Note: Descriptions are shown in the official language in which they were submitted.
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ANTI-VIBRATION PLUG-IN NIPPLE
BACKGROUND OF THE INVENTION
Technical Field
This invention relates to a device for connecting a pneumatic or hydraulic
tool to a coupling,
linking it with a liquid- or gaseous-fluid feed line; a fitting designed to
cushion the pulsations,
vibrations and mechanical shocks of percussion tools; and a method for
cushioning or absorbing
pulsations, vibrations and mechanical shocks in the operation of pneumatic or
hydraulic
percussion and/or vibrating tools.
Fittings are used in conjunction with couplings which serve as detachable
interconnec6ng
elements between rigid pipes and flexible conduits for fluids, i.e. liquid or
gaseous substances,
especially compressed air. Pneumatic or hydraulic tools such as impact,
percussion or vibrating
tools which are driven by pneumatic or hydraulic fluids such as compressed
air, are connected to
and disconnected from their respective feed lines via the aforementioned
intermediate couplings.
Examples of compressed-air-driven tools include road-construction equipment or
pneumatic tools
for tightening and/or removing automobile wheel nuts and studs etc., in all
cases involving the
transfer of strong vibrational forces, pulsating or hammering action from the
percussion tool by
way of the rigid connecting line to the coupling in which coupling the fitting
is securely fastened. A
contact surface of the fitting protrudes into a mating port in the coupling
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where it can be releasably locked in position either via a screw-collar or
bayonet-type clamp or by
a swivel or twist-lock mechanism in the coupling.
The manufacturers of quick-connect couplings and fittings take for granted
that the users view
these couplings and fittings merely as connectors subject to wear and tear
and, hence, to periodic
replacement. Their useful lifespan is limited as a function of the product and
material quality, and
the user still reviews only the cost/benefit ratio of his investment in
couplings and fittings. Yet our
experience in the most diverse fields of application of couplings and fittings
has provided ample
evidence to the effect that connectors of this type are predominantly used for
feeding compressed
air to pneumatic tools and frequently so-called vibrating screwdrivers,
wrenches and hammers.
The associated above-average wear, however, is ignored by the typical user
until the coupling
fails to function. In most cases, such failure exhibits itself in that
detachable couplings come apart
by themselves, whereby the two connecting elements, for instance a coupling
and a fltting in the
case of a flexible conduit, become uncontrollable, separating with a so-called
whiplash effect as a
result of the sudden compressed-air blowout and flying off with a
corresponding velocity. This has
led to accidents with the gravest consequences for those directly involved,
for which the
manufacturers of the couplings and fittings as well may be held liable.
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At this juncture, work with compressed air is the subject of certain national
and international
regulations whereby a coupling must meet specific safety standards in terms of
its connecting and
disconnecting properties before it can be marketed as a so-called safety
coupling. There is no
comparable regulation, however, regarding the physical design of such
connectors especially with
respect to technical provisions aimed at preventing premature wear and tear of
the locking
elements which easily goes unnoticed by the non-expert.
Prior art has attempted to address this problem by interpositioning between
the fitting and the
connecting port on the tool a flexible tube section, but the configuration of
the flexible conduit and
its attachment to the fitting and, respectively, to the tool port turned out
to be so complex and
costly that this approach never really materialized.
There has also been a two-part fitting with an elastic, shock-attenuating
intermediate layer which
elastic layer is surrounded by a sleeve shrunk onto the elastomer material for
generating radial
inward pressure. In practice, this design has quickly led to fatigue or
embrittlement of the
elastomer material, causing the fitting to break apart.
Then there is Swiss patent CH 518.481 which describes an anti-vibration device
intended to
cushion the pulsations in a fluid-transmitting line. That document refers to
the attenuation of
pulsations in liquid-carrying lines which again fails to provide a suitable
solution for a fitting
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or junction that connects a fluid line to a tool. Besides, the document
describes a stepped through-
hole which is hardly desirable in a fluid line.
SUMMARY OF THE INVENTION
It is therefore the objective of this invention to introduce a system by means
of which the
aforementioned pulsations, vibrations and hammering action are cushioned or
absorbed so as not
to be transferred to the interconnecting coupling, causing the fitting to
break out of the coupling.
Specifically, the invention is aimed at providing a so-called "anti-vibration
fitting" whose basic
physical design is such as to allow the transfer to the coupling of either
none or only highly
cushioned movements from the percussion- or vibration-type compressed-air
tool. In the absence
of vibrations or percussions at the coupling, the locking elements of the
coupling are not
constantly exposed to excessive shock loads and thus to extraordinary wear
which would
normally be noticed only after the connection, presumed by the user to be
safe, starts to leak or
even comes apart.
