Bearing system for wave generator drive

A bearing system for a wave generator includes at least two laterally positioned rolling discs each of which is supported eccentrically through an eccentric ring and an intermediate bearing. The eccentric rings are frictionally clamped to each other with one of the rings being adjustable relative to the other to provide eccentricity. The exterior faces of the discs roll against a flexible ring. Axial movement of the flexible ring relative to the rolling discs is precluded through the use of collars or clips which radially project from the rolling discs. The axial end faces of the flexible ring sealingly engage the interior faces of the collars.

FIELD OF THE INVENTION 
This invention relates generally to harmonic drive systems and more 
particularly to an improved wave generator bearing arrangement. 
BACKGROUND OF THE INVENTION 
In U.S. Pat. No. 4,580,957 a bearing arrangement for a wave generator 
capable of eccentrically deflecting a flexible ring of a rotary piston 
engine was disclosed. The bearing arrangement included a pair of rolling 
discs arranged side by side and supported on a drive shaft through 
eccentrics which were pivotable against each other. A flexible ring was 
engaged by the radially external face of each of the rolling discs. The 
flexible ring constituted the engine piston ring and was forced against 
the inner face of a cylinder wall. The piston ring was flexed or deflected 
through rolling contact between its inner face and the external faces of 
the rolling discs. 
Among the problems encountered with such arrangement was the fact that the 
flexible piston ring accumulated foreign matter including combustion 
byproducts on its inner face. Such accumulations were in some instances 
due to engine ventilation. 
Further, when a comparatively soft material was utilized for the flexible 
piston ring, such as austintite, the flexible piston ring deformed, i.e. 
became wavy, in the rolling contact area between the external faces of the 
rolling discs and the inner face of the flexible piston ring. The 
deformation was primarily due to flexing in the exhaust suction direction. 
In view of the requirements for sealing the cylinder and piston ring in 
the engine, piston ring deformations were undesirable. 
In addition, the disclosed bearing arrangement presented difficulties in 
connection with the balancing of the comparatively large revolving masses. 
Balancing requirements presented increased manufacturing costs. 
Another wave generator bearing arrangement has been disclosed in U.S Pat. 
No. 4,003,272 in conjunction with a harmonic drive planetary gear. The 
invention therein disclosed included three identical rolling discs 
positioned side by side. The radially external faces of the discs 
contacted the inner face of a flexible splined planet wheel. 
To support the rolling discs, identical roller bearings were provided 
between each rolling disc and interiorly positioned eccentric rings, also 
arranged side by side. The bearing assembly was relatively long in an 
axial direction and was thus not practical in applications with limited 
space requirements. Further, as a result of an endless bearing ring which 
extended over the same axial length as the flexible planet wheel, 
relatively large radial forces and concomitant bearing loads were 
generated. 
In addition, since the radial force exerted on the central rolling disc was 
twice that exerted on each of the lateral rolling discs, the central 
bearing received twice the load than the bearings which supported the 
lateral rolling discs. As a result, the useful life of the wave generator 
was determined by that of the central bearing. 
Also, because the three rolling bearings were of identical construction, 
assembly of the bearing system required a three part design of the driving 
eccentric. In addition, relatively high system imbalance resulted due to 
the fact that eccentric rings, rolling bearings and rolling discs of 
identical design were employed. Such system imbalanced resulted in 
additional balancing expenses and relatively high manufacturing costs. 
SUMMARY OF THE INVENTION 
A bearing system for wave generators includes at least two rolling discs 
which are positioned side by side with each disc being supported 
eccentrically through a radially interior bearing and an eccentric ring. 
The eccentric rings are adjustably frictionally joined to one another. 
A flexible ring is engaged by the radially external faces of the discs and 
is restrained against axial movement by a pair of collars or circular 
clips which project radially from the rolling discs adjacent the two outer 
sides. The axial end surfaces of the flexible ring sealingly seat against 
the interior sides of the collars or circular clips. 
Relative eccentric axial adjustment between the eccentric rings results in 
radial displacement of the corresponding rolling discs which are carried 
by their associated bearings. 
In instances where three rolling discs are provided, the central disc and 
its support bearing and eccentric ring are significantly larger in axial 
length than the laterally positioned rolling discs, associated bearings 
and eccentric rings. Such structure compensates for the fact that the 
radial load on the central rolling disc is greater than the radial load on 
each of the lateral rolling discs and also simplifies system balancing. 
