U.S. patent application number 10/469892 was filed with the patent office on 2004-04-22 for solar energy reflector array.
Invention is credited to Mills, David, Schramek, Philipp.
Application Number | 20040074490 10/469892 |
Document ID | / |
Family ID | 3827575 |
Filed Date | 2004-04-22 |
United States Patent
Application |
20040074490 |
Kind Code |
A1 |
Mills, David ; et
al. |
April 22, 2004 |
Solar energy reflector array
Abstract
A heliostat which comprises a reflector element and a carrier
that is arranged to support the reflector element above a ground
plane. A drive means is arranged to impart pivotal drive to the
carrier about a fixed, first axis that is, in use of the heliostat,
disposed substantially parallel to the ground plane. The heliostat
further comprises a means mounting the reflector element to the
carrier in a manner which permits pivotal movement of the reflector
element with respect to the carrier and about a second axis that is
not parallel to the first axis. A drive means arranged to impart
pivotal movement to the reflector element about the second axis.
The reflector element, which may be flat or curved, may be
constituted by a plurality of sub-reflector elements. Also, a
plurality of the reflector elements may be supported by a single
carrier. A plurality of the above defined heliostats may form a
solar energy reflector array with the heliostats being arranged to
reflect incident solar radiation to at least one target
collector.
Inventors: |
Mills, David; (Roseville,
AU) ; Schramek, Philipp; (Starnberg, AU) |
Correspondence
Address: |
Richard J Streit
Ladas & Parry
Suite 1200
224 South Michigan Avenue
Chicago
IL
60604
US
|
Family ID: |
3827575 |
Appl. No.: |
10/469892 |
Filed: |
November 10, 2003 |
PCT Filed: |
March 7, 2002 |
PCT NO: |
PCT/AU02/00261 |
Current U.S.
Class: |
126/600 ;
126/684; 126/906 |
Current CPC
Class: |
F24S 2023/872 20180501;
F24S 2030/136 20180501; F24S 23/77 20180501; F24S 30/455 20180501;
Y02E 10/47 20130101; F24S 23/70 20180501 |
Class at
Publication: |
126/600 ;
126/684; 126/906 |
International
Class: |
F24J 002/38 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2001 |
AU |
PR3566 |
Claims
1. A heliostat which comprises: a reflector element, a carrier that
is arranged to support the reflector element above a ground plane,
a drive means arranged in use to impart pivotal drive to the
carrier about a fixed, first axis that is, in use of the heliostat,
disposed substantially parallel to the ground plane, means mounting
the reflector element to the carrier in a manner which permits
pivotal movement of the reflector element with respect to the
carrier and about a second axis that is not parallel to the first
axis, and a drive means arranged in use to impart pivotal movement
to the reflector element about the second axis.
2. The heliostat as claimed in claim 1 wherein the drive means that
is arranged to impart pivotal motion of the carrier comprises a
first drive means and wherein the drive means that is arranged to
impart pivotal movement to the reflector element comprises a second
drive means which is separate from the first drive means.
3. The heliostat as claimed in claim 1 or 2 wherein the reflector
element comprises a glass mirror.
4. The heliostat as claimed in claim 1 or claim 2 wherein the
reflector element comprises a metallic mirror.
5. The heliostat as claimed in any one of the preceding claims
wherein the second axis about which the reflector element is
pivotally mounted to the carrier is disposed orthogonally with
respect to the first axis.
6. The heliostat as claimed in any one of the preceding claims
wherein the reflector element has a polygonal shape.
7. The heliostat as claimed in any one of the preceding claims
wherein the reflector element is mounted to the carrier in a manner
such that the second axis lies in a line that passes through two
most distant points on the periphery of the reflector element.
8. The heliostat as claimed in claim 6 wherein the reflector
element has a hexagonal form.
9. The heliostat as claimed in claim 8 wherein the hexagonal form
of the reflector element comprises three pairs of substantially
parallel sides embracing a central rectangular portion and two
triangular end portions.
10. The heliostat as claimed in claim 9 wherein the sides of the
hexagonal configuration are proportioned such that arcs of an
imaginary circle that passes through the four corners of the
rectangular portion will lie wholly within the triangular end
portions and, in the limiting condition, will lie tangential to two
adjacent sides of each of the triangular portions.
