Title of Invention	FITTING FOR A VEHICLE SEAT, IN PARTICULAR FOR A MOTOR VEHICLE SEAT
Abstract	The invention relates to a fitting (10) for a vehicle seat, more particularly for a motor vehicle seat, comprising a first fitting part (11), a second fitting part (12) that is in geared connection with the first fitting part (11), a driver (21) and wedge segments (27a, 27b) which at least partly define a cam that is rotatably mounted in the first fitting part (11) for driving a rolling movement of the first fitting part (11) the second fitting part (12) against one another, and with a first sliding bearing (28) or rolling bearing, by means of which the wedge segments (27a, 27b) are mounted on the second fitting part (12) with a small amount of friction, at least a first (27a) of the two wedge segments (27a, 27b) being mounted on the first fitting part (11) with a small amount of friction by means of a second sliding bearing (41) or rolling bearing.

Title of Invention

FITTING FOR A VEHICLE SEAT, IN PARTICULAR FOR A MOTOR VEHICLE SEAT

Abstract

The invention relates to a fitting (10) for a vehicle seat, more particularly for a motor vehicle seat, comprising a first fitting part (11), a second fitting part (12) that is in geared connection with the first fitting part (11), a driver (21) and wedge segments (27a, 27b) which at least partly define a cam that is rotatably mounted in the first fitting part (11) for driving a rolling movement of the first fitting part (11) the second fitting part (12) against one another, and with a first sliding bearing (28) or rolling bearing, by means of which the wedge segments (27a, 27b) are mounted on the second fitting part (12) with a small amount of friction, at least a first (27a) of the two wedge segments (27a, 27b) being mounted on the first fitting part (11) with a small amount of friction by means of a second sliding bearing (41) or rolling bearing.

