Hinge fitting for motor vehicle seats

A hinge fitting for motor vehicle seats having an adjustable backrest comses a fixed hinge member, which is associated with the seat, and a swivelling hinge member which is associated with the backrest. The two hinge members are connected via an eccentric so as to swivel, and both hinge members comprise sets of toothing which engage with each other and form part of a wobble mechanism. The eccentric may be swivelled about a first swivelling axis in a first pivot bearing relative to the other hinge member. Both pivot bearings are arranged eccentrically relative to each other. The pivot bearings are formed by plain bearing bushings which are mounted in the hinge members. For the purpose of calibration by means of a calibrating mandrel, the plain bearing bushings are plastically compressible. The running surfaces of the plain bearing bushings observe, in each case, the smallest spacing from the associated axis of the hinge member which accommodates the respective plain bearing bushings. The hinge fitting has an only small overall width and has a high internal stability, even against high forces such as may arise during accidents. In addition, the hinge fitting has extremely small bearing clearances which are obtained with simple manufacturing methods.

TECHNICAL FIELD 
The invention relates to a hinge fitting for motor vehicle seats. 
BACKGROUND OF THE INVENTION 
Hinge fittings for motor vehicle seats are parts which are manufactured on 
an industrial scale and in numbers of several million annually. Nowadays, 
the assembling, in this regard, is carried out fully automatically, 
comprising a screening inspection, and is continued round the clock, for 
an optimal utilization of the machines and assembling apparatus. Under 
these given circumstances, a high degree of reliability must be striven 
for from the outset when designing a hinge fitting, such that it is 
possible to carry out the assembly rapidly and, above all, fully 
automatically and trouble-free. This high degree of reliability may be 
ensured relatively readily by providing suitably large positive allowances 
for the assembly of the individual parts. In the case of a hinge fitting 
for motor vehicle seats, considerable limits are, however, imposed in this 
regard, since the sum total of all allowances makes itself felt as a 
certainly considerable and unpleasant backlash at the upper edge of the 
backrest. Since the requirement is to keep the play of the backrest as 
small as possible, the designer of the hinge fitting is thus obliged to 
aim for the narrowest tolerances possible. Thus, in conjunction with the 
dependability, which is referred to as operating reliability, in the 
automatic manufacture of parts on an industrial scale, this results in 
distinctly conflicting objectives. 
In a hinge fitting of the kind which is presupposed as being known for 
example from DE 27 24 637, the mounting of the eccentric is statically 
overdesigned. The statically overdesigned mounting has the drawback that a 
satisfactory adjustment is possible only when the backrest fitting 
mounting plates, which are provided on different sides of the eccentric, 
are arranged such that the mounting bores are accurately aligned. In 
industrial scale manufacture, this requirement cannot be met to the 
desired extent. When there are alignment errors, the swivelling axis is 
out-of-true, resulting in a sluggish adjustment together with a 
considerable reduction in comfort. To give practical effect to this 
construction, it is necessary that the positive mounting allowances in the 
two mounting bores are designed to be correspondingly large. Although this 
ensures the desired smooth adjusting action, it does have the drawback 
that an undesirably large backrest backlash must set in. 
In addition, a further hinge fitting of the kind is known (DE 32 26 714 
C2), in which the eccentric is mounted in a statically defined manner. 
Only one bearing is provided per hinge member. Loading of the backrest 
tends to twist the two hinge members relative to each other. The resultant 
forces are transferred to the swivelling axis bearing regions via the 
bearings. This causes a moment which brings about an out-of-true position 
of the axis. This out-of-true position results in canting of the bearings 
and in a resultant stiff adjusting action. This problem is particularly 
serious when the bearings are formed by steel-on-steel bearings having a 
grease lubrication. 
