Note: Descriptions are shown in the official language in which they were submitted.
~L~0~53
This invention relates to a combined air/electrical
swivel which allows unlimited rotational movement of a cable
and air line in either direction without loss of air or
introduction of electrical noise. It is intended to be used
for communication and air supply for personnel wearing
plastic suits for working in contaminated areas. It may also
be used for robots and equipment requiring instrument air and
electrical connection incorporated into one unit. It is not
however restricted solely to these uses.
I Couplings which provide a rotatable connection and per-
mix the transfer of electrical energy as well as air through
the couplings are already known. There is for example,
Canadian Patent Serial Number 872,125 issued June 1, 1971,
to David F. Downy and entitled "Current Conducting Rotatable
Air Flow Coupling for a Vacuum Cleaner". However, there is
still need for a combined air/electrical swivel which is no-
liable and rugged in construction and yet which contains a
minimum number of separate parts and is easy to assemble.
In the air/electrical swivel of this invention, both
air and electrical cabling are brought into the swivel fitting
as paired, concentric or separate units. The main body of
the swivel comprises an inner swivel body and outer swivel
body which are intermitted along the common axis and which
provide an air passage through the swivel from one end to the
other. The inner and outer swivel bodies are rotatable with
respect to one another about the longitudinal axis. A seal is
used to seal the air passage at the junction of the inner and
outer swivel bodies.
Electrical continuity is maintained during rotational
movement by employing slip rings on the inner swivel body and
split brushes which maintain electrical contact with the
slip rings during rotation. The C-shaped brushes contact the
rings on each side, and with the split brush ends four contacts
per brush are obtained. I`
An important feature of the present invention which
facilitates assembly is the ball bearing which maintains the
inner and outer swivel bodies in spaced relationship in the
radial direction. The arrangement, which will be described
more fully hereinafter, is such as to not only provide a
bearing but also to lock the inner and outer swivel bodies
from separating in the axial direction after installation of
the ball bearing.
A second important feature of the invention is a
thrust bearing which provides a very stable connection between
the inner and outer swivel bodies This bearing consists of
a nylon sleeve fixed to the outer portion of the outer swivel
body and making contact with a radial surface on the outer
portion of the inner swivel body. Thus the stability is ox-
twined by having the two bearing arrangements which are
axially spaced from one another, viz., the ball bearing race
and the nylon sleeve thrust bearing. Ease of rotation is
provided by polishing the bearing surfaces of the thrust
beating.
It is an object of the invention to provide a rugged
and durable air/electrical swivel which contains a minimum
number of parts and which is easy to assemble.
It is a further object of the invention to provide
an air/electrical swivel of good stability.
In accordance with one aspect of the invention there
is provided a confined air/electrical swivel comprising: an
outer swivel body; an inner swivel body; said inner and outer
swivel bodies being intermitted, being rotatable with respect
to one another about a longitudinal axis, and being aperture
along said axis to provide an air passage throughout the
length of said combined air/electrical Sue; a plurality
of electrically conductive slip rings fixedly mounted in no-
lotion to said outer swivel body, each of said electrical brush means slid ably contacting one of said slip rings so as
to provide continuous electrical connection between said
inner and outer swivel bodies upon relative rotation thereof;
a plurality of electrical conductors connected to said slip
rings; a plurality of electrical conductors connected to said
brush means; a sealing ring of resilient material positioned
along the sir passage between said inner and outer swivel
bodies; ball bearing means located between said inner and
outer swivel bodies and serving to retain said inner and outer
swivel bodies from separating in the axial direction.
There is also provided in accordance with the invent
lion a method of assembling an air/electrical swivel come
prosing: providing a compressible insulating sleeve; placing
said slip rings over said sleeve by first compressing said
sleeve; installing said sleeve on said inner swivel body with
the associated electrical conductors extending through an
aperture in said inner swivel body; locating the air seal in
said outer swivel body surrounding the end of the air passage
therein; inserting said inner swivel body into said outer
swivel body and forcing said inner and outer swivel bodies
together to compress said air seal; while maintaining said
air seal compressed inserting said ball bearing means; no-
leasing the compressive force to lock said inner and outer
swivel bodies together; fixing a thrust bearing and brush
mount means on said outer swivel body with said thrust bearing
in contact with a bearing surface of said inner swivel body.
An embodiment of the invention will now be described
which is to be read in conjunction with the accompanying
drawings in which:
Fig. 1 is a side view of the air/electrical swivel
shown partly in section;
Fig. 2 is a right end view of the assembly as shown
in Fig. l;
Fig. 3 is a cross-section of the inner swivel body
shown in section;
Fig. 4 is a cross-section of the outer swivel body
shown in section;
Fig. 5 is a cross-section of the assembly of the air/
electrical swivel taken along lines 5-5 of Fig l;
Fig. 6 is a cross-section of the assembly of the air/
elect rival swivel shown along the lines 6-6 of Fix. l;
I
--4--
Fig. 7 is a cross-section of the air/electrical swivel
shown along lines 7-7 offing 1.
