US005707035A A’
`A
`
`[11] Patent Number:
`
`5,707,035
`
`[45] Date of Patent:
`
`Jan. 13, 1998
`
`
`
`O
`Umted States Patent
`
`[19]
`
`Kargol et al.
`
`[54] VEHICLE SEAT ADJUSTER
`
`5,299,853
`5,313,916
`
`4/1994 Gdswold at 31- -
`5/1994 Murphy
`
`384/612 X
`
`[75]
`
`Inventors: James A. Knrgol, Farmington Hills;
`Robert W. Jones. Novi; Bruce A.
`m¢mSt!‘83 Marc 13- H¢Wk0. 130311 Of
`Ann Arbor, all Of Mich; Yannis
`P5111108. T010409 Ohio: Rfilllld R
`Srezrist. Grass lake. Mich-; Wee Tue
`GIIIII. Tl°Y~ M1011-3 Difiid W- Hllsteds
`Ann Arbor. Mich.; Chester S. Fudala,
`'11-oy, Mich,
`
`[73] Assignee: Hoover Universal, Inc.. Plymouth,
`Mich’
`
`OTHER PUBLICATIONS
`“Information About Specialty Lubricants". Specification
`Note. 1991, Dow Corning Corporation. Midland Michigan.
`“New Product Infommlion Molycoat D 31 Anti—friction
`Coating". product form No. 65-027-92, Dow Corning Cor-
`poration. Midland Michigan.
`
`Primary Examiner—-Leslie A. Braun
`Assistant Examz'ner——Gwendolyn W. Baxter
`Attorney Agent, or Firm—Hax-ness. Dickey & Pierce. P.L.C.
`[57]
`ABSTRACT
`
`Ana‘ 31' 1994
`
`
`[21] APPL N03 293399
`_
`filed‘
`[221
`mm 13/00
`Int. Cl.‘
`[51]
`248/429; 248/430
`[52] US. Cl.
`243/429, 430;
`[58] Field ofsearch
`428/451; 334/5.": 13' 907_ ;
`, I
`1 184/5
`00
`5 9
`References Cited
`
`Apowa seat adjuster for bucket type vehicle seats includes
`inboard and outboard track assemblies each including a
`fixed lower section. a movable upper or movable section and
`a precision sliding interface including roller bearings
`between the moving upper wk and fire fixed lower trade.
`“"5 ‘“'f“‘=°S °f “‘° ‘mks ‘M 3" °“8‘*8°" “Y '*'° ‘°“°‘
`bearings being crowned to provide a bearing surface that is
`slightly convex when the seal is unoccupied but which
`becomes nearly flat when the seat is occupied. and the
`bearing surfaces of the track being coated will: a multi-layer
`dzy film lubricant including a base coating ofan anti-friction
`U-S- PATENT DOCUMENTS
`"“"°‘“‘1 3”‘ ‘, ‘°P ‘E°"““'8 °f ‘"1 ““j‘“°k '“"‘°‘,‘“l 711°
`2,336,433 12/1943 Wiona
`PW“-Y 9°“ adJ"s‘°‘ m°1“d°5 WWW d“"° m°°hi““-‘mi f°'
`3,637,497
`1/1972 Fitz Simmons
`providing horizontal fore-and-aft adjustment, vertical
`4,o4o_591
`3/1977 memes _
`up-and-down adjustment and adjustment in the inclination
`4.223.947
`9/1980 (kemer.
`of the seat back. with the length of travel being limited by
`4,331,313
`S/1982 Pickls .
`txavd fixnit stops that include anti-jam mechanisms which
`4,478,383 10/1984 Uni .................................... 248/430 X
`are adapted to reduce the breakaway torque required to
`4-511-187
`4/1985
`
`;,°,;°,‘§;,=,;1=;V,;=;°“;;:,*;f“‘°=“°W ‘“V°m°°‘“m“W=¥
`2:3i%:Z33
`‘#322 o....... ,,.:.:;_:,........... 243/430x
`9°
`4,924,584
`5/1990 Haney.
