Note: Descriptions are shown in the official language in which they were submitted.
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The present inven-tion relates to a surface bearing comprising a
rubber strip or plate material penetrated by hollow channels and
cavities. The cavities and hollow channels all lie in a single
plane at least essentially parallel or complementary in shape to
the principal surface of the bearing, each cavity being
penetrated in each case by only one ]hollow channel.
Resilient surface bearings of this kind are generally used for
cushioning relatively large masses, e.g. in mattress and machine
construction, the soft cushioning of drive assemblies and engines
of motor vehicles with little noise being o~ particular interest.
The achievement o~ a good combination of the effects of soft
springing, i.e. of a shallow spring characteristic, as long a
service life as possible and good acoustic decoupling, has always
presented difficulties since, on the one hand, the material used
should not be too hard and, on the other hand, the mechanical
stressability and durability should not be too low. A further
economic aspect is, in addition, the expenditure involved in
production.
The previously used solid elastomer pads of relatively soft
materials, in which rapld material fatique was to be observed,
have nowadays largely been replaced by bearings which are
penetrated by hollow channels and cavities to reduce material
loading. When the bearing is loaded, the cavities accommodate
displaced elastomer material, while the hollow channels serve to
connect the cavities, a pressure compensatlon thereby being made
possible between said cavities.
In general, when used correctly, surface bearings are sub;ect to
only relatively small loads per unit area. However, as soon as
higher loads occur, the cavity walls buckle (buckling effect)~the
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restoring force thereby largely being lost. The spring
characteristic then has a horizontal or, in most cases, falling
gradient. As soon as the cavities present have been completely
compressed, the shallow reglon of proportionality makes a rapid
transition to the progressivP region with a steeply rising
characteristic. The bearing then shows the typical, here
undesired, behaviour of a solid elastomer pad.
Bearings whose cavities and channels are filled with a fluid, are
described as dampers. A bearing o~ this kind, the cavities oE
which are filled with a damping fluid, the effect of a hydraulic
surface damper thereby being achieved, is disclosed in Japanese
Laid-Open Specification JP 52 37675 A and is used in the known
form as, inter alia, a rebound wall or rail support. In this
surface damper, the cavities are designed as vertical cylinders,
i.e. the cylinder axes extend in the direction of the applied-
load vector. In the case of the strip-like embodiment, these
cylinder cavities are connected to one another by linear
restrictor channels or in the case of the sheet-like
configuration are connected by a hexagonal restrlctor-channel
network, i.e. three channels penetrate each hollow cylinder.
A connection of this type between the cavities permits the
damping fluid to overflow out of the loaded cavities into the
unloaded and/or less loaded cavities, which are thereby expanded
by virtue of the elasticity of the bearing material, as a result
of which the materlal loading is reduced due to the reduction in
the inhomogeneous stress concentration.
Disadvantages of bearings of this type are that the fluid-filled
and thus resiliently reinforced dampers, which are closed all
round, do not respond to high frequency low amplitude
oscillat~ons and hence work relatively noisily and that, due to
the inertia caused, inter alia, by the narrow restrictor
channels, which is associated with great elastomer compression
and thus a relatively steep rise in the spring characteristic,
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desirably soft cushioning is not possible to the desired extent
unless a softer materlal were used, although this in turn would
considerably shorten the service life.
A further disadvantage is that, due to the adhesively bonded
laminated structures, the production of bearings of this kind is
expensive in terms of time, production and personnel and hence
has to be carried out in a cost-intensive way.
The present invention provides a surface bearing from a durable,
relatively firm elastic material~ which is suitable for
cushioning high loads as stipulated and which nevertheless has a
shallow spring characterlstic over a wide restorlng range, i.e.
has a soft spring characteristic, which furthermore permits good
acoustic decoupling and long service lives with undiminished
functioning capacity and, in addition, can be produced easily,
rapidly and economically.
According to the present invention there is provided a surface
bearing comprising a rubber strip or plate having in the rubber
matrix a plurality of hollow channels and cavities all of which
lie in a single plane at least essentially parallel to the
principal surface of the sheet material or complemtary in shape
to said principal surface, each cavity being penetrated in each
case by only a single hollow channel, wherein the hollow channels
are open on at least one side and have a clear cross-section, the
area of which is at least 1/4 of the size of the largest cross-
sectional area of the nearest cavity penetrated by this hollow
channel. Thus according to the present invention the hollow
channels are open on at least one side and have a clear cross-
section, the area of which is at least one ~uarter of the size of
the largest cross-sectional area of the nearest cavity penetrated
by this hollow channel.
The surface bearing comprises a rubber strip or a rubber plate,
in which uniformly distributed cavities and hollow channels are
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formed which all lie in a single plane a-t least essentially
parallel or complementary in shape to the principal surface of
the surface bearing. Each cavity of the rubber matrix is
penetrated by only one of the hollow channels, which preferably
extend rectilinearly and are open on at least one side. In the
preferred embodiment, the cavities are of spherical or spheroidal
design, while the hollow channels preferably have a circular
cylindrical form. In partlcular, al:l cavities and hollow
channels are arranged ln such a way that the center of each
~o spherical cavity lies on the central axis of the hollow channel
intersecting this cavity.
Essential here is that the hollow channels, which nei~her
intersect nor touch, have a clear cross-section, the area of
which ls at least a quarter of the size of the greatest cross-
sectional area of the nearest cavity penPtrated by this hollow
channel.