11. The heliostat as claimed in any one of the claims 2 to 10
wherein the first drive means includes a drive shaft that is
supported for rotation about an axis that lies parallel to the
first axis and which is arranged to impart rotary drive to the
heliostat carrier.
12. The heliostat as claimed in any one of the claims 2 to 11
wherein the second drive means includes a drive member which is
connected to the rear (non-reflecting) side of the reflector
element of the heliostat and which is arranged to be driven in a
manner to impart pivotal movement to the reflector element about
the second axis.
13. The heliostat as claimed in claim 12 wherein the drive member
is connected to the rear side of the reflector element by way of an
adjustable joint.
14. The heliostat as claimed in any one of the preceding claims
wherein the carrier for the reflector element of the heliostat has
an arcuate shape and is connected at each of its ends of the
reflector element.
15. The heliostat as claimed in any one of the preceding claims
wherein the carrier has a semi-circular shape and has its centre of
radius coincident with the geometric centre of the reflecting
surface of the reflector element.
16. The heliostat as claimed in any one of the preceding claims
wherein the reflector element has a flat reflecting surface.
17. The heliostat as claimed in any one of the claims 1 to 15
wherein the reflector element has a curved reflecting surface.
18. A solar energy reflector array comprising a plurality of
heliostats as claimed in any one of the preceding claims and
wherein the heliostats are arranged in rows to reflect incident
solar radiation to at least one target collector.
19. The solar energy reflector array as claimed in claim 18 when
dependant on claim 11 wherein the carriers of at least some of the
heliostats in each row of the array are coupled together by a
common said drive shaft.
20. The solar energy reflector array as claimed in claim 19 wherein
at least some of the first drive means incorporate a single motor
for imparting drive to a plurality of the drive shafts.
21. The solar energy reflector array as claimed in claim 19 wherein
a single motor is employed to impart drive to all of the drive
shafts in the heliostat array.
22. The solar energy reflector array as claimed in any one of
claims 18 to 21 wherein a plurality of the reflector elements
within a given row of the array is coupled together by connecting
respective ones of the drive members to a common motion translating
mechanism which forms a part of the second drive means.
23. The solar energy reflector array as claimed in claim 22 wherein
means are provided for adjusting the length of the drive members
whereby ganged motion translation may be imparted to the plural
drive members by adjusting the length of the drive members.
24. The solar energy reflector array as claimed in claim 22 wherein
means are provided for adjusting the length of the drive members
whereby ganged motion translation is imparted to the plural drive
members by adjusting the operating plane of the motion translating
mechanism to accommodate angular travel of the drive members.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a solar energy reflector array
that incorporates a plurality of heliostats and to a heliostat for
use in the array. In the context of the specification the term
"heliostat" is to be understood as meaning a device which is
arranged to reflect incident solar radiation to a target (which may
change from time-to-time) and to be driven to follow relative
movement of the sun.
BACKGROUND OF THE INVENTION
[0002] Solar arrays, including so-called multi-tower solar arrays
have been proposed and in some cases developed for reflecting
toward one or more target collectors solar radiation that falls
incident on heliostats within the arrays. Various array
arrangements have been proposed for minimising mutual blocking and
shading of heliostats in order to maximise reflection and, hence,
concentration of incoming solar radiation. In this context,
reference may be made to International Patent Applications
PCT/AU96/00177 and PCT/AU97/00864 dated Mar. 28, 1996 and Dec. 19,
1997 respectively, and to the following two publications:
[0003] Multi-Tower Solar Array (MTSA) with Ganged Heliostats;
Mills, D. R. and Schramek, P.--9.sup.th International Symposium on
Solar Thermal Concentrating Technologies, Solar Paces, Font-Romeu
France, June 1998.
[0004] Potential of the Heliostat Field of a Multi-Tower Solar
Array; Schramek, P. and Mills, D. R.--10th International Symposium
on Solar Thermal Concentrating Technologies, Solar Paces, Sydney,
Australia, March 2000.