Full Text	The invention relates to a fitting for a vehicle seat with the features of the precharacterizing clause of claim 1. In the case of a fitting of this type known from DE 44 36 101 Al, the wedge segments sit directly on a collar extension of the first fitting part. The static friction on account of the material pairing of steel on steel contributes to the safety from running-down of the fitting. When the fitting is driven, the wedge segments move with the lower sliding friction around the collar extension. The invention is based on the object of improving a fitting of the type mentioned at the beginning. This object is achieved according to the invention by a fitting with the features of claim 1. Advantageous refinements are the subject matter of the subclaims. Owing to the fact that at least a first of the two wedge segments is mounted with little friction on the first fitting part by means of a second sliding bearing or rolling bearing, i.e. is mounted on both sides by means of sliding bearings or rolling bearings, with the friction between the sliding bearing (or rolling bearing) and the component sliding relative thereto being lower than the direct friction between the wedge segments and the fitting parts, the losses during the driving of the fitting, i.e. during the adjusting movement, are reduced, thus increasing the efficiency of the fitting. For the same output power, a lower driving power is therefore required. The freedom from play and the strength are maintained. The lower friction of the sliding bearing in comparison to conventional steel is based on a special surface processing and/or treatment. The lower friction of the rolling bearing in comparison to the sliding friction of conventional 2 steel is based on the rolling friction of the rolling bodies. The sliding bearings or rolling bearings may also be provided in a mixed combination. The wedge segments within the meaning of the invention can also be formed in each case on a disk, with the two (eccentric) disks then being arranged in an axially offset manner with respect to each other. Since the backrest is loaded more to the rear than to the front, a wedge segment is subjected to a higher load, and therefore a higher degree of friction basically occurs thereon. The wedge segment which is subjected to a higher load is preferably therefore the wedge segment which is mounted on both sides by means of sliding bearings. However, the other wedge segment or - likewise preferably - both wedge segments can also be mounted on both sides by means of sliding bearings. The fitting according to the invention can be operated both manually and by motor, and can be used in vehicle seats, preferably in order to adjust the inclination of the backrest or the inclination of the seat cushion or a thigh support or the seat height. The driver may be in a single part or in a number of parts. Since a wedge segment which is mounted on both sides by means of sliding bearings is no longer self-locking, and also the fitting would therefore possibly be no longer self-locking, a brake for said wedge segment is provided at least on one side of the vehicle seat, said brake holding the wedge segment in the inoperative state of the fitting and being released during the driving of the rolling movement. A fitting of this type is safe with regard to running-down as well as favorable with regard to efficiency. A brake of this type does not need to be provided in 3 the fitting on the other side of the vehicle seat. A preferred brake is a wrap spring brake which supplies a high locking moment on the output side, but, when a torque is introduced on the drive side, rotates with a freewheeling moment which is low in relation to the locking moment. Instead of a wrap spring brake, a clamping roller freewheel may also be provided. The wrap spring brake produces its locking moment preferably by bearing against a wrap spring bushing which is rotationally fixed with respect to the second fitting part, preferably by means of a positive fit between suitable projections, for example radially protruding arms, of the wrap spring bushing and an inner toothing (present because of the production process) of the second fitting part. The wrap spring brake is preferably arranged within the wrap spring bushing such that it bears against the inner wall thereof and its customarily present wrap spring arms protrude radially inward. The latter are preferably arranged in such a manner that a cam of one or both wedge segments, upon bearing against a wrap spring arm, acts on the wrap spring brake in a closing manner, and one or two cams of the driver rotating during the driving operation, upon bearing against a wrap spring arm, acts or act on the wrap spring brake in an opening manner. The invention is explained in more detail below with reference to two exemplary embodiments illustrated in the accompanying drawings, in which: Fig. 1 shows an exploded illustration of the first exemplary embodiment, Fig. 2 shows a partial view of the first exemplary embodiment with 4 the driver only partially indicated, Fig. 3 shows a longitudinal section of a fitting according to the invention, Fig. 4 shows a schematic illustration of a vehicle seat, Fig. 5 shows an exploded illustration of the second exemplary embodiment, and Fig. 6 shows a partial view of the second exemplary embodiment without a driver. A vehicle seat 1 for a motor vehicle has a seat part 3 and a backrest 4 which can be adjusted in its inclination relative to the seat part 3. A hand wheel 5, which can be actuated manually in order to adjust the inclination, on one side of the vehicle seat 1 rotates a drive shaft (not illustrated specifically) which is arranged horizontally in the transition region between seat part 3 and backrest 4 and, on both sides of the vehicle seat 1, engages in a rotationally fixed manner in a respective fitting 10. The backrest 4 is connected to the seat part 3 by means of the two fittings 10. The fitting 10 is designed as a geared fitting, in which a first fitting part 11 and a second fitting part 12 are connected to each other for adjustment and fixing via a gear designed as an eccentric epicyclic gear which is self- locking at least in the case of one of the two fittings 10 of the vehicle seat 1. The two fitting parts 11 and 12 have an essentially flat shape and are composed of steel. The first fitting part 11 is connected fixedly to the 5 