U.S. patent application number 11/396659 was filed with the patent office on 2006-11-23 for igniter assembly.
This patent application is currently assigned to Daicel Chemical Industries, Ltd.. Invention is credited to Atsushi Hatomoto.
Application Number | 20060260498 11/396659 |
Document ID | / |
Family ID | 37447121 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260498 |
Kind Code |
A1 |
Hatomoto; Atsushi |
November 23, 2006 |
Igniter assembly
Abstract
The present invention provides an igniter assembly comprising:
an igniter main body comprising a metallic header, a conductive pin
fixed to the metallic header, a heat generating body provided on
the metallic header and electrically connected to the conductive
pin, a metallic cup having a upper surface of the metallic cup and
a side surface on an exterior of the metallic cup and an ignition
charge being in contact with the heat generating body, a collar
supporting the igniter main body and a resin covering a part of the
upper. surface of the metallic cup and the side surface of the
metallic cup, an other portion than the part of the upper surface
of the metallic cup being exposed.
Inventors: |
Hatomoto; Atsushi;
(Tatsuno-Shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Daicel Chemical Industries,
Ltd.
Sakai-Shi
JP
|
Family ID: |
37447121 |
Appl. No.: |
11/396659 |
Filed: |
April 4, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60669886 |
Apr 11, 2005 |
|
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|
Current U.S.
Class: |
102/202.14 ;
102/530 |
Current CPC
Class: |
F42B 3/103 20130101 |
Class at
Publication: |
102/202.14 ;
102/530 |
International
Class: |
F42B 3/12 20060101
F42B003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 5, 2005 |
JP |
2005-108612 |
Claims
1. An igniter assembly, comprising: an igniter main body comprising
a metallic header, a conductive pin fixed to the metallic header, a
heat generating body provided on the metallic header and
electrically connected to the conductive pin, a metallic cup having
a upper surface of the metallic cup and a side surface on an
exterior of the metallic cup and an ignition charge being in
contact with the heat generating body; a collar supporting the
igniter main body and a resin covering a part of the upper surface
of the metallic cup and the side surface of the metallic cup, an
other portion than the part of the upper surface of the metallic
cup being exposed.
2. The igniter assembly according to claim 1, wherein the upper
surface of the metallic cup has an edge portion of the upper
surface and a central portion of the upper surface, the resin
covers at least a part of the edge portion of the upper surface,
and the central portion of the upper surface is exposed in the
surface of the metallic cup.
3. The igniter assembly according to claim 1, wherein the upper
surface of the metallic cup has an edge portion of the upper
surface and a central portion of the upper surface, the resin
covers the part of the upper surface including the central portion
of the upper is surface, and a part of the edge portion of the
upper surface is exposed in the surface of the metallic cup.
4. The igniter assembly according to claim 1, wherein the metallic
cup has a fragile portion provided at the upper surface exposing
the surface of the metallic cup.
5. The igniter assembly according to claim 2, wherein the metallic
cup has a fragile portion provided at the upper surface exposing
the surface of the metallic cup.
6. The igniter assembly according to claim 3, wherein the metallic
cup has a fragile portion provided at the upper surface exposing
the surface of the metallic cup.
7. The igniter assembly according to claim 1, wherein the collar
comprises a metal material, the resin is further located between
the igniter main body and the collar as a insulation material, and
the igniter main body and the collar are fixed together by the
resin.
8. The igniter assembly according to claim 2, wherein the collar
comprises a metal material, the resin is further located between
the igniter main body and the collar as a insulation material, and
the igniter main body and the collar are fixed together by the
resin.
9. The igniter assembly according to claim 3, wherein the collar
comprises a metal material, the resin is further located between
the igniter main body and the collar as a insulation material, and
the igniter main body and the collar are fixed together by the
resin.
10. The igniter assembly according to claim 4, wherein the collar
comprises a metal material, the resin is further located between
the igniter main body and the collar as a insulation material, and
the igniter main body and the collar are fixed together by the
resin.
11. The igniter assembly according to claim 5, wherein the collar
comprises a metal material, the resin is further located between
the igniter main body and the collar as a insulation material, and
the igniter main body and the collar are fixed together by the
resin.