[0005] In order to achieve optimum ground area utilisation,
heliostats within a solar array must be arranged and constructed to
facilitate closely-spaced positioning of the heliostats and, at the
same time, to permit non-interfering relative movement of adjacent
ones of the heliostats. This latter requirement applies
particularly in multi-tower solar arrays, in which adjacent
heliostats may be required to reflect incident radiation to
different tower mounted collectors and in which any one heliostat
may need be actuated to change its orientation from one collector
to another. Also, in the interest of maximising drive efficiency
and minimising capital costs, it is required that the heliostats be
arranged and constructed to facilitate ganging of the heliostats
and employment of common drive arrangements for groups of the
heliostats within an array. The meeting of these requirements is
assisted by the fact that, except in those instances when a
heliostat is to be re-orientated, the heliostats collectively need
only be moved in dependence on the movement of the sun. That is,
whereas the orientations of the heliostats would normally be
different from one another, depending upon their positions relative
to the target collector(s), all heliostats would be driven to turn
through the same angle d.phi..sub.H=d.phi..sub.S/- 2 in the same
direction, where d.phi..sub.H is the change in angle of the
reflectors of the heliostats and d.phi..sub.S is the change in
angle of incident radiation. However, even when allowing for this
convenience, difficulties have been experienced in designing
arrangements that facilitate non-interfering close spacing of
heliostats, as well as economical drive arrangements, for the very
large number of heliostats that must be provided in any array that
might serve to reflect a useful level of solar energy to associated
target collectors.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a heliostat which is
suitable for positioning within an array and which, in a preferred
form, is arranged to meet the above-mentioned requirements.
[0007] Broadly defined, the present invention provides a heliostat
which comprises:
[0008] a reflector element,
[0009] a carrier that is arranged to support the reflector element
above a ground plane,
[0010] a drive means arranged in use to impart pivotal drive to the
carrier about a fixed, first axis that is, in use of the heliostat,
disposed substantially parallel to the ground plane,
[0011] means mounting the reflector element to the carrier in a
manner which permits pivotal movement of the reflector element with
respect to the carrier and about a second axis that is not parallel
to the first axis, and
[0012] a drive means arranged in use to impart pivotal movement to
the reflector element about the second axis.
[0013] The drive means that is arranged to impart pivotal motion of
the carrier preferably comprises a first drive means and the drive
means that is arranged to impart pivotal movement to the reflector
element preferably comprise a second drive means which is separate
from the first drive means.
[0014] The reflector element, which may be flat or curved, may be
constituted by a plurality of sub-reflector elements. Also, a
plurality of the reflector elements may be supported by a single
carrier. However, in order to gain the full benefit of the
invention with the latter arrangement, the plural reflector
elements would need to be mounted to the carrier by way of
non-parallel second axes.
[0015] The heliostat may be employed in large scale arrays, such as
those that occupy ground areas in the order of 100 hectares, or in
relatively small arrays such as may be located on the tops of
buildings or in other confined spaces. Thus, the term "ground
plane" as used in this specification should be understood as
designating a notional (horizontal or inclined) plane above which
the heliostats are located. In the case of a large scale array, the
ground plane will comprise the ground area that is occupied by the
heliostats, but it should be understood that the ground area of
itself need not be planar. Topographical variations in the ground
area may be accommodated by positional adjustment of individual
ones of the reflector elements relative to one another. Also, at
least a portion of the ground area that is occupied by the
heliostats may form a part of a hill and so be inclined to the
horizontal.
[0016] With the foregoing in mind, the present invention may be
defined further as providing a solar energy reflector array which
comprises a plurality of the above defined heliostats located in
rows and arranged to reflect incident solar radiation to at least
one target collector. The carriers of at least some of the
heliostats in each row of the array preferably are coupled to one
another, and the reflector elements of at least some of the
heliostats in each row of the array preferably are coupled to one
another.
[0017] Thus, in the preferred arrangement, each of the first and
second drive means may be employed to impart pivotal motion to a
plurality of the heliostats, and control of the drive means may be
shared for a large number of the heliostats within an array. This
is important in terms of capital cost savings to be obtained in
large area arrays.
[0018] Common drive control is made possible by the potential for
ganging a large number of the heliostats and this in turn is
facilitated by the pivotal mounting of the reflector element of
each heliostat to its pivotally mounted carrier. This also
facilitates close spacing of the heliostats within an array, even
with relative movement occurring between adjacent reflector
elements.