Starting out from the above-mentioned state of the art, the invention is 
based on the object of designing a hinge fitting of the kind presupposed 
as being known, such that the drawbacks of the known pertinent hinge 
fittings are avoided. It is intended to provide a hinge fitting which has 
a smooth action even when the tolerances in the bearings are kept 
relatively small. Besides, it should be possible to adhere, with a 
relatively low manufacturing outlay, to such very small bearing clearance 
tolerances and to achieve a high degree of process reliability in the 
manufacture of the individual members and in the assembly. 
SUMMARY OF THE INVENTION 
In accordance with the present invention there is provided a hinge fitting 
for motor vehicle seats having an adjustable backrest, in which a fixed 
hinge member, which is associated with the seat, and a swivelling hinge 
member, which is associated with the backrest, are connected via an 
eccentric, and both hinge members are provided with sets of toothing, 
which engage each other and form part of a wobble mechanism, wherein the 
eccentric may be swivelled about a first swivelling axis in a first pivot 
bearing relative to one hinge member and about a second swivelling axis in 
a second pivot bearing relative to the other hinge member. Both pivot 
bearings are arranged eccentrically relative to each other and the pivot 
bearings are formed by plain bearing bushings which are mounted in the 
hinge members and/or the eccentric the running surfaces of which bushings 
observe, in each case, the shortest spacing from the associated axis of 
the hinge fitting which accommodates the respective plain bearing bushing, 
the plain bearing bushings being plastically compressible for calibration 
by means of a calibrating mandrel. 
The design of the pivot bearings as plain bearing bushings, which are 
mounted in the hinge members, and their arrangement as well as their 
plastic compressibility have considerable advantages: 
Already the use of plain bearing bushes, in conjunction with stamped sheet 
metal parts which can be manufactured economically, is advantageous. The 
arrangement of the plain bearing bushings in such a way that the larger 
plain bearing encircles the smaller plain bearing, in each case with a 
clearance, and a common plane extending through the plain bearing bushings 
and through the cooperating toothing, results in that cantings in the 
eccentric drive decreases. In addition, an only small axial overall width 
and a considerable internal stability of the hinge fitting are achieved, 
even against high forces which may arise during accidents. 
The plain bearing or plain bearing bushings may be calibrated by means of a 
calibrating mandrel. This results, on the one hand, in the desired very 
narrow bearing tolerances with, at the same time, economical manufacture 
and, on the other hand, in achieving the desired high degree of operating 
reliability. 
The plain bearing bushings may co-operate with unhardened associated 
sliding members. By dispensing with a hardening operation, errors 
resulting from distortions on hardening are prevented. In addition, the 
use of unhardened individual components increases the desired high degree 
of operating reliability. 
The plain bearing bushings which are usually used are composed of a, 
preferably slotted, steel ring which takes up about 90% of the bearing 
volume. Onto this steel ring, a bronze layer, comprising about 9% of the 
bearing volume, is applied and a sliding layer of about 1% of PTFE 
(polytetrafluoroethylene) and lead is, in turn, applied onto said bronze 
layer. The non-steel volume of the plain bearing permits a calibration of 
the plain bearing within certain limits. After mounting and calibrating, a 
defined bearing diameter with a precision of a few thousandths of 
millimeters is ensured. When the calibrating mandrel has been driven 
through the bearing, in the course of the fully automatic assembling 
operation, it is thus ensured that a minimum dimension, which is required 
for production, is provided. It is then also possible to mount the 
eccentric with the desired minimum bearing clearance and to turn it 
readily. The fact that the bearings may be calibrated permits an increase 
in the precision during the manufacturing process, and this may be 
exploited to reduce the play and, at the same time, to increase the 
operating reliability. 
A subsequent precision increase of the bearings during the assembly 
operation is not known in the relevant state of the art for hinge 
fittings. Indeed, in the state of the art, the precision of the bearings 
was heretofore exclusively determined by the precision of the bearings 
themselves which were used and the associated bearing seats. The precision 
of the calibrated bearings has the result that the actuating moment of the 
fitting is smaller than that which would be required for ergonomic 
reasons. The result hereof is a reserve which may be used for a braking 
moment, which is to be provided artificially, with the aid of an installed 
friction brake. 