`4,940,285
`7/1990
`'
` 8 Claims, 9 Drawing Sheets
`5,188,329
`2/1993
`
`[55]
`
`245/430
`25739
`
`
`
`Page 1 of 19
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`Hyundai Exhibit 1009
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`Hyundai Exhibit 1009
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`U.S. Patent
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`Jan. 13, 1993
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`Sheet 1 of 9
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`U.S. Patent
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`Jan. 13, 1993
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`5,707,035
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`U.S. Patent
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`Jan. 13, 1993
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`U.S. Patent
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`Jan. 13, 1993
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`5,707,035
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`U.S. Patent
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`Jan. 13, 1998
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`Sheet 5 of 9
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`U.S. Patent
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`Jan. 13, 1993
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`Sheet 6 of 9
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`5,707,035
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`U.S. Patent
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`Jan. 13, 1993
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`U.S. Patent
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`Jan. 13, 1993
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`Sheet 3 of 9
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`5,707,035
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`5,707,035
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`1
`VEHICLE SEAT ADJUSTER
`
`BACKGROUND OF THE INVENTION
`This invention relates to seat assemblies for motor
`vehicles. and more particularly to seat adjusters for vehicle
`seat assemblies.
`
`Seat adjusters for vehicle seat assemblies include track
`mechanisms which support the vehicle seat at each side of
`the seat and provide for adjustment in the positioning of the
`seat. The track mechanisms include upper and lower tracks.
`The lower track is fixed to the floor of the vehicle and the
`uppfi track is supported on the lower track and adapted for
`manual movement, or to be motor driven, relative to the
`Iowa track to provide fore-and-aft adjustment in the posi-
`tion of the seat. In addition. many seat adjusters also provide
`up and down adjustment and independent tilting of the front
`and rear of the seat and tilting of the back to accommodate
`a wide variety of drivers.
`To facilitate horizontal movement and provide smooth
`adjustment, bearing assemblies including roller bearings
`have been proposed for the track mechanisms of seat adjust-
`ers. The roller bearings provide a smooth, precise guide
`between the moving upper track and the fixed lower track.
`However, under load. the tracks tend to bow at their centers
`so that there is less roller to track contact at the center of the
`rollers. decreasing lubricant effectiveness and resulting in
`accelerated wearing of the tracks, particularly at the edges of
`the rollers. This is particularly true when the sliding inter-
`face includes steel roller bearings and the tracks are made of
`a light weight material such as aluminum. In recent years,
`tracks made of lightweight metal. such aluminum. have been
`introduced. The use of aluminum provides significant
`weight savings which can be about 10% less than a con-
`ventional steel track system.
`Another consideration is that in most seating adjusters
`presently available. the mating moving parts are lubricated
`with grease. The use of grease on mating parts can result in
`the transfer of grease to occupants of the passenger com-
`partment of the vehicle if a pant cufl’ or coat hem should
`inadvertently contact a greased surface. Various types of dry
`lubricants are known, such as polytetrafiuoroethylene,
`molybdenum disulfide, graphite. and the like. Although
`polytetrafluoroethylene has a low coeificient of friction, its
`use is limited to load conditions that are substantially lower
`than those experienced in the operation of seat track mecha-
`nisms. Molybdenum disulflde is suitable for use under high
`load conditions. but the high hardness binder in the coating
`promotes roller squeaking due to the roller sliding over the
`hard dry lubricant surface. resulting in undesirable noise.
`Moreover. it has been found that in a mixture of polytet—
`rafluoroethylene and molybdenum disulfide, there is a weak-
`ening of the binder of the molybdenum disulfide which
`promotes build up of dry lubricant flakes that prevent proper
`travel of the steel rollers in the uacks.
