Note: Descriptions are shown in the official language in which they were submitted.
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FLUtD COUPLINGS
RELATED PATENT APPLICATION:
This application is a continuation in part of U.S. Patent Application No.
091793,731,
filed February 27, 2001, now allov~ied.
FIELD OF THE INVENTION:
The present invention is directed to fluid couplings. More particularly; the
present
invention is directed to fluid couplings for coupling a reinforced hose to a
metal tube
wherein the couplings and hose are suitable for use in hydraulic vehicle brake
systems.
BACKGROUND OF THE INVENTION:.
As has been succinctly stated in U.S. Patent No. J,460,247 and reiterated
here,
there have been difficulties with brake hoses reinforced with braided wires.
in order to
accommodate necessary relafiive motion between the sprung and unsprung masses
of a
motor vehicle (i.e., the chassis and suspended wheels), suspension mounted
hydraulic
brakes are connected to the chassis by flexible hydraulic hoses. These hoses
are typically
fabricated farm fabric braid reinforced elastomers.
Standard original equipment of such fabric reinforced flexible brake hoses for
motor
vehicles expand or swell to some extent under pressure, thus consuming
available brake
pedal travel which can result in a relatively "soft" feel to the brake pedal.
This soft feel
reduces the precision of brake modulation by the driver. These conditions are
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unacceptable in racing cars. Far over 30 years, racing cars have been equipped
with
flexible brake hoses having a stainless steel braid layer over extruded
Teflon. These
hoses exhibit considerably less expansion under pressure resulting in higher
and firmer
brake pedal and a larger margin of safety because of more even friction pad
wear and.
more precise brake modulation.
Despite an outstanding record of performance and reliability in racing and off-
highway use, these high performance flexible brake hoses have not been
certified far
highway use because they have been unable to comply with the Basic Motor
Vehicle
Safety Standard 7 06, Section 56.3 (whip resistance test) set by the U.S.
Department of
Transportation (DOT).
Past efforts to substitute stainless steel' braid protected Teflon flexible
hose for the
original equipment elastomeric brake hose on vehicles has usually led to
fatigue failure of
the protective braid at the end of the crimp or swedged collar ar socket of
the hose end
fitting followed by fatigue failure of the Teflon hose and resultant loss of
pressure.
Consequently, there is a need for flexible brake hose assemblies that
accommodate
necessary relative motion between the chassis and wheels of a vehicle and
passes all
aspects of the whip resistance test required by the DOT.
One approach is to remove the stainless steel, braided reinforcement from the
hose
in the area of a metal coupling, but since the hose is made of
polytetrafluoroethylene
(PTFE), the hose tends not to meet pressure requirements when exposed to high
pressure
hydraulic fluid.
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Hydraulic brake lines are one recognizable need far the invention, other needs
arise
when reinforced hoses are attached to other devices which may or may not be
connected
by tubes
While hoses made of PTFE have difficulties with respect to DOT tests, there is
also
a need to improve fluid couplings for hoses of other materials, such as
polyethylene,
polypropylene, poiyamide (NYLON~), PTFE alloys and the like so that hoses of
these
materials will pass DOT tests. In addition there is a need to make these types
of brake
hoses less expensive while maintaining their attractive appearance for use on
vehicles
such as motorcycles. In addition, there is a need to improve strain relief
elements used
with the brake hoses.
SUMMARY OF THE INVENTION:
In view of the aforementioned considerations, the present invention is
directed to a
fluid coupling for coupling a hose to a device wherein the hose includes a
deforrnable,
resilient inner layer, a wire reenforcement layer over the inner layer and an
outer protective
layer over the wire reinforcement layer- The fluid coupling comprises a
fitting or "eyelet"
having a first and a second portion; the first portiori having a bore adapted
to communicate
with the device and a second portion having a projecting nipple for receipt in
the hose, the
eyelet further having an annular exterior groove therein. A crimping cup
having first and
second ends for mounting on the eyelet, wherein the crimping cup is disposed
around the
projecting nipple and initially has an inside diameter greater than the
outside diameter of
the hose. The crimping cup~further-has an inwardly projecting lip aligned with
the exterior
CA 02468094 2004-05-20
groove in the eyelet and a bell shaped pocket adapted to be disposed adjacent
to an end
portion of the hose which has been stripped of the outer layer. A coaxially
strain relief
element is disposed in the bell shaped pocket and is urged against the wire
enforcement
when the crimping cup is deformed radially inwardly to press the inner layer
of the hose
against the nipple and the inwardly projecting lip into the exterior groove in
the tube fitting
in accordance with a preferred embodiment of the present invention, the
coaxial
strain relief element is an annular ring having contoured exterior surface
with a bulge
received in the pocket of bell shaped end and a portion adapted to extend over
the outer
layer of the hose.