12. The igniter assembly according to claim 6, wherein the collar
comprises a metal material, the resin is further located between
the igniter main body and the collar as a insulation material, and
the igniter main body and the collar are fixed together by the
resin.
Description
[0001] This non-provisional application claims priority under 35
U.S.C. .sctn. 119(a) on Patent Application No. 2005-108612 filed in
Japan on 5 Apr. 2005 and 35 U.S.C. .sctn. 119(c) on U.S.
Provisional Application No. 60/669,886 filed on 11 Apr. 2005, which
are incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an igniter assembly that
can be used in a human restraining apparatus for protecting
passengers and pedestrians.
[0004] 2. Description of the Related Art
[0005] A known example of an electric igniter used in a human
restraining apparatus or the like has a center pin (a conductive
pin) attached to a metallic header via an insulating member and an
earth pin (an other conductive pin) attached directly to the
metallic header. A heat generating body is laid across a head
portion of the conductive pin and the metallic header, a metallic
cup for holding an ignition charge is mounted on the metallic
header, and the metallic cup is electrically connected to the earth
pin.
[0006] In this type of electric igniter, when the conductive pin is
functioning as the earth pin and an electric current flows from the
outside into the metallic cup, the electric current flows into the
heat generating body, causing an incorrect operation of the
igniter. To prevent such the incorrect operation, an insulation
material is provided on an outer surface of the metallic cup and a
means for ensuring that the conductive pin and earth pin are
connected correctly is taken.
[0007] U.S. 2002/0069783 A1 discloses a header assembly 20
including an eyelet 60 and a can 65 surrounding the outside of the
eyelet 60, having an ignition charge in an accommodating chamber
formed in the can, and attached to the eyelet 60 by welding 61. A
whole of the igniter is covered with the insulation material by
molding. The whole outside surface of the metallic cup is covered
with a resin as the insulating member.
[0008] The igniter main body is held in a shaping die by gripping
the conductive pin tightly in order to prevent the igniter main
body from moving under the pressure applied during injection. As a
result, the conductive pin is easily damaged, and this damage may
cause the conductive pin to rust. When rust occurs, the conduction
performance is adversely affected.
[0009] In such the igniter assembly, the resin also has a fragile
portion in which the thickness is reduced so that the metallic cup
can be broken easily upon an activation of the igniter assembly.
However, it is difficult to produce the resin with a process for
partially reducing the thickness of the resin as the insulating
member, and that leads to a lack of quality stability of the
ignition assembly. The ignition assembly has also have a demand of
reducing a manufacturing cost.
SUMMARY OF THE INVENTION
[0010] The present invention is to provide an igniter assembly
enabling improved ignition performance, improved quality stability,
and reduced manufacturing cost.
[0011] The present invention relates to an igniter assembly
comprising:
[0012] an igniter main body comprising [0013] a metallic header,
[0014] a conductive pin fixed to the metallic header, [0015] a heat
generating body provided on the metallic header and electrically
connected to the conductive pin, [0016] a metallic cup having an
upper surface of the metallic cup and a side surface on an exterior
of the metallic cup, [0017] an ignition charge charged into the
metallic cup, [0018] the metallic cup being placed over the
metallic header and [0019] an ignition charge being in contact with
the heat generating body, [0020] a collar supporting the igniter
main body and [0021] a resin covering a part of the upper surface
of the metallic cup and the side surface of the metallic cup,
[0022] an other portion than the part of the upper surface of the
metallic cup being exposed.
[0023] When the collar comprises a metal material, the resin is
located between the igniter main body and the collar as an
insulation material, and the igniter main body and the collar are
fixed together by the resin.
[0024] In the igniter assembly of the present invention, the whole
of the cylindrical side surface and a part of the upper surface of
the metallic cup are covered with a resin that is an insulation
material, and the metallic surface of the metallic cup is exposed
at the remainder of the part of the upper surface covered with the
resin. By providing these constitutional elements, the object
described above can be achieved, and the ignition assembly has
functions and effects described below in (A) and (B) are
exhibited.
