U.S. patent application number 13/480595 was filed with the patent office on 2012-11-29 for header for heat exchanger.
This patent application is currently assigned to VISTEON GLOBAL TECHNOLOGIES, INC.. Invention is credited to RICHARD ARMSDEN, JOEL JENNINGS, STEPHEN JOYCE, ALEX MCDONNELL, NIGEL SEEDS, KEITH WILKINS.
Application Number | 20120298344 13/480595 |
Document ID | / |
Family ID | 44310531 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120298344 |
Kind Code |
A1 |
MCDONNELL; ALEX ; et
al. |
November 29, 2012 |
HEADER FOR HEAT EXCHANGER
Abstract
A header for a heat exchanger includes an elongate header plate
having a pair of substantially parallel long edges. The header
plate includes an elongate slot extending in a first direction
across the header plate and a pair of ridges extending in a second
direction along the header plate. The second direction is
substantially perpendicular to the first direction. Edge regions of
the header plate are formed on sides of the ridges adjacent the
long edges. At least one of the edge regions lie in a first plane
and crests of the ridges lie in a second plane. The first plane is
substantially parallel to and offset from the second plane.
Inventors: |
MCDONNELL; ALEX; (HORSHAM
ST. FAITH, GB) ; WILKINS; KEITH; (GOLDHANGER, GB)
; ARMSDEN; RICHARD; (BILLERICAY, GB) ; JOYCE;
STEPHEN; (REDHILL, GB) ; JENNINGS; JOEL; (WEST
WICKHAM, GB) ; SEEDS; NIGEL; (BENFLEET, GB) |
Assignee: |
VISTEON GLOBAL TECHNOLOGIES,
INC.
VAN BUREN TWP.
MI
|
Family ID: |
44310531 |
Appl. No.: |
13/480595 |
Filed: |
May 25, 2012 |
Current U.S.
Class: |
165/173 |
Current CPC
Class: |
F28F 9/18 20130101; F28D
1/0391 20130101; F28F 9/02 20130101 |
Class at
Publication: |
165/173 |
International
Class: |
F28F 9/02 20060101
F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 2011 |
GB |
1108977.8 |
Claims
1. A header for a heat exchanger, comprising: a header plate having
a first surface, an opposing second surface, and substantially
parallel edges, the header plate including: at least one slot
formed in the header plate and extending in a first direction
across the header plate; a plurality of ridges extending in a
second direction along the header plate, the second direction being
substantially perpendicular to the first direction; and a plurality
of edge regions adjacent the edges, wherein the at least one slot
extends across the ridges, and wherein at least one of the edge
regions of the header plate lie in a first plane and at least one
crest of at least one of the ridges lies in a second plane, and
wherein the first plane is substantially parallel to and offset
from the second plane, the second plane disposed further from the
second surface of the header plate than the first plane.
2. The header according to claim 1, wherein the edges of the header
plate extend in the second direction.
3. The header according to claim 1, wherein the edge regions are of
substantially equal width such that a first distance between one of
the edges of the header plate and the crest of one of the ridges,
and a second distance between another one of the edges of the
header plate and the crest of another one of the ridges are
substantially equal.
4. The header according to claim 1, wherein the header plate
includes at least one trough formed between the ridges, the at
least one trough having a base which lies in the first plane.
5. The header according to claim 1, wherein the header plate
includes at least one trough formed between the ridges, the at
least one trough having a base which lies in a third plane
substantially parallel to the first plane and the second plane.
6. The header according to claim 5, wherein the third plane is
located between the first plane and the second plane.
7. The header according to claim 1, wherein the at least one crest
is formed by a substantially planar section of the header plate
extending substantially parallel to the first plane.
8. The header according to claim 1, wherein the at least one crest
is formed by a curved section of the heater plate.
9. The header according to claim 8, wherein the curved section has
a generally convex curvature in respect of the first plane.
10. The header according to claim 1, wherein sides of at least one
of the ridges is formed from a substantially planar section of the
header plate.
11. The header according to claim 1, wherein sides of at least one
of the ridges is from from a curved section of the header
plate.
12. The header according to claim 1, wherein the header plate
includes at least one trough formed from a substantially planar
section of the header plate.
