Note: Descriptions are shown in the official language in which they were submitted.
1046108 - ~
This invention relates to pneumatic tyre and wheel ~
rim assemblies, and in particular to an improved means of ~ -
filling a well in one-piece well-base rim in order to ensure
that the tyre beads cannot be dislodged from the rim in a
tyre deflation.
~ umerous means of blanking off the well of a well-
base rim have been proposed, including bands which cover
the mouth of the well, rubber rings which fill the well and
rigid segmental fillers which can be assembled in the well
and linked together or encircled by a suitable band.
When using a blanking means for this kind the filler
or band has to be inserted in the well after the tyre has
been placed on the rim, and removed from the well before the -
tyre can be taken from the rim. These steps are easier the
closer the location of the well to a rim flange. On the other
hand bead seats for the beads of a tyre are required adjacent
the flanges of the rim. In order to satisfactorily serve this
purpose the filler must be capable of stably supporting the
bead against the various forces exerted upon it.
According to the present invention there is provided
a pneumatic tyre and wheel rim assembly comprising a
one-piece wheel rim having a well and a well filler, the
well being in a position in which the well filler is required
to serve as at least a part of the-bead seat, the well filler
including a band of resilient polymeric material in the base of
the well and an overlying segmental filler comprising
a plurality of segments of rigid material,
the contact between the segmental filler and
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~046~08
the resilient band at the interface between them being
rendered discontinuous by means of contouring of at least
one of the contacting surfaces to allow for distortion to
compensate for irregularities in the dimensions of the
wheel rim.
A well-filler which i8 rigid should provide a
secure base for the bead of the tyre but in practice its use
in this manner leads to numerous difficulties owing to lack
of concentricity in the base of the rim-well. The arrange-
ment of the well filler in this invention permits the well-
filler as a whole to compensate for irregularities in the
rim by distortion of the resilient band as the segmental
filler is tightened upon it. It also permits the external
diameter of the well-filler to be accurate in dimensions and
if desired, a taper could be introduced on the external
surface of the filler in the manner of a normal bead seat.
Preferably the depth of the resilient band in the
base of the well is no more than 3~/~ of the depth of the well.
The segmental filler preferably consists of segments
of a plastics material or a metal or metal alloy. The dis-
continuous interface between the segmental filler and the band
may suitably be provided f~r by corrugations or castellations
on the radially inner surface of the filler. The corrugations
or castellations preferably run transversely of the segmental
filler i.e. in a direction parallel to the rotational axis of
the wheel.
The well must be wide enough to accommodate at least
one bead of the tyre so that the well filler may provide the
whole of one b~ad seat of the wheel rim assembly. If desired,
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~046108
however, a ledge ma~ be provided immediately adjacent the
wheel rim flange to act as part of the bead seat and provide
a location for the heel of a tyre bead.
An air-seal may be provided between the band of
resilient polymeric material and the segmental filler by
incorporating on the band at least one radially outwardly
extending portion at the side of the well filler to act as
lip seals against the side of the segmental filler.
In an alternative arrangement the segmental filler
may have a smooth cylindrical surface and the band of
resilient polymeric material may have a plurality of ribs on
its outer surface~ Preferably these ribs extend circum-
ferentially of the band to form a seal with the inner surface
of the segmental filler.
The wheel-rim and well-filler of the type described
in this invention may be utilized in the wheel and tyre
assembly described in our co-pending U.K. Patent Application
~o. 22,114/75 (DD.5579/5658), in this case a second well being
required in the wheel rim which will subsequently be axially
compressed when a tyre has been mounted on the rim.
A pneumatic tyre and wheel rim assembly in accordance
with the invention will now be described in more detail, by
way of example only with reference to the accompanying drawings,
in which:-
Figure 1 is a cross-sectional view of a pneumatic
tyre and wheel rim assembly taken in a
plane parallel to the axis of rotation,
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1046108
Figure 2 i9 a second cross-sectional view taken
in the plane A-A of Figure 1,
Figures 3, 4 and 5 illustrate, in cross-section,
the well portions of three further
embodiments of the invention, and
Figures 6 and 7 illustrate methods of linking the
segments of the segmental well filler.
The pneumatic tyre and wheel rim assembly shown in
Figure 1 includes a one-piece wheel rim having a pair of
annular flanges 10, 11 a bead seat 12 adjacent the flange 11,
a substantially flat central portion 13, a well 14 and a ledge
15 on the opposite side of the well 14 immediately adjacent the
flange 10. The well filler consists of a segmental filler 16
of rigid plastics material or light alloy and a band 17 of
rubber in the base of the well.
One bead of the tyre is seated on the bead seat 12,
but the other bead is seated partly on the ledge 15 and partly
on the radially outer surface of the segmental filler 16.
As shown in Figure 2 the segmental filler consists of
three arcuate segments 16 which, when assembled together
substantially fill the portion of the well 14 left unoccupied
by the band 17 of rubber.
The radially inner surface of the segments 16, whlch
contacts the radially outer surface of the band 17 is of
corrugated shape so that the contact is discontinuous. This
leaves space for distortion of the rubber to take place and
thus enables the assembly to accommodate local high and low
spots on the base of the wheel rim well without localized high
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1046~08
loadings on the rigid Yegments of the segmental filler.
In the assembly illustrated in Figure 3 a band of
rubber 18 is provided which has a pair of tapered side pieces
19 extending up the sides of the well. The segmental well
S filler 20 has correspondingly profiled sides and the side
pieces 19 extend beyond the depth of the corrugations on the
inner surface of the segment~ (shown by a dotted line in
Figure 3) 90 that an air seal may be obtained by the wedging
of the segments against the pieces 19. It will also be
noted that in the embodiment shown in Figure 3 a well 21 is
provided immediately adjacent a wheel rim flange 22, there
being no ledge on the flange to support the heel of the bead.
Figure 4 illustrates a similar assembly to that
shown in Figure 3 except that in this embodiment the segments
23 are not as wide as the well, and a rubber band 24 is
provided which has a single side piece 25 extending up the
whole of one side of the segments to act as an air seal
against the underside of a tyre bead (not shown).
Figure 5 illustrates an embodiment similar to that
shown in ~igure 1 except that the inner surface of its
segments 26 is smooth and cylindrical, and a rubber band 27
is provided, which has circumferentially extending ribs on its
outer surface. The latter are designed to be compressible and
to form an air-seal against the inner surface of the segments.
Figures 6 and 7 illustrate schematically, in side-view,
methods of linking together segments, Figure 7 showing a simple
pivoting link and Figure 6 showing an interlock arrangement
which may be used to push together the free ends of two segments
which are pivotally linked at their other ends.
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