Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
Thermal Isolation Coupling System
BACKGROUND OF THE INVENTION
The present invention relates to coupling systems for transmission of fluids, and
in particular to coupling systems for attaching a conduit for high temperature fluid to
a housing in such a way that heat is not transferred from the high temperature conduit
into the housing.
One environment in which such coupling systems has become important is the
automotive industry. As part of the current trend of manufacturing automobiles with
lighter construction, utilizing aluminum instead of steel, and plastic instead of metal
and so on, it has become increasingly popular for designers to replace more and more
metal parts witlh parts made from plastic material. Only recently, however, has it
become possible to replace metal automotive engine components with plastic
components, because of the various strength, durability and heat resistance
characteristics which the particular components must possess. While high strength,
high heat resistant plastic and ceramic materials do exist, such materials are extremely
costly and are sometimes brittle, and are therefore not economically feasible.
However, certain engine componenl:s can be replaced, if they are low strength
requirement components which can be effectively isolated from high heat and
temperature sources. These particular components can then be manufactured from
relatively inexpensive thermoplastic materials such as ABS. Such inexpensive plastic
components must be protected from temperatures that are in excess of approximately
350 degrees Fahrenheit.
One such automotive engine component which, among others, can be
manufactured from inexpensive plastic material, if properly isolated, is the air intake
manifold. Through the use of the proper gasketing or other suitable isolation
technique, the main body of an air intake manifold housing can be effectively
substantially thermally isolated from the remainder of an engine block. However, there
exists one feature which is becoming increasingly prevalent in modern, fuel efficient,
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low emission engine, which presents particular difficulties with respect to isolation
from heat. In orcler to improve the fuel efficiency and emissions quality of automobile
engines, it has become common practice to direct hot exhaust gases from the exhaust
manifold into the intake manifold, in order to elevate the temperature of the incoming
air to improve the efficiency of the combustion process, as well as to combust unused
fuel vapor which exists in all automobile exhaust. However, while the ambient air
which is brouglht into the air intake manifold may be[,] as much as 125 degrees
Fahrenheit, the exhaust gases which are being recirculated in to the air intake manifold
may have a temperature as high as 1300 degrees Fahrenheit. Such extreme
temperatures would lead to the destructive transmission of heat from the exhaust gas
recirculation (EGR) tube, which must be made of metal, into the portions of the
housing to whic:h the EGR tube is attached. Low temperature plastics would quickly
begin to degrade or even melt or burn under prolonged exposure to such heat unless
properly insulated from the EGR tube.
Various attempts have been made to provide for inexpensive adequate
insulation between the hot EGR tube and the plastic housing. One such proposed
solution is to provide a metal flange which centers the hot tube end within a much
larger aperture in the housing. The flange, often in the shape of a cup, is then affixed
to a cylindrical collar which extends from the housing, surrounding the aperture.
However, since the flange or cup is manufactured from metal, the heat is simply
transferred through the flange into the portion of the collar which makes contact with
the flange. Although this transferred heat is slightly less intense than at the extreme
end of the EGR tube, the transferred heat is still sufficient to cause the premature
degradation and/or melting of the plastic surfaces which are in direct contact with the
flange. Accordingly, it has been the practice to provide that portions of the plastic
collar are replaceable and separable from the main housing body. Such replaceable
portions are, in fact, designed to degrade and be replaced on a regular basis. Such a
construction is undesirable from the standpoint of the cost and inconvenience ofreplacement of the removable portions.
Another proposed solution is to position a cylindrical insulator body between the
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hot EGR tube end and the collar portion of the housing. However, to provide
significant effec:tive insulation capabilities, high performance insulating materials must
be used, as previously described, which are prohibitively expensive, and as well, may
have other undesirable performance characteristics, such as brittleness, low durability,
susceptibility to fatigue and so on.
It is accordingly desirable to provide a system for coupling a high temperature
tube or conduit to a housing in such a way that the heat from the high temperature
conduit is not transferred into the material of the housing itself, so that the housing
may be manufactured from common or at least non-high performance material.
