Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02238515 1998-OS-26
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GROMMET CUP PACKING MADE OF ELASTOMERIC
MATERIAL FOR HYDRAULIC APPARATUS
F~P~c~ of the Invention
This invention relates to a grommet cup packing made of
( elastomeric material for hydraulic apparatus.
~3ac- grnnnrl of the Invention
These packings are used to form a seal between two
cooperating parts of a hydraulic apparatus, primarily faucets and
cartridges for faucets. The cup packing is inserted in a seat
that is recessed in one of the two parts between which a seal must
be established, and it is forced into contact with the other part.
The force is often applied by a spring housed inside the cup
packing, but it can also be applied by means of diverse or
diversely arranged members or by the elasticity of the elastomeric
material comprising the cup packing. To establish the best
possible hydraulic seal these packings should be made of an
elastomeric material that has a high degree of elastic yield. As
a rule, conventional cup packings have a circular cross-section.
The conventional and known cup packings have serious
disadvantages. For both technical and regulatory reasons
hydraulic apparatus must be able to resist high pressures which,
according to some standards, attain 50 bar and even 120 bar. If
the cup packings are comprised of elastomeric material under high
pressures, and especially in the case of pressure surges, they can
become deformed and can even burst. This means that such packings
must be made with relatively rigid elastomeric material which is
unable to establish the best possible seal. This phenomenon is
also present when the packings are installed under operationally
static conditions.
When such packings are used under operationally dynamic
conditions, i.e., when they must establish a seal between
r reciprocally movable parts, there is yet another disadvantage.
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When one of the two parts, between which the cup packing
establishes a seal, is shifted with respect to the other part in
which the cup packing is seated, then the packing tends to be
dragged, due to friction, and is deformed. If the movable part is
a shutter that has passage openings which must be open or closed
during displacement, then the deformation of the packing modifies
the relative positions in which the passage openings are
controlled, and if said deformation is excessive it impairs the
precision of the shutter's operation and may even actually
jeopardize the proper closing, for example, of a faucet.
It has been proposed to rigidify a cup packing by inserting
a bushing made of rigid material such as a plastic. However, this
procedure has not proven to be sufficiently effective due to the
fact that the pressure can be transmitted to the interface between
the cup packing and the inserted bushing, and it can thus act on
the packing itself causing the above discussed disadvantages.
One purpose of this invention is to provide a cup packing
consisting of a relatively yielding elastomeric material which
would be able to establish a good seal and which will be able to
resist high pressures and pressure surges.
Another purpose of this invention is to provide a cup packing
which would be particularly suitable for dynamic operation due to
the fact that it does not undergo excessive deformation due to
fiction by the displacement of the parts between which the seal is
established.
Yet another object of the invention is to provide a cup
packing which can be formed with a noncircular cross-section.
~1--~y of the Iny nti nn
These obj ects are attained according to this invention by
virtue of the fact that the packing has a composite structure.
This composite structure is comprised of an elastomeric material ,
(which can have considerable yielding capacity) in the portions
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intended to establish a seal and of a rigid or semirigid
material (such as a suitable plastic material or a metallic
material) corresponding to a core that is at least partly
incorporated in the elastomeric material of the packing.
This invention relates to a grommet cup packing
for a hydraulic apparatus having a first part and a second
part, the second part having a recessed seat, wherein the
packing forms a hydraulic seal between the first part and
the second part, the packing comprising: an elastomeric
insert having a body portion and a head portion, the body
portion being inserted within the recessed seat of the
second part, and the head portion being in sealing contact
with the first part of the hydraulic apparatus; and a core
member having a substantially cylindrical body section, the
body section having a top end and a bottom end, a top
section extending inwardly from the top end of the body
section to form an inner annular ledge, and a tail section
extending outwardly from the bottom end of the body section
thereby forming an annular flange, the core member being
embedded within the elastomeric insert, such that the top
section and the tail section of the core member provide
reinforcement to the elastomeric insert, and wherein the top
and tail sections of the core member are perforated.
In this composite structure the elastomeric
material only functions to establish the hydraulic seal. It
is thus practically relieved of all of the mechanical
resistance functions of the packing which are entirely or
almost entirely performed by the incorporated core, which
takes the stresses to which the packing is subjected, both
under static conditions and under dynamic conditions. This
means that one can separately design with different
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criteria, especially with regard to the choice of materials,
the two parts of the packing's structure. The packing of
the instant invention has a high degree of sealing due to
the choice of a sufficiently yielding elastomer and a high
degree of resistance to deformations due to the choice of
appropriate shapes and composition of the core.
Preferably, the core which is incorporated in the
elastomeric material is provided with anchoring means that
can secure the elastomeric material to the core itself.
In particular, the core can consist of a portion
that extends axially, having a cross-section that
substantially corresponds to the cross-section of the
packing, from which laterally extend sections of flange that
at least partly extend radially in the elastomeric material.
The packing of this invention is preferably made
by injecting an elastomeric material in the fluid state into
a mold so as to incorporate a rigid or semirigid core, and
then cross-linking the elastomeric material that constitutes
the packing.
In contrast to known and conventional cup
packings, the packing of this invention need not have a
circular cross-section. The packing can considerably
diverge from this usual circular
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shape, providing that the seat in which it is seated has a
corresponding shape. It is also possible to provide different
shapes to the portion of the packing that is seated in a seat of
one of the two parts between which the seal is established and to
the portion of the packing that provides the seal.
