Note: Descriptions are shown in the official language in which they were submitted.
21 63963
A Seal for a Shaft Opening for a Cross-country Vehicle
The present invention relates to a seal between a wheel hub
and a wheel mounting of a cross-country vehicle, this
consisting of at least one shaft seal and a coarse seal that
is arranged on the outside of this, this coarse seal
consisting of a first ring and a second ring, the first such
ring being connected to the wheel hub and the second being
connected to the wheel mounting in such a manner as to be
unable to rotate independently of it.
In cross-country vehicles, regardless of whether they are
wheeled or tracked vehicles, there is a problem in that when
negotiating bodies of water or swamp, it is not only water but
also the sand that is always contained in this water that has
to be kept away from the sensitive shaft seals.
A seal of this type is known from AT-PS 389 361. In this seal,
the ring that is fixed to the wheel hub is a collar that is
oriented towards the outside and forms a trap space, and the
ring that is secured to the wheel mounting is a similar collar
with an edge that overlaps the first ring on the outside. This
thus forms a sealing gap that extends in a radial direction.
It has being found that when this solution is used, water and
abrasive dirt cannot be kept away from the annular seal under
extreme conditions (sand, great depths of water).
Consequently, its sensitive and soft sealing lip wears very
rapidly and is destroyed. In addition, the sealing gap depends
to a very great extent on maintaining the most precise size,
installation, and roundness tolerances and this makes
manufacture more costly. In addition, there is also the fact
that the annular seal that is fixed to the shaft and intended
to act as a thrower ring is not effective at low vehicle
speeds. However, the consequence of rapid wear of the sealing
ring is loss of function and may even result in the total
failure of the drive system. In any case, the sealing ring
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must be replaced very frequently, and this entails extra costs
and requires large amounts of time, since the seal is
installed in a location that is difficult toget to and very
confined.
For this reason, it is the task of the present invention to
create a seal that effectively keeps water and abrasive dirt
away from the seal under the severest conditions and, at the
same time, imposes only small demands with respect to
accuracy.
According to the present invention, this has been achieved in
that one of the rings incorporates an axial groove and the
other ring incorporates an axial collar that fits into this
groove; a ring that is of a soft and compressible material
being installed in the groove and the space between the two
rings within the groove being filled with grease. It is
preferred that the ring be of felt.
First of all, this creates an axial sealing gap that is not
subject to precise tolerances. It is not necessary to center
the rings, and at least one of the rings need only be bolted
to its supporting element without any centering lugs. Because
of the flexibility of the felt, installation does not have to
be extremely precise in the axial direction, either. The felt
ring, working in conjunction with the grease that is installed
and acts radially within the system, provides a reliable and
effective seal, even when the vehicle is stationary in deep
water. The felt ring forms a flexible but nevertheless tight
plug for the grease filling, as it were.
An advantageous development is such that the first ring also
accommodates at least a shaft seal. This simplifies
installation without any extra costs, since the sealing ring
has to be precisely centered in any case. In addition, both
installation and retro-fitting are simplified if the second
ring incorporates the groove and the first ring incorporates
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the collar.
The present invention will be described in greater detail
below, on the basis of embodiments that are shown in the
drawings appended hereto. These drawings show the following:
igure 1: a longitudinal cross section through a first
embodiment of a seal according to the present
invention;
igure 2: a variation of Figure 1.
Figure 1 shows part of a wheel mounting 1 of a cross-country
vehicle; the axis of rotation of the wheel is numbered 2. The
wheel mounting 1 consists of a flange 3 that supports the king
pin bearing (indicated by dashed lines, no reference number)
and of a tubular section 4 that supports the roller bearings
on which a hub 6 is supported so as to be able to rotate. Only
the roller bearing 5 is shown in the drawing; the second
bearing is located to the left of this, beyond the drawing. A
brake disk 8 is secured to the hub 6 by means of threaded
bolts 7. Within the wheel mounting there is a wheel drive
shaft 9 that is driven by a constant-velocity joint 10, is
supported in bearings 11, and sealed by a seal 12, which is
not an object of the present invention. The wheel drive shaft
9 is connected to the hub 6,so as to transmit driving force,
at a point that is located outside the illustration.
A seal 20 is provided to ensure sealing between the wheel
mounting 1 and the wheel hub 6; in this case, this is a
radial-lip sealing ring. This is installed in a first ring 21
that is centered relative to the hub 6 and secured by means of
a flange 22 that is similarly secured by threaded bolts 7.
Between the first ring 21 and the wheel hub there is an O-ring
23. This first ring 21 incorporates an axial groove 24 on its
outer side that faces the wheel mounting l; a felt ring 25 is
installed in the bottom of this groove. The thickness and
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density of this seating ring 2S are selected so as to be
appropriate.
A second ring 31 is secured, uncentered, to the wheel mounting
1 by means of threaded bolts 30. In this case, uncentered is
understood to mean that no centering lugs are provided on the
wheel mounting l; centering is effected only by the threaded
bolts 30. The second ring 31 incorporates an axial collar 32
that fits into the axial groove 24 of the first ring 21 and
touches the felt ring 25. The space between the two rings 21,
31, the wheel mounting, and the felt ring 25 contains the
grease filling 33. The two rings 21, 31, the felt ring 25, and
the grease filling 33 form the coarse seal that keeps water
and the sand that it may contain away from the seal 20, even
when it is under great pressure.
The embodiment that is shown in Figure 2 differs from the
above only in that the first ring 21' incorporates the axial
collar 32' and the second ring 31' incorporates the axial
groove 24. This embodiment functions in the same way as the
one described heretofore.