structure supporting the hand wheel 5 and the drive shaft (in the present case, the structure of the backrest 4), for which reason, in the exemplary embodiment, the first component 11 is illustrated in a manner fixed on the backrest and therefore at the top in the drawing. Accordingly, in the exemplary embodiment, the second fitting part 12 is fixed on the seat part, i.e. is connected to the structure of the seat part 3, and is illustrated at the bottom in the drawing. The positions of the fitting parts 11 and 12 may be interchanged, depending on requirements. In order to form the gear, a toothed wheel 16 with an outer toothing is embossed on the second fitting part 12 and a toothed ring 17 with an inner toothing is embossed on the first fitting part 11, said toothings meshing with each other. The diameter of the outside circle of the outer toothing of the toothed wheel 16 is smaller by at least one tooth height than the diameter of the root circle of the inner toothing of the toothed ring 17. The corresponding difference in the number of teeth of toothed wheel 16 and toothed ring 17 permits a rolling movement of the toothed ring 17 on the toothed wheel 16. On the side facing the toothed wheel 16, the first fitting part 11 has an integrally formed collar extension 19 concentrically with respect to the inner toothing of the toothed ring 17. A driver 21 is mounted with play by means of a hub 22 in the collar extension 19. The driver 21, which is composed of plastic and the arrangement of which defines the direction details used, is provided centrally with a bore 23 which matches the external splines of the drive shaft and runs axially. Furthermore, the driver 21 has an integrally formed driver segment 25 which is arranged in a sickle-shaped manner about part of the collar extension 19. Two wedge segments 27a and 27b are supported, at least indirectly by means of their 6 curved inner side, on the collar extension 19 and, by means of their curved outer sides, support a first sliding bearing 28 which is pressed into the second fitting part 12 in a rotationally fixed manner. The friction between the outer side of the metallic wedge segments 27a and 27b and the inner side of the bushing-shaped, first sliding bearing 28 is significantly lower than the direct friction between the wedge segments 27a and 27b and the fitting parts 11 or 12 would be. The driver segment 25 grasps with play between the narrow sides of the wedge segments 27a and 27b while the mutually facing wide sides of the wedge segments 27a and 27b each support an angled end finger of a spring coiled annularly, referred to below as omega spring 30. The omega spring 30 pushes the wedge segments 27a and 27b apart in the circumferential direction and therefore positions the fitting 10 in a manner free from play in the inoperative state. The driver 21 is secured axially on the outer side of the first fitting part 11 by means of a securing ring 31 which is clipped on. In order to absorb the axially acting forces, a respective holding plate (not illustrated in the drawing) is welded in a manner known per se onto the two fitting parts 11 and 12 and engages over the other fitting part in each case without obstructing the adjustment movement. The driver segment 25 and the wedge segments 27a and 27b define an eccentric which, as an extension of the direction of eccentricity, presses the toothed wheel 16 and the toothed ring 17 into each other at an engagement point defined in this manner. During driving by means of the rotating drive shaft, a torque is first transmitted to the driver 21 and then to the eccentric which is defined in this manner and which slides along the first sliding bearing 28, shifting the direction of eccentricity and 7 therefore shifting the engagement point of the toothed wheel 16 in the toothed ring 17, which is depicted as a wobbling rolling movement of the fitting parts 11 and 12 on each other. Owing to the weight of the backrest 4, which is customarily situated obliquely, and a pressure exerted on the backrest 4 by the occupant, a differentiation can be made in the case of the wedge segments 27a and 27b between a first wedge segment 27a, which is subjected to a higher load and is in front during an upward movement of the backrest 4, and a second wedge segment 27b which is subjected to a lower load. The efficiency of the fitting 10 depends noticeably on the friction between the first wedge segment 27a and the collar extension 19. According to the invention, in order to reduce this friction, a second sliding bearing 41 is provided which sits in a more or less immovable manner on the first wedge segment 27a and slides with little friction on the collar extension 19, i.e. corresponds functionally to the first sliding bearing 28. In the first exemplary embodiment, the second sliding bearing 41 is designed as a ring segment which extends over somewhat less than the inner side of the first wedge segment 27a, while, in the second exemplary embodiment, the second sliding bearing 41 is designed as a ring which is more or less completely closed and on which the wedge segment 27 which is subjected to a lower load also sits. Since the two exemplary embodiments otherwise correspond - apart from geometrical adaptations to the shape of the second sliding bearing 41, components which are identical and act in an identical manner bear the same reference numbers. In a modification to both exemplary embodiments, the second sliding bearing 41 on the inner side of the collar extension 19 is arranged in a region free from the hub 22, and the wedge segment 27a which is 8 subjected to a stronger load is mounted therein by means of an extension arm. The friction between the first wedge segment 27a and the collar extension 19 not only has an effect on the efficiency but also on the self-locking of the gear of the fitting 10. So that at least one of the two fittings 10 of the vehicle seat 1 remains self-locking in spite of the first wedge segment 27a being mounted in a sliding manner on two sides, according to the invention, in the case of this fitting 10, a brake which is effective in the inoperative state of the fitting 10 is provided, in the present case a wrap spring brake 44, which is arranged in a wrap spring bushing 46 and, on account of its prestress, bears frictionally against the inner wall thereof. The wrap spring bushing 46, which is produced, for example, from plastic, is