Note: Descriptions are shown in the official language in which they were submitted.
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Motor vehicle seat
The present invention relates to a motor vehicle seat
comprising a seat frame and a backrest frame which is in each
case connected pivotably to the seat frame at the side via
fittings. The invention also relates to a motor vehicle
equipped with at least one motor vehicle seat of this type.
DE 20 2010 000 807 Ul discloses a motor vehicle seat of the
type in question comprising a seat frame and an associated
backrest frame which is connected pivotably to the seat frame
via lateral fittings. In this case, a connection between the
fittings and the seat frame is realized via a screw connection.
The seat frame is substantially formed from a base surface
element, the front edge and the two side edges of which are
used to form a first oval tube which is bent in a U-shaped
manner and has an upwardly oriented cross section. In general,
this embodiment is intended to provide a motor vehicle seat
which is firstly constructed as simply as possible
structurally, but secondly is as robust as possible, in
particular for military vehicles.
US 6,543,855 52, US 7,083,215 52 and FR 2 842 476 Al disclose
further motor vehicle seats, each comprising a seat frame and a
backrest frame.
A common feature of all of the motor vehicle seats known from
the prior art is that a backrest frame is in each case screwed
to lateral fittings which, in turn, are fastened in an
articulated manner to the seat frame of the associated motor
vehicle seat. However, a disadvantage of the known motor
vehicles is that, in the event of a crash, an extremely
unfavorable loading, namely a torsional loading with lever
forces which are not to be underestimated, acts on the screw
connection.
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The present invention therefore deals with the problem of
providing an improved embodiment for a motor vehicle seat of
the type in question, said embodiment being distinguished in
particular by an improved crash performance.
In a broad aspect, the present invention provides a motor
vehicle seat 1 comprising a seat frame 2 and a backrest
frame 3 which is in each case connected pivotably to the
seat frame 2 at the sides via fittings 4, wherein the
fittings 4 are screwed at least to the seat frame 2,
characterized in that a screwing(-in) direction of at least
one screw 8 fixing one fitting 4 in each case to the
associated seat frame 2 runs substantially in the vertical
direction z of the vehicle.
The present invention is based on the general concept of
rotating a screwing-in direction of screws screwing a seat
frame to lateral fittings by 900 such that the screwing(-in)
direction of said screws, i.e. the longitudinal axis
thereof, no longer runs as previously in the transverse
direction of the vehicle, but rather now runs in the
vertical direction of the vehicle, i.e. parallel to a z
axis, and, as a result, in the event of a crash, said screws
are not subjected to torsional loadings but rather
exclusively to transverse forces, for which said screws are
designed and are also dimensioned and which can be
significantly better absorbed by said screws. The motor
vehicle seat according to the invention has a seat frame and
a backrest frame, wherein the latter is in each case
connected pivotably to the seat frame at the sides via
fittings. The screw connection according to the invention of
the fittings to the seat frame, i.e. in particular also the
orientation according to the invention of the screws in the
vertical direction of the vehicle, means that, in the event
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of a crash, i.e., for example, in the case of a rear impact,
the screws are not subjected to a torque having a lever arm,
but rather merely to a transverse force via the respective
tension and compression straps of the seat frame. In
addition, the arrangement according to the invention and the
orientation of the screws in the vertical direction of
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the vehicle enable the distance of said screws from a neutral
fiber to be maximized and, as a result, the force absorption
of said screws to be optimized. This is because, the greater
the distance from the neutral fiber, the smaller are the
forces which are to be applied there in order to be able to
provide a required holding moment. In this connection, a
further important advantage to be mentioned is that the
orientation of the screws in the vertical direction of the
vehicle now corresponds to the demolding direction, as a
result of which, in particular, improvements in terms of the
manufacturing technology can be obtained.
In an advantageous development of the solution according to
the invention, at least one of the fittings has a U-shaped
design with two U limbs bordering the seat frame, wherein said
U limbs run parallel to the transverse direction of the
vehicle and at least one screw running parallel to the
vertical direction of the vehicle is guided through each U
limb and is screwed to the seat frame. By means of this
embodiment of the fittings or of a lower part of said fitting
that faces the seat frame, the fitting can be of comparatively
stiff design per se and, by means of the configuration
surrounding the seat frame, can be connected in a particularly
stiff manner to same.
The backrest frame expediently has tension and compression
straps, wherein the fittings are in each case screwed directly
to the tension and compression strap. The direct screwing of
the fittings to the tension and compression straps of the
backrest frame enables a particularly favorable force flux to
be achieved, in particular in the event of a rear impact,
wherein the tension and compression straps are also designed
to be particularly stiff and for the absorption of large
loadings. The tension and compression straps customarily run
on an upper or lower side of the seat frame.
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In a further advantageous embodiment of the solution according
to the invention, the seat frame and/or the backrest frame
are/is formed from light metal, in particular from cast
magnesium. Magnesium is, for example, lighter than aluminum by
again approx. 30%, but a significantly increased strength can
be achieved by adding corresponding alloy elements. Of
particular advantage in the case of magnesium alloys of this
type are, in particular, the very good casting properties
thereof, which also permit the production of complicated die
castings having high surface quality. A further great
advantage in this case is that magnesium does not have such a
corrosive effect on the steel crucibles and molds as, for
example, an aluminum melt, and that the operation can be
carried out with smaller draft angles.