In order to reduce radial load on the wave generator bearing system, the 
flexible ring body may optionally include an axial slit. 
From the foregoing compendium, it will be appreciated that it is an aspect 
of the present invention to provide a bearing system for a wave generator 
of the general character described which is not subject to the 
disadvantages of the background art aforementioned. 
A consideration of the present invention is to provide a bearing system for 
a wave generator of the general character described which is relatively 
low in cost and simple in design. 
A feature of the present invention is to provide a bearing system for a 
wave generator of the general character described which provides both a 
highly compacted narrow profile in an axial direction and a relatively 
high load capacity. 
Another feature of the present invention is to provide a bearing system for 
a wave generator of the general character described with enhanced 
operational safety and relatively long useful life. 
To provide a bearing system for a wave generator of the general character 
described for eccentrically flexing a flexible ring by rolling off the 
interior face of the flexible ring while sealing such interior face 
against foreign matter and other contaminants is another feature of the 
present invention. 
A further consideration of the present invention is to provide a bearing 
system for a wave generator of the general character described which can 
be assembled with conventional commercially available bearings. 
A still further feature of the present invention is to provide a bearing 
system for a wave generator of the general character described wherein the 
relative radial displacement of eccentric rings may be easily adjusted and 
set. 
Yet a further aspect of the present invention is to provide a bearing 
system for a wave generator of the general character described which may 
be equally employed with a flexible ring body functioning as a piston ring 
for a thin walled rotary piston, a bearing wheel or a splined planet 
wheel. 
To provide a bearing system for a wave generator of the general character 
described which may be readily employed at relatively high speeds and 
heavy loads while accomplishing both size and weight reductions is a 
further consideration of the present invention. 
Another consideration of the present invention is to provide a bearing 
system for a wave generator of the general character described which may 
be produced utilizing low waste manufacturing techniques. 
An additional feature of the present invention is to provide a bearing 
system for a wave generator of the general character described which 
facilitates low cost manufacturing through the utilization of relatively 
inexpensive materials and without requiring use of a hardened flexible 
ring. 
A further consideration of the present invention is to provide a wave 
generator of the general character described with reduced radial restoring 
forces. 
An additional consideration of the present invention is to provide a 
bearing system for a wave generator of the general character described 
which is equally well adapted in both high and low speed operations for 
utilization of conventional self-lubricating sliding bearings as well as 
rolling bearings. 
Other aspects, features and considerations of the present invention in part 
will be obvious and in part will be pointed out hereinafter. 
With these ends in view, the invention finds embodiment in the various 
combinations of elements and arrangements of parts by which the said 
aspects, features and considerations and certain other aspects, features 
and considerations are attained, all with reference to the accompanying 
drawings and the scope of which is more particularly pointed out and 
indicated in the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now in detail to the drawings, wherein like numerals are employed 
to denote like components of the various embodiments of the invention, 
FIG. 1 illustrates a wave generator having a bearing system constructed in 
accordance with and embodying the invention. The bearing system includes a 
pair of lateral outer rolling annular discs 2, 6 between which a central 
annular rolling disc 4 is positioned. The discs 2, 4, 6 are arranged side 
by side in a axial direction. 
In accordance with the invention, the discs 2, 4, 6 are offset radially 
from a system rotational axis denoted by the reference numeral 8 and serve 
the function of dynamically deforming a flexible ring 10 from an 
unstressed circular configuration. 
The two lateral rolling discs, 2, 6 are of identical construction and are 
assembled facing one another with the central rolling disc 4 
intermediately positioned. The lateral rolling discs, 2, 6 are each 
supported on an eccentric ring, 22, 26, respectively, with a conventional 
bearing such as a ball bearing assembly 12, 16, respectively, mounted 
between the eccentric rings 22, 26 and the respective rolling discs 2, 6. 
It should be noted that the bearings 12, 16 rotate about a bearing axis 18 
which is eccentric to the longitudinal axis 8. 
The central rolling disc 4 is rotatably mounted about a central eccentric 
ring 24 through a conventional bearing 14, typically illustrated as a 
cylindrical roller bearing. The roller bearing 14 rotates about an axis 20 
which is arranged eccentric to the longitudinal axis 8 in an opposite 
direction than the axis 18 of the bearings 12, 16. 