[0025] (A) When manufacturing the igniter assembly by fixing the
igniter main body to the collar with a method of fixing the igniter
main body to the collar by injecting the resin of an insulation
material between the collar and igniter main body that are held in
a shaping die, the igniter main body can be supported by contacting
the shaping die with the surface of the metallic cup that is not
covered with the resin instead of by gripping the conductive
pin.
[0026] (B) When the upper surface of the metallic cup is partially
covered with the resin, the amount of used resin per unit is
reduced, and the reduction of the amount of used resin during mass
production of the ignition assembly becomes extremely large, and
then manufacturing costs of the ignition assembly can be reduced.
This is also advantageous from the viewpoint of resource
conservation.
[0027] The igniter assembly is used when incorporated into a gas
generator for an air bag or the like. When the metallic cup of the
igniter assembly contacts a housing or other metallic member of the
gas generator, the part of the upper surface of the metallic cup is
insulated in accordance with the internal structure of the gas
generator.
[0028] A shape of the upper surface of the metallic cup covered
with the resin (a pattern of the resin covering the upper surface
of the metallic cup) and an area of the upper surface of the
metallic cup exposing the surface of the metallic cup are not
limited.
[0029] The metallic surface of the metallic cup may be exposed in
the remainder of the upper surface, uncovered with the resin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The present invention will become more fully understood from
the detailed description given herein below and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention and wherein:
[0031] FIG. 1 shows a longitudinal sectional view of an igniter
assembly according to the present invention;
[0032] FIG. 2 shows a view showing patterns of a resin that covers
a part of an upper surface of a metallic cup according to the
present invention;
[0033] FIG. 3 shows a longitudinal sectional view of an igniter
assembly according to another embodiment of the present
invention;
[0034] FIG. 4 shows an axial sectional view of a conventional gas
generator;
[0035] FIG. 5 shows a partial sectional view showing the igniter
assembly according to the present invention and incorporated into
FIG. 4;
[0036] FIG. 6 shows an axial sectional view of a conventional
inflator; and
[0037] FIG. 7 shows a partial sectional view showing the igniter
assembly according to the present invention and incorporated into
FIG. 6.
DETAILED DESCRIPTION OF THE INVENTION
[0038] The present invention further relates to the igniter
assembly, wherein a peripheral edge portion of the upper surface of
the metallic cup is covered with the resin of an electric
insulation resin, and a central portion of the upper surface is
exposed in the surface of the metallic cup. In so doing, the
functions and the effects of (A) and (B) are obtained.
[0039] The present invention further relates to an igniter
assembly, wherein a part of the upper surface of the metallic cup
including the central portion of the upper surface may be covered
with the resin of the electric insulation resin and then a part of
the a peripheral edge portion of the upper surface may be exposed
in the surface of the metallic cup. In so doing, the functions and
the effects of (A) and (B) are obtained.
[0040] The present invention further relates to the igniter
assembly, wherein a fragile portion is provided in a part of the
upper surface of the metallic cup being exposed.
[0041] The fragile portion may be formed by applying a method of
reducing the thickness of the appropriate part or a method of
forming notches in a cross shape, radial shape, or similar.
[0042] The present invention further relates to the igniter
assembly, wherein the collar comprises a metal material, the resin
is further located between the igniter main body and the collar as
an insulation material, and the igniter main body and the collar
are fixed together by the resin.
[0043] The igniter main body and the collar may be fixed together
at the same time as the igniter main body is covered with the resin
in a single resin injection process.
[0044] The igniter assembly may be applied to an inflator using a
gas generating agent as a gas source, an inflator using a
pressurized gas as a gas source, or an inflator using both the gas
generating agent and the pressurized gas. Furthermore, the igniter
assembly is capable of exhibiting an equally favorable ignition
performance when incorporated into the inflators having various
different internal structures.
[0045] In the igniter assembly, a part of the upper surface of the
metallic cup charged with an ignition charge is covered with resin,
and the remainder of the part of the upper surface of the metallic
cup is exposed in the surface of the metallic cup. As a result, the
functions and the effects of (A) and (B) can be exhibited.
[0046] A thickness of the resin may be set within the range of 0.3
to 1.5 mm, and preferably 0.5 to 1.2 mm, in order to secure
electric insulation of the metallic cup.