In accordance with a further embodiment of the invention, the fluid coupling
is a
coupling for connecting a hydraulic brake hose having a braided reinforcement
layer to a
metal tube.
!n accordance with stilt another aspect of the invention, the deformable
resilient
inner layer is selected from the group of materials comprising PTFE,
polyethylene,
polypropylene, NYLON~ (polyamide), PTFE alloys, ar other polymeric crass
linked
materials.
In accordance with still another aspect of the invention, the braided
reinforcement is
zinc plated carbon steel wire, such as nickel-plated carbon steel or arimid
fiber, such as
KEVLAR~.
In accordance with still another aspect of the invention the preferred strain
relief
element is made of a cross-finked polymeric material such as, but not limited
to,
polyethylene, polypropylene, urethane, polyurethane or N9ETALLOCENE~.
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BRIEF DESCRIPTION OF THE DRAWINGS:
Various other features and attendant advantages of the present invention will
be
more fully appreciated as the same becomes better understood when considered
in
conjunction with the accompanying drawings, in which like reference characters
designate
the same or similar parts throughout the several views, and wherein:
Fig. 1 is a side elevation of a first embodiment of a fluid coupling
configured in
accordance with the present invention.
Fig. 2 is a side view showing a hose and hose coupling in accordance with the
present invention separated prior to joining the hose to the hose coupling;
Fig. 3 is a side elevation showing the hose and hose coupling joined prior to
crimping so as to create the hose coupling of Fig. 1;
Fig. 4 is a view taken along lines 4-4 of Fig. 1 showing crimps in a crimping
cup
surrounding the hose, and
Fig. 5 is a side elevation showing a second embodiment of the present
invention.
DETAILED DESCRIPTION:
Referring naw to Fig. 1 there is shown a fluid coupling 10 configured in
accordance
with the present invention wherein a hose 12 is coupled to a device such as
for example a
metal tube using an eyelet 15. The eyelet 15 has a stepped bore 18 in which
the metal
tube 14 is fixed by brazing 19 (shown in dotted lines). While a metal tube 14
is used as the
CA 02468094 2004-05-20
device if the invention is applied to a brake system, it is to I~e kept in
mind that the device
maybe any other instrumentality which uses fluid.
As best seen in the exploded view of Fig. 2, the hose 12 comprises in one
embodiment a bore 18 through a Teflon~ (polytetrafluoroethyiene, PTFE) tubular
inner
layer 20 of the hose 12. Alternatively, if the hose 12 is not :>ubjected to
high temperatures
in the range of 400°F, the tubular layer 12 is made of less expensive
materials such as, but
not limited to, polyethylene, NYLON~ (poiyamide) and polyi:etrafluoroethylene
PTFE alloys
which are mixtures of PTFE and other polymers. A stainless steel braided layer
24
surrounds the inner layer 20 and an outer layer 26 of clear or colored
polyvinylchloride
(PVC) surrounds the stainless steel braided layer 24. Alternatively, the outer
layer 26 can
be polyurethane, poiypropyiene or another polymeric material. Alternatively,
zinc plated
carbon steel, nickel plated carbon steel, KEVLAR or arimid fibers, can replace
stainless
steel in the braided Payer 24. The PVC layer 26 has as c~ primary purpose
keeping the
braided layer from abraiding adjacent parts when the ho:>e is used as a brake
hose on
vehicles such as motorcycles. In accordance with the present invention, an end
portion 28
of the hose has the PVC layer 26 removed so that the braided layer 24 is
exposed.