arranged in a rotationally fixed manner on the second fitting part 12 by three groups of three radially (and/or axially) protruding wrap spring bushing arms 48 which are offset with respect to one another by 120° in each case engaging with a positive fit in the inner toothing produced on the rear side of the toothed wheel 16 by the embossing operation. For actuation, the wrap spring brake 44 has a radially inwardly protruding wrap spring arm 50 at each of its ends. The first wedge segment 27a is provided with an axially protruding brake cam 51 which is arranged between the two wrap spring arms 50 with play in the circumferential direction, i.e. in the region within the same. A bearing of the brake cam 51 against a wrap spring arm 50 acts on the wrap spring brake 44 in a closing manner, i.e. brakes the wrap spring brake 44 and prevents rotation of the components defining the eccentric relative to the second fitting part 12. With blockage of the eccentric, the first fitting part 11 is also fixed 9 relative to the second fitting part 12. In order to cancel the braking action of the wrap spring brake 44 during driving of the driver 21, firstly, at the end of the driver segment 25 which is assigned to the first wedge segment 27a, a first driver cam 53 is provided on the driver 21 and, secondly, a second driver cam 55 is provided in the region which is arranged at approximately identical radial spacing between the ends of the driver segment 25, said driver cams both protruding axially. The wrap spring arms 50 together with the brake cam 51 are arranged with play between the two driver cams 53 and 55, i.e. the driver cams 53 and 55 are arranged in the circumferential direction outside the wrap spring arms 50. When the driver 21 is rotated, first of all one of the driver cams 53 or 55 passes to bear against a wrap spring arm 50, which acts on the wrap spring brake 44 in an opening manner and cancels the braking action. As the movement continues, the eccentric drives the above-described rolling movement of the fitting parts 11 and 12 on each other. 10 List of reference numbers 1 Vehicle seat 3 Seat part 4 Backrest 5 Hand wheel 10 Fitting 11 First fitting part 12 Second fitting part 16 Toothed wheel 17 Toothed ring 19 Collar extension 21 Driver 22 Hub 23 Bore 25 Driver segment 27a First wedge segment 27b Second wedge segment 28 First sliding bearing 30 Omega spring 31 Securing ring 41 Second sliding bearing 44 Wrap spring brake 46 Wrap spring bushing 48 Wrap spring bushing arms 50 Wrap spring arm 51 Brake cam 53 First driver cam 11 55 Second driver cam 12 WE CLAIM: 1. A fitting for a vehicle seat, in particular for a motor vehicle seat, with a first fitting part (11), a second fitting part (12) in geared connection with the first fitting part (11), with a driver (21) and wedge segments (27a, 27b), which at least partially define an eccentric which is mounted rotatably in the first fitting part (11) and is intended for driving a rolling movement of first fitting part (11) and second fitting part (12) on each other, and with a first sliding bearing (28) or rolling bearing, by means of which the wedge segments (27a, 27b) are mounted with little friction on the second fitting part (12), characterized in that at least a first (27a) of the two wedge segments (27a, 27b) is mounted with little friction on the first fitting part (11) by means of a second sliding bearing (41) or rolling bearing. 2. The fitting as claimed in claim 1, characterized in that the first wedge segment (27a) is the one of the two wedge segments (27a, 27b) which is subjected to a higher load during driving of the fitting (10). 3. The fitting as claimed in claim 1 or 2, characterized in that both wedge segments (27a, 27b) are mounted with little friction on the first fitting part (11) by means of the sliding bearing (41) or a respective second sliding bearing (41). 4. The fitting as claimed in one of claims 1 to 3, characterized in that the first wedge segment (27a) is held in the inoperative state of the fitting (10) by means of a brake (44) which is released during the driving of the rolling movement. 5. The fitting as claimed in claim 4, characterized in that a wrap spring brake (44) which, in particular, has two wrap spring arms (50) is provided as the brake. 6. The fitting as claimed in claim 5, characterized in that the wrap spring brake (44) bears against a wrap spring bushing (46) which is rotationally fixed with respect to the second fitting part (12). 7. The fitting as claimed in claim 6, characterized in that the wrap spring bushing (46) has a plurality of radially protruding wrap spring bushing arms (48) which engage with a positive fit in an inner toothing of the second fitting part (12). 8. The fitting as claimed in one of claims 5 to 7, characterized in that at least one of the wedge segments (27a), in particular the first wedge segment (27a), has a brake cam (51) which, upon bearing against a wrap spring arm (50), acts on the wrap spring brake (44) in a closing manner. 9. The fitting as claimed in one of claims 5 to 8, characterized in that the driver (21) has at least one driver cam (53, 55) which, upon bearing against a wrap spring arm (50), acts on the wrap spring brake (44) in an opening manner. 10. A vehicle seat, in particular motor vehicle seat, with a seat part (3) and a back rest (4) which can be adjusted in its inclination relative to the seat part (3) and is attached to the seat part (3) on at least one side of the vehicle seat (1) by means of a fitting (10) as claimed in one of claims 1 to 9. 15 The invention relates to a fitting (10) for a vehicle seat, more particularly for a motor vehicle seat, comprising a first fitting part (11), a second fitting part (12) that is in geared connection with the first fitting part (11), a driver (21) and wedge segments (27a, 27b) which at least partly define a cam that is rotatably mounted in the first fitting part (11) for driving a rolling movement of the first fitting part (11) the second fitting part (12) against one another, and with a first sliding bearing (28) or rolling bearing, by means of which the wedge segments (27a, 27b) are mounted on the second fitting part (12) with a small amount of friction, at least a first (27a) of the two wedge segments (27a, 27b) being mounted on the first fitting part (11) with a small amount of friction by means of a second sliding bearing (41) or rolling bearing.