Another object of the invention is to provide such a thermal isolation coupling
system, in which the actual coupling components themselves may further be
fabricated from relatively inexpensive, low temperature, low performance materials.
These and other objects of the invention will become apparent in light of the
present Specification, Claims and Drawings.
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SUMMARY OF THE INVENTION
The present invention is directed to a thermal isolation coupling system for
operably maintaining an end of a tube in substantially sealed insertably received
attached alignment, within a housing aperture which has an inner surface and at
least one engagement surface operably disposed adjacent the aperture. The
housing further has a substantially atmospheric ambient temperature fluid flow
established therein, while the tube has a substantially greater than atmosphericambient temperature fluid flow directed therethrough into the housing. The thermal
isolation coupling system operably promotes transfer of heat away from the tube
to, in turn, reduce the heat of the tube where it is attached to the housing.
The therrnal isolation coupling system comprises locking means operably
associated with the tube end and cooperating with the housing to removably affixthe tube end in~to a predetermined position relative to the aperture and the
substantially atrnospheric ambient temperature fluid flow. A tube support member,
having an extreme tip, operably interconnects the tube end to the locking means.The tube support means is affixed at its extreme tip to the extreme tip of the tube
end, with the tube support member circumferentially surrounding the tube end. The
tube support member is further interlockingly received and circumferentially
surrounded by lthe locking means at an end of the tube support member distal to
the extreme tip thereof to enable positioning of the extreme tips of the tube end
and of the tube support member, respectively, operably within the established
substantially atrnospheric ambient temperature air flow and to thermally isolate the
tube support member, and in turn, the tube end from the inner surface of the
aperture to substantially preclude heat conductive contact between the inner
surface of the aperture and the tube support member. Sealing means are also
operably associated with the tube support member and the locking means, to
preclude escape of fluid from the substantially greater than atmospheric ambienttemperature fluid flow from said aperture, and to facilitate the isolation of the tube
support means.
The locking means includes a first locking member which operably
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circumferentially surrounds and is received by the distal portion of the tube support
member. At least one engagement member is operably disposed on the first lockingmember for interlocking engagement with the at least one engagement surface.
The locking means further includes at least one attachment member disposed on
the first locking member and a second locking member, which has at least one
attachment surface for cooperative interlocking releasable engagement with the at
least one attachment member, so that when the at least one attachment member
and the at least one attachment surface are brought into engagement, a portion of
the distal end of the tube support member is retained between the first and second
locking members.
In a preferred embodiment of the invention, the system also includes
gripping means for engaging the tube support member and the locking means, to
permit resistive relative rotational movement between the tube support member
and the locking means. The gripping means includes a first gripping member
engageable with the just-mentioned portion of the distal end of the tube supportmember, a first set of gripping contours arranged on the first gripping member, and
a second set of gripping contours arranged on the second locking member, for
engagement wil:h the first set of gripping contours, when the first and second
locking members are engaged.
In a preferred embodiment of the invention, the second locking member also
includes a plurality of tool engagement surfaces arranged circumferentially around
the second locking member.
Alignment means may also be provided, which are associated with the
gripping means for facilitating centering of the tube end relative to the locking
means and the distal end of the tube support member. The alignment means
includes a plurality of alignment members which are arranged circumferentially
around the first gripping member, and projecting radially inwardly therefrom.
The tube support member is to be formed, preferably, as a substantially
cylindrical member, having first and second open ends, with the first open end
disposed at the extreme tip of the tube support member. The second open end is
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disposed at the distal end, and has a diameter substantially greater than that of the
tube end adjacent the distal end of the tube support member.
The tube support member is likewise preferably affixed to and in
heat-conductingl contact with the extreme tip of the tube end, and substantiallyonly at said respective extreme tips of the tube end and the tube support member.
In a preferred embodiment of the invention, the first and second locking
members are fabricated from relatively low temperature resistant thermoplastic
material or the like.
The sealing means may be formed as a resilient sealing member arranged
circumferentially around the tube support member, and configured to sealingly fit
between the tube support member and the inner surface of the aperture. A resilient
retainer member may also be circumferentially disposed around the tube support
member.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevation, in section, of a prior art coupling system.