Preferred embodiments of the present invention are set out in detail in the 
following description of the drawings.

DETAILED DESCRIPTION OF VARIOUS AND PREFERRED EMBODIMENTS OF THE INVENTION 
In the Figures of the drawing, identical or corresponding parts bear the 
same reference numbers or reference numbers which are distinguished by the 
number of apostrophes or by a numeral which is greater by 100. 
In the embodiments according to FIGS. 1 to 4, a hinge member 2 is connected 
to the seat 212 of the motor vehicle seat, while a hinge member 1 is 
connected to the backrest 213 of the motor vehicle seat. In the case of 
the embodiments according to FIGS. 5 to 12, the hinge member which is 
firmly connected to the seat is designated by reference number 102, and 
the hinge member which is connected to the backrest 213 is designated by 
reference number 101. The seat-fixed hinge member 2 or 102 is firmly 
secured to a hinge member 210 which can swivel about the swivelling axis 
214, in order to tilt the backrest 213 forward. The backrest 213 is locked 
in position by means of a latch 211. 
The handwheel 209 serves to rotate the eccentric. 
The relevant design of the hinge fitting is more clearly visible in the 
various cross-sectional drawings. 
Referring, firstly to the embodiment shown in FIGS. 2-4, it can be seen 
that both hinge members 1 and 2, in each case, comprise two sets of 
toothing which, in each case, are arranged to be staggered. The hinge 
member 1 comprises the staggered rows 1a and 1b of teeth, the row 1a of 
teeth having a smaller reference diameter than the row 1b of teeth. The 
hinge member 2 is provided with correspondingly staggered toothing with 
differing reference diameters which are designated by the reference 
numbers 2a and 2b. 
In the illustrated exemplified embodiments 2 to 4, the rows 1a and 1b of 
teeth engage in the upper region with the rows 2a and 2b of teeth, whereas 
they do not engage in the lower region. The rows of teeth which are in a 
working connection form the toothed part of a wobble mechanism which is 
known in hinge fittings for motor vehicle seats. 
The hinge member 1 comprises a bearer 7, together with a bearer bore 7a. A 
plain bearing bushing 5, which extends concentrically relative to the 
bearer bore 7a and relative to the swivelling axis 20, is provided on the 
outer edge of the bearer 7. 
An eccentric 4 is supported for rotation on the plain bearing bushing 5, 
the rotation of which eccentric is carried out via a central square by 
means of a drive shaft which is not illustrated. 
The eccentric 4, in turn, abuts on all sides with its outer eccentric 
surfaces on a plain bearing bushing 6 which is secured in the hinge member 
2. The plain bearing bushings 5 and 6 are offset eccentrically relative to 
each other. The arrangement of the plain bearing bushings 5 and 6 is 
selected such that not only the plain bearing bushings but also the rows 
1a or 1b of teeth are disposed in the region of a common plane which 
extends perpendicularly relative to the axis of rotation 20. 
A bowl-like locking plate 3, which serves as a stop member, is attached to 
the hinge member 2. A brake disc 10 is arranged between the inwardly 
directed flat side of the locking plate 3 and an opposite, 
parallel-extending shouldered region of the eccentric 4. The eccentric 4 
is pressed in the axial direction against the circumferential rib 7b of 
the bearer 7, by the brake disc 10. In a rotation of the hinge members 
relative to each other, which is brought about by the drive of the 
eccentric 4, the flat end faces of the brake disc 10 become operative. 
The eccentric comprises a wave-like region 8a which is guided with a 
clearance in the bearer bore 7a. This construction permits a very flat 
design. 
In the embodiment according to FIG. 3, the fundamental design of the hinge 
members 1 and 2, the rows 1a and 2a of teeth, the plain bearing bushings 5 
and 6, is virtually identical to that of the first embodiment. A 
difference lies, primarily, in the design of the eccentric 4', which 
comprises a wave-like region 8a. At the end of this wave-like region 8a, 
toothing 11 is provided, as is a square socket 9'. The drive of the 
wave-like region 8' may be provided by a drive motor or by hand. 