Pursuant to the invention, the eccentric rings 22, 26 are centered with 
respect to one another through an inner support sleeve 28, the ends of 
which are seated in a circumferential groove 30 formed on the interior 
side of each lateral eccentric ring, 22, 26. 
In order to adjust for the eccentricity of the wave generator, an adjusting 
screw 32 is threadingly received within a bore of the support sleeve 28 
along a radial axis. 
Through bolts or screws may be employed for connecting the eccentric rings 
22, 26 for unitary rotation and for frictionally securing the central 
eccentric ring 24 between the interior faces of the lateral eccentric 
rings 22, 26 and maintaining the eccentric adjustment set by the adjusting 
screw 32. 
In FIG. 1, the dot and dash lines designated by the numeral 34 represent 
the axes for such screws. Threaded apertures may be provided along such 
axis through the rings 22 and 26 or, the ring 26 may include an oversize 
bore or slot 60 along such axes. In addition, an oversize bore 60 is 
provided along these axes through the central eccentric ring 24 as 
illustrated in FIG. 2. 
In order to adjust the double eccentricity of the wave generator bearing 
system, the through bolts extending along the axes 34 are loosened and the 
adjusting screw is then rotated to set the distance between the bearing 
axes 18 and 20. After precise adjustment is made by rotation of the screw 
32, the through bolts are tightened, frictionally clamping the central 
eccentric ring 24 between the lateral eccentric rings 22, 26. As a result, 
a high degree of safety in operation is ensured. 
In the event excessive forces are encountered, additional support for the 
eccentric positioning of the wave generator is provided through the 
adjusting screw as well as through the support sleeve 28 secured between 
the eccentric rings 22, 26. 
The wave generator may be coupled to an input drive shaft 36 by the through 
bolts which are employed to frictionally clamp the central eccentric ring 
24. The through bolts pass through suitable apertures formed along the 
axes 34 in a perpendicular flange 38 fixed to the end of the input shaft 
36. 
To obtain overload protection, the screw 32 can be removed after the axes 
18 and 20 have been set relative to the axis 8 and the torque applied to 
the through bolts which clamp the eccentric rings 22, 24, 26 and the drive 
shaft flange 38 may be preset such that upon exceeding a specified load, 
the frictional engagement retaining the central eccentric ring 24 is 
overcome and radial movement of the eccentric rings relative to one 
another takes place. As a result, fracture or failure of the wave 
generator components is avoided. 
It should also be noted that the central roller bearing 14 is required to 
carry a load which is essentially the equivalent of the sum of the load 
carrying capacities of the two bearings 12, 16 which carry the lateral 
rolling discs, 2, 6, respectively. As a result, smaller conventional 
bearings may be selected as the bearings 12, 16 than for the bearing 14 
thereby achieving a reduction in axial length of the bearing system and a 
reduction in the total weight of the wave generator. In addition, the 
masses of the various mutually eccentric parts are matched for the purpose 
of avoiding system imbalance. For example, the mass of each lateral 
rolling disc 2, 6 is approximately one-half the mass of the central 
rolling disc 4. 
Pursuant to the invention, the flexible ring 10 may be formed of a 
conventional metal or other material without the requirement for surface 
hardening or heat treatment. Preferably, high surface strength is achieved 
through the utilization of a precision spring steel strip 40 against which 
the rolling discs 2, 4, 6 roll. 
The central rolling disc 4 includes a radially external face 54 having a 
width designated by the double arrow 44 in FIG. 1. Such width 44 is 
essentially equal to the sum of the corresponding widths, designated by 
the arrows 42, 46 of the external faces 52, 56 of the lateral rolling 
discs 2, 6. As a result, uniform load and material utilization is 
provided. 
In accordance with the invention, the flexible ring 10 is restrained from 
axial movement through the utilization of collars, 48, 50 which project 
radially from the sides of the rolling discs, 2, 6 beyond their radially 
external faces 52, 56. Alternately, circular clips may be employed in lieu 
of integral collars 48, 50. 
The axial gap or space between the collars 48, 50 and the axial end 
surfaces of the flexible ring 10 is adjusted relatively tightly to provide 
a seal which prevents the entrance of contaminants but may possibly permit 
excess grease or other lubricant to be expelled. 
