Longitudinal adjustment device in a vehicle seat, especially for two-door motor vehicles

A longitudinal adjusting device on a motor vehicle seat having a seat back adjustable relative to the seat part and forwardly foldable after releasing an arresting device, has movable rails on which the seat is fastened. The moveable rails can slide in guide rails attached to the vehicle. One movable rail has a locking device that releasably locks the moveable rail on the guide rail. The locking device has a positioning device for returning the seat to its previous longitudinal position. The positioning device has a positioning disc with locking teeth and an arresting lever with a toothed segment engaging the locking teeth. The arresting lever can be released from the locking teeth to allow rotation of the positioning disc during longitudinal adjustment of the seat. A spring-loaded winding drum is arranged coaxially to the positioning disc and allows the seat part to slide forward by a tension member attached to the seat part or the guide rail.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The invention pertains to a longitudinal adjusting device for the seat of a
 motor vehicle, especially two-door motor vehicles, the back of which seat
 can be tilted adjustably with respect to the seat part by means of
 adjusting hardware, and which, after the release of an arresting device,
 can be flipped forward, where the seat part is attached to movable rails
 which can slide along guide rails permanently attached to the vehicle, and
 where at least one movable rail has a locking device which can be
 disengaged from the guide rail, to which locking device a positioning
 device is assigned, which makes it possible for the seat to be returned to
 the original longitudinal position selected for it, which positioning
 device comprises a positioning disk with a set of external teeth, into
 which the toothed segment of an arresting lever engages, which lever is
 supported in a fixed position with respect to the movable rail but which
 can be moved out of the way if needed, where, coaxial to the positioning
 disk, a spring-loaded winding drum is mounted, by means of which the seat
 part can be shifted forward by the intermediate action of a tension member
 permanently attached to the vehicle floor or to the guide rail, the
 winding drum being provided with a stop for limiting the extent to which
 it can be rotated in the reverse direction by a counterstop on the
 positioning disk.
 2. Description of the Related Art
 A longitudinal adjusting device of the type described above can be derived
 from DE 196-47,447, in which the locking device can be released in two
 different ways so that the seat can be shifted longitudinally. First, by
 lifting a release handle in the forward area under the seat, the locking
 device attached to the movable rail can be released via a transverse lever
 from the position in which it is connected to the guide rail; that is, the
 locking catches of the locking device are lifted out of the row of teeth
 on the guide rail against the force of self-restoring springs. As this
 occurs, the end part of the release handle carries a connecting lever
 along with it in the release direction; this connecting lever lifts the
 toothed segment of an arresting lever out of the external teeth of a
 positioning disk. In this case, the previously selected terminal stop
 position used as a guide for returning the seat to the originally selected
 position is lost. So that the vehicle seat can be shifted without losing
 the position of the terminal stop, the connecting lever is detached from
 the release lever by way of an unlocking lever supported on the movable
 rail, so that the arresting lever remains undisturbed; as a result, the
 locking position of the positioning disk is pre-served. Nevertheless, the
 unlocking lever simultaneously presses the release handle against the
 transverse lever, so that this lever lifts the locking catches of the
 locking device out of the row of teeth on the guide rail. Thus, the
 previously selected stop position remains preserved in the memory module,
 while the seat part along with the forward-tipped back can be slid forward
 and back again to the previously selected stop. To assist the forward
 sliding movement of the seat, a previously mentioned winding drum is
 provided, which is spring-loaded in the direction of the forward sliding
 movement. This drum is connected by way of a tension member either to the
 floor of the vehicle in the forward area of the rail arrangement or to the
 forward end of the guide rail. The position of the stop used as a guide
 for returning the seat to its originally selected longitudinal position
 can be adjusted when the seat is slid backwards by allowing the rotation
 of the winding drum, which carries another stop, to move the stop of the
 positioning disk along until, upon completion of the rearward sliding
 movement of the seat, the locking device holds the movable rail in a fixed
 position on the guide rail. At this point, the pivoting of the release
 handle back to its original position also causes the positioning disk to
 be held by the arresting lever, so that the position which the stop on the
 positioning disk reached at that time is fixed. So that the winding drum
 can now be allowed to make several revolutions without the need to release
 the positioning disk, two check rings are inserted between the stop on the
 positioning disk and the stop on the winding drum; these rings in turn
 have their own stops, which can be carried along in succession by the
 winding drum. Thus, while the seat is being slid backwards, the stops on
 the check rings move the stop on the winding drum into a stop position
 with respect to the stop of the positioning disk, while the stop position
 of the positioning disk is being maintained. To ensure that the check
 rings function properly, they must be installed in the correct order one
 behind the other; otherwise, it is impossible for the originally selected
 position of the seat to be restored. In addition, if it desired to allow
 the seat to slide a long distance, the number of check rings arranged in a
 row must be increased. This requires a large amount of space in the width
 direction, and it also increases the cost.