Full Text

The invention relates to a fitting for a vehicle seat with the features of the
precharacterizing clause of claim 1.
In the case of a fitting of this type known from DE 44 36 101 Al, the
wedge segments sit directly on a collar extension of the first fitting part.
The static friction on account of the material pairing of steel on steel
contributes to the safety from running-down of the fitting. When the
fitting is driven, the wedge segments move with the lower sliding friction
around the collar extension.
The invention is based on the object of improving a fitting of the type
mentioned at the beginning. This object is achieved according to the
invention by a fitting with the features of claim 1. Advantageous
refinements are the subject matter of the subclaims.
Owing to the fact that at least a first of the two wedge segments is
mounted with little friction on the first fitting part by means of a second
sliding bearing or rolling bearing, i.e. is mounted on both sides by means
of sliding bearings or rolling bearings, with the friction between the
sliding bearing (or rolling bearing) and the component sliding relative
thereto being lower than the direct friction between the wedge segments
and the fitting parts, the losses during the driving of the fitting, i.e. during
the adjusting movement, are reduced, thus increasing the efficiency of the
fitting. For the same output power, a lower driving power is therefore
required. The freedom from play and the strength are maintained. The
lower friction of the sliding bearing in comparison to conventional steel is
based on a special surface processing and/or treatment. The lower friction
of the rolling bearing in comparison to the sliding friction of conventional
2

steel is based on the rolling friction of the rolling bodies. The sliding
bearings or rolling bearings may also be provided in a mixed
combination. The wedge segments within the meaning of the invention
can also be formed in each case on a disk, with the two (eccentric) disks
then being arranged in an axially offset manner with respect to each
other.
Since the backrest is loaded more to the rear than to the front, a wedge
segment is subjected to a higher load, and therefore a higher degree of
friction basically occurs thereon. The wedge segment which is subjected
to a higher load is preferably therefore the wedge segment which is
mounted on both sides by means of sliding bearings. However, the other
wedge segment or - likewise preferably - both wedge segments can also
be mounted on both sides by means of sliding bearings.
The fitting according to the invention can be operated both manually and
by motor, and can be used in vehicle seats, preferably in order to adjust
the inclination of the backrest or the inclination of the seat cushion or a
thigh support or the seat height. The driver may be in a single part or in a
number of parts.
Since a wedge segment which is mounted on both sides by means of
sliding bearings is no longer self-locking, and also the fitting would
therefore possibly be no longer self-locking, a brake for said wedge
segment is provided at least on one side of the vehicle seat, said brake
holding the wedge segment in the inoperative state of the fitting and
being released during the driving of the rolling movement. A fitting of
this type is safe with regard to running-down as well as favorable with
regard to efficiency. A brake of this type does not need to be provided in
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the fitting on the other side of the vehicle seat.
A preferred brake is a wrap spring brake which supplies a high locking
moment on the output side, but, when a torque is introduced on the drive
side, rotates with a freewheeling moment which is low in relation to the
locking moment. Instead of a wrap spring brake, a clamping roller
freewheel may also be provided. The wrap spring brake produces its
locking moment preferably by bearing against a wrap spring bushing
which is rotationally fixed with respect to the second fitting part,
preferably by means of a positive fit between suitable projections, for
example radially protruding arms, of the wrap spring bushing and an
inner toothing (present because of the production process) of the second
fitting part. The wrap spring brake is preferably arranged within the wrap
spring bushing such that it bears against the inner wall thereof and its
customarily present wrap spring arms protrude radially inward. The latter
are preferably arranged in such a manner that a cam of one or both wedge
segments, upon bearing against a wrap spring arm, acts on the wrap
spring brake in a closing manner, and one or two cams of the driver
rotating during the driving operation, upon bearing against a wrap spring
arm, acts or act on the wrap spring brake in an opening manner.
The invention is explained in more detail below with reference to two
exemplary embodiments illustrated in the accompanying drawings, in
which:
Fig. 1 shows an exploded illustration of the first exemplary
embodiment,
Fig. 2 shows a partial view of the first exemplary embodiment with
4