It should be noted that the relative movement between the end surfaces of 
the flexible band 10 and the rolling disc collars 48, 50 is relatively 
small. The movement of a point of the end face of the flexible ring 10 
relative to the face of an associated collar 48, 50 approximately 
corresponds to an evolute. The relative movements are comparable to 
overlapping movements with excess pressure and excessive wear being 
reliably avoided. 
In FIG. 2, the wave generator and bearing system is illustrated with the 
rolling bearings 14 and the spring steel strip 40 omitted for the purpose 
of better illustrating the remaining components. The flexible ring 10 is 
shown to include an axial slit 58 which serves to reduce radial restoring 
forces. For example, with an axial flexible ring 10 having width of 20 
mm., an outside diameter of 100 mm. and an inside diameter of 94 mm., a 
restoring force of 16 kg. is obtained with an ovalization of 2 mm. when 
the flexible ring includes the slit 58. The corresponding restoring force 
of an identically dimensioned flexible ring 10 without the slit 58 is 
approximately 130 kg. 
Turning now to FIG. 3 which shows an alternate embodiment of the invention, 
depicted, for the purposes of simplification only, without illustrating a 
plurality of rolling discs 2, 4, 6 and a drive shaft. The embodiment 
illustrated in FIG. 3 is particularly well adapted for high speed 
operation and does not include a central eccentric ring 24 positioned 
between a pair of lateral eccentric rings 22, 26. In lieu of a central 
eccentric ring 24, an inner race 62 of a central bearing 14 is clamped 
directly between a pair of lateral eccentric rings, 22, 26. The engagement 
surfaces of the eccentric rings 22, 26 and the bearing race 62 is enlarged 
at the eccentric rings 22, 26 by radial collars 64 on the eccentric rings. 
The collars 64 also serve as a lateral seat for the outer races of the 
lateral bearings 12, 16. An adjusting screw 32 is engaged in a central 
support sleeve 28 and bears directly against the inner race of the central 
bearing 14. 
A gap 66 is presented between the support sleeve 28 and the lateral 
eccentric ring 22 for the purpose of permitting the frictional clamping of 
the support sleeve 28 between the two lateral eccentric rings 22, 26. 
In FIG. 4, a further embodiment of the invention is illustrated wherein the 
bearing system is used in conjunction with a wave generator for a 
planetary gear having a flexible splined planet wheel 74. The planet wheel 
74 includes external teeth 76 and internal teeth 78. Planetary gears of 
this type have been disclosed in German patent document DE-PS 37 38 521. 
The planetary gear includes a sun gear 80 having external teeth 82 which 
are engageable in the set of internal teeth 78 of the flexible splined 
planet wheel 74. 
As illustrated in FIG. 4, the external teeth 76 of the flexible planet 
wheel 74 are capable of engaging internal teeth 84 of a ring gear 86. The 
sets of teeth 82 and 84 have different numbers of teeth. 
The wave generator is actuatable to urge the flexible splined planet wheel 
74 in a radial direction into the tooth gaps of the respective gears, i.e. 
the teeth 76 into the gaps between the teeth 84 and the teeth 78 into the 
gaps between the teeth 82 in predetermined engagement zones. 
Four engagement zones are distributed over the circumference of the 
planetary gear. In two of the engagement zones, the flexible planet wheel 
74 meshes with the ring gear 86 and, in the other two engagement zones, 
offset by 90 degrees, the planet wheel 74 meshes with the sun wheel 80. 
The wave generator bearing system depicted in FIG. 4 includes a pair of 
rolling discs 4, 6 each of which is supported by an associated 
conventional rolling bearing 14, 16 which, in turn, is mounted to an 
eccentric ring 24, 26, respectively. The radially external faces of the 
rolling discs 4, 6 roll off the inner face of a flexible ring 10. 
In lieu of employing radially projecting collars on the external faces of 
the discs 4, 6, the axial ends of the flexible ring 10 include radially 
inwardly projecting collars 88 for preventing axial movement of the 
flexible band 10. The flexible band 10 may include an optional axial slit 
and is deformed by the bearing system of the wave generator. As previously 
mentioned, conventional roller bearings 14, 16 are employed; deformable 
rolling bearings are not required. 
The flexible ring 10, which forms the outer ring of the bearing system of 
the invention, is arranged directly next to the sun wheel 80 and the 
widths of the rolling discs 4, 6 are substantially narrower in the region 
of the engagement of their faces with the flexible band then in the region 
of their respective bearings 14, 16. 
