U.S. patent number 3,749,090 [Application Number 05/151,372] was granted by the patent office on 1973-07-31 for combination aspirator and fluid delivering surgical instrument.
This patent grant is currently assigned to Stewart Research, Inc.. Invention is credited to James M. Stewart.
United States Patent |
3,749,090 |
Stewart |
July 31, 1973 |
COMBINATION ASPIRATOR AND FLUID DELIVERING SURGICAL INSTRUMENT
Abstract
A combination surgical instrument is provided for applying
vacuum and delivering fluid to a work area. The instrument includes
a readily detachable work tool having a fluid delivering tube and
an integrally attached vacuum-applying tube, with the entrance end
of the vacuum tube projecting beyond the entrance end of the fluid
tube; and a handle connectable to sources of fluid and vacuum and
resistant to sterilizing temperatures and having a first passage
for receiving the fluid delivery tube; and a second passage having
a cutaway portion to expose an elongated section of the passage
along an exterior surface of the handle for receiving the
vacuum-applying tube.
Inventors: |
Stewart; James M. (West Palm
Beach, FL) |
Assignee: |
Stewart Research, Inc. (West
Palm Beach, FL)
|
