rod  40  extends beyond drive nut  50 . In this position, removal of drive nut  50  is prevented. 
     In operation, drive nut  50  is moved by motor,  30  which operates to angularly move bracket  60  from one position to another but not to permit disengagement from bracket  60  while functioning as a fore and aft seat adjuster. Thus, the present invention provides a simple easy to assemble and quiet linkage assembly for vehicle seats. While the drive nut screw and bracket of the present invention have been shown in the context of a fore and aft seat adjuster, it is to be understood that these components can be sued in other adjuster mechanisms including a vertical seat adjuster, recliner, etc, where a screw, nut and bracket are used employing the teachings of the invention. 
     From the foregoing disclosure and detailed description of certain preferred embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with breath to, which they fairly, legally, and equitably entitled.