 SUMMARY OF THE INVENTION
 The task of the invention is to improve a longitudinal adjusting device of
 the general type described above in such a way that, first, the
 above-cited disadvantages can be avoided, and, second, that the number of
 components, especially of the memory module, can be reduced. This task is
 accomplished by a link block, which is guided in a spiral connecting link
 and which makes it possible for the winding drum to rotate, being provided
 between the stop of the winding drum and the counter stop of the
 positioning disk. As a result, check rings, such as those used in the
 solution according to the state of the art described above, can be
 completely eliminated in the solution according to the invention. Another
 advantage is that, depending on the design of the spiral connecting link
 and the link block, it is possible, if needed, for the winding drum to
 execute more than the approximately two revolutions which can be achieved
 with the check rings known according to the state of the art, which means
 that the movable rails can be slid much farther along the guide rails.
 A practical embodiment of the spiral connecting link and the link block can
 be achieved by designing the link block preferably as a ring segment,
 which has a guide rib which engages with the spiral connecting link. The
 connecting link takes the form of a groove recessed into the sidewall of
 the positioning disk. The spiral connecting link in this case is
 preferably designed so that it begins a short radial distance from the hub
 of the positioning disk and ends at the counterstop on the positioning
 disk, located radially just below the locking teeth; the pitch of the
 spiral connecting link is such that the radially outward directed
 component of the link block's motion can carry it underneath and past the
 counterstop of the positioning disk before the block makes its last
 revolution.
 The link block can be given precise radial guidance as the positioning disk
 rotates by providing guide fingers on the link block, one projecting from
 each of the two end surfaces of the block, both pointing at the hub of the
 positioning disk. These guide fingers are arranged with respect to each
 other like a fork and project across the hub at a tangent to its outer
 circumference. It is obvious that the guide fingers must be long enough to
 remain in contact with the outside surface of the hub of the positioning
 disk even after the greatest possible radial distance between the link
 block and the hub of the positioning disk has been reached.
 As previously mentioned, the counterstop is assigned to the positioning
 disk, whereas the stop is assigned to the winding drum. The stop on the
 winding drum can preferably be formed by the outsidewalls of an insertion
 pocket for a lead retainer seal of the tension member.
 So that the winding drum can be rotated freely with respect to the
 positioning disk, the counterstop of the positioning disk projects axially
 only so far from its sidewall that the ribs and insertion pocket of the
 winding drum can be rotated freely past the counterstop. The axial length
 of the link block, furthermore, is greater than the axial length of the
 counterstop, because, when the link block is resting against the
 counterstop of the positioning disk, it must also form an abutment for the
 stop of the winding drum.

DESCRIPTION OF THE PREFERRED EMBODIMENT
 The vehicle seat shown schematically in FIG. 1 consists of a seat part 10
 and a seat back 11, which is attached to the seat part by a hinge
 mechanism (not shown), which allows the angle of the back to be adjusted.