13. The header according to claim 1, wherein the header plate
includes at least one trough formed from a curved section of the
header plate.
14. The header according to claim 13, wherein the curved section
has a generally concave curvature in respect of the second
plane.
15. A heat exchanger comprising: at least one tube including a seam
extending along a central region of the at least one tube; and a
header including a header plate having a first surface, an opposing
second surface, and substantially parallel edges, the header plate
including: at least one slot having a first end and a second end,
the slot extending in a first direction across the header plate; a
plurality of ridges extending in a second direction along the
header plate, the second direction being substantially
perpendicular to the first direction; and a plurality of edge
regions formed on sides of the ridges adjacent the edges of the
header plate, wherein at least one of the ends of the at least one
slot is located within the edge regions, and wherein the at least
one slot extends across the ridges, and wherein the edge regions of
the header plate lie in a first plane and at least one of a
plurality of crests of the ridges lie in a second plane, and
wherein the first plane is substantially parallel to and offset
from the second plane, the second plane located further from the
second surface of the header plate than the first plane, and
wherein an end of the at least one tube is received within the at
least one slot and the seam of the at least one tube is
substantially aligned with a central region of the header plate,
and wherein at least one of the crests of at least one of the
ridges intersects the at least one tube further from the end of the
at least one tube than the edge regions of the header plate.
16. The heat exchanger according to claim 15, wherein the header
plate includes at least one trough formed between the ridges, and
the seam of the tube coincides with a base of the at least one
trough.
17. The heat exchanger according to claim 15, wherein the edge
regions are of substantially equal width such that a first distance
between one of the edges of the header plate and the crest of one
of the ridges, and a second distance between another one of the
edges of the header plate and the crest of another one of the
ridges are substantially equal.
18. The heat exchanger according to claim 15, wherein the header
plate includes at least one trough formed between the ridges, and a
base of the at least one trough lies in the first plane.
19. The heat exchanger according to claim 15, wherein the header
plate includes at least one trough formed between the ridges, the
at least one trough having a base which lies in a third plane
substantially parallel to and located between the first plane and
the second plane.
20. A heat exchanger comprising: at least one tube; and a header
including a header plate having a first surface, an opposing second
surface, and substantially parallel edges, the header plate
including: at least one slot extending in a first direction across
the header plate; a plurality of ridges extending in a second
direction along the header plate, the second direction being
substantially perpendicular to the first direction; a plurality of
edge regions formed on sides of the ridges adjacent the edges of
the header plate, wherein the edge regions of the header plate lie
in a first plane and at least one of a plurality of crests of the
ridges lie in a second plane, and wherein the first plane is
substantially parallel to and offset from the second plane, the
second plane located further from the second surface of the header
plate than the first plane; and at least one trough formed between
the ridges.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of United Kingdom Patent
Application No. 1108977.8 filed May 27, 2011, the entire disclosure
of which is hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to heat exchangers,
and more particularly to a header for a heat exchanger.
BACKGROUND OF THE INVENTION
[0003] Typically, automotive vehicles are provided with a cooling
system for an engine including a heat exchanger such as a radiator,
for example. When the engine is running, heat is transferred from
the engine to a coolant that flows through the engine. The coolant
then flows from the engine to the heat exchanger through a series
of conduits. At the heat exchanger, heat is transferred from the
coolant to cooler air that flows over the outside of the heat
exchanger. This process repeats itself in a continuous cycle
thereby cooling the engine.
[0004] A typical heat exchanger includes a series of tubes
supported by two chambers or headers positioned at either end of
the heat exchanger. One type of conventional header is a flat
header. These are so named because, when these flat headers are
joined to a respective tube, for example, by brazing, the joint
between the header and the tube lies in a substantially flat
plane.
[0005] During operation of the engine and cooling system, the tubes
are subject to thermal cycling (rise and fall of the temperature of
the heat exchanger components). The thermal cycling leads to
stresses as adjacent tubes may expand to different degrees,
imposing axial loads on adjacent tubes. These types of header/tube
combinations are, therefore, prone to failure because of the stress
concentrations that occur along the header/tube joint. In
particular, these designs of header are prone to failure around a
nose of the tubes.
