Continuous recliner

A tilt adjustment mechanism for a vehicle seat that is used to adjust the angular orientation of a seat back relative to a seat base. The tilt adjustment mechanism has a driver that has two protrusions that are rotated with the driver by a drive shaft. Initially the driver rotates independently of a cam assembly until a driving protrusion of the cam assembly is engaged. The movement of the driver continues to release a locking wedge that releases the seat back for adjustment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to seat tilt adjustment mechanisms having constantly engaged gears.

2. Background Art

Vehicle seats normally include a seat base and a seat back. Adjustment mechanisms are provided for vehicle seats that allow the seats to be positioned to accommodate different body types and the personal comfort of seat occupants. Adjustment mechanisms are provided for fore-and-aft positioning, lumbar support, seat height and the angular orientation of the seat back relative to the seat base. Adjustment mechanisms that adjust the angular orientation of the seat back relative to the seat base may be referred to as seat tilt adjusters.

Power seat adjusters are generally of the continuous engagement type in which gears having offset centers of rotation are constantly engaged. Power seat adjusters are driven by a bi-directional motor that provides torque to the seat adjuster to increase or decrease the angle at which the seat back is oriented relative to the seat base. Seat tilt adjusters must meet or exceed performance specifications and performance requirements of customers. Power seat adjusters must be manufactured to close tolerances to assure acceptable performance. Once the angular orientation of the seat back is adjusted, the seat back may be subject to loads or vibrations that cause the seat to chuck or vibrate. The term “chuck” refers to free movement of the seat back after the seat back position is established. Chucking is generally undesirable and many attempts have been made to eliminate this phenomenon. Seat tilt adjusters that are designed to eliminate chucking require manufacturing the parts of the seat tilt adjuster to very close tolerances. Failure to meet the tolerances required for such parts may lead to inconsistent results, unacceptable levels of scrap, and other manufacturing problems.

The present invention is directed to overcoming the above problems as summarized below.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a tilt adjustment apparatus for a vehicle seat comprises an inner gear plate and an outer gear plate that is selectively locked together by an expandible cam assembly and a driver. A drive shaft provides torque to adjust the tilt adjustment apparatus. An inner gear plate has a plurality of internal teeth disposed in a circular array on one side thereof and has a first axis of rotation. An outer gear plate has a second plurality of external teeth disposed in a circular array on one side of the outer gear plate and has a second center of rotation that is offset from the first axis of rotation. The inner and outer gears are engaged at one point on each gear so that rotation of one gear causes one gear to orbit relative to the other gear. The outer gear plate defines a bearing ring in which the expandible cam assembly is disposed. The cam assembly has a driving protrusion extending radially outwardly from an outer diameter of the cam. The cam has a locking peripheral section extending radially outwardly from an outer diameter of the cam that is spaced from the driving protrusion. A pair of locking elements selectively engage the bearing ring and the locking peripheral section of the cam. A spring engages the locking elements and biases the locking elements into engagement with the bearing ring and the locking peripheral section of the cam to selectively lock the cam to the bearing ring. A driver is assembled to the cam assembly and the drive shaft. The driver has first and second driver segments that are disposed in opposite circumferential sides of the driving protrusion of the cam. The first and second driver segments are disposed between the driving protrusion and one of the locking elements. The driver transfers torque received from the drive shaft to the driving protrusion of the cam. One of the locking elements is then engaged by the other driver segment depending upon the direction of rotation of the drive shaft in a face-to-face driving relationship to cause the outer gear plate to rotate relative to the inner gear plate. Rotation of the drive shaft releases the biasing force applied by the spring to the other locking element.

According to other aspects of the present invention, the driver may comprise an axially extending hub that extends through an opening in the cam and in the inner and outer gear plates. A driver cap may be secured to a distal end of the hub of the driver to hold the apparatus together. A dust cap may be secured between the driver cap and the outer gear plate.

According to further aspects of the invention relating to the spring, the spring may be a substantially circular spring that is radially outboard of the bearing and disposed between the driver and the outer gear plate. The spring may have first and second ends that extend in an axial direction and are received in a notch formed in one of the locking elements.