The wave-like region 8' is supported in the bearer bore 7a. The wave-like 
region is form-lockingly connected to the eccentric region 4' via a 
square. The eccentric region 4' extends, with its outer surface, in the 
plain bearing 6 and, with its inner surface, in the plain bearing 5. At 
its end face, the wave-like region 8' of the eccentric is provided with a 
spherical projection 12 which abuts against the bowl-shaped locking plate 
3' which is firmly connected to the hinge member 2. A wave-shaped disc 
10', which serves as a brake disc, is provided between that end face of 
the eccentric 4' which faces the locking plate 3' and the inner side of 
the locking plate 3'. The brake disc 10' presses the end face 13 of the 
eccentric 4' against the hinge member 1. 
The embodiment according to FIG. 4 essentially corresponds to the 
embodiment according to FIG. 2. The differences reside, primarily, in the 
design of the eccentric, the design of the hinge member 1' and the 
arrangement of the brake disc 10". 
The hinge member 1' comprises a fixed hub region 14. The eccentric 4" is 
supported inwardly on a plain bearing 5 which is concentric with the axis 
of rotation 20. The eccentric outer region of the eccentric 4" runs in the 
plain bearing 6 which is secured in the hinge member 2. 
A locking plate 3" which is fixed to the hinge member 2, presses the 
eccentric 4" with its end face, in the direction of the brake disc 10". 
The drive of the eccentric is provided in the same manner as in the case 
of the embodiment according to FIG. 2, via a square socket 9 in the 
eccentric 4". 
With reference to FIGS. 5 to 12 the hinge fitting shown comprises two hinge 
members 101 and 102. The hinge member 102 is connected to the stationary 
seat of the motor vehicle seat, while the hinge member 101 is firmly 
connected to the tilting backrest of the motor vehicle seat. 
Both hinge members comprise, in each case, two sets of toothing which are, 
in each case, arranged to be staggered. The hinge member 101 comprises the 
staggered rows of teeth 101a of teeth 101b the row of teeth 101a having a 
smaller reference diameter than the row of teeth 101b. The hinge member 
102 is provided with corresponding staggered toothings which have 
differing reference diameters and are designated by reference numbers 102a 
and 102b. 
In the exemplified embodiments illustrated, the rows of teeth engage 101a 
and 101b, in the upper region, with the rows of teeth engage 102a and 
102b, while they do not engage in the lower region. The rows of teeth 
which are in a working connection form the toothed part of a wobble 
mechanism which is known in hinge fittings for motor vehicle seats. 
The hinge member 101 comprises a collar or bearer 107, together with a 
bearer bore 107a. A plain bearing bushing 105, which extends 
concentrically relative to the bearer bore 107a and relative to the axis 
of rotation 120 of the movable hinge member 101, is mounted in the bearer 
bore 107a. The collar 107 has an outside diameter 107b. 
An eccentric 104, which is designed to be substantially disc-shaped, is 
mounted for rotation in the plain bearing bushing 105. The rotation of the 
eccentric is carried out via a central square bore 109 by means of a drive 
shaft, which is not illustrated. The eccentric 104, in turn, is supported 
on all sides with its outer eccentric surface in a plain bearing bushing 
106 which is supported in a centre bore 126 of the hinge member 102. The 
plain bearing bushing 105 and 106 are offset eccentrically relative to 
each other. The arrangement of the plain bearing bushes 105 and 106 is 
selected such that not only the plain bearing bushings but also the rows 
1a or 1b of teeth are disposed in the region of a common plane which 
extends perpendicularly relative to the axis of rotation 20. 
Reference number 121 designates the axis of the centre bore 126 or of the 
plain bearing bushing 106, respectively. 
An end plate 103 is secured to the hinge member 101. An annular brake disc 
110 is arranged between the flat inner surface of the end plate 103 and 
the opposite flat region of the eccentric 104. Reference number 108 
designates a cylindrical region of the eccentric 104, which region 
surrounds, with a small clearance, the outside diameter of the collar 107. 