[0019] The target collector or, in the case of multi-tower solar
arrays, the target collectors may comprise any type of collector
that is capable of receiving solar energy and converting it to
another form of energy. For example, each target collector may
comprise a bank of solar absorptive collector elements through
which a heat exchange fluid is passed. Alternatively, in a smaller
scale system, the target collector may comprise an array of
photo-voltaic cells.
PREFERRED FEATURES OF THE INVENTION
[0020] The reflector element of the heliostat preferably comprises
a glass mirror that is pivotally mounted to the carrier. Also, the
second axis about which the reflector element is pivotally mounted
to the carrier preferably is disposed orthogonally with respect to
the first axis. Thus, in the preferred arrangement, the carrier is
mounted for pivotal movement about a fixed, first axis that is
disposed parallel to the ground plane and the reflector element is
mounted to the carrier for pivotal movement about a second axis
that is orthogonal to the first axis.
[0021] The reflector element of the heliostat preferably has a
polygonal shape and, in order to achieve maximised ground coverage,
most preferably is mounted to the carrier in a manner such that the
second axis lies in a line that passes through two most distant
points on the periphery of the reflector element. The reflector
element may, for example, have a square form, in which case the
second axis preferably will lie in the line of a diagonal of the
reflector element. As a further alternative, the reflector element
may (and preferably will) have an hexagonal form. In this case, the
second axis will lie in a line that intersects oppositely disposed
angles of the hexagon and preferably will pass through two most
distant points.
[0022] The reflector element most preferably has an hexagonal form
comprising three pairs of substantially parallel sides. In this
case the hexagon may notionally be divided into a rectangular
central portion and two triangular end portions.
[0023] The sides of the hexagonal configuration are most preferably
proportioned such that arcs of an imaginary circle that passes
through the four corners of the rectangular portion will lie wholly
within the triangular end portions and, in the limiting condition,
will lie tangential to two adjacent sides of each of the triangular
portions. It has been determined that the use of a plurality of
such reflectors permits up to 100% ground coverage.
[0024] The first drive means preferably includes a drive shaft that
is supported for rotation about an axis that lies parallel to the
first axis and which is arranged to impart rotary drive to the
heliostat carrier. When a plurality of heliostats is located in an
array, the carrier of at least some of the heliostats in each row
of the array may be coupled together by a common such drive shaft.
Also, the first drive means preferably incorporates a single motor
for imparting drive to a plurality of the drive shafts in an array
of the heliostats. Furthermore, in the case of a relatively small
array, a single motor most preferably will be employed to impart
drive to all of the drive shafts in the heliostat array.
[0025] The second drive means preferably includes a drive member
which is connected to the rear (non-reflecting) side of the
reflector element of the heliostat and which is arranged to be
driven in a manner to impart pivotal movement to the reflector
element about the second axis. Also, the drive member preferably is
connected to the rear side of the reflector element by way of a
lockable ball joint (or other universal joint) to permit positional
adjustment of the reflector element relative to the drive member.
This arrangement permits adjacent reflector elements to be
positioned individually during the setting-up of an array of the
heliostats and permits the drive members within a given row of
heliostats to be positioned parallel to one another, regardless of
the relative angular positions of adjacent reflector elements
within the array.
[0026] A plurality of the reflector elements within a given row of
an array of the heliostats preferably is coupled together by
connecting respective ones of the drive members to a common motion
translating mechanism which forms a part of the second drive means.
Ganged motion translation may then be imparted to the plural drive
members by either adjusting the length of the drive members or
adjusting the operating plane of the motion translating mechanism
to accommodate angular travel of the drive members.
[0027] The carrier for the reflector element of the heliostat
preferably has an arcuate shape and is connected at each of its
ends to the rear side of the reflector element. The carrier most
preferably has a semi-circular shape and, in both cases, will have
its centre of radius coincident with the geometric centre of the
reflecting surface of the reflector element.