According to the invention, this is accomplished by an anti-vibration fitting
for connecting a
vibrating pneumatic or hydraulic tool with an intermediate coupling attached
to a fluid feed line,
comprising:a first part provided with an adapter section designed to permit
insertion in and
releasable connection with a port in the intermediate coupling, and a first
sleeve; a second part
provided with a connector section for rigid connection with the vibrating
pneumatic or hydraulic
tool, and a second sleeve, wherein the first and second sleeves form an inner
sleeve and an outer
sleeve respectively with a space therebetween; and an elastic junction layer
comprising an
elastic, rubber-like material provided in the space therebetween, wherein the
inner sleeve, the
elastic junction layer and the outer sleeve form a common through-hole in the
form of a smooth
bore.
The device proposed is a so-called nipple-type fitting which serves to connect
a pneumatic or
hydraulic tool, especially for instance a percussion or vibration tool, to a
coupling which links it
with a liquid or gaseous-fluid-carrying feeder or supply line, whereby the
said device or fitting
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incorporates at least one first part with a protruding contact section which
can be inserted or
plugged into and thus releasably connected to a mating port in the coupling. A
second part,
incorporating a connector section, is so designed and provided as to permit
solid connection to
and with the tool. Both parts include at least one additional section each
whereby the additional
section of one part radially surrounds that of the other part with a space in
between and an elastic
junction is provided in that space between the two sections, which junction is
produced by casting,
injection-molding, extruding and/or, where appropriate, by reactive cross-
linking or by vulcanizing
an elastic, rubber-like material or thermosetting an elastic polymer between
the two additional
sections.
The device introduced by this invention is particularly suitable as a so-
called anti-vibration fitting
for connecting percussion tools such as pneumatic tools to quick-connect
couplings. An anti-
vibration fltting of this type essentially consists of two metal parts where
one part is designed to
attach firmly to the percussion tool while the other metal part, nipple-
shaped, is so designed that it
can be inserted and locked in the quick-connect coupling. Interpositioned
between the two metal
parts is a layer of an elastomer material or a vulcanized rubber serving
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to absorb or cushion vibrations or pulsations originating from the percussion
tool. By predefining a
specific Shore hardness the degree of attenuation between the percussion tool
and the quick-
connect coupling can be selected.
The anti-vibration fitting described above extends the life of the unions
since the locking elements
are exposed to a certain impact only when being connected or disconnected,
which is tantamount
to normal wear. The fitting described is generally suitable for all and any
existing union and
coupling systems since the nipple end of the fitting can be adapted to
whatever connecting
system is employed.
In producing the device per this invention, or anti-vibration fitting just
described, it is possible to
provide each of the two metal parts with a cylindrical or sleeve-type section,
with one sleeve-type
section radially enveloping the other section. The space left between the two
sleeve-type sections
can now be filled with the eiastomer material or rubber which is introduced by
casting or injection-
molding and which, if desired, can then be vulcanized to a particular Shore
hardness.
Alternatively, the inner sleeve-type or cylindrical section can be jacketed
with the elastomer
material or rubber by the extrusion method, after which the other section is
slipped over it. In this
case as well it is possible, where appropriate, either by heat-treating or by
other suitable
measures to produce a partial cross-linking or vulcanization effect in the
elastomer or rubber
material for arriving at a particular Shore hardness.
1
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BREIF DESCRIPTION OF THE DRAWINGS
The following examples will explain this invention in more detail, with
reference to the attached
drawings in which:
Fig. 1 is a longitudinal cross-sectional view of the device and
interconnecting fitting per
this invention;
Fig. 2 shows, with a partial cut-away view, an example of a practical
embodiment of the anti-
vibration fitting analogous to the design per fig. 1;
Fig. 3 is a schematic, perspective view of a percussion tool attached to a
quick-connect
coupling by means of an anti-vibration fitting per this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The longitudinal sectional view in fig. 1 illustrates a device per this
invention, i.e. an anti-vibration
fitting I suitable for connecting a hydraulic or pneumatic tool to a coupling
which serves to
connect the tool with a feed or supply line carrying the liquid or gaseous
fluid that drives the tool.
The fitting 1 per this invention incorporates a connector part 3 which is
provided with a connector
section 5 that is designed to attach to the tool. That section 5 may be of the
threaded, bayonet-
mount, snap-lock or similar type by means of which the fitting 1 is solidly
attached to the tool. The
connector part 3 is also provided with a sleeve-like or cylindrical section 9
which surrounds the
outside of an inner, cylindrical section 17 that extends from the plug end
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11. The plug end 11 also features a nipple-shaped adapter section 13 designed
to permit insertion
in a recess or housing port of the coupling. The adapter i.e. nipple section
13 is so configured that
it can be held in place by means of locking elements in the recess or coupling
housing port. The
method of locking the fitting in the coupling will not be discussed in detail
at this point since there
exist various coupling designs which permit a firm, releasable connection
between the fitting and
the coupling by different means, e.g. plug collar, snap-, swivel- or twist-
lock, bayonet-type mount
or the like.