The central axis of the cylindrical region 108 coincides with the axis of 
rotation 120. 
In the drawing FIG. 6, the two hinge members 101 and 102 are illustrated 
individually, calibrating mandrels 122 and 123 also being shown. The plain 
bearing bushing 106 is mounted in the centre bore 126 of the hinge member 
102 and is then calibrated by the calibrating mandrel 123. The calibration 
of the small plain bearing bush 105 is carried out in a corresponding 
manner, said bush first being mounted in the bearer bore 107a before it is 
calibrated by the calibrating mandrel 122. Assembling apparatus is 
available, by means of which the mounting and subsequent calibrating of 
the plain bearing bushes 105 and 106 are carried out in a single working 
step. 
In the case of the embodiment according to FIG. 7, the hinge members in 
each case have only one row of teeth and the eccentric 104' is designed, 
in this instance, to be annular. The opposing surface for the small plain 
bearing bushing 105 is, in this case, the outside diameter 107b of the 
collar 107. The annular eccentric 104' may be manufactured as a 
precision-stamped part or as a sintered product. It is provided with 
driving pins 104a which engage in corresponding bores 125 of a carrier 
124. The drive is, in this instance, provided via a connecting rod, which 
is not illustrated, via the square 109' in the carrier 124. 
The drawing FIG. 8 shows the eccentric ring 104' with the associated 
calibrating mandrel 122' and the hinge member 102, together with the 
mounted plain bearing 106 and the calibrating mandrel 123 which is 
provided. By means of the calibrating mandrel 122', a calibrated bearing 
diameter 105a is produced, and by means of the calibrating mandrel 123, a 
calibrated bearing diameter 106a of the plain bearing 106. 
FIGS. 9 to 11 show different designs of carriers 124', 124" and 124'", 
which co-operate with the eccentric ring 104'. 
In its various forms, the carrier may be designed to vary greatly, for 
example, as a die-cast zinc part or even as a plastics part. In the 
embodiment according to FIG. 9, a carrier 124'" is shown, which is 
inwardly provided with the square bore 109' to receive a connecting rod 
111 (see FIG. 12). In addition, it is provided with a levelling 130, for 
connection to a handwheel. The corresponding fitting on the other side of 
the backrest is merely provided with a simple carrier 124, such as is 
shown in FIG. 12. 
FIG. 10 shows a carrier 124" which, for an electric drive, comprises a 
toothing 127 in which a pinion of a geared motor can engage. In addition, 
a square socket bore 109" is provided to accommodate a connecting rod 111. 
In the embodiment according to FIG. 11, a carrier 124'" is illustrated 
which may be assembled differently. It is provided, on both sides, with 
receiving bores having a multi-spline profile 128 and 128'. Various 
structural components may be pressed therein or secured in any other 
manner, for example, by means of clips. Thus, for example, on the 
left-hand side a handwheel support 130' comprising a multi-spline journal 
29 is illustrated and, on the right-hand side, a toothed belt hub 131 
comprising a toothed profile 132. The drive may be provided via the 
toothed profile 132, by means of a toothed belt, by means of a handwheel 
which is arranged to be offset. 
The design according to FIG. 11 permits that the fitting comprising the 
integrated carrier 124'" may be equipped, after assembly, to meet the 
widest range of customer requirements. It is sufficient to manufacture a 
single standard fitting. 
Finally, in FIG. 12, a right-hand and a left-hand embodiment of a fitting 
are illustrated. Each of the backrest struts, which are not illustrated, 
is connected to the movable hinge member 101 of a fitting. A connecting 
rod 111 is supported in the square bores 109 of the eccentrics 104, or in 
the square bores 109' of the carrier 124. The left-hand square 111b is 
designed to be longer, such that the handwheel used for adjusting may be 
attached thereto. By means of the connecting rod 111, it is ensured that 
the adjusting operation is carried out synchronously in both fittings, 
thus tilting the backrest completely uniformly.