the driver only partially indicated,
Fig. 3 shows a longitudinal section of a fitting according to the
invention,
Fig. 4 shows a schematic illustration of a vehicle seat,
Fig. 5 shows an exploded illustration of the second exemplary
embodiment, and
Fig. 6 shows a partial view of the second exemplary embodiment
without a driver.
A vehicle seat 1 for a motor vehicle has a seat part 3 and a backrest 4
which can be adjusted in its inclination relative to the seat part 3. A hand
wheel 5, which can be actuated manually in order to adjust the
inclination, on one side of the vehicle seat 1 rotates a drive shaft (not
illustrated specifically) which is arranged horizontally in the transition
region between seat part 3 and backrest 4 and, on both sides of the
vehicle seat 1, engages in a rotationally fixed manner in a respective
fitting 10. The backrest 4 is connected to the seat part 3 by means of the
two fittings 10.
The fitting 10 is designed as a geared fitting, in which a first fitting part
11 and a second fitting part 12 are connected to each other for adjustment
and fixing via a gear designed as an eccentric epicyclic gear which is self-
locking at least in the case of one of the two fittings 10 of the vehicle seat
1. The two fitting parts 11 and 12 have an essentially flat shape and are
composed of steel. The first fitting part 11 is connected fixedly to the
5

structure supporting the hand wheel 5 and the drive shaft (in the present
case, the structure of the backrest 4), for which reason, in the exemplary
embodiment, the first component 11 is illustrated in a manner fixed on
the backrest and therefore at the top in the drawing. Accordingly, in the
exemplary embodiment, the second fitting part 12 is fixed on the seat
part, i.e. is connected to the structure of the seat part 3, and is illustrated
at the bottom in the drawing. The positions of the fitting parts 11 and 12
may be interchanged, depending on requirements.
In order to form the gear, a toothed wheel 16 with an outer toothing is
embossed on the second fitting part 12 and a toothed ring 17 with an
inner toothing is embossed on the first fitting part 11, said toothings
meshing with each other. The diameter of the outside circle of the outer
toothing of the toothed wheel 16 is smaller by at least one tooth height
than the diameter of the root circle of the inner toothing of the toothed
ring 17. The corresponding difference in the number of teeth of toothed
wheel 16 and toothed ring 17 permits a rolling movement of the toothed
ring 17 on the toothed wheel 16.
On the side facing the toothed wheel 16, the first fitting part 11 has an
integrally formed collar extension 19 concentrically with respect to the
inner toothing of the toothed ring 17. A driver 21 is mounted with play by
means of a hub 22 in the collar extension 19. The driver 21, which is
composed of plastic and the arrangement of which defines the direction
details used, is provided centrally with a bore 23 which matches the
external splines of the drive shaft and runs axially. Furthermore, the
driver 21 has an integrally formed driver segment 25 which is arranged in
a sickle-shaped manner about part of the collar extension 19. Two wedge
segments 27a and 27b are supported, at least indirectly by means of their
6

curved inner side, on the collar extension 19 and, by means of their
curved outer sides, support a first sliding bearing 28 which is pressed into
the second fitting part 12 in a rotationally fixed manner. The friction
between the outer side of the metallic wedge segments 27a and 27b and
the inner side of the bushing-shaped, first sliding bearing 28 is
significantly lower than the direct friction between the wedge segments
27a and 27b and the fitting parts 11 or 12 would be.
The driver segment 25 grasps with play between the narrow sides of the
wedge segments 27a and 27b while the mutually facing wide sides of the
wedge segments 27a and 27b each support an angled end finger of a
spring coiled annularly, referred to below as omega spring 30. The omega
spring 30 pushes the wedge segments 27a and 27b apart in the
circumferential direction and therefore positions the fitting 10 in a
manner free from play in the inoperative state. The driver 21 is secured
axially on the outer side of the first fitting part 11 by means of a securing
ring 31 which is clipped on. In order to absorb the axially acting forces, a
respective holding plate (not illustrated in the drawing) is welded in a
manner known per se onto the two fitting parts 11 and 12 and engages
over the other fitting part in each case without obstructing the adjustment
movement.
The driver segment 25 and the wedge segments 27a and 27b define an
eccentric which, as an extension of the direction of eccentricity, presses
the toothed wheel 16 and the toothed ring 17 into each other at an
engagement point defined in this manner. During driving by means of the
rotating drive shaft, a torque is first transmitted to the driver 21 and then
to the eccentric which is defined in this manner and which slides along
the first sliding bearing 28, shifting the direction of eccentricity and
7