[0047] In order to cover a desired positions of the part of the
upper surface of the metallic cup with the resin, a method may be
applied in which the upper surface of the metallic cup is pressed
against a predetermined shaping die which is molded in advance such
that the resin covering can be performed in the desired shape (the
pattern desired), whereupon the resin is injected.
[0048] The upper surface of the metallic cup pressed against the
shaping die is not covered with resin, and as a result a part of
the surface of the metallic cup is exposed.
EMBODIMENTS OF THE INVENTION
[0049] (1) Igniter Assembly of FIG. 1
[0050] FIG. 1 is a longitudinal sectional view of an igniter
assembly 10.
[0051] The igniter assembly 10 includes an igniter main body 11 and
a metallic igniter collar 12 that are fixed together integrally by
a resin 13. The resin 13 may be charged using an injection molding
method.
[0052] A center pin 16a (conductive pin) and an earth pin 16b
(other conductive pin) are fixed to a metallic header 15. The earth
pin 16b may be fixed on the metallic header 15 by welding as FIG. 1
shows in block line.
[0053] A part of a periphery portion of the center pin 16a is
surrounded by an insulating member 17 (glass or the like), such
that the center pin 16a does not contact the metallic header 15
directly. The earth pin 16b is electrically connected to the
metallic header 15. An upper end face of the center pin 16a, an
insulating body 17, and a surface of the metallic header 15 are
formed to be flush with each other. Both the center pin 16a and the
earth pin 16b may be attached to the metallic header via an
insulating member.
[0054] A bridge wire 18 is laid across the center pin 16a and the
metallic header 15 as an electric resistance wire (a heat
generating body). The bridge wire 18 is used to convert electric
energy (in other words, an electric signal) into a thermal energy.
A platinum wire (having melting point 1870.degree. C.), a nichrome
wire (having melting point 1400.degree. C.), or similar may be used
as the bridge wire 18. The bridge wire 18 may be connected to the
center pin 16a and the metallic header by welding.
[0055] A metallic cup 20 is placed on the metallic header 15, and
an ignition charge 21 is charged into the interior space thereof (a
space of accommodating an ignition charge) so as to contact the
bridge wire 18. A material of the ignition charge 21 which is
ignited and burned by the heat generated by the bridge wire 18,
such as zirconium potassium perchlorate, may be used as the
ignition charge 21.
[0056] The metallic cup 20 is fixed to the surface of the metallic
header 15 at an opening portion side the metallic cup by welding
such that the metallic cup 20 and metallic header 15 contact each
other.
[0057] The metallic cup 20 has a cylindrical side surface 20a and
an upper surface 20b. The whole of the cylindrical side surface 20a
and a part of the upper surface 20b are covered with a resin 25
that is an electric insulating resin. The remainder of the part of
the upper surface 20b is not covered with the resin 25, and hence a
surface of the metallic cup 20 (a part of the upper surface 20b) is
exposed (the exposed part of the upper surface 20b will be referred
to hereafter as an "exposed surface 30"). A fragile portion of the
metallic cup may be provided in a part of the exposed surface 30 by
reducing the thickness thereof or forming a cross-shaped notch
therein. When the igniter assembly 10 is activated, the metallic
cup 20 is broken at the exposed surface 30 (or at the fragile
portion when the fragile portion is provided).
[0058] The pattern in which the resin 25 covers the upper surface
20b of the metallic cup 20 is adjusted within a range enabling the
aforementioned functions and effects of (A) and (B) to be
exhibited.
[0059] FIGS. 2(a) to 2(f) shows examples of a pattern of the resin
covering the part of the upper surface of the metallic cup.
[0060] In FIG. 2(a), a peripheral edge portion of the upper surface
20b of the metallic cup 20 is covered by the resin 25 in annular
form, and the surface of the metallic cup is exposed in a central
portion of the upper surface. A circular fragile portion 26 of the
central portion of the metallic cup having a reduced thickness is
provided on the exposed surface 30. The resin 25 may be formed in
the pattern shown in FIG. 2(a) in the following manner, for
example.