[0006] A different header, designed to overcome these problems is
disclosed in U.S. Pat. No. 7,426,958. However, when used in heat
exchangers including folded tubes, or `B-tubes`, having a
longitudinal seam separating two channels, the failure point is
known to have moved from the nose of the tube to the intersection
of the seam of the tube with the header.
[0007] It is, therefore, an object of the present invention to
provide an improved heat exchanger header that overcomes the above
problems.
SUMMARY OF THE INVENTION
[0008] In concordance and agreement with the present invention, a
header for a heat exchanger of the present invention, has been
surprisingly invented.
[0009] In one embodiment, a header for a heat exchanger comprises:
a header plate having a first surface, an opposing second surface,
and substantially parallel edges, the header plate including: at
least one slot formed in the header plate and extending in a first
direction across the header plate; a plurality of ridges extending
in a second direction along the header plate, the second direction
being substantially perpendicular to the first direction; and a
plurality of edge regions adjacent the edges, wherein the at least
one slot extends across the ridges, and wherein at least one of the
edge regions of the header plate lie in a first plane and at least
one crest of at least one of the ridges lies in a second plane, and
wherein the first plane is substantially parallel to and offset
from the second plane, the second plane disposed further from the
second surface of the header plate than the first plane.
[0010] In another embodiment, a heat exchanger comprises: at least
one tube including a seam extending along a central region of the
at least one tube; and a header including a header plate having a
first surface, an opposing second surface, and substantially
parallel edges, the header plate including: at least one slot
having a first end and a second end, the slot extending in a first
direction across the header plate; a plurality of ridges extending
in a second direction along the header plate, the second direction
being substantially perpendicular to the first direction; and a
plurality of edge regions formed on sides of the ridges adjacent
the edges of the header plate, wherein at least one of the ends of
the at least one slot is located within the edge regions, and
wherein the at least one slot extends across the ridges, and
wherein the edge regions of the header plate lie in a first plane
and at least one of a plurality of crests of the ridges lie in a
second plane, and wherein the first plane is substantially parallel
to and offset from the second plane, the second plane located
further from the second surface of the header plate than the first
plane, and wherein an end of the at least one tube is received
within the at least one slot and the seam of the at least one tube
is substantially aligned with a central region of the header plate,
and wherein at least one of the crests of at least one of the
ridges intersects the at least one tube further from the end of the
at least one tube than the edge regions of the header plate.
[0011] In yet another embodiment, a heat exchanger comprises: at
least one tube; and a header including a header plate having a
first surface, an opposing second surface, and substantially
parallel edges, the header plate including: at least one slot
extending in a first direction across the header plate; a plurality
of ridges extending in a second direction along the header plate,
the second direction being substantially perpendicular to the first
direction; a plurality of edge regions formed on sides of the
ridges adjacent the edges of the header plate, wherein the edge
regions of the header plate lie in a first plane and at least one
of a plurality of crests of the ridges lie in a second plane, and
wherein the first plane is substantially parallel to and offset
from the second plane, the second plane located further from the
second surface of the header plate than the first plane; and at
least one trough formed between the ridges.
[0012] Preferably, the header plate includes a trough between the
two ridges and the seam of the tube coincides with a base of the
trough.
[0013] Typically, the header comprises more than one slot and the
slots are arranged parallel to each other. Preferably, the first
direction is perpendicular to the long edges of the header plate,
such that when a tube is inserted in the one or more slots the
width of the tube extends across the width of the header.
[0014] Preferably, the header has mirror symmetry along a
longitudinal centre line of the header so that the two edge regions
are of equal width. In this way, a first distance between the crest
of a first ridge and a first long edge of the header plate, and a
second distance between the crest of a second ridge and a second
long edge of the header plate are equal.
[0015] In preferred embodiments, the thickness of the header plate
is constant over the whole area of the header plate such that the
stiffness of the header plate does not vary significantly over its
area.
[0016] In some designs of heat exchanger it may be desirable if the
depth of a trough formed between the two ridges in the header plate
is equal to the height of the ridges. As such a base of the trough
and the two edge regions of the header all lie in the first
plane.