Fig. 2 is c3 side elevation, in section, of another prior art coupling system.
Fig. 3 is a side elevation, in section, of still another prior art coupling system.
Fig. 4 is a plan view of the thermal isolation coupling system attaching one
end of a high temperature fluid tube to a housing.
Fig. 5 is an exploded perspective view of the various elements of the thermal
isolation coupling system of the present invention.
Fig. 6 is .3 side elevation, in section, of the coupling system according to Fig.
5, assembled and in position within an aperture in a housing.
Fig. 7 is a side elevation, partially in section, of an aperture and surroundingstructure, for which the present fluid coupling system may be configured.
Fig. 8 is .3 side elevation, partly in section, of the aperture and surrounding
structure accorcling to Fig. 7.
Fig. 9 is a side elevation, partly in section, showing the external structure ofthe thermal isolation coupling system according to Fig. 5.
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DETAILED DES('RIPTION OF THE DRAWINGS
While this invention is susceptible of embodiment in many different forms,
there is shown iin the drawings and will be described herein in detail, a specified
preferred embodiment, with the understanding that the present disclosure is to be
considered as an exemplification of the principles of the invention and is not
intended to limit the invention to the embodiment illustrated.
Figs. 1 thlrough 3 show three different prior art systems for positioning the
end of a tube, c:arrying a high temperature fluid flow, such as an exhaust gas
recirculation (E(iR) tube within an aperture in a housing, such as an intake manifold
housing, in particular where the housing is fabricated from a high temperature
sensitive material such as nylon or other thermoplastic material. Exhaust gases
within an EGR tube are typically in a temperature range of 1200 - 1300 degrees
Fahrenheit.
Fig. 1 shows tube 10 centered within aperture 1 1 of housing 12 by cup 14.
Flange 15 of cup 14, however, is in direct contact with flange 16 of housing 12.Accordingly, heat from the incoming recirculated exhaust gases is transferred from
the incoming flow, indicated by the arrow, into tube 10, through the annular joint
17, between tube 10 and cup 14, and along cup 14 to flange 15 and in turn into
flange 16. There is little opportunity for the heat being transferred into tube 10 to
be dissipated as it is conducted into cup 14 and flange 15. Further, there is
substantial comlmon surface area between flanges 15 and 16. The heat accordinglywill cause the premature degradation of the material of the housing in the general
area of the aperture 11 and in particular in the region of flange 16, necessitating
the complete replacement of ~he housing 12, which is typically a molded
continuous unit.
Fig. 2 discloses another prior art coupling configuration in which tube 20 is
centered within aperture 21 of housing 22 through the use of an insulator 23.
Insulator 23 is ~ypically configured from either a solid ceramic or plastic material. If
the material is high-temperature resistant ceramic or plastic, while the usable life
span of the insulator may be improved somewhat, the substantial increased cost of
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such materials is undesirable. Such high-temperature resistant materials would be
necessary, since insulator 23 otherwise would also require replacement at short
intervals, due to the fact that the heat being transferred from the flow into tube 20
will tend to be transferred directly into insulator 23, and not be transferred
elsewhere.
Fig. 3 shows a further coupling configuration in which tube 30 is aligned
with aperture 31 of housing 32 through the use of a diaphragm 33 which has
integrally formed therewith inwardly projecting tube portion 34. Heat from the high
temperature fluid flow is transferred either from tube 30, or directly into tubeportion 34, and then into diaphragm 33. Ultimately, the heat is transferred into the
retaining portion 35 of collar 36 which surrounds aperture 31. Similarly to the prior
art configuration of Fig. 1, the prior art configuration of Fig. 3 includes metal
elements which are in direct heat conducting contact with the plastic surfaces of
the housing.