`
`In most power seat adjusters. horizontal. vertical and
`recliner adjustment is provided by screw drive mechanisms
`which include a drive screw and a drive nut. The drive nuts
`of horizontal, vertical and recliner screw drive mechanisms
`of currently available seat adjusters are formed from metal
`tubes. Although the drive nuts may include a threaded plastic
`insert for receiving the associated drive screw to eliminate
`the metal-to-metal connection between the drive screw and
`the drive nut, known screw drive mechanisms provide
`metal-to-metal connections between the vertical drive nut
`and the coupling mechanism that connects the drive nut to
`the seat support and between the recliner drive nut and the
`
`10
`
`20
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`25
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`30
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`35
`
`45
`
`2
`seat back frame. This metal-to-metal connection results in
`noise, higher friction and reduced efliciency caused by
`relative movement between these parts during adjustment in
`the vertical positioning of the seat or in adjustment of the
`inclination of the seat back.
`
`In power seat adjusters, adjustment of the horizontal
`positioning of the vehicle seat assembly is provided using a
`direct drive for one track mechanism, such as the outboard
`track. and a slave drive for the inboard track. The drive
`screw of the horizontal drive mechanism of the outboard
`track is connected through a transmission unit directly to the
`motor and the drive screw mechanism of the inboard track
`is connected to the drive motor through a transmission unit
`and a flexible shaft. In known power seat adjusters, travel
`limit stops are provided both on the master drive screw drive
`mechanism and on the slave screw drive mechanism. Due to
`manufacturing tolerances,
`if the slave drive mechanism
`reaches its end of n'avel stop before the master drive
`mechanism reaches its end of travel stop, the drive motor
`can continue to drive the master drive mechanism because
`the flexible shaft that connects the slave drive mechanism to
`the motor can twist, resulting in over travel in the outboard
`track section after the inboard track section has reached its
`end of travel stop, a condition referred to as horizontal
`matchboxing. A further consideration is that because there is
`high energy rrmning into a stop, the screw drive mechanisms
`jam when they reach their two extreme stop positions and
`the drive screw mechanisms lock up. Consequently, a
`greater force is required to overcome frictional forces to
`reverse the movement drive screws in moving the drive
`screw away from its extreme stop positions.
`SUMMARY OF THE INVENTION
`
`The present invention provides a seat adjuster for vehicle
`seat assemblies which is characterized by smooth operation.
`low noise and low cost. The seat adjuster includes a pair of
`track assemblies each including a lower track and an upper
`track. Horizontal movement is facilitated by precision slid-
`ing interfaces each comprised of ball bearings and roller
`bearings. The weight of the vehicle seat and its occupant is
`carried by the roller bearings. while the ball bearings provide
`a smooth, precise guide between the moving upper track and
`the lower track that is anchored to the vehicle’s frame. Also,
`the ball bearings provide lateral stability. In accordance with
`the invention, the bearing surfaces of the tracks that are
`engaged by the roller bearings are crowned so that the
`bearing surfaces have a slightly convex profile when the seat
`is unoccupied. Consequently, under the loading conditions
`that exists when the seat is occupied, the bearing smfaces
`approach a fiat so, allowing the roller hearings to be main-
`tained in contact with the bearing surfaces, distributing the
`load more evenly across the width of the tracks. In addition,
`the bearing surfaces are coated with a multi-layer dry film
`coating that includes a base coat of an anti—friction coating
`and a top coating of an anti-stick material. The ball and roller
`bearings ride on this greaseless surface providing smooth,
`low-noise operation. The addition of the separate non—stick
`top coating permits the use of a higher hardness binder in the
`base coat which provides resistance to flaking and with the
`non-stick top coating preventing roller sliding to prevent
`squeaking. Moreover. use of a dry film lubricant at least on
`the tracks of the seat adjuster substantially eliminates the
`risk of pant culfs or coat hems contacting greased surfaces.
`The screw drive mechanisms of the horizontal, vertical
`and recliner drive assemblies include molded plastic drive
`nuts that have a molded-in metal insut. The molded plastic
`drive nuts minimize metal—to-metal contact between mating
`
`Page11of19
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`Page 11 of 19
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`5,707,035
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`3
`surfaces. thereby increasing etficiency and minimizing noise
`during operation of the seat adjustment mechanisms. The
`travel limit stops of the horizontal drive. the vertical drive
`and the recliner drive assemblies include anti-jamming
`mechanisms that lower the breakaway torque from either
`end position of the drive screw. preventing jamming when
`the screw drive mechanism reaches its extreme stops. The
`anti—jamrning mechanisms include a bearing assembly inter-
`posed between the rotating parts of the screw drive mecha-
`nism to minimize flat contact areas between the drive screw
`and the travel limit stop. In addition. the travel limit stop
`mechanism of the horizontal drive mechanism is deployed in
`a manner so as to eliminate the possibility of matchboxing.