The double eccentric offset of the bearing system is formed, as with the 
prior embodiments, by the two radially offset eccentric rings 24, 26 which 
are screwed to each other. For securely mounting the rolling bearings 14, 
16, in the bearing assembly, internal shoulders are provided on the discs 
4, 6 and external shoulders are provided on the eccentric rings 24, 26. 
The bearing system of the wave generator presents a complete transmission 
in an extremely compact configuration. 
The embodiments of the invention depicted in FIG. 5, FIG. 6 and FIG. 7 find 
particular utility in conjunction with manually operable adjusting drives, 
such as motor vehicle seat adjustment mechanisms for the adjustment of 
seat height and/or back rests. 
In the embodiment illustrated in FIGS. 5 and 7, a bearing system which 
includes two ring gears, 100, 102 is illustrated. Each of the ring gears 
100, 102 includes internal teeth 104, 106, respectively, with the number 
of teeth 104 of the ring gear 100 being different than the number of teeth 
106 in the ring gear 102. 
One of the ring gears, for example, the ring gear 100 is connected with an 
automotive seat frame or chassis of the motor vehicle while the other ring 
gear 102 may be connected with an adjustable back rest or seat bottom. The 
ring gears 100, 102 including their internal teeth 104, 106 are preferably 
formed by stamping. 
The bearing system as illustrated in FIG. 5 includes a flexible splined 
planet wheel 74 having both external and internal teeth. The flexible 
splined planet wheel 74 is supported on three rolling discs, 2, 4, 6. The 
lateral rolling discs, 2 and 4 each have a lateral collar 48, 50, 
respectively, for restraining axial movement of the flexible splined 
planet wheel 74 and the ring gears 100, 102. The collars 48, 50 have an 
outer diameter which is considerably larger than the dedendum circle of 
the internal teeth 104, 106 of the ring gears 100, 102, respectively and 
thus provide axial support for the ring gears 100, 102. This is of 
particular significance in motor vehicle applications. As a result, the 
bearing system of the embodiment illustrated in FIG. 5 provides a sturdy 
operating adjustment drive with relatively few parts, little material and 
low manufacturing costs. 
It should be noted that the rolling discs 2, 4, 6 of this embodiment are 
each supported on a corresponding eccentric ring 22, 24, 26, respectively 
by a self-lubricating solid bearing 108, 110, 112, respectively. 
To promote low cost fabrication with minimum material waste, the eccentric 
rings 22, 24, 26 may be produced from the cores of the stamped ring gears 
100, 102. In addition, the rolling disc 4 may also be stamped from the 
punched out core of one of the ring gears. Accordingly, waste in 
manufacture is minimized and the adjusting drive can be produced at 
relatively low cost. 
In order to secure the rolling discs 2, 4, 6 and their associated bearings 
108, 110, 112, the two lateral eccentric rings, 22, 26 include collars 
extending radially outwardly adjacent their external faces. 
It should also be noted that the adjusting drive is relatively compact in 
an axial length and requires little material, resulting in weight savings 
which is particularly advantageous in automotive applications. 
In order to drive the ring gears 100, 102, each of the eccentric rings 22, 
24, 26 has a central opening 114, 116 which is in the form of a square. A 
square shaft having an adjusting wheel for manual adjustment is mounted 
through the openings 114, 116. 
The adjusting drive of this embodiment is highly reliable under shock loads 
which act, for example, through the seat back rest and the ring gear 102. 
It should also be noted that the flexible splined planet wheel 74 has four 
engagement zones distributed over its circumference. Under load, forces 
are transmitted not only in the four engagement zones, but also through 
the tooth tips of the flexible splined planet wheel outside the engagement 
zones that is by abutting contact of tooth heads which is encountered in 
four support zones. The support zones are positioned between the four 
engagement zones. As a result, the adjustment drive provides a high degree 
of shock resistance and safety which is especially desirable in motor 
vehicle applications and which is accomplished within relatively small 
dimensional bounds. 