[0061] The igniter main body 11 and the igniter collar 12 are
disposed in a shaping die (an upper die and a lower die) such that
a predetermined space is provided therebetween. At this time, the
igniter collar 12 is fixed (gripped) between the lower die and the
upper side. As for the igniter main body 11, the center pin 16a and
earth pin 16b are inserted into a hole of the shaping die, provided
in the lower die, for example, and a part of the upper surface 20b
of the metallic cup 20 corresponding to the exposed surface 30 is
pressed against a predetermined site of the upper die. Thus the
igniter main body 11 is supported by the center pin 16a and earth
pin 16b, which are inserted into the hole in the lower die, and the
exposed surface 30 pressed against the upper die. When the resin is
then charged into an internal space portion of the shaping die, the
part of the upper surface 20b of the metallic cup 20 contacting the
upper die is not covered with the resin. As a result, the igniter
assembly 10 having the exposed surface 30 shown in FIGS. 1 and 2(a)
is obtained.
[0062] In FIG. 2(b), the peripheral edge portion of the upper
surface 20b of the metallic cup 20 is covered by the resin 25 in
the pattern shown in the drawing such that the surface of the
metallic cup 20 is exposed in the central portion of the upper
surface 20b. A radial notched fragile portion 27 is provided on the
exposed surface 30 as shown in the drawing.
[0063] In FIG. 2(c), the peripheral edge portion of the upper
surface 20b of the metallic cup 20 is covered by the resin 25 in
the pattern shown in the drawing such that the surface of the
metallic cup 20 is exposed in the central portion of the upper
surface 20b. A radial notched fragile portion 28 is provided on the
exposed surface 30 as shown in the drawing.
[0064] In FIG. 2(d), the central portion of the upper surface 20b
of the metallic cup 20 is covered by the resin 25 in a circular
shape, and the surface of the metallic cup 20 is exposed in the
peripheral edge portion of the upper surface 20b. A fragile portion
of the metallic cup 20 may be provided similarly on the exposed
surface 30.
[0065] In FIG. 2(e), a part of the upper surface 20b of the
metallic cup 20 including the central portion of the metallic cup
20 is covered by the resin 25 in the pattern shown in the drawing
(in which the resin 25 covering the cylindrical side surface 20a
and the resin 25 covering the upper surface 20b are connected), and
the surface of the metallic cup is exposed in the four parts of the
peripheral edge portion of the upper surface 20b. The fragile
portion may be provided similarly on the exposed surface 30.
[0066] In FIG. 2(f), a part of the upper surface 20b of the
metallic cup 20 including the central portion of the upper surface
is covered by the resin 25 in a cross shape (such that the resin 13
covering the cylindrical side surface 20a and the resin 25 covering
the upper surface 20b are connected), and the surface of the
metallic cup 20 is exposed in the four fan-shaped portions. A
fragile portion of the metallic cup may be provided similarly on
the exposed surface 30.
[0067] In FIGS. 1 and 2, except of FIG. 2(d), the resin 25 and the
resin 13 are formed simultaneously by a single injection when the
igniter main body 11 and collar 12 are to be integrated.
[0068] The upper surface 20b of the metallic cup of the igniter
main body 11 is covered by the resin 25 in the pattern shown in
FIG. 2(a), and when the ignition charge 21 is ignited and burned
upon activation of the igniter assembly 10, thereby generating an
ignition energy which breaks the exposed surface 30 (the fragile
portion 26). The ignition energy is then discharged through a
ruptured portion of the exposed surface 30. The exposed surface 30
is a trace formed when the igniter main body 11 is in contact with
the shaping die, and hence the functions and effects of (A) can be
exhibited. Furthermore, an amount of the resin can be reduced in
accordance with the exposed surface 30, which leads to a huge
overall reduction when the igniter assembly 10 is manufactured in
units of several million, for example, and hence the functions and
effects of (B) can also be exhibited.
[0069] (2) Igniter Assembly of FIG. 3
[0070] FIG. 3 is a longitudinal sectional view of an igniter
assembly 100 according to another embodiment of the present
invention. Identical reference numerals to those used in FIG. 1
denote identical elements.
[0071] In the igniter assembly 100, the igniter main body 11 is
manufactured first, whereupon the igniter main body 11 and the
metallic collar 12 are fixed integrally by caulking an annular
protrusion 12a of the metallic collar 12. The pattern in which the
resin 25 covers the upper surface 20b of the metallic cup 20 may be
selected from those shown in FIGS. 2(a) to 2(f).