As is best seen in Fig. 2, the eyelet 15 has a first end 30 with a stepped
bore 34 in
which the tube 14 is braised and a second end 32 with a nipple 36 which is
received in the
bore 18 of the hose 12. The nipple 36 has at least one, or preferably two,
annular lands 40
and a tapered end 44. A groove 45 is positioned in the eyelet 15 just inboard
of a stop
surface 46 adjacent to the nipple 36. A crimping cup 50 is positioned
coaxially around the
nipple 36 and has at a first end 52 an annular lip 53 which i:; aligned with
the groove 45. At
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a second end 55 of the crimping cup 50, the crimping cup has a bell-shaped
portion 56 that
defines a pocket 57. During assembly, a rubber O-ring 58 is placed over the
portion 28 of
the hose 12 which has had the PVC layer 26 stripped and the hose is shoved
over the
nipple 36 so that the nipple is received in the bore 18 of the hose. When the
end of the
hose 12 abuts the stop surface 46, the hose is properly positioned with
respect to the
crimping collar 50. Upon being crimped, the crimping collar 50 reduces its
diameter to form
crimps 59 (Fig. 4); presses the.annularlip 53 into the grove 45 of the eyelet,
and presses
the interior surface 51 of the crimping collar directly against the exposed
.portion of the
braided reinforcement 24 (see Figs. 1 and 4). The rubber O=ring 60 is also
retained
against the braided stainless steel reinforcement layer 24.
The O-ring 60 serves as a strain relief element and a shock absorber so that
as the
hose 12 is flexed during a whip resistance test, such as that acquired by the
Department of
Transportation for highway use vehicles, the braided wire reinforcement layer
24 does not
fray or fail and thus provides dynamic, coaxial strain relief for the
reinforced hose 12.
Referring now to Fig. 5; there is shown a second embodiment 10' of the
invention in
which a second embodiment 61 of the strain relief element is shown, all of the
other
elements being the same. In accordance with one embodiment, the strain relief
element
61 is made of thermoplastic polymeric material and has a contoured surface 62
comprising
a first bulge 64 and a second bulge 66 defining a valley 67 there between. The
first bulge
64 is received in the pocket 57 of the crimping cup 50 and overlies the
portion 28 stripped
of PVC from the stainless steel braided wire reinforcement 24. The coaxial
strain relief
element 61 has an extended portion 72 which includes the second bulge 66 and
extends
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axially over the braided reinforcement 24 as well as over the PVC outer layer
26. The PVC
outer layer 26 under the extended portion preferably remains on the hose 12
but can be
removed from the hose. By extending past the end 55 of the crimping cup 5Q,
the coaxial
strain relief element 61 moves stresses further out onto the hose 12 away from
a pinch
point 74 where the collar portion of a crimping cup is pressed directly in
engagement with
the stainless steel, braided wire reinforcement 24. By moving the stresses
further out onto
the hose 12 the braided reinforcement 24 remains rigid out beyond the pinch
point 74, and
thus the required stress relief is accomplished which resulia in the hose 12
withstanding
the aforementioned whip test.
In other embodiments of the invention, the strain relief element &1 is made of
a
cross-linked polymeric material such as, but not limited to, polyethylene,
polypropylene,
urethane, polyethylene or METALLOCENE~, as well as the previously identified
NYLON.
By using a cross-linked polymeric material a seal can be achieved with the PVC
outer layer
2E because cross-linked polymeric materials can be heat shrunk. A hermetic
sea! with the
clean PVC layer 26 keeps moisture away from the reinforcement layer 24 and
thus
minimizes the possibility of rust when the reinforcement layer is made of
steel such as, but
not limited to, zinc-plated carbon steel or nickel-plated carbon steel.
The couplings 10 and 10' make reinforced hoses suitable for highway use
because
the hoses can pass the Department of Transportation Whip test, as well as
provide hoses
which are resistant to rust.
From the foregoing description, one skilled in the art can easily ascertain
the
essential characteristics of this invention, and without departing form the
spirit and scope
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thereof, can make various changes and modifications of the invention to adapt
ifto various
usages and conditions.
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