According to other aspects of the invention relating to the driver segment, the driver segment may have a first radially extending face and a second radially extending face on opposite sides of the driving protrusion that are oriented to engage the first and second driver segment, which may engage one of the locking elements. The locking element may further comprise a pair of wedges wherein the radially extending face of each of the first and second driver segments each have a wedge engaging surface that is oriented to engage one of the wedges. The driver is permitted to freely rotate relative to the cam to a limited extent prior to the driver segments engaging the driving protrusion of the cam and one of the wedges when the drive shaft is rotated.

According to another aspect of the present invention, a tilt adjustment apparatus for a vehicle seat is provided. The tilt adjustment apparatus comprises a drive shaft that provides torque for adjusting the tilt adjustment apparatus. An inner gear plate having a plurality of radially inwardly oriented teeth disposed in a circular array on one side of the first gear plate. An outer gear plate having a plurality of radially outwardly oriented teeth disposed in a circular array on one side of the second gear plate. The second gear plate defines a receptacle opening that is spaced inward from the second plurality of teeth. A bearing ring may be disposed in the receptacle opening of the outer gear plate. A cam assembly may be disposed within the bearing ring. The cam assembly comprises a driving protrusion extending radially outwardly from an outer diameter of the cam. A pair of wedges are inserted between the bearing ring and the wedge lock engaging peripheral section of the cam. The cam assembly has a wedge lock engaging peripheral section extending radially outwardly from the outer diameter of the cam. A spring engages each of the wedges and biases the wedges into engagement between the bearing ring and the wedge lock engaging peripheral section of the cam to selectively lock the cam and bearing ring together. A driver is assembled between the cam and the drive shaft that has first and second driver segments that are disposed on opposite circumferential sides of the driving protrusion of the cam. Each of the driver segments are disposed between the driving protrusion and one of the wedges. The driver transfers torque from the drive shaft through one of the first and second driver segments and, in turn, to the driving protrusion of the cam and one of the wedges depending upon the direction of rotation of the drive shaft. The driver segments contact the driving protrusion and one of the wedges in a face-to-face driving relationship that causes the outer gear plate to rotate relative to the inner gear plate.

According to other aspects of the invention as described above, torque applied to the driving protrusion of the cam and one of the wedges releases the biasing force applied by the spring to the other wedge. Rotation of the drive shaft may cause the other of the first and second driver segments to engage the driving protrusion of the cam assembly which causes the cam assembly to rotate. Rotation of the cam assembly results in the rotation of the wedge lock engaging peripheral section of the cam which releases the other of the pair of wedges. A bi-directional motor drive may be provided that is operable to rotate the drive shaft selectively in one rotational direction or in the opposite rotational direction.

According to another aspect of the present invention, a vehicle seat comprising a seat base and a seat back that is supported by a recliner adjuster in a selected angular rotation relative to the seat base. The recliner adjuster is driven by a bi-directional motor that rotates a driver. The recliner adjuster has a first armature that defines an internal gear and a second armature that defines an external gear that is smaller than and engages the internal gear at a single meshing point. A locking assembly has locking elements that selectively lock the first and second armatures together by fixing the meshing point and also includes a cam that engages the locking elements. The bi-directional motor drive rotates the driver that moves relative to the cam before engaging the driving protrusion of the cam. The driver segment then directly engages one of the locking elements and the cam to release the locking assembly and rotate the external gear relative to the internal gear to change the meshing point of the gears and adjust the angular orientation of the seat back.

According to other aspects of the invention as it relates to the vehicle seat, rotation of the driver causes the driver segments to engage a driving protrusion of the adjuster which causes the cam to rotate. The locking element may comprise first and second wedges. The driver directly engages the driving protrusion of the cam and the first wedge.

These and other features of the invention will be better understood in view of the attached drawings and the following detailed description of the illustrated embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Referring toFIG. 1, the vehicle seat10is illustrated that includes a seat base12and a seat back14that are interconnected by a tilt adjuster16, or tilt adjustment apparatus. The tilt adjuster16is driven by a motor18by means of a flexible drive shaft20that is shown diagrammatically inFIG. 1. It should be noted that two tilt adjusters16are shown inFIG. 1.