[0072] (3) Gas Generator Incorporating Igniter Assembly 10 of FIG.
1 (Using a Gas Generating Agent as a Gas Source)
[0073] FIG. 4 shows a gas generator for an air bag as same as one
illustrated in FIG. 1 of JP-A No. 10-95302. In FIG. 1 of JP-A No.
10-95302, 4 denotes an igniter, and hence the igniter 4 and a
collar part integrated therewith are replaced by the igniter
assembly 10 shown in FIG. 1 of the present invention.
[0074] In the gas generator shown in FIG. 4, a transfer charge
container 53 accommodating a transfer charge 5 is disposed in an
ignition device accommodating a chamber 23. The transfer charge
container 53 is generally formed from a conductive material such as
aluminum.
[0075] As shown in FIG. 5(a), at the upper surface 20b of the
metallic cup (having the resin covering pattern of FIG. 2(a)) of
the igniter assembly 10, the resin 25 covering a part of the
peripheral edge portion of the upper surface contacts a base
surface 53a of the transfer charge container 53, and the exposed
surface 30 does not contact the base surface 53a.
[0076] Hence, even when an electric current flows into a housing 1
of the air bag gas generator, the electric current does not flow
into the metallic cup 20 and metallic header 15, and therefore
malfunctions of the igniter main body 11 do not occur.
[0077] In FIGS. 4 and 5(a), the igniter 4 (the igniter assembly 10
when replaced) and the igniter transfer charge container 53 have
matching central axes in the axial direction (shown by the dot-dash
line in the drawing), but depending on the internal structure of
the gas generator, the igniter 4 and the transfer charge container
53 may have non-matching central axes in the axial direction (for
example, the igniter 4 in FIG. 4 may be disposed slightly to the
left side).
[0078] As shown in FIG. 5(b), in such a case, only the part of the
upper surface 20b of the metallic cup in close proximity to, or in
contact with, the transfer charge container 53a needs to be covered
with the resin 25.
[0079] (4) Inflator Incorporated with Igniter Assembly 10 of FIG. 1
(Using a Pressurized Gas as a Gas Source)
[0080] FIG. 6 shows an inflator as same as illustrated in FIG. 1 of
JP-A No. 2003-25951. In FIG. 1 of this publication, 26 denotes an
igniter, and hence the igniter 26 and a collar part integrated
therewith are replaced by the igniter assembly 10 shown in FIG. 1
of the present invention.
[0081] When the igniter assembly 10 is incorporated into FIG. 6, a
gap exists between the upper surface 20b of the metallic cup and a
rupturable plate 19, but depending on an internal structure of the
inflator, the upper surface 20b of the metallic cup and the
rupturable plate 19 may be disposed in closer proximity. However,
even in such a case, the upper surface 20b of the metallic cup and
the rupturable plate 19 may be set in a similar state of contacting
between the upper surface 20b of the metallic cup and base surface
53a shown in FIG. 5(a), and therefore an incorrect operation
(malfunctions) do not occur.
[0082] Further, in FIG. 6 the igniter 26 (the igniter assembly 10
when replaced) and the rupturable plate 19 have matching central
axes in the axial direction, but depending on the internal
structure of the inflator, the igniter 26 (the igniter assembly 10
when replaced) and the rupturable plate 19 may have non-matching
central axes in the axial direction (for example, the igniter 26 in
FIG. 6 may be disposed slightly toward the lower side).
[0083] In this case, as shown in FIG. 7, a lower half of the upper
surface 20b of the metallic cup is covered by the resin 25 and an
upper half of the upper surface 20b is set as the exposed surface
30. In so doing, it is possible to cover only a portion of the
upper surface of the metallic cup that is closest to the rupturable
plate 19 with the resin 25.
[0084] As described above, the igniter assembly of the present
invention may be applied to gas generators having various
well-known internal structures and using various well-known gas
sources, and is capable of exhibiting a similar ignition
performance regardless of the gas generator in which it is
incorporated.
[0085] The invention thus described, it will be obvious that the
same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modification as would be obvious to one skilled in the
art are intended to be included within the scope of the following
claims.
* * * * *