It is the goal of Applicant's invention to provide a coupling system with
significantly more effective thermal isolation than that provided in the
above-described prior art systems. Applicant's invention provides, as described
hereinafter, a coupling system which may be advantageously used, for example, toconnect an EGR tube 40 (Fig. 4) from an exhaust housing 41 to an intake manifoldhousing 42 in such a manner that the heat from the high-temperature recirculatedexhaust gases are not transferred from tube 40 into the plastic housing collar 43
surrounding aperture 39 (see Fig. 9), without requiring either the provision of costly
high-temperature resistant insulating materials to separate the tube from the
housing, or the fabrication of the housing itself from high-temperature resistant
materials.
Figs. 5 - 9 show the thermal isolation fluid coupling system 50 of Applicant's
invention.
Exhaust !3as recirculating tube 40 is typically configured, as shown in Fig. 6,
as being formed from a central thin-walled metal tube 40, which may be fabricated
from light gage heat resistant or corrosion resistant steel. Along its length, tube 40
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may be provided with circumferential or spiral grooves 45 and ridges 46 to
facilitate manipulation of tube 40 into any desired or required position. Insulation
cover 47 prevents loss of heat from the exhaust gases through the sides of tube
40. Typically, ir1sulation cover 47 is formed as a knit, woven or braided fabriccover made frolm an insulating fiber material. Tube 40 includes tube end 48 and
extreme tip 49, which is to be positioned within and aligned with aperture 39 inhousing 42.
Coupling system 50 is shown in exploded view in Fig. 5. Tube end 48 is
shown surrounded by cup 51. Extreme tip 49 of tube end 48 is affixed to extreme
tip 52 of cup 51, as indicated in Fig. 6. Flange 53 extends radially outwardly from
the end of cup 51, opposite extreme tip 52. Flange 53 has a number of rectangular
notches 54 arranged at regularly spaced intervals around its periphery. Notches 54
are configured to accommodate hooks 56 which are positioned at regular intervalsaround the periphery of retainer ring spring 55. Retainer ring spring 55 additionally
has prongs 57 extending inwardly and at a substantial angle to the plane of mainportion 58 of retainer ring spring 55. In the preferred embodiment of the invention
prongs 57 and hooks 56 are arranged in one to one correspondence around the
periphery of retainer ring spring 55, with a respective prong 57 and hook 56
positioned in radially aligned relation to each other. Positioned in between each
respective prong 57 and hook 56 pair, are detents 59. In the preferred embodiment
of the invention, detents 59 are positioned substantially midway between adjacent
hook 56 and prong 57 pairs.
First lock:ing ring 60 is formed as a short cylindrical annulus, configured to
slidingly fit around the larger diameter portion of cup 51. Positioned at
circumferentially spaced intervals around first locking ring 60 are a plurality of
engagement members 61. A substantially wedge-shaped hook 62 projects inwardly
from each engagement member 61. In addition, substantially c-shaped lock pins 63emanate from opposite portions of first locking ring 60. Second locking ring 70 is
substantially hexagonal shaped with substantially rectangular sides 71. Sector
shaped projections 72 are arranged in uniformly circumferentially spaced positions
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around one end of second locking ring 70. Each projection 72 straddles the edge
73 between adjacent sides 71. Arcuate ledges 74 are positioned between adjacent
projections 72, with the circumferential spacing between adjacent projections 72configured to snugly accommodate engagement members 61. Coupler system 50
also includes 0-ring 78 and split ring retainer 79.
In practice, the assembly and operation of coupling system 50 is illustrated
in Figs. 6-9. A desired length of tube 40 is prepared, and provided with insulation
cover 47. Secc,nd locking ring 70 may then be fitted over tube end 48. Retainer
ring spring 55 fits loosely juxtaposed to flange 53 of cup 51. The radial width of
main portion 58 of retainer ring spring 55, in the preferred embodiment of the
invention, is substantially equal to the radial width of flange 53. Prongs 57 are
directed into the interior 64 of cup 51. First locking ring 60 slidingly fits over cup
51 with engagement members 61 pointing toward flange 53 and away from
extreme tip 52. Engagement members 61 and hooks 62 are, in the preferred
embodiment of the invention, configured so as to provide a diameter slightly less
than that of the outside diameter of flange 53, so that engagement members 61
must be sprung outwardly slightly in order for flange 53 to pass hooks 62, so that
flange 53 may be brought up against interior ledge 65 of first locking ring 60. The
assembled cup 51, first locking ring 60, retainer ring spring 55, are then slid upon
tube 40 and insulation cover 47. Preferably, prongs 57 are configured so that they
will grippingly slide over cover 47, to enable the just described assembly to bepushed up a desired distance along tube 40, until extreme tip 52 of cup 51 and
extreme tip 49 of tube end 48 can be aligned, as shown in Fig. 6. Extreme tips 52
and 49 can then be affixed together permanently, by any suitable method, such aswelding, brazing, etc., so long as any heat applied is sufficiently controlled to
prevent damage to first locking ring 60.