`The travel limit stop for the recliner drive includes a radial
`stop mechanism including a guide collar that floats on the
`recliner drive screw and cooperates with a stop member that
`is fixed to the recliner drive screw to define a travel limit stop
`when the recliner drive screw is driven to its full extended
`position. The stop member includes a radial projection that
`is moved into interference with a radial projection of the
`guide collar so that a positive stop position is defined at the
`extreme travel limit stop position. with minimal metal-to
`metal contact between the two members of the radial stop
`mechanism.
`The invention consists of certain novel features and
`structural details hereinafter fully described. illustrated in
`the accompanying drawings. and particularly pointed out in
`the appended claims.
`it being understood that various
`changes in the details may be made without departing from
`the spirit. or sacrificing any of the advantages of the present
`invention.
`
`DESCRIPTION OF THE DRAWINGS
`
`For the purpose of facilitating an understanding of the
`invention. there is illustrated in the accompanying drawings
`preferred embodiments thereof, from an inspection of
`which. when considered in connection with the following
`description. the invention. its construction and operation,
`and many of its advantages will be readily understood and
`appreciated.
`FIG. 1 is an isometric view of the vehicle seat adjuster
`provided by the present invention, viewed from the front
`outboard corner;
`FIG. 2 is an isometric view of the vehicle seat adjuster of
`FIG. 1. but viewed from the front inboard corner;
`FIG. 3 is an isometric view of the inboard track sub-
`assembly of the vehicle seat adjuster;
`FIG. 4 is an exploded isometric view of the upper frame
`sub-assembly of the vehicle seat adjuster;
`FIG. 5 is an isometric view of aroller bearing and retainer
`assembly of the outboard track sub-assembly;
`FIG. 6 is an enlarged fragmentary view of the torsion tube
`illustrating the mechanical joint that connects the link to the
`torsion tube;
`FIG. 7 is a simplified representation of the upper and
`lower tracks and the roller bearing and retainer assembly of
`a track sub—assembly. illustrating the convex crown on the
`roller bearing contact surfaces of the upper and lower tracks
`in accordance with the invention;
`FIG. 8 is a simplified representation of the upper and
`lows tracks of a track sub-assembly and illustrating the dry
`lubrication coating that is provided on the contact surfaces
`of the tracks in accordance with the invention;
`FIG. 9 is an enlarged fragmentary view of a portion of the
`horizontal drive screw of the horizontal drive mechanism.
`illustrating the anti-jamrning mechanism in accordance with
`the invention;
`
`4
`FIG. 10 is an enlarged perspective view of a bearing
`assembly of the anti-jamming mechanism of FIG. 9;
`FIG. 11 is a section view taken along the line 11—11 in
`FIG. 1, illustrating the cross-section of the tube enclosing
`the flexible drive shaft of the horizontal slave drive mecha-
`nrsm:
`
`FIG. 12 is a view similar to FIG. 11, but illustrating an
`altmnative cross-section for the tube;
`FIG. 13 is a perspective view of a ferrule clip which
`secures the tube to the housings of the drive motor and the
`transmission unit;
`FIG. 14 is a top view of the ferrule clip of FIG. 13;
`FIG. 15 is a side view of the vertical drive nut of the
`vertical drive mechanism;
`FIG. 16 is a top view of the vertical drive nut;
`FIG. 17 is a section view taken along the line 17—17 of
`FIG. 15 of the vertical drive nut and illustrating the vertical
`drive screw;
`FIG. 18 is a top view of the metal insert of the vertical
`drive nut;
`FIG. 19 is a side view of the metal insert of the vertical
`drive nut;
`FIG. 20 is side View of the recliner drive nut of the
`recliner drive mechanism. and illustrating the recliner drive
`screw:
`FIG. 21 is an end view of the recliner drive nut:
`FIG. 22 is a section view taken along line 22-22 of FIG.