[0017] In other designs of heat exchanger it may be desirable if
the depth of a trough formed between the two ridges in the header
plate is less than the height of the ridges. As such, a base of the
trough lies in a third plane, parallel to the first and second
planes and located between the first and second planes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above, as well as other advantages of the present
invention, will become readily apparent to those skilled in the art
from the following detailed description of the preferred embodiment
when considered in the light of the accompanying drawings in
which:
[0019] FIG. 1 is a schematic front elevational view of a heat
exchanger, as is known in the prior art, including a header and a
plurality of tubes;
[0020] FIG. 2a is a perspective view of a portion of the heat
exchanger illustrated in FIG. 1 showing a connection between one of
the tubes and the header, the header being of a geometry known in
the prior art;
[0021] FIG. 2b is a cross-sectional view of the portion of the heat
exchanger illustrated in FIG. 2a, taken along section line II-II of
FIG. 2a;
[0022] FIG. 3a is a perspective view of a portion of a heat
exchanger illustrated in FIG. 1 showing a connection between one of
the tubes and the header, the header being of a geometry known in
the prior art;
[0023] FIG. 3b is a cross-sectional view of the portion of the heat
exchanger illustrated in FIG. 3a, taken along section line III-III
of FIG. 3a;
[0024] FIG. 4a is a perspective view of a portion of a heat
exchanger showing a connection between one of a plurality of tubes
and a header according to an embodiment of the present
invention;
[0025] FIG. 4b is a cross-sectional view of the portion of the heat
exchanger illustrated in FIG. 4a, taken along section line IV-IV of
FIG. 4a;
[0026] FIG. 5 is a cross-sectional view of a portion of a heat
exchanger, having a header according to a further embodiment of the
present invention; and
[0027] FIG. 6 is a cross-sectional view of a portion of a heat
exchanger, having a header according to a yet another embodiment of
the present invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0028] The following detailed description and appended drawings
describe and illustrate various embodiments of the invention. The
description and drawings serve to enable one skilled in the art to
make and use the invention, and are not intended to limit the scope
of the invention in any manner.
[0029] FIG. 1 illustrates a known heat exchanger 10, which in this
example is part of an automotive radiator assembly. The heat
exchanger 10 includes a plurality of tubes 12 extending between two
headers 14, 16 connected to a first end 18 and a second end 20 of
the tubes 12. The tubes 12 extend parallel to each other and are
joined at the first or second ends 18, 20 to adjacent tubes such
that a fluid flow path is established through the heat exchanger
10. A number of fins 22 are arranged to span the spaces between the
adjacent tubes 12 in an orientation such that, in use, air is able
to flow over the surface of the fins 22 and between the tubes
12.
[0030] During operation of an engine (not shown) connected to the
heat exchanger 10, heated coolant from the engine flows through the
tubes 12 and transfers heat energy from the coolant to walls of the
tubes 12. The heat energy is, in turn, transferred to the fins 22
which radiate the heat energy, aided by a flow of cool air over and
around the fins 22. Cooled coolant then flows back into the engine
to complete the cycle.
[0031] FIGS. 2a and 2b show a prior art configuration of the tube
12 and the header 14 used in the heat exchanger 10. The
configuration of the header 14 shown in FIGS. 2a and 2b is known as
a flat header 14 because a joint 24 between the tube 12 and the
header 14 lies in a substantially flat plane 26. Typically, the
tube 12 and the header 14 are formed from an aluminium material and
the joint 24 between the tube 12 and the header 14 is brazed.
[0032] As the coolant flows through the heat exchanger 10 and
transfers the heat energy to the tubes 12 and to the surrounding
air, the components of the heat exchanger 10 undergo thermal
cycling due to a rise and a fall of a temperature thereof.
Furthermore, a difference in the temperature is often created
across a width of the tube 12 and between adjacent tubes 12 because
the coolant cools as it flows across the heat exchanger 10. The
difference in the temperature causes the adjacent tubes 12 to
expand and contract to different degrees, which in turn leads to
axial stresses being imposed on the tubes 12.
[0033] The externally induced stresses typically act along a whole
of the joint 24 between the tube 12 and the header 14 due to a
restriction in a deformation of the tubes 12 in this region caused
by the header 14. Furthermore, due to a geometry of the joint 24,
stresses are concentrated at the ends 28 of the tube 12, known as a
nose 28 of the tube 12. Stress concentration is a physical property
and is related to the geometry of the tube /header joint 24.