therefore shifting the engagement point of the toothed wheel 16 in the
toothed ring 17, which is depicted as a wobbling rolling movement of the
fitting parts 11 and 12 on each other.
Owing to the weight of the backrest 4, which is customarily situated
obliquely, and a pressure exerted on the backrest 4 by the occupant, a
differentiation can be made in the case of the wedge segments 27a and
27b between a first wedge segment 27a, which is subjected to a higher
load and is in front during an upward movement of the backrest 4, and a
second wedge segment 27b which is subjected to a lower load. The
efficiency of the fitting 10 depends noticeably on the friction between the
first wedge segment 27a and the collar extension 19. According to the
invention, in order to reduce this friction, a second sliding bearing 41 is
provided which sits in a more or less immovable manner on the first
wedge segment 27a and slides with little friction on the collar extension
19, i.e. corresponds functionally to the first sliding bearing 28.
In the first exemplary embodiment, the second sliding bearing 41 is
designed as a ring segment which extends over somewhat less than the
inner side of the first wedge segment 27a, while, in the second exemplary
embodiment, the second sliding bearing 41 is designed as a ring which is
more or less completely closed and on which the wedge segment 27
which is subjected to a lower load also sits. Since the two exemplary
embodiments otherwise correspond - apart from geometrical adaptations
to the shape of the second sliding bearing 41, components which are
identical and act in an identical manner bear the same reference numbers.
In a modification to both exemplary embodiments, the second sliding
bearing 41 on the inner side of the collar extension 19 is arranged in a
region free from the hub 22, and the wedge segment 27a which is
8

subjected to a stronger load is mounted therein by means of an extension
arm.
The friction between the first wedge segment 27a and the collar extension
19 not only has an effect on the efficiency but also on the self-locking of
the gear of the fitting 10. So that at least one of the two fittings 10 of the
vehicle seat 1 remains self-locking in spite of the first wedge segment 27a
being mounted in a sliding manner on two sides, according to the
invention, in the case of this fitting 10, a brake which is effective in the
inoperative state of the fitting 10 is provided, in the present case a wrap
spring brake 44, which is arranged in a wrap spring bushing 46 and, on
account of its prestress, bears frictionally against the inner wall thereof.
The wrap spring bushing 46, which is produced, for example, from
plastic, is arranged in a rotationally fixed manner on the second fitting
part 12 by three groups of three radially (and/or axially) protruding wrap
spring bushing arms 48 which are offset with respect to one another by
120° in each case engaging with a positive fit in the inner toothing
produced on the rear side of the toothed wheel 16 by the embossing
operation.
For actuation, the wrap spring brake 44 has a radially inwardly protruding
wrap spring arm 50 at each of its ends. The first wedge segment 27a is
provided with an axially protruding brake cam 51 which is arranged
between the two wrap spring arms 50 with play in the circumferential
direction, i.e. in the region within the same. A bearing of the brake cam
51 against a wrap spring arm 50 acts on the wrap spring brake 44 in a
closing manner, i.e. brakes the wrap spring brake 44 and prevents rotation
of the components defining the eccentric relative to the second fitting part
12. With blockage of the eccentric, the first fitting part 11 is also fixed
9

relative to the second fitting part 12.
In order to cancel the braking action of the wrap spring brake 44 during
driving of the driver 21, firstly, at the end of the driver segment 25 which
is assigned to the first wedge segment 27a, a first driver cam 53 is
provided on the driver 21 and, secondly, a second driver cam 55 is
provided in the region which is arranged at approximately identical radial
spacing between the ends of the driver segment 25, said driver cams both
protruding axially. The wrap spring arms 50 together with the brake cam
51 are arranged with play between the two driver cams 53 and 55, i.e. the
driver cams 53 and 55 are arranged in the circumferential direction
outside the wrap spring arms 50. When the driver 21 is rotated, first of all
one of the driver cams 53 or 55 passes to bear against a wrap spring arm
50, which acts on the wrap spring brake 44 in an opening manner and
cancels the braking action. As the movement continues, the eccentric
drives the above-described rolling movement of the fitting parts 11 and
12 on each other.
10