Further important features and advantages of the invention
emerge from the dependent claims, from the drawings and from
the associated description of the figures with reference to
the drawings.
It goes without saying that the features mentioned above and
those which have yet to be explained below can be used not
only in the respectively stated combination but also in other
combinations or on their own without departing from the scope
of the present invention.
Preferred exemplary embodiments of the invention are
illustrated in the drawings and are explained in more detail
in the description below, wherein the same reference numbers
refer to identical or similar or functionally identical
components.
In the drawings, in each case schematically,
fig. 1 shows a motor vehicle seat according to the
invention in a side illustration,
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fig. 2 shows the screw connection according to the
invention for holding of the seat frame on the
associated fitting.
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According to figure 1, a motor vehicle seat 1 according to the
invention has a seat frame 2 and a backrest frame 3, wherein
the backrest frame 3 is in each case connected to the seat
frame 2 at the sides via corresponding fittings 4 (cf. also
the detailed illustration in figure 2). In this case, each of
the fittings 4 consists of an upper part 5 facing the backrest
frame 3 and of a lower part 6 facing the seat frame 2, wherein
the two parts 5, 6 of the respective fitting 4 are mounted
pivotably on each other and thereby permit pivoting of the
backrest frame 3 relative to the seat frame 2 in a customary
manner. The upper part 5 of the fittings 4, and therefore the
fitting 4 itself, is in this case screwed to the backrest
frame 3, wherein here a screwing(-in) direction of at least
one screw 7, i.e. a longitudinal axis of same, runs preferably
in the longitudinal direction of the vehicle, i.e. in the x
direction. This brings about particularly good holding of the
backrest frame 3 in the event of a crash, in which particular
impact forces occur in the longitudinal direction of the
vehicle. In order also to be able optimally to conduct the
high forces occurring in particular in the event of a crash
into the seat frame 2, provision is made in the motor vehicle
seat 1 according to the invention for a screwing(-in)
direction of at least one screw 8 fixing the respective
fitting 4 to the associated seat frame 2 to run substantially
in the vertical direction z of the vehicle. In addition to the
improved force absorption, the screws 8 running in the
vertical direction z of the vehicle are also particularly
favorable in terms of manufacturing technology, since said
screws run parallel to the demolding direction. By this means,
in particular, improved assembly and disassembly of the motor
vehicle seat 1 can be obtained. In order to clarify the force
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profile improved by the screws 8 arranged according to the
invention, reference is made in particular to figure 2.
Looking therefore at figure 2, it can be seen that an
effective distance A between the two initiating forces F, and
therefore also a lever arm A/2, with respect to the neutral
fiber 9 is significantly greater than is the case hitherto
with screws 8' (merely illustrated by the broken line
according to figure 2) running in the transverse direction y
of the vehicle. With screws 8' running in the transverse
direction y of the vehicle, the lever arm is merely A*/2 and
is thereby significantly shorter than A/2, as a result of
which, with the same screw quality, a smaller amount of force
could be absorbed. The screws 8 arranged according to the
invention therefore maximize the lever arm A/2 with respect to
the neutral fiber 9 and thereby permit a significantly
increased force absorption, which has a positive effect in
particular in the event of a crash. In this case, the moment
zero always prevails in the neutral fiber 9.
Looking at the lower part 6 of the fitting 4 in figs. 1 and 2,
it can be seen that said fitting has a U-shaped design with
two U limbs 10, 10' bordering the seat frame 2, wherein said U
limbs 10, 10' run parallel to the transverse direction y of
the vehicle, and wherein at least one screw 8 preferably
running parallel to the vertical direction z of the vehicle,
or, as shown in Fig. 1 two screws 8, is or are guided through
each U limb 10, 10' and screwed to the seat frame 2.
The seat frame 2 and/or the backrest frame 3 are preferably
formed from light metal, in particular from cast magnesium,
and therefore, owing to the reduced weight, are particularly
suitable for manufacturing sports cars. As an alternative, for
example, the backrest frame 3 can also be designed as a shaped
sheet metal part.
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The seat frame 2 also has tension and compression straps 13,
13' via which force is introduced and via which the fittings 4
are connected or screwed to the seat frame 2. Since the
fittings 4 themselves have to withstand particularly high
loadings, said fittings are preferably designed as steel parts
and are therefore capable of absorbing high forces. The
tension and compression straps 13, 13' are illustrated
according to figure 2 by arrows and by broken line, wherein,
depending in each case on the moment introduced, the tension
strap 13 runs either along the upper U limb 10 or along the
lower U limb 10'.
Of course, a padding 12 with a cover can be arranged in a
known manner on both the seat frame 2 and on the backrest
frame 3, said padding being pulled over and covering the seat
frame 2 and the backrest frame 3 and enabling pleasant and
comfortable sitting on the motor vehicle seat 1.
With the motor vehicle seat 1 according to the invention, a
motor vehicle 11 equipped therewith can in particular be
formed safely, since a comparatively high force absorption in
the connecting region between the fittings 4 and the seat
frame 2 is possible by means of the screw connection according
to the invention and orientation of the screws 8. By means of
the relatively large lever arm, the screws 8 can also be
dimensioned to be smaller and therefore reduced in weight, but
nevertheless can absorb the same forces. In addition, by means
of the screwing direction of the screws 8 running
substantially parallel to the demolding direction, i.e. in the
vertical axis z of the vehicle, the assembly or disassembly of
the motor vehicle seat 1 can be facilitated.