`20;
`FIG. 23 is a side view of the metal insert of the recliner
`drive nut;
`FIG. 24 is a top view of the metal insert of the recline-
`drive nut;
`FIG. 25 is an isometric view of the guide member of the
`radial stop of the recliner drive mechanism;
`FIG. 26 is a plan view of the guide member of FIG. 25;
`FIG. 27 is an end view of the guide member of FIG. 25;
`FIG. 28 is an isometric view of the collar of the radial
`stop;
`FIG. 29 is a plan view of the collar of FIG. 28;
`FIG. 30 is an end view of the collar of FIG. 28; and
`FIG. 31 is a simplified representation of the radial guide
`illustrating the angle of friction between engaging surfaces
`of the guide member and the collar.
`DESCRIPTION OF PREFERRED
`EMBODIIVIENTS
`
`10
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`15
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`2.0
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`25
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`30
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`35
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`45
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`50
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`Referring to FIGS. 1 and 2, the seat adjuster for a vehicle
`seat assembly provided by the present invention is desig-
`nated generally at 10. The seat adjuster 10 is associated with
`a bucket type vehicle seat (not shown) having a seat portion
`and a reclineable seat back, but features of the seat adjusta
`may be incorporated into a seat adjuster adapted for use with
`bench type seats. The seat adjuster includes an upper frame
`sub-assembly 12 which is mounted on an outboard track
`sub-assembly 14 and an inboard track sub-assembly 16. The
`upper frame sub-assembly 12 includes mounting brackets 13
`which facilitate mounting of the vehicle seat on the seat
`adjuster.
`Referring additionally to FIG. 3, which is an isometric
`view of the inboard track sub-assembly 16, the inboard track
`sub-assembly 16 includes a lower track 20 that is adapted to
`be mounted on the floor of the vehicle. secured to the frame
`of the vehicle. and an upper track 21 that is supported on the
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`5,707,035
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`5
`lower track and movable relative to the lower track. The
`upper track 21 is supported on the lower track 20 for
`fore-and-aft movement relative to the fixed lower track.
`Horizontal movement is facilitated by a precision sliding
`interface which includes a front bearing and retainer assem-
`bly 23, shown in FIG. 5. and a rear bearing and retainer
`assembly 24. The bearing assemblies 23 and 24 are inter-
`posed between the upper and lower tracks. Similarly, the
`outboard track sub-assembly 14 includes a lower track 18
`that is adapted to be mounted on the floor of the vehicle,
`secured to the frame of the vehicle. an upper track 19 that is
`supported on and movable relative to the lower track, and
`front and rear bearing and retainer assemblies (not shown).
`Referring to FIGS. 1 and 2. the seat adjuster 10 includes
`a horizontal drive mechanism which includes a master drive
`portion 26 and a slave drive portion 28, a from vertical drive
`mechanism 30, a rear vertical drive mechanism 31. and a
`recliner drive mechanism 32. The horizontal drive mecha-
`nism provides fore and aft movement for the upper support
`frame 12. The front and rear vertical drive mechanisms 30
`and 31 provide independent, substantially vertical adjust-
`ment of the front and rear edges of the upper seat frame to
`provide vertical and tilt adjustment. The recliner drive
`mechanism 32 provides pivoting movement of the seat back.
`permitting adjustment in the angle of inclination of the seat
`back (not shown).
`The master drive portion 26 of the horizontal drive
`mechanism is associated with the outboard side of the
`vehicle seat and includes a drive motor 34. a transmission
`unit 35. a drive screw 36 and a horizontal drive nut 37. The
`slave drive portion 28 of the horizontal drive mechanism is
`associated with the inboard side of the vehicle seat and is
`slaved to the master drive portion 26 by a flexible drive shaft
`29 and includes a transmission unit 38, a drive screw 39 and
`a horizontal drive nut 40. The drive motor 34 is mounted
`oriented 90” relative to the drive screws 36 and 39 and the
`shaft of the drive motor is coupled to the drive screw 36 by
`transmission unit 35 and through flexible drive shaft 29 and
`transmission unit 38 to drive screw 39.