List of reference numbers
1 Vehicle seat
3 Seat part
4 Backrest
5 Hand wheel
10 Fitting
11 First fitting part
12 Second fitting part
16 Toothed wheel
17 Toothed ring
19 Collar extension
21 Driver
22 Hub
23 Bore
25 Driver segment
27a First wedge segment
27b Second wedge segment
28 First sliding bearing
30 Omega spring
31 Securing ring
41 Second sliding bearing
44 Wrap spring brake
46 Wrap spring bushing
48 Wrap spring bushing arms
50 Wrap spring arm
51 Brake cam
53 First driver cam
11

55 Second driver cam

12

WE CLAIM:
1. A fitting for a vehicle seat, in particular for a motor vehicle seat,
with a first fitting part (11), a second fitting part (12) in geared
connection with the first fitting part (11), with a driver (21) and
wedge segments (27a, 27b), which at least partially define an
eccentric which is mounted rotatably in the first fitting part (11)
and is intended for driving a rolling movement of first fitting part
(11) and second fitting part (12) on each other, and with a first
sliding bearing (28) or rolling bearing, by means of which the
wedge segments (27a, 27b) are mounted with little friction on the
second fitting part (12), characterized in that at least a first (27a) of
the two wedge segments (27a, 27b) is mounted with little friction
on the first fitting part (11) by means of a second sliding bearing
(41) or rolling bearing.
2. The fitting as claimed in claim 1, characterized in that the first
wedge segment (27a) is the one of the two wedge segments (27a,
27b) which is subjected to a higher load during driving of the
fitting (10).
3. The fitting as claimed in claim 1 or 2, characterized in that both
wedge segments (27a, 27b) are mounted with little friction on the
first fitting part (11) by means of the sliding bearing (41) or a
respective second sliding bearing (41).
4. The fitting as claimed in one of claims 1 to 3, characterized in that
the first wedge segment (27a) is held in the inoperative state of the

fitting (10) by means of a brake (44) which is released during the
driving of the rolling movement.
5. The fitting as claimed in claim 4, characterized in that a wrap
spring brake (44) which, in particular, has two wrap spring arms
(50) is provided as the brake.
6. The fitting as claimed in claim 5, characterized in that the wrap
spring brake (44) bears against a wrap spring bushing (46) which is
rotationally fixed with respect to the second fitting part (12).
7. The fitting as claimed in claim 6, characterized in that the wrap
spring bushing (46) has a plurality of radially protruding wrap
spring bushing arms (48) which engage with a positive fit in an
inner toothing of the second fitting part (12).
8. The fitting as claimed in one of claims 5 to 7, characterized in that
at least one of the wedge segments (27a), in particular the first
wedge segment (27a), has a brake cam (51) which, upon bearing
against a wrap spring arm (50), acts on the wrap spring brake (44)
in a closing manner.
9. The fitting as claimed in one of claims 5 to 8, characterized in that
the driver (21) has at least one driver cam (53, 55) which, upon
bearing against a wrap spring arm (50), acts on the wrap spring
brake (44) in an opening manner.
10. A vehicle seat, in particular motor vehicle seat, with a seat part (3)

and a back rest (4) which can be adjusted in its inclination relative
to the seat part (3) and is attached to the seat part (3) on at least one
side of the vehicle seat (1) by means of a fitting (10) as claimed in
one of claims 1 to 9.
15

The invention relates to a fitting (10) for a vehicle seat, more particularly
for a motor vehicle seat, comprising a first fitting part (11), a second fitting part
(12) that is in geared connection with the first fitting part (11), a driver (21) and
wedge segments (27a, 27b) which at least partly define a cam that is rotatably
mounted in the first fitting part (11) for driving a rolling movement of the first
fitting part (11) the second fitting part (12) against one another, and with a first
sliding bearing (28) or rolling bearing, by means of which the wedge segments
(27a, 27b) are mounted on the second fitting part (12) with a small amount of
friction, at least a first (27a) of the two wedge segments (27a, 27b) being
mounted on the first fitting part (11) with a small amount of friction by means
of a second sliding bearing (41) or rolling bearing.

FITTING FOR A VEHICLE SEAT, IN PARTICULAR FOR A MOTOR VEHICLE SEAT

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