These and other features, purposes and advantages of this
invention will be apparent from the following description of some
of the embodiments illustrated in the attached drawings.
Brief D -~rri ~fi i ~n pf ~hr~
Drawinn~
FIGURE 1 schematically illustrates in axial cross-section how
a prior art and conventional packing is deformed by high internal
pressure;
FIGURE 2 illustrates one embodiment, in axial cross-section,
of a packing of the instant invention; and
FIGURE 3 illustrates a second embodiment, in axial cross-
section, of the packing of the instant invention.
Conventional and prior art packing, illustrated in Fig. 1, is
intended to establish a seal between a first part 1 (for example,
the bottom of a faucet or a cartridge for a faucet) and a second
part 4 (for example, a fixed~flow control plate) having respective
passages 2 and 5 therein. The first part has a recessed seat 3 in
which the packing is inserted. The conventional and prior art
packing comprises a body 6 made of elastomeric material provided
with external peripheral projections to provide a seal in seat 3
of first part 1. The body 6 at its upper extremity forms a head
7 which makes a seal with the lower surface of second part 4. A
spring 8 is disposed in body 6 of the packing and works between
the bottom of seat 3 and head 7 of the packing so as to push the
head 7 into contact with the second part 4 at a pressure effective
to establish a seal.
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When a high pressure is transmitted to the inside of body 6
through passages 2 and 5, head 7 of said packing tends to be
pushed toward the outside in the space that separates the two
parts 1 and 4, become deformed, as shown at 7A in the left side of
Fig. 1. This deformation can be permanent and can compromise the
operation of the packing. This leads to the previously mentioned
disadvantages which the instant invention seeks to prevent.
Figs. 2 and 3 show two embodiments of the cup packing of the
instant invention. In these two figures parts corresponding to
those in Fig. 1 are labeled with the same reference numerals and
will not be described any further.
The packing of the embodiment illustrated in Fig. 2 comprises
a body 9 made of elastomeric material with peripheral projections
for the seal in seat 3 of first part 1 and a head 10 adapted to
provide a seal against the lower surface of second part 4. In
body 9 and head 10 there is at least partly incorporated a core
made of rigid material consisting of a portion 11 that extends
axially along body 9 with a cross-section that substantially
corresponds to that of the cup packing, and upper flange sections
12 that extend inside head 10. The presence of this core prevents
the deformation of said body, specifically of head 10, in the
'presence of high pressures that are transmitted through passages
2 and 5 to the inside of body 9. A proper selection of the shape
of core 11, 12 and of material comprising it will enable the
packing's pressure resistance to attain any value that may be
required for technical or regulatory reasons.
Preferably, as shown in Fig. 2, portion 11 of the core
extends downwardly to form sections of flange 13 that support the
bottom of body 9 made of elastomeric material, thus contributing
to its stability.
In the embodiment illustrated in Fig. 3, portion 11 of the
core has its upper flange sections 12 incorporated into the head
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of the packing which, as shown, are turned toward the outside
rather than toward the inside as in the embodiment in Fig. 2. The
flanges can also be provided on both sides of portion 11, that is
to say, facing or extending toward the inside and toward the
outside. This arrangement is shown in Fig. 3 by flange section 14
which are arranged so as to correspond to the lower surface of
head 10 and which serve the functions of providing a rigid support
surface for spring 8. It is to be understood that flanges 13, as
illustrated in Fig. 2, and flanges 14, as illustrated in Fig. 3,
could be found in the same structure.
Flange sections 12, 13 and 14 can extend in a continuous
manner all around portion 11 of the core to give the latter
greater resistance to radial stresses. As an alternative, the
flange sections can also be interrupted or perforated to ensure
more perfect anchorage of the core with respect to the elastomeric
material. For the same purpose, portion Z1 can also have
perforations.
The cup packing is preferably prepared by injecting an
elastomeric material in the fluid state to form body 9 and head IO
into a mold containing a core 11 and flanges 12, 13, 14 comprised
of rigid or semirigid material and cross-linking the elastomeric
material that comprises the packing. This procedure constitutes
a convenient and easy process of making the composite packings.
The procedure is facilitated if (as in the embodiments shown) the
incorporated core remain partly uncovered toward the outside.
This makes it possible to provide in the mold effective supports
for the core to be incorporated in the elastomeric material.
In the embodiments illustrated in Figs. 2 and 3 the packing
is moved into engagement with part 4 by a spring 8 housed in body
9. However, spring 8 can be arranged in a different way, or it
can be replaced by any other elastic means. In particular, the
lower portion of body 9 can be extended beyond the end of core 11
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and so arranged as to rest against the bottom of seat 3 and to
provide the elastic push required by the packing.
In view of the great resistance that can be imparted to the
cup packing of the instant invention, the packing is not limited
to a circular cross-section and can be different from the shape
being inserted in a corresponding seat 3. In particular, head 10
of the packing can have a shape that is different from that of
body 9.
While the invention has been described in combination with
specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the foregoing description.
Accordingly, it is intended to embrace all such alternatives,
modifications and variations as fall within the spirit and broad
scope of the appended claims.