`
`Referring additionally to FIG. 4, the from vertical drive
`mechanism 30 includes a drive motor 41, a transmission unit
`42, a drive screw 43. a vertical drive nut 44 and a dual link
`coupling mechanism. including a torsion tube 45 having a
`drive link 46, outboard coupling links 47 and an inboard
`coupling link 48 mounted thereon. The vertical drive nut 44
`has a bifurcated end 116 (FIG. 16) having apertures 128
`theretlnough to facilitate connection to the drive link 46 as
`is known in the art.
`
`The torsion tube 45 is pivotally mounted to the upper
`track by mounting brackets 49 at each end. The brackets 49
`connect the ends of the torsion tube 45 to the upper track.
`The links 47 and 48 are secured to the torsion tubes by lock
`bead mechanical joints 50 which position the links in proper
`orientation to the torsion tube. The lock bead mechanical
`joints 50 include an upset potion 143 of the torsion tube on
`one side of the link and an upset potion 144 of the torsion
`tube on the other side of the link to prevent axial movement
`of link relative to the torsion tube. Each of the links. such as
`inboard coupling link 48 shown in FIG. 6. has a recess 145
`that is adapted to receive material 146 of the torsion tube that
`is forced into the recess to provide a finger lock for pre-
`venting radial movement of the link relative to the torsion
`tube. In the alternative. the links can be weldedto the torsion
`tubes.
`The rear vertical drive mechanism 31 is similar to the
`front vertical drive mechanism 30. and accordingly corre-
`
`6
`sponding elements of the rear vertical drive mechanism 31
`have been given the same reverence numerals. In the rear
`vertical drive mechanism, the drive link and the outboard
`coupling links are a common member which has been given
`the reference numeral 147. In the exemplary embodiment.
`the drive motors 41 of the front and rear vertical drives are
`mounted oriented 90° relative to the drive screws 43. and the
`shafts the drive motors 41 are coupled to the drive screws 43
`by nansmission units 42.
`The recliner drive mechanism 32 includes a drive motor
`52. a transmission unit 53. a drive screw 54 and a recliner
`drive nut 55. The drive motor 52 is mounted to the frame
`sub-assembly 12 oriented at 90° relative to the drive screw
`54 and is coupled to the drive screw by the transmission unit
`53 which is mounted on the frame sub-assembly 12. The
`recliner drive nut 55 is carried by the recliner drive screw
`and is movable fore-and aft relative to the support as the
`recliner drive screw is rotated. The recliner drive nut has a
`mounting portion 142 that is adapted to be secured to the
`seat back frame beneath the pivot axis in the manner known
`in the art.
`
`Track Sub-assembly
`
`Referring to FIGS. 1-3 and 5. the lower track 20 and the
`upper track 21 of the inboard track sub-assembly 16 and the
`lower track 18 and the upper track 19 of the outboard track
`sub-assembly 14 are extruded fi'om aluminum. The lower
`track 20 of the inboard track sub-assembly is an elongated
`member having a generally U-shaped cross~section with a
`pair of vertical sides 56 interconnected at their lower ends by
`a horizontal rail 57, the upper surface 58 of which defines the
`bearing surface for the lower track. The upper ends of the
`sides 56 are bent
`inwardly and downwardly. defining
`grooves 59 which open downwardly. The upper track 19 has
`an upright portion 61 having an inwardly directed upper
`flange 62, an outwardly directed flange 63 and 3 depending
`lower portion 64 which has a generally rectangular cross-
`section. but includes an inwardly directed. lateral channel 65
`on each side. The channels 65 are arcuate in cross-section
`and extend the length of the upper track. The lower depend-
`ing portion 64 of the upper track has a lower surface 66
`which defines a bearing surface for the upper track The
`upper inner corner of the depending portion defines a
`projection 68 which is received in the groove 59 of the lower
`track in interlocking relationship when the upper and lower
`tracks are assembled When the upper and lower tracks are
`assembled together, the bearing surface 66 is located in an
`opposing spaced relationship with the bearing srnface 58,
`defining a space in which the roller bearing and retainer
`assemblies 23 and 24 are located. The outboard track
`sub-assembly is similar to the inboard n'ack sub-assembly,
`and accordingly will not be described in detail. The inboard
`and outboard track subassemblies include mounting flanges
`and mounting holes for connecting to the vehicle seat
`assembly and to the floor of the vehicle. and because such
`mounting is elfected in the conventional manner and a
`detailed description of the connections and mounting is not
`necessary for an understanding of the invention.