The important aspect of this invention is that the two cylindrical or sleeve-
shaped sections, with a
circular or again cylindrical space between them, are connected with each
other via an
elastomeric material, i.e. an elastomer layer 19. This elastomer layer,
consisting of an elastomeric
polymer or a rubber-like material, is capable of at least partially absorbing
or cushioning
vibrations, pulsations or hammering action transferred from the tool via the
connector section 5 to
the fitting 1. This prevents the hammering action or vibrations from
propagating from the tool via
the adapter section 13 to the coupling, which could otherwise cause damage to
the coupling,
resulting in a leaky connection between the fitting 1 and the coupling and
ultimately even in the
accidental separation of the adapter section 13 from the coupling.
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Fig. 2 illustrates a practical embodiment of an anti-vibration fitting 1 per
this invention, with
components analogous to those in fig. I bearing the same reference numbers.
Clearly visible
between the two cylindrical or sleeve-shaped sections 9 and 17 is the
elastomer or rubber-like
material 19 serving to cushion or absorb the hammering action or vibrations.
Equally visible is the
central bore 21 which extends throughout the anti-vibration fitting 1 from the
opening 7 in the
connector section 5 to the opening 15 in the adapter section 13. Through this
bore passes the
hydraulic or pneumatic fluid that drives the tool.
The anti-vibration fitting 1 per fig. 2 may consist for instance of two metal
parts 3 and 11 as well as
a vulcanized rubber layer of a predefined Shore hardness of perhaps 50 to 55.
In its connector
section 5, the metal part 3 is provided with an external or internal thread
which is screwed onto or
into the correspondingly threaded port of the tool. The other metal part, 11,
is composed of the
inner sleeve-like or cylindrical part 17 and of the distal nipple-shaped
adapter end 13. Both parts
are firmly but flexibly connected with each other, thus preventing vibrations
and/or mechanical
shocks from being transmitted to the coupling. The design described avoids an
overexposure of
the anti-vibration fitting to lateral forces. The combination of the quality
of the elastomer or rubber
material employed, the Shore hardness selected and the overall length of the
anti-vibration fitting
determines the capacity of the device as a so-called
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shock absorber between the tool and the coupling.
For a better visualization of this invention, fig. 3 is a perspective
illustration of a percussion tool
connected to a quick-connect coupling. In this example, the pneumatic tool 41
may be an impact
wrench with a percussion-type screw-driving mechanism 43 for mounting
automobile wheel nuts.
The tool connects to the anti-vibration fitting 1 illustrated in fig. 2 and
incorporating the two sleeve-
like or cylindrical sections 9 and 17 which are connected with each other for
instance via the
rubber material installed by vulcanization.
The anti-vibration fitting 1 connects to a quick-connect coupling 31 via the
adapter section 13. The
fitting is held in place in the coupling housing 33 by means of appropriate
locking elements. In the
example of the quick-connect coupling 31 illustrated in fig. 3, the design is
that of a swivel
coupling in which case the fitting enters the coupling housing 33
perpendicular to the longitudinal
axis of the coupling and is then swiveled 90 , whereby the locking elements
hold the fitting in
place in an axial position. After the locking process the fluid in the feed
line 35, such as
compressed air, can pass through to the pneumatic tool.
Vibration tests were conducted in which conventional fittings, both with and
without shock-
absorbing or attenuating provisions, were compared with anti-vibration
fittings per this invention.
Fittings without attenuating provisions were defective, or leaking seriously
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enough to be rendered unusable, after as little as 125 hours. Fittings with
attenuating provisions
per prior art, i.e. with shrink-collar-clad elastomer material, were defective
or unusable after 134
hours. While fittings without attenuating provisions displayed leaks within
the coupling housing
due to worn locking elements, the shock load applied in the tests on fittings
with attenuating
provisions led to breaks in the flexible material.
In contrast thereto, the vibration tests on the anti-vibration fittings per
this invention were stopped
after 210 hours without any leaks having been discovered.
The description given with reference to figures 1 to 3 is merely intended to
serve for a better
visualization of this invention, representing only one example of a possible
form of implementation
without in any way limiting the scope of this invention. Especially the quick-
connect coupling per
fig. 3 is shown solely as an example of how a fitting according to this
invention can be connected
to the coupling. Similarly, the design of the fitting or anti-vibration
fltting per this invention can be
altered, modified or complemented in any desired fashion. In particular, for
producing the elastic,
shock attenuating or absorbing layer the most diverse elastomers can be used,
such as different
elastomeric polymers or rubber-like materials similar to the above-mentioned,
preferred rubber
materials applied by vulcanization. Even the
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choice of material used for the parts connected via the elastomer material can
be made in
essentially arbitrary fashion from among stainless steel, aluminum or other
suitable materials.
The important feature of the fitting per this invention is that the elastic
material connecting the two
rigid parts is not forcibly applied for instance by shrink-mounting a metal
ring or a metal sleeve
over it but is obtained by casting, injection-molding or extruding the
elastomer material or rubber
and, where practical, subsequently treating or applying it by vulcanization or
partial cross-linking.
J