Referring toFIG. 2tilt adjuster16is shown in an exploded perspective view. An inner gear plate24and an outer gear plate26are shown separated from each other. A driver28is provided on the outer side of the outer gear plate26. A cam ring20which is received within the outer gear plate26supports the first and second wedges32and34within a bearing ring36. A spring40is operatively interposed between the first and second wedges32and34to bias the wedges32,34into engagement with the cam ring30and bearing ring36. A driver cap42is provided on the opposite side of the inner gear plate24that is secured to the driver28to hold the tilt adjuster16together. A dust cap44is provided between the outer gear plate26and the driver28to shield the component parts of the tilt adjuster16from contaminants.

The inner gear plate24is provided with a plurality of internal gear teeth48. The inner gear plate24also has a central bore50in which the driver28is partially received. Rivet receiving openings52are provided in the inner gear plate24to secure the inner gear plate24to the seat base12as shown inFIG. 1. The outer gear plate26has a plurality of external gear teeth56that are engaged at a single meshing point with internal gear teeth48of the inner gear plate24. The number of external teeth56is less than the number of internal gear teeth48. The number of external gear teeth56may be at least one tooth less than the number of internal gear teeth48. The central axis of the internal gear teeth48and the external gear teeth56are offset relative to each other. A bearing bore58is defined by the outer gear plate26that receives the bearing ring36. The outer gear plate26also has rivet opening60in which rivets54, or other fasteners, are received to secure the outer gear plate26to the seat back14.

The cam ring30includes a driving protrusion64that extends radially outwardly from the cam ring. A locking peripheral section66is also provided on the cam ring30that extends radially outwardly from an outer diameter68of the cam ring30.

The wedges32,34each include a bearing engaging surface72and a cam engaging surface74. Notches76are provided in the wedges32and34that receive first and second axially extending ends78,80of the spring40.

The driver28includes first and second driver segments84,86that are assembled to the cam ring30on the surface designated as the outer diameter68of the cam ring30. The first driver segment84and second driver segment86are inserted between the driver protrusion64and one of the first and second wedges32,34. The driver also includes a drive shaft receiving bore88that has a plurality of splines90that are engaged by splines92formed on the drive shaft20.

Referring toFIGS. 1,3and4, operation of the tilt adjuster16will be described. When a seat occupant wishes to change the angular orientation of the seat back14the motor18is actuated to rotate the drive shaft20. With reference toFIGS. 3 and 4, the drive shaft20rotates the driver28, for example in the clockwise direction and the first and second driver segments84,86move with the driver28freely until the second driver segment86contacts the driving protrusion64, of the cam30. The first driver segment84, in turn, contacts a shoulder87′ that is formed on the cam ring30. At this point, the wedge32is released and moves toward the wedge34against the biasing force exerted by the spring40. The wedge32is also contacted by the driver segment84as movement of the driver segment84continues. The wedges32,34are at this point released from the bearing ring and the entire cam assembly including the cam ring30, first wedge32and second wedge34slip on the bearing ring36allowing the outer gear plate26to rotate relative to the inner gear plate24. The external gear teeth56rotate on the internal gear teeth48to change the point of engagement of the inner gear plate24and outer gear plate26. The first and second driver segments84and86each include a radially extending face94that may engage a radially extending end96formed on each of the wedges32and34. The faces94initially contact the shoulders87′ or87″, depending upon the direction of rotation, prior to contacting one of the wedges32and34.

To operate the locking mechanism in the opposite direction the drive shaft20is rotated in the counterclockwise direction and the cam assembly rotates in the opposite direction. First driver segment84engages the driving projection64of the cam ring30. Second driver segment86engages shoulder87″ that is formed on the cam ring30. The radially extending face94of the second driver segment86engages the radially extending end96of the second wedge34.

Referring toFIG. 5, the tilt adjuster16is shown assembled together. The tilt adjuster includes an inner gear plate24that is secured to the outer gear plate26. The dust cap44is retained on the inner gear plate24. The drive shaft receiving bore88and the splines90provided in the bore88are also shown inFIG. 5.