 The back can also be flipped forward with respect to seat part 10 around a
 pivot point 14 by pulling on a handle 13 connected to an arresting device
 12. Each of the two longitudinal sides of seat part 10 are connected along
 the bottom to a movable rail 15, which engages in a guide rail 16, both
 guide rails being attached permanently to the floor of the vehicle.
 Movable rail 15, as can be seen especially in FIG. 8, is supported on
 guide rail 16 by rolling elements 17, 18 to allow freedom of longitudinal
 movement. On its incurved bottom, guide rail 16 has a longitudinal row of
 openings (not labeled separately), spaced a certain distance apart, which
 form a row of teeth. Into these openings, at least one of several locking
 catches 20 engages, these catches being components of a locking device 19,
 mounted in a fixed position on movable rail 15. The catches can be
 disengaged against the action of springs by a transverse lever 21, also
 mounted on movable rail 15; to accomplish this, a release handle 22, also
 in a fixed position on movable rail 15, is actuated. Locking device 19 of
 the longitudinal seat adjusting device, however, can also be released by
 handle 13 on seat back 11 together with arresting device 12 of the seat
 back, in that an unlocking lever 24 is actuated by way of a Bowden cable
 23. This unlocking lever acts by way of an angled section 25 on release
 handle 22 in the unlocking direction and thus also actuates transverse
 lever 21 in such a way as to disengage locking catches 20 from the row of
 teeth in guide rail 16. The unlocking lever is supported by a pivot 26 on
 a mounting plate 27, which is attached in turn to movable rail 15. A
 housing 28, consisting of a lower housing part 29 and an upper housing
 part 30, which holds positioning device 31 and its winding drum 32,
 designed as a rotating element, is also attached to this mounting plate
 27.
 Can-shaped upper housing part 30, which can be seen in FIG. 5, is connected
 by way of clip projections 33 along the edges, which can also be seen in
 FIGS. 4a-4c, to disk-shaped lower housing part 29, this lower housing part
 29 being permanently connected in a manner not shown to mounting plate 27
 attached to movable rail 15. An inward-projecting axle 34 is provided in
 the center of cup-like upper housing part 30. A positioning disk 35 is
 supported with freedom of rotation on this axle 34; a set of locking teeth
 36 extends around the entire outside circumference of the disk. On the
 side facing disk-shaped lower housing part 29, positioning disk 35 has a
 recess, in which a spiral spring 37, functioning as a torsion spring, is
 held. The inner, angled, end of this spring engages in a recess 38 in axle
 34, whereas the outer end of the spring is held in a manner not shown in
 detail in the circumferential area of the recess in positioning disk 35.
 Together with positioning disk 35, the previously mentioned winding drum 32
 is also supported on axle 34 so that it can rotate independently of the
 positioning disk. On the side facing away from positioning disk 35,
 winding drum 32 has a recess 39, which also holds a spiral spring 40,
 which functions as a torsion spring. In a manner known in itself, the
 inner end of this spring is attached to axle 34, whereas the outer end is
 attached to the outside lateral surface of winding drum 32. The outside
 lateral surface of winding drum 32 has a section 41 of reduced diameter,
 which forms the holding space for a tension member 42, which is attached
 to the winding drum and which can be in the form of a belt, for example.
 Underneath reduced-diameter section 41, there is an insertion pocket 43,
 oriented toward the center of winding drum 32, in which a lead retainer
 seal 44, permanently attached to one end of tension member 42, fits. Each
 of the two outsidewalls of insertion pocket 43 extending in the axial
 direction forms a stop 45, the purpose of which will be described later.
 In addition to the walls of insertion pocket 43, which serve to increase
 the rigidity between the outside lateral surface and the hub of winding
 drum 32 and also form stops 45, ribs 46 are also provided between the hub
 and the outside lateral surface of winding drum 32. At the free end of
 tension member 42, a lock-in-position piece 47 is provided, by means of
 which tension member 42 is attached to guide rail 16, mounted in a fixed
 position on the floor.