[0028] The invention will be more fully understood from the
following description of a preferred embodiment of a heliostat and
a heliostat array. The description is provided with reference to
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In the drawings:
[0030] FIG. 1 shows a diagrammatic representation of a rectangular
reflector element mounted to a carrier,
[0031] FIG. 2 shows a plan view of a portion of an array of square
reflector elements,
[0032] FIG. 3 shows a plan view of a portion of an array of
hexagonal reflector elements,
[0033] FIG. 4 shows diagrammatically a side view of a heliostat
having a single reflector element mounted to an arcuate
carrier,
[0034] FIG. 5 shows a single row of the heliostats and,
diagrammatically, first and second drive means for imparting
pivotal movement to the carriers and reflector elements of the
heliostats,
[0035] FIG. 6 illustrates an array composed of plural rows of the
heliostats shown in FIG. 5,
[0036] FIGS. 7 and 8 show alternative ways of translating motion to
a reflector element of a single heliostat, to effect pivoting of
the reflector element with respect to its carrier,
[0037] FIG. 9 shows diagrammatically the mounting of one reflector
element to a reduced size carrier, and
[0038] FIG. 10 shows three, alternative, preferred geometric
configurations of the reflector elements.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0039] FIG. 1 shows in plan a diagrammatic representation of a
heliostat that has a rectangular reflector element 10 which is
supported within a carrier 11 in the form of a rectangular frame
12. The carrier 11 functions to support the reflector element above
a ground plane 13 (as shown in FIG. 4) and the carrier is itself
pivotally mounted to a support structure 14. The pivot axis 15 for
the carrier (herein referred to as the "first axis") is fixed and
lies parallel to the ground plane 13.
[0040] The reflector element 10 is pivotally mounted to the carrier
11 about a pivot axis 16 (herein referred to as the "second axis")
that is orthogonally disposed with respect to the first axis 15.
Thus, the reflector element 10 may be regarded as being supported
in a gymbal mounting such that the carrier 11 and the supported
reflector element may be turned about the first, fixed axis 15
whilst the reflector element is independently pivotable, relative
to the carrier, about the second axis 16. As a development of this
arrangement it may be shown that a heliostat array may be
constructed to provide optimised ground coverage if:
[0041] 1. the first axis 15 is disposed in fixed, parallel
relationship to the ground plane 13,
[0042] 2. the second axis 16 lies in a line that passes through the
most distant points of the reflector element 10, and
[0043] 3. the reflector element 10 has a shape that permits close
packing of the heliostats.
[0044] The second criterion is not met in the case of the
arrangement shown in FIG. 1, to the extent that the second axis 16
does not pass through the diagonal of the rectangle. Also, it will
be established later in this specification that the third criterion
may best be met by the employment of hexagonal reflectors having
specifically defined geometrical forms.
[0045] FIGS. 2 and 3 do show arrangements that are superior to that
shown in FIG. 1, in that FIG. 2 shows an array of square reflector
elements 10 which are pivotably mounted to respective carriers 11
by way of second axes 16 that pass through diagonals of the
squares. Similarly, FIG. 3 shows an array of hexagonal reflector
elements 10 which are pivotably mounted to respective carriers 11
by way of second axes 16 that pass through opposing angles of the
hexagons.
[0046] However in the arrangements shown in FIGS. 2 and 3, at least
some of the carriers 11 may shade the reflectors from incident
solar radiation under certain inclinations of the carriers and/or
the reflector elements within the carriers. This will reduce the
performance of the array and it will be necessary to separate at
least some of the heliostats within the array and thereby reduce
the effective ground coverage. Moreover, the carriers may
themselves preclude an arrangement that provides for optimum ground
coverage.
[0047] These problems may be avoided by adopting the carrier
arrangement as shown diagrammatically in FIGS. 4 to 6.
[0048] As illustrated in FIGS. 4 to 6, the carrier 11 extends
rearwardly from the reflector element 10 and has an arcuate or,
more specifically, a semi-circular shape. The radius centre 17 of
the carrier is coincident with the geometric centre of the
reflecting surface of the reflector element and is aligned with the
first axis 15. End portions 18 of the carrier are connected to the
reflector element by bearing-supported axles (not shown) that are
positioned coincidentally with the second axis 16.
[0049] Although it is shown in a diagrammatic way, the carrier 11
would normally be fabricated as a metal or plastics material frame
and be mounted upon a supporting structure 19 to position the
reflector element 10 at a required height above the ground plane
13.