Stresses are, therefore, concentrated in a region of the nose 28
due to a change in the geometry and a small radius of curvature of
this part of the tube 12. As such, failure of the heat exchangers
10 shown in FIGS. 2a and 2b usually occurs by radial fracture at or
near an intersection of the nose 28 of the tube 12 with the header
14.
[0034] One design of the header 14 used to overcome the above
problem is disclosed in U.S. Pat. No. 7,426,958. As shown in FIGS.
3a and 3b, the header 114 includes a raised central portion 102 so
that the header 114 has a substantially trapezoidal cross sectional
shape. The raised central portion 102 of the header 114 lies in a
second plane 152 parallel to and offset from a plane 126 which
includes edge regions 146 of the header 114. The geometry of header
114 distributes stresses more evenly over a joint 124 between a
tube 112 and the header 114, thereby increasing a life of the
header 114. In particular, the raised central portion 102 alters a
distribution of stress along the joint 124. The stresses caused by
a twisting of the header 114 and a bending of the tubes 112 during
thermal cycling is now within the raised central portion 102 of the
header 114, and therefore separated from regions of greatest stress
concentration around a nose 128 of the tube 112.
[0035] Reference is now made to FIGS. 4a and 4b. In other designs
of heat exchangers, it is increasingly desirable to use folded
tubes 212 having a cross-section generally in the shape of a "B".
In certain embodiments, the tubes 212 are formed from sheet metal
and folded to create a central seam 230 which is then brazed to
seal the tube 212. The tube 212 increases the heat transfer surface
area of the tube 212, thereby increasing an efficiency of the heat
exchanger (not shown). In addition, the tubes 212 have increased
strength while allowing a use of thinner and lighter materials in a
construction thereof.
[0036] However, the seam 230 increases a rigidity of the tube 212
in a central region 232. The tube 212 is, therefore, less flexible
to accommodate stresses caused by thermal cycling. When the tubes
212 are inserted into a flat header 14, as described above, an
additional potential point of failure is then created at an
intersection of the seam 230 of the tube 212 and the header 14.
Furthermore, if the tube 212 is used in combination with a
trapezoidal header 114 described above, the problem is exacerbated
as a location of the seam 230 coincides with a region of greatest
loading in the central portion 102.
[0037] FIGS. 4a and 4b show a part of the tube 212 and the header
214 according to an embodiment of the present invention. The tube
212 has a folded design provided with the central brazed seam 230,
as described above. The header 214 includes a header plate 234
having a first face such as an upper face, for example. The header
plate 234 has a substantially rectangular shape and includes two
opposing longer edges 236a, 236b and two opposing shorter edges
(not shown). A series of slots 238 for receiving a first end 218
(shown in FIG. 4b) of each of the tubes 212 is formed in the header
plate 234. The slots 238 extend across almost a full width of the
header 214. A length of the slots 238 is perpendicular to a
longitudinal axis 240 of the header 214.
[0038] The header 214 may also include a second face (not shown),
opposing the first face of the header plate 234. In certain
embodiments, the second face forms a base of the header 214. Four
side walls, portions of two of which 242a, 242b are shown, extend
between the first face and the second face around a periphery of
the first face 234 and the second face, thereby forming an enclosed
volume within the header 214.
[0039] Typically, the header 214 is made from a suitable metal such
as an aluminium or steel, for example. The header 214 may be
provided with any number of the slots 238 for receiving the tubes
212. In certain embodiments, the header 214 includes between six
and two hundred slots 238. As a non-limiting example, a spacing
between the slots 238 is about 4 mm to 15 mm and each of the slots
238 is about 1 mm to 12 mm wide. A length of the slots 238 can vary
from 10 mm to 110 mm, depending on an application of the heat
exchanger. Once the tube 212 has been positioned in a respective
one of the slots 238, the tube 212 can be fixed in position by
brazing, soldering, or other suitable joining means as desired.
[0040] The header plate 234 of the header 214 includes two ridge
portions 244 thereby forming a corrugated profile to the header
plate 234. The ridges 244 extend longitudinally along a full length
of the header plate 234. The slots 238 cut perpendicularly across
the ridges 244 such that a line of intersection between the tube
212 inserted into the slot 238 and the header plate 234 do not lie
in a single plane.