Second locking ring 70 may then be aligned with first locking 60 so that
engagement members 61 are brought into registry with ledges 74. Preferably,
detents 59 on retainer ring spring 55 are sized so that when first locking ring 60
and second loc:king ring 70 are pressed together, when hooks 62 have passed
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ledges 74, detents 59 of retainer ring spring 55 produce a compression fit, suchthat hooks 62 are being forced against ledges 74 and engagement members 61 are
in tension. As a result of this construction, retainer member 55 is pressed against
cup 51 and relative rotation between joined first locking ring 60 and second locking
ring 70 is prevented. Relative rotation is permitted between cup 51 and second
locking ring 70. Detents 59 of retainer ring spring 55 nest into teeth 88 of locking
ring 70, which resist relative motion, but will allow rotational indexing with some
minor torque applied, to allow assembled first and second locking rings 60 and 70
to rotate relative to tube 40, cup 51 and retainer ring spring 55, with a
"ratcheting" effect. This effect permits the installation of coupling system 50, with
tube end 48 affixed, after the other end of tube 40 has already been secured to the
exhaust manifold 41, in that first and second locking rings 60 and 70 may be
rotated to lock into housing 42, while tube 40, and in particular, tube end 48
remains or is held motionless. O-ring 78 and split ring retainer 79, the function of
which are described hereinafter, slidingly fit about cup 51 so that O-ring 78 isabutted against first locking ring 60 and held in place by split ring retainer 79.
Figs. 7, 8 and 9 depict a typical aperture configuration which may be
provided in housing 42. Collar 43 projects outwardly from housing 42. Collar 43
includes first and second cylindrical portions 80 and 81, respectively. Cylindrical
portion 80 may have longitudinally extending ridges 82 which project radially
inwardly. Outer cylindrical portion 81 has an interior diameter which is greater than
the interior diarneter of cylindrical portion 80. Cup 51 of coupling system 50 is
configured such that the outside of the diameter of the larger cylindrical portion of
cup 51 is less 1han the inner diameter of cylindrical portion 80, with cup 51 having
a clearance between it and ridges 82. Flange 53 of cup 51 has an outside diameter
which is greater than the inside diameter of cylindrical portion 80, but is less than
the internal diameter of cylindrical portion 81. The outside diameter of first locking
ring 60 and second locking ring 70 are configured to be slightly less than the
interior diameter of cylindrical portion 81, so that the assembled coupling system
50 can be insertingly received by collar 43.
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Cylindrical portion 81 is additionally provided with longitudinally extending
notches 84 and corresponding circumferentially extending slots 85 which intersect
with notches 84. Lock pins 63 which extend from opposite portions of first locking
ring 60, are configured to be received by notches 84. Upon rotation of coupling
system 50, by applying torque to second locking ring 70, lock pins 63 move alongslots 85. In order to assure that coupling system 50 is tightly held within collar 43,
O-ring 78 and split ring retainer 79 have been provided. Split ring retainer 79, in
addition to holding O-ring 78 against first locking ring 60, is configured to bear
against the inner surface 86 of collar 43, the transition region between cylindrical
portion 80 and cylindrical portion 81.
As can be seen from Fig. 5, lock pin 63 has a curved, C-shaped surface.