 A hub 49 projects from sidewall 48 of positioning disk 35; this hub points
 toward winding drum 32 and surrounds axle 34. A short radial distance away
 from this hub 49, a spiral connecting link 50 begins, and it ends at a
 counterstop 51, which projects from sidewall 48 of positioning disk 35
 just below locking teeth 36. This counterstop 51 does not project far
 enough in the axial direction from sidewall 48 of positioning disk 35 to
 prevent either the radially oriented boundary walls of insertion pocket 43
 or ribs 46 of winding drum 32 from rotating freely past counterstop 51.
 Spiral connecting link 50 is formed by a groove recessed into sidewall 48
 of positioning disk 35. A guide rib 53 of a link block 52 engages in the
 groove which forms spiral connecting link 50. Link block 52, designed as a
 ring segment, forms an intermediate member between the associated stop 45
 of winding drum 32 and counterstop 51 of positioning disk 35. The axial
 dimension of the link block is selected so that it can come to rest,
 first, against the associated stop 45 of the winding drum and, second,
 against counterstop 51 of positioning disk 35. To provide guidance, a
 guide finger 55 projects out from each end 54 of link block 52. These
 guide fingers 55 are arranged to form a fork, and even in the most extreme
 radial position, they remain tangent to hub 49 of positioning disk 35 on
 both sides.
 Upper housing part 30 has on its circumferential area, adjacent to
 disk-shaped lower housing part 29, a cut-out section 56, through which
 toothed segment 58 of an arm of disengagable arresting lever 57 can pass,
 so that it can engage with locking teeth 36 of positioning disk 35. This
 arresting lever 57 is able to pivot around a pivot 59 on mounting plate
 27, and its toothed segment is held in engagement with locking teeth 36 of
 positioning disk 35 by a locking spring 60, attached to an arm projecting
 from housing 28. Now, in the same way as previously described in
 accordance with the state of the art, it would be possible for a
 connecting lever to be connected to arresting lever 57, and this
 connecting lever could have a catch which would engage in a releasable
 manner in the tube at the end of the release handle. In the present
 embodiment, however, a downward-pointing fork lever 62 is nonrotatably
 attached to the same hub 61 as arresting lever 57, but offset in the axial
 direction. A plunger 64 of a sleeve 63 extends into the open space between
 the sidepieces of fork lever 62. The end of the plunger has a transverse
 head 72 projecting out toward both sides, and the sleeve is attached to
 the terminal area of release handle 22 in such a way that it is free to
 move in the longitudinal direction but is not free to rotate. The terminal
 area of release handle 22 begins behind transverse tube 65, which is
 permanently connected to release handle 22 by welding, for example. As a
 result of this tube, release handle 22 is pivotably supported in bearing
 brackets 66 permanently attached to the rails. One end of a compression
 spring 67, which surrounds release handle 22, is braced against transverse
 tube 65; the other end of the spring acts on sleeve 63. Sleeve 63, which
 contains axially guided plunger 64, has a laterally projecting pin 68,
 which, as a result of the action of compression spring 67, is held against
 an adjusting finger 69 of unlocking lever 24. The inside surfaces of the
 sidepieces of fork lever 62 have radial cam sidepieces 70, with which
 plunger 64 can come into contact when the rear part of release handle 22
 is pivoted downward.
 While seat part 10 is being held in the desired position, release handle
 22, unlocking lever 24, and arresting lever 57 with its fork lever 62 are
 in the position shown in FIG. 4a. When now the longitudinal position of
 the seat part of the seat is to be adjusted to a new position, handle
 lever 22 is pulled upward, so that its rear area pivots downward. During
 this pivoting movement, handle lever 22 presses transverse lever 21 (FIG.