[0050] The carrier 11 is supported upon idler rollers 20 that
accommodate rotary motion of the carrier about the radius centre
17, and a drive shaft 21 is provided for imparting rotary drive to
the carrier by way of a geared connection (not shown) between the
drive shaft and the carrier. The axis of the drive shaft 21 lies
parallel with the first axis 15 and, also not shown, the drive
shaft 21 is coupled to an electric or hydraulic motor which is
energised when required to impart turning motion to the reflector
element 10 about the first axis.
[0051] A drive member 22 is connected to the rear side of the
reflector element 10 by way of a lockable ball joint (not shown),
so that the reflector element may initially be orientated in a
required direction relative to the drive member 22. A linearly
movable motion translating mechanism 23 (see FIGS. 5 and 6) is
employed to impart pivotal movement to the drive member 22 and, so,
to effect pivoting of the reflector element 10 about the second
axis 16.
[0052] FIG. 5 of the drawings shows a plurality of carrier-mounted
reflector elements positioned in a row, and FIG. 6 shows a number
of the rows located within a small array of heliostats. In each
case the heliostats within each row are coupled together by a
single drive shaft 21. Also, the plurality of parallel drive
members 22 that extend rearwardly from the respective reflector
elements 10 are coupled together in each row by a single motion
translating shaft 23.
[0053] FIGS. 7 and 8 show alternative ways of translating motion to
the reflector element 10 of a single heliostat, to effect pivoting
of the reflector element about the second axis 16 with respect to
the carrier 11. Given that the drive member 22 will change its
effective length (in a vertical direction) as it pivots to effect
turning of the reflector element 10, provision needs to be made to
maintain the coupling between the drive member 22 and the motion
translating shaft 23. This may be achieved as shown in FIG. 8, by
making the drive member telescopic or, as shown in FIG. 7, by
raising and lowering the motion translating shaft 23 with
application of pivoting drive to the drive member 22.
[0054] Although the carrier 11 has been illustrated in most of the
figures as having a length between its end portions 18 that
corresponds with the length of the major axis of the reflector
element 10, in the interest of avoiding shading between adjacent
heliostats, the carrier 11 may beneficially be made with a smaller
dimension. This is illustrated in FIG. 9 and it will be understood
that with this change in dimension, special arrangements may need
to be made to facilitate application of drive to the drive members
22.
[0055] As indicated previously, the reflector element 10 should be
shaped in a manner to permit optimum, close packing of the
heliostats. This may be achieved by forming the reflector element
in one or other of the (generalised) ways indicated in FIGS. 10A, B
and C. In each case the reflector element 10 has an hexagonal
configuration comprising three pairs of parallel sides and as a
consequence four sides 24 having equal length. Also, in each case,
the major diagonal a has a length that is greater than that of the
distance b between two opposing sides 25 of each element. The sides
of the hexagonal configuration are proportioned such that arcs 27
of an imaginary circle that passes through the four corners of the
rectangular portion lie wholly within the triangular end portions
26 and, in the limiting condition, lie tangential to two adjacent
sides of each of the triangular portions. In this case the
proportions of the hexagon satisfy the criteria
a.gtoreq.c+b.sup.2/c Eq.1
[0056] wherein in any one case c corresponds to the length of each
side 25. It has been determined that in an array of closely spaced
reflectors with each of the reflectors proportioned such that Eq.1
is satisfied, collision of the reflectors can be avoided when the
heliostats are driven. As a consequence such an array facilitates
up to 100% ground coverage even when the reflectors are closely
spaced.
[0057] It is to be understood that, the references that are made to
prior art documents
[0058] PCT/AU96/00177 dated Mar. 28, 1996,
[0059] and PCT/AU97/00864 dated Dec. 19, 1997,
[0060] Multi-Tower Solar Array (MTSA) with Ganged Heliostats,
Mills, D. R. and Schramek, p.--9.sup.th International Symposium on
Solar Thermal Concentrating Technologies, Solar Paces, Font-Romeu
France, June 1998, and
[0061] Potential of the Heliostat Field of a Multi-Tower Solar
Array, Schramek, P. and Mills, D. R.--10th International Symposium
on Solar Thermal Concentrating Technologies, Solar Paces, Sydney,
Australia, March 2000,
[0062] do not constitute an admission that these prior art
documents form a part of the common general knowledge in the art,
in Australia or any other country.
[0063] Variations and modifications may be made in the invention as
above described and as defined in the following statements of
claim.
* * * * *