`Referring to FIGS. 1, 3 and S, the front roller bearing and
`retainer assembly 23 includes a linear roller bearing 70, four
`ball bearings 71 and a bearing retainer 72. The roller bearing
`and the ball bearings are made of hardened steel. The
`bearing retainer 72 is molded from plastic.
`The bearing retainer is generally U-shaped and has par-
`allel opposing upright portions with cylindrical ball bearing
`support portions 73 at one end and a horizontally extending
`
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`5 ,707.035
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`7
`bottom wall 74 which includes a slot 75 for locating the
`roller bearing 70 which extends through the slot 75. The
`thickness of the bottom wall 74 is dimensioned so that the
`roller bearing 70 is centered in the slot when the upper and
`lower tracks are assembled. and the upper and lower por-
`tions of the roller bearing 70 extend. respectively, above and
`below the bottom wall 74 of the bearing retainer 72.
`Each of the support portions 73 includes openings 76 with
`indentations 77 in the support portions 73 for receiving the
`ball bearings 71 in a snap-fit relation for retaining the ball
`bearings. The lateral width of the retainer corresponds to the
`inner width of the upper track. The rear roller bearing and
`retainer assembly 24 is similar to the front roller bearing and
`retainer assembly 3 but is slightly longer to accommodate
`two roller bearings 70. Accordingly. the elements of the rear
`roller bearing and retainer assembly have been given the
`same reference numerals as corresponding elements of the
`front roller bearing and retainer assembly. The bearing and
`retainer assemblies for the outboard track sub-assembly are
`similar to the those for the inboard sub-assemblies and
`accordingly will not be described.
`The front and rear roller bearing and retainer assemblies
`are mounted on the depending portion 64 of the upper track
`21 with the outer portions of the ball bearings 71 extending
`into the arcuate channels 65 defined in the side of the neck.
`The roller bearings 70 are located in engagement with the
`bearing surface 58 of the lower track 18 and the bearing
`surface 66 of the upper track 19 when the upper and lower
`tracks are assembled together.
`The weight of the vehicle seat and its occupant is carried
`by the roller bearings. while the ball bearings provide a
`smooth. precise guide between the moving upper track 21
`and the lower track 20 that is anchored to the vehicle’s
`frame. Also, the ball bearings provide lateral stability. The
`bearing retainers capture the ball bearings and the roller
`bearings and maintain the roller bearings and ball bearings
`in a given axial spacing in horizontal travel of the upper
`track relative to the lower track, providing stability and
`enabling the components of the roller bearing and retainer
`assemblies to run synchronized as the bearing retainer slides
`along the track.
`
`Crown
`
`15
`
`20
`
`30
`
`35
`
`Referring to FIG. 7. the bearing surface 58 of the lower
`track 20 and the bearing surface 66 of the upper track 21 of
`the inboard track sub-assembly 16, as well as the bearing
`surfaces of the upper and lower tracks of the outboard track
`sub-assembly 14. are formed with a down. The degree of
`crowning is dependent upon the geometry of the lower and
`upper tracks 20 and 21 and the roller bearings 70. In the
`exemplary embodiment. the crown is arcuate in shape and
`although its profile is exaggerated for purposes of
`illustration. in practice. the maximum thickness "I"’ of the
`crown 78 is in the range of about 0.05 millimeters to 0.14
`millimeters at the center of the track. and preferably is
`approximately 0.07 millimeters at the center of the tack
`under no load conditions, that is. when the vehicle seat is
`unoccupied.