 8), so that the locking catches 20 of the locking device are lifted out of
 the row of teeth in guide rail 16; it thus becomes possible to slide
 movable rails 15, to which the seat is attached, in the one or the other
 longitudinal direction of the vehicle. Simultaneously, however, when the
 rear part of handle lever 22 pivots downward, transverse head 72 of
 plunger 64 in sleeve 63 arrives at radial cam surfaces 70 and thus presses
 fork lever 62 forward. This lever therefore pivots around pivot 59 in the
 clockwise direction, and as a result toothed segment 58 is lifted out of
 the locking teeth of positioning disk 35. This actuating position is shown
 in FIG. 4c. It must also be pointed out that, as a result of a circular
 path 71 on adjusting finger 69 of unlocking lever 24, which path curves
 around the center point of transverse tube 65, sleeve 63 and thus also its
 plunger 64 retain their positions with respect to the terminal area of
 release handle 22. This is so because no change has been made to the
 position of seat back 11, and therefore unlocking lever 24 has not been
 actuated; it thus remains in the position shown in FIGS. 4a and 4b. When
 now, in the actuating position shown in FIG. 4c, the seat is slid forward
 or back, tension member 42 is paid out or rolled up on winding drum 32. As
 a result, the cooperation of stop 45 on the drum, link block 52 resting
 against it, and counterstop 51 causes positioning disk 35 to rotate along
 with the drum, which it is free to do because arresting lever 57 has been
 swung out of position. As soon as the desired longitudinal position of the
 seat has been reached and release handle 22 has been let go, the handle
 swings back to its original position as shown in FIG. 4a under the force
 of the spring-loaded locking catches acting in the locking direction. At
 the same time, arresting lever 57 is swung back by locking spring 60 into
 its locking position as shown in FIGS. 4a and FIG. 6, where it holds
 positioning disk 35 in a fixed position.
 When now seat back 11 is flipped forward and the seat is pushed forward out
 of this selected longitudinal seat position to allow more convenient
 access to the rear seat, the act of flipping back 11 forward has the
 effect of pulling on Bowden cable 23. As a result, unlocking lever 24 is
 pivoted in the clockwise direction around pivot 26, so that, on the one
 hand, bent section 25 of the lever presses the rear part of release handle
 22 down. As this is happening, pin 68 on sleeve 63 follows adjusting
 finger 69 as the finger pivots forward in the clockwise direction under
 the force of compression spring 67, with the result that transverse head
 72 of plunger 64, occupying the gap inside fork lever 62, arrives in the
 free space between fork lever 62 and housing 28, so that, when the rear
 part of release handle 22 is pushed down by bent section 25 for the
 purpose of pressing transverse lever 21 down, transverse head 72 of
 plunger 64 cannot come in contact with radial cams 70. Arresting lever 57
 therefore remains in the position in which its toothed segment 58 is
 engaged with locking teeth 36 of positioning disk 35. The start of this
 actuating process is shown in FIG. 4b. When transverse lever 21 is pressed
 down, however, it is possible, as a result of the sliding of locking
 catches 20 out of the row of teeth of the guide rail, for the seat to be
 pushed forward. During this sliding movement of the seat, link block 52
 can be moved away from counterstop 51 of positioning disk 35, because this
 stop, carried along in spiral connecting link 50 by stop 45, is able to
 yield. When now the vehicle seat, which has had its back flipped forward
 and been pushed forward, is returned to its original position, winding
 drum 32 rotates against the action of spiral spring 40, as a result of
 which link block 52 is carried along again by stop 45 until link block 52
 comes to rest against the unchanged counterstop 51 of positioning disk 35.
 At this point the originally selected longitudinal position of the seat is
 reached again.
 As previously mentioned, the embodiment of the object of the invention
 illustrated and described above presents only an example, to which the
 invention is in no way limited. On the contrary, additional designs and
 embodiments of the object of the invention are also possible. All of the
 features shown in the drawing and mentioned in the description,
 furthermore, are essential to the invention, even if they are not
 explicitly stated in the claims.