When O-ring 78 and split ring retainer 79 are in place, and coupling system 50 is
inserted into collar 43, ridges 82 are used to prevent O-ring 78 and split ring
retainer 79 from being vibrated or worked off of cup 51 during operation of the
vehicle. Instead, the sides of lock pins 63 are positioned so that edges 86, where
slots 85 intersect notches 84, abut lock pins 63. Upon the further application of
thrusting force and twisting force to coupling system 50, O-ring 78 is compressed
and edges 86 ride up on the curves portions of lock pins 63, in a cam-follower type
of movement, permitting lock pins 63 to move into slots 85. The curved surfaces
of lock pins 63 may be configured to deform slightly, which can serve to preventcracking or other damage to either of the locking rings and to enhance the locking
action. O-ring 78, being compressed, exerts a thrusting force, pushing first locking
ring 60 outwardly, in turn pressing lock pins 63 against the outer walls of slot 85,
creating frictional resistance to further rotational movement of coupling system 50,
in the absence of intentionally applied twisting force in the return direction.
Once the components of the present coupling system have been assembled,
the configuration serves to thermally isolate the tube end 48, by centering tube end
48 within aperture 39. Further, cup 51 is prevented by first and second locking
rings 60 and 7(), and O-ring 78, from making heat conductive contact with collar43 of housing 42. Split ring retainer 79 additionally only makes intermittent contact
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with collar 43, as a result of engine vibration, and so does not serve to transfer any
significant amounts of heat from cup 51 to collar 43. The potential heat transfer at
this location is also not significant since, the temperature of cup 51, where split
ring retainer 79 is positioned, has been so significantly reduced, as described
hereinafter.
To obtain the desired effect of transferring heat away from tube 40, in
particular extreme tip 49 of tube end 48, cup 51, first locking ring 60 and second
locking ring 70 have been configured so that once coupling system 50 is fully
assembled and positioned within collar 43, extreme tip 52 of cup 51 extends
beyond aperture 39 and into the established substantially atmospheric ambient
temperature flow within housing 42.
Substantial cooling effect has been observed utilizing the above-described
configuration of Applicant's invention. In particular, if the substantially greater than
atmospheric ambient temperature fluid flow, within tube 40 is approximately 1300degrees Fahrenheit, and if the substantially atmospheric ambient temperature flow
established within the housing 42 is approximately 125 degrees Fahrenheit
(approximating the heated air present over a highway on a 100 degrees Fahrenheitday), temperatures at extreme tip 52 have been observed to be approximately
1,240 degrees l~ahrenheit. Due to the convection cooling effect of positioning the
extreme tip 52 within the cooler air flow, temperatures of approximately 300
degrees Fahrenheit have been observed at a position midway along the longitudinal
length of cup 51, and temperatures on the inward cylindrical surface of second
locking ring 70 of 200 to 250 degrees Fahrenheit have been maintained. Such
substantial cooling enables the use of relatively inexpensive plastic material to be
used for the fabrication of the first and second locking rings 60 and 70,
respectively, as well as the use of non-high temperature resistant elastomeric
material for 0-ring 78. In addition, the molded plastic material from which housing
42 is fabricated, need not be high temperature resistant and may be formed as a
single molded member.
The particular configuration of cup 51, first locking ring 60, second locking
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ring 70 are dependent upon the necessary and/or desired contiguration of collar 43
which surrounds aperture 39 of housing 42. However, the inventive concept of
positioning extreme tip 49 of tube 40 into the established lower temperature airflow within hou.sing 42 is not affected by the particular configuration of coupling
system 50 which is used to achieve the desired positioning. Additionally, the
configuration of the various described elements may be varied without departing
from the inventive desired configuration which precludes direct heat conducting
contact between high temperature metal portions of tube end 48 or of cup 51, andinstead provides only for the intermittent limited contact from split ring retainer 79,
at which position, the temperature has been substantially reduced to values which
relatively inexpensive, non-high temperature resistant plastic materials can
withstand .
The foregoing description and drawings merely explain and illustrate the
invention and the invention is not limited thereto except insofar as the appended
claims are so lirnited, as those skilled in the art who have the disclosure before
them will be able to make modifications and variations therein without departingfrom the scope of the invention.