[0041] As shown most clearly in FIG. 4b, edge regions 246a, 246b of
the header plate 234 lie in a first plane 248 and crests 250 of the
ridges 244 lie in a second plane 252 parallel to and offset at a
distance from the first plane 248. In a non-limiting example, the
crests 250 of the ridges 244 are raised at a distance from the
first plane 248 such that the crests 250 intersect the tube 212
further from the end 218 of the tube 212 which is located within
the header 214.
[0042] In the embodiment shown, the ridges 244 are dimensioned and
positioned such that the crests 250 intersect the tube 212 at
points approximately one quarter and three quarters of the way
across a width of the tube 212. A trough 254 formed between the two
ridges 244 is aligned with the central portion 232 of the tube 212
so that a base 256 of the trough 254 coincides with the seam 230 of
the tube 212. In certain embodiments, a depth of the trough 254
between the ridges 244 is such that the base 256 of the trough 254
lies at a point between the first plane 248 and the second plane
252. In other embodiments, the base 256 of the trough 254 may lie
in the first plane 248.
[0043] The ridges 244 shown are formed from a number of
substantially planar sections. In particular, the crests 250 of the
ridges 244 and the base 256 of the trough 254 are formed by
substantially planar sections extending parallel to the first plane
248 and perpendicular to the seam 230 of the tube 212. Sides of the
ridges 244 are also formed from substantially planar sections. In a
non-limiting example, the sides of the ridges 244 are at an angle
of between 20.degree. and 70.degree. to the first plane 248.
[0044] FIGS. 5 and 6 show additional embodiments of the invention.
In
[0045] FIG. 5, crests 450 of ridges 444 are formed from
substantially planar or flat sections of a header plate 434 and lie
in a second plane 452. Outer side portions 462 of the ridges 444,
extending between one of opposing long edges 436a, 436b and the
crest 450 of a respective one of the ridges 444, are formed from
substantially curved sections of the header plate 434. In a
non-limiting example, an upper surface 464 of the header plate 434
has a substantially concave curvature in respect to the second
plane 452. A trough 454 between the two ridges 444 is formed from a
continuously curved section of the header plate 434, with an upper
surface 464 having a concave curvature in respect to the second
plane 452.
[0046] In FIG. 6, edge regions 546a, 546b of a header plate 534 lie
in a first plane 548, as in the embodiment of the invention shown
in FIG. 4b. A base portion 556 of a trough 554 is formed from a
substantially planar or flat section of the header plate 534
aligned with a central portion 532 of a tube 512. Ridges 544 in the
header plate 534 are formed from continuously curved sections such
that an upper surface 564 of the header plate 534 is convex in
respect to the first plane 548.
[0047] In the embodiments of the invention described above, it is
important that a point of intersection of the tube 212, 412, 512
with the respective header plate 234, 434, 534 is located closer to
an end of the tube 212, 412, 512 in regions around a nose of the
tube 212, 412, 512 and adjacent to the seam of the tube 212, 412,
512 than in regions therebetween.
[0048] Larger stresses, caused by twisting of the header and
bending of the tubes 212, 412, 512 due to thermal cycling, are
imparted to the joint between the header and the tube 212, 412, 512
at greater distances from the end of the tube 212, 412, 512 because
the tube 212, 412, 512 is able to deform to a greater degree due to
a difference in temperature further from the header. Closer to the
header, deformation is restricted due to the fixed joint between
the tube 212, 412, 512 and the header plate 234, 434, 534.
[0049] In this way, the ridged profile of the header plate 234,
434, 534 according to the present invention separates regions of
higher loading, i.e. regions of intersection further from the end
of the tube 212, 412, 512, from regions of higher stress
concentration, i.e. regions of small radius of curvature around the
nose of the tube 212, 412, 512, and regions of increased rigidity
adjacent the seam of the tube 212, 412, 512.
[0050] The present invention, therefore, provides an improved
header for use in folded-tube heat exchangers that maximizes life
span as compared with current designs of the header.
[0051] From the foregoing description, one ordinarily skilled in
the art can easily ascertain the essential characteristics of this
invention and, without departing from the spirit and scope thereof,
make various changes and modifications to the invention to adapt it
to various usages and conditions.
* * * * *