FIG. 6 shows a further embodiment of the invention in conjunction with 
adjusting drives. The FIG. 6 embodiment is similar to that of FIG. 5, 
however, there is no central rolling disc and central eccentric ring. The 
adjusting drive includes two rolling discs 4, 6 and two eccentric rings 
24, 26, respectively. Between the rolling discs 4, 6 and the eccentric 
rings 24, 26 self-lubricating solid bearings are positioned. In a manner 
similar to that of the embodiment of FIG. 5, the eccentric rings 24, 26 
have radially outwardly projecting collars for securing the rolling discs 
4, 6 in an axial direction. 
Also in a manner similar to that of the FIG. 5 embodiment, the rolling 
discs 4, 6, include collars or clips 48, 50 for axially securing both the 
flexible splined planet gear 74 and a pair of ring gears 100, 102 having 
internal teeth. 
To assemble the adjusting drives of the FIG. 6 embodiment, the eccentric 
rings 22, 24 are directly connected as, for example, by screws, rivets or 
spot welding. In addition, the central eccentric ring 24 of the FIG. 5 
embodiment may be similarly directly secured. 
As with the rolling disc 4 of the embodiment of FIG. 5, in the FIG. 6 
embodiment, the rolling discs 4, 6 may be made from the scrap cores 
remaining after stamping the ring gears 100, 102. Thus, the adjusting 
drives of the present invention are particularly well suited for 
economical mass production fabrication with a minimum of scrap. 
A further embodiment of the invention is illustrated in FIG. 8 wherein two 
rolling discs 4, 6, engage a flexible ring 10. The rolling discs 4, 6 each 
include a radially inwardly projecting collar 128, 126, respectively which 
extend from opposed internal faces of the discs. Projecting from the 
lateral faces of the rolling discs 4, 6, in a radially outward direction 
are collars or clips 48, 50, respectively, which secure the flexible ring 
10 against axial movement. 
A drive shaft 36 having a rotation axis 8 is shown in engagement with the 
bearing system. The drive shaft 36 includes a perpendicular end flange 38 
which is positioned between a pair of eccentric support rings 24, 26. The 
eccentric support rings 24, 26 may be clamped together by through bolts or 
other means along screw axes 34 illustrated in dot and dash lines. The 
clamping engagement serves to frictionally retain the drive shaft flange 
38 for driving engagement. 
The eccentric rings 24, 26 each include a radially outwardly projecting 
collar 90, 91, respectively, which extend adjacent their outer faces. 
Roller bearings which support the discs 4, 6 are engaged between the 
eccentric ring external collars 90, 91 and internal collars 128, 126, of 
the rolling discs 4, 6. The collars 90, 91 serve to fix the inner races of 
the bearings while the outer bearing races in engagement with the collars, 
128, 126 axially fix the rolling discs 4, 6. 
It should be appreciated that the rolling discs 4, 6, their bearings and 
the eccentric rings 24, 26 as well as the flexible ring 10 present 
substantially the same axial width while providing reliable and sturdy 
support and thus, a sturdy and dependable wave generator. 
It is significant that in all embodiments employing two rolling discs, the 
height, depicted in FIG. 8 by the numeral 130, of the collars or clips 48, 
50 in a radial direction, is greater than the eccentricity or the maximum 
radial distance between the external faces 54, 56 of the rolling discs 4, 
6. This is to assure that the flexible ring 10 will always be restrained 
against axial movement by the collars 48, 50. 
In the embodiments wherein three rolling discs are employed, the height of 
the collars 48, 50 in a radial direction must be greater than the 
eccentricity or the maximum radial distance between the external face 54 
of the central rolling disc and the external faces 52, 56 of the lateral 
rolling discs. 
Referring again to the embodiment of FIG. 8, it should also be noted that 
the drive shaft 36 includes a trunnion 132 which extends into a bore of 
the eccentric support ring 24. An adjusting screw 32 is threaded 
transversely through the trunnion 132 and bears against the eccentric ring 
24 for the purpose of adjusting eccentricity in accordance with the 
invention. After adjustment of the screw 32, the eccentric support rings 
24, 26 are tightened together. 
Thus it will be seen that there is provided a bearing system for a wave 
generator drive which achieves the various aspects, features and 
considerations of the present invention and which is well suited to meet 
the conditions and practical usage. 
Since various possible embodiments might be made of the present invention 
and various changes might be made in the exemplary embodiments set forth 
herein, it is to be understood that all matters described herein or shown 
in the accompanying drawings should be interpreted as illustrative and not 
in a limiting sense.