`The hardened steel roller bearings 70 are three times
`harder than the aluminum upper and lower tracks. It has
`been determined that for tracks having flat bearing surfaces,
`the forces exerted on the aluminum tracks by the linear roller
`bearings under load conditions. that is when the vehicle seat
`is occupied, cause the center of the tracks to bow outwardly
`away from the roller bearings, resulting in stress at the ends
`of the roller bearings. Because uniform contact
`is not
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`8
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`provided between the roller bearings and the bearing Sll1'-
`faces of the upper and lower tracks under load conditions.
`the lubricant is less effective resulting in accelerated wear.
`In accordance wil:h the present invention wherein the
`bearing surfaces of the upper and lower tracks of the inboard
`and outboard sub-assemblies are formed with a crown. the
`crowned surfaces of the tracks approach a flat under load
`conditions. but do not become flat. Consequently, the roller
`bearings are maintained in contact with the bearing surfaces
`over substantially the entire length of the roller bearings.
`providing a more even distribution of the load on the bearing
`surfaces. An additional advantage is that the use of the
`crown on the bearing stnfaces of the tracks eliminates the
`need for surface hardening the tracks.
`
`Dry Lubricant Track Coating
`
`Referring to FIG. 8, the stnfaces of the inboard and
`outboards tracks, including the bearing surfaces. are coated
`with a dry film lubricant 80. In accordance with one aspect
`of the invention, the dry film lubricant 80 is a mnlti-laya
`coating including one or more layers of a base coating 81 of
`an anti—friction material and one or more layers of a top
`coating 82 of an anti-stick material. In the exemplary
`embodiment. the base coating comprises a mixture of solid
`lubricants dispersed in organic binder waxes and solvents.
`One material suitable for this application is the bonded
`lubricant commercially available from Dow Corning Cor-
`poration under the tradename MOLYKOTE 106. This com-
`mercially available bonded lubricant contains solid lubricat-
`ing pigments of molybdenum disulfide and graphite in a
`thermoset heat curable binder. When used as a dry film
`coating for bearing surfaces of tracks in a seat adjuster, the
`pigments provide lubrication under the high normal loads. in
`the thousands of psi, encountered during operation of the
`mechanism under the occupant load, and transmitted to the
`aluminum track through the roller bearings. These pigments
`produce low track operating efforts and smooth travel during
`cyclic track operation in service. The heat aired binder
`provides strength to retain the lubricating pigments at the
`aluminum alloy track-to-roller interface.
`The top coating 82 consists of a material which provides
`a high tack. non-stick surface. Materials suitable for this
`application include paraifin. polyethylene or polytetrafluo-
`roethylene. In the exemplary embodiment. the top coating
`consists of a clear polytetrafluoroethylene (PTFE), com-
`monly referred to as TEPLON. with or without a binder.
`The ball bearings and roller bearings of the bearing and
`retainer assemblies 23 and 24 (FIG. 3) roll on the greaseless
`surfaces of the tracks. providing substantially noise-free
`operation. The base coating 81 has the high load carrying
`capability that is required for this application. but testing has
`shown that in a rolling track operation in which one element
`rolls relative to the other, a build up of dry film lulxicant
`coating flakes resulted from cohesive failure of the dry
`lubricant binder. The high hardness binder prevented the
`coating flakes from pulverizing into a powder, which
`enabled the coating flakes to interfere with roller bearing
`motion. Although a higher hardness binder could be used.
`the higher hardness would promote roller bearing slip and
`squeak, resulting in undesired noise. Moreover. testing has
`demonstrated that a mixture of polytetrafluoroethylene and
`molybdenum disulfide was not suitable as a dry lubricant for
`rolling track operations. such as those associated with the
`use of roller bearings of steel. for example. riding on metal
`tracks, there is a weakening of the binder of the molybde-
`num disulfide which promotes build up of dry lubricant
`
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`flakes that prevent proper travel of the steel rollers in