By means of this cross-section ratio it is ensured that, overall,
a sufficiently large hollow volume ls available inside the
surface bsaring, which can accommodate the displaced rubber
material when the bearing body is compressed without extreme
material stresses arising. The channels thus do not ~unction as
restrictor channels but themselves represent a deflection space
for the rubbermaterial, resulting in a softening of the surface
bearing and a shallower spring characteristic. Due to the
uniform distributlon of the cavities and channels in the matrix
of the surface bearing, the mechanical strength of the bearing
body is not impaired despite the remarkable pore volume and, even
under considerable applied loads, has a long service life. ~he
deformation stresses occurring upon loading, which primarily
affect the free internal and external surfaces of the rubber
mairix, are distributed uniformly over the entire bearing body,
with the result that, even when the bearing consists of a
relatively firm and mechanically stable engineerin~ material, the
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sprlng characteristic is decidedly soft and the sprlng
characteristlc accordingly has a broad and shallow region of
proportionality and makes the transition into the progressive
region with moderate curvature under only a relatively high load.
In preferred embodiments of the invention, the hollow channels
are aligned in such a way that they extend nonparallel to at
least one or to the longitudinal principal axis of the sheet
material and preferably enclose an angle of go or 45 with said
axis, the channels being open on one or both sldes. In the case
of the channels open on only one side, the openings preferably
lie alternately on the in each case opposite sides of the sheet
material.
The channels here extend parallel to one another or form a
plurality of groups of in each case mutually parallel channels,
the central axes of which intersect one another without the
hollow channels themselves intersecting or touching, thus for
example forming a herringbone pattern.
Alternatively, in the case of an essentially regularly polygonal
or circular sheet material, the hollow channels can be aligned so
as to extend radially to the center, although they neither
intersect nor touch in the center and are thus only open on one
side.
In the center of the novel surface bearing it is furthermore
possible for an opening to be formed which, extending in the
direction of the normal to the principal surface, i.e. in the
direction of the applied-load vector, is a through opening or an
opening closed on one side in the manner of a blind hole or a
groove, none of the cavities or hollow chann21s opening into this
central channel. A central opening of this kind permits numerous
constructional possibilities, e.g. fixing possibilities.
Additional lateral stabilization can be achieved by means of a
stabilizing or guide rod passed through this opening. In this
arrangement, the spring or acoustic properties of the bearlng are
in no way diminished.
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Also surprising, overall, is the fact that, even ln the case of a
relatively shallow surface bearing penetrated in a single layer
by cavities and hollow channels, mar]cedly good spring properties
and substantial acoustlc decoupling can already be achieved.
The novel surface bearing is produced by compresslon molding or
in~ection molding of rubber blends in a mold cavity contalning
mold cores. After the solidification of the elastomer mass, the
reusable mold cores, consisting, for example, of steel, are
removed from the mold cavity together with the molding, i.e. the
molding is demolded. The rod-shaped mold cores, which are
provided at regular intervals with thickened portions, are pulled
out laterally, individually or in groups, from the molding. The
surface-bearing obtained is then immediately ready for use, the
surface-bearings of engines or drives assemblies of motor
vehicles being envisaged in particular as applicat~ons.
The invention is explained in greater detail below with reference
to the accompanying drawings in which:
Fig. l shows, in schematic representation, a horizontal sectlon
through a surface bearing according to the first embodiment of
the invention;
Fig. 2 shows the bearing according to Fig. l in side view;
Fig. 3 shows a vertical section in accordance with III-III in
Fig. l;
Fig. 4 shows, in schematlc representation, a horizontal section
through a second embodiment of the bearing according to the
invention;
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Fig. 5 shows, in schematlc representa-tion, a horizontal section
through a thlrd embodiment of the novel bearing; and
Fig. 6 shows a vertical section in accordance with VI-VI in Fig.
5 5.
In the surface bearing 1 shown in Fiqs. 1 to 3, the cavities 2
formed in the rubber matrix and the hollow channels 3 are
dlstributed in su~h an arrangement that, as can be seen in
particular in Figs. 2 and 3, they lie in a single plane parallel
or complementary in shape to the principal surface of the sheet
material.
The channels 3 extend at an anyle of 90 to the longitudinal axis
lS of the bearing, which in the drawing is oriented from the top to
the bottom, parallel to one another, and are open on one side and
alternately towards the opposite sides of the bearing body 1.
Preferably, the spacing between the individual channels 3 is of
equal size in each case. Each channel 3 penetrates a plurality
of cavities 2, which are preferably at equal distances from one
another, while, conversely, each cavity 2 is only penetrated by a
single channel 3. The cross-sectional area of the circular
cylindrical channels 3 is at least a quarter of the largest
cross-sectional area of the spherical cavlties 2, thP centers 4
of the cavities 2 lying on the central axis 5 of the respective
channel 3.
In contrast, the surface bearing 1 shown in Fig. 4 has hollow
channels 3 which extend at an angle of 45 to the longitudinal
axis of the bearing and are open on both sides.
The novel surface bearing 1 shown in Figs. 5 and 6 comprises a
cir~ular sheet material in which the hollow channels 3 are once
again formed so as to be open on only one side and extend
radially towards the center. However, their length is such that
they do not quite reach the opening 6 which i9 present in the
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center and extends in the direction o~ the normal to the
principal surface, i.e. do not open into said opening. The
central hole channel 6 is open on both sides, i.e. passes through
the surface bearing 1 over its entire thickn~ss.
Given correct use, the surface bearings 1 shown in the
accompanying drawings are loaded in t:he dlrection of the normal
to the principal surface, the elastomer material displaced being
accommodated by the cavities 2 and the channels 3 or even 6. A
soft spring acttion, free from the buckling effect, and good
acoustic decoupling are thereby obtained. The demands made on
surface bearings for engines in automotive construction are here
ful~illed in all respects.
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