The combined air/electrical swivel as shown in the
assembly of Fig. 1 comprises an inner swivel body 1 and an
outer swivel body 2. An air passage extends longitudinally
through each of the swivel bodies. The swivel bodies are in-
terfitted so as to align the air passages and so provide a
continuous air passage through the air/electrical swivel.
Air seal 3, which is located in a recess in the outer
swivel body and which is contacted by the right end of the
inner swivel body, prevents the egress of air between the inner
and outer swivel bodies. The air seal is composed of a flexible
material, e.g., polyurethane. It has the shape of a ring with
a concave inner surface to permit it to flex more readily when
it is compressed between the inner and outer swivel bodies.
A plurality of ball bearings 4 are located in a race
formed between a cutout in a ring extending from the inner
portion of the outer swivel body and another cutout in the
outer surface of the inner swivel body. The two cutouts are
so dimensioned and positioned that as explained hereinafter,
the ball bearings are locked between the cutouts.
A thrust bearing and brush mount sleeve 8 is positioned
over the outer swivel body and extends in the axial direction
to contact the bearing surface 11 and surface 12 of the inner
swivel body. In order to reduce friction and thus allow the
swivel to rotate freely, the surface of the thrust bearing and
surfaces 11 and 12 of the inner swivel body are polished. The
thrust bearing and brush mount is fixed to the oilier swivel
body by a plurality of screws 9.
The slip rings, of which there are three shown in
Fig. 1, consist of metallic bands surrounding an insulating
sleeve 5 which is preferably made of acrylic. The slip rings
are mounted in parallel relation to one another in grooves on
the outer surface of the insulating sleeve. The insulating
sleeve is firmly fitted over the inner swivel body. The elect
tribal conductors which are connected to the slip rings are
I 3
--5--
brought out through apertures 17 in the inner swivel body.
The insulating body, as shown in cross-section in Fig. 5,
is not a complete ring but rather has a gap in its circus-
furriness in order that it may be compressed to permit the
slip rings to be positioned over it and locked in position in
the grooves (not shown).
A pair of brushes 10 contact each of the slip rings.
These brushes, as shown in Figs. 1 and 6, are mounted on the
thrust bearing and mount, are of generally U-shaped configure-
lion, and have their arms extending through apertures in the
thrust bearing and mount to contact the slip rings. Each
brush has a pair of arms which contact the associated slip
ring on either side. The second brush of each pair contacts
a slip ring at different portions of the circumference thereof
than the first brush. Also, the brushes as shown in Fig. 1
have split ends so that each end of each brush contacts the
associated slip ring at two points. This arrangement ensures
good connection between the brushes and the slip rings at all
positions of rotation.
The slip rings are composed of a highly resilient
metallic material such as beryllium copper preferably flashed
with gold.
Although three slip rings are shown, it is understood
that the number may be either more or less than three. Like-
wise although the ends of the brushes are shown as having two
fingers, the number of fingers may be more than two.
Electrical conductors 10 are connected to the brushes,
as e.g., by soldering, and hence rotate with the outer swivel
body.
The inner and outer swivel bodies 1 and 2 are shown
as having nipples for connection to air hoses. It is to be
understood that other forms of connection to air lines are
within the scope of the invention.
The assembly of the combined air/electrical swivel
will now be described. The slip rings with connection wires
--6--
attached are assembled onto the insulating sleeve 5 by come
pressing the sleeve enough to allow the rings to be slipped
over into the grooves in the sleeve. The sleeve with rings is
then installed in the inner swivel body l with the wires passing
through the aperture 17 in the inner swivel body. The inner
swivel body is then inserted into the outer swivel body in
which the air seal 3 has already been located as shown in Fig.
1. By applying compressive force to the inner and outer
swivel bodies, and thereby compressing the air seal 3, all
the ball bearings may be dropped through the loading hole 16
and located in the curved cutouts previously referred to and
shown in Fig. 1. When the compressive force is removed the
seal assumes its normal shape and the inner and outer swivel
bodies withdraw slightly from one another by an amount of the
order of 0.5 mm to prohibit the ball bearings from falling out.
This in turn locks the inner and outer swivel bodies in that
the ball bearings prevent them from being withdrawn from one
another in the axial direction. The thrust bearing and brush
mount 8 is then pushed over the outer swivel body and fixed in
place by screws 9. Each brush is then pushed into sleeve 3
through the apertures as above-noted to make contact with the
slip rings. The two brushes which contact the same slip ring
are then joined by soldering.
A test has been performed on a model constructed in
accordance with the above-noted embodiment. In this test the
air/electrical swivel was rotated 7,500 times in one direction
and again an equal number of times in the opposite direction
while air pressure in the passage within the swivel was main-
twined at 90-100 pi
In a second test the swivel was rotated 3,000 times
while maintaining a lateral pressure of 10 lobs. upon it.
The swivel was found to be in good working condition
after both of the above-noted tests.
The embodiment of the invention described in the fore-
going is exemplary only. umber of-other variations of the
fix
structure will occur to those skilled in the art. The invent
lion includes all such variations as would occur to such
skilled person and is delineated not by the preceding example
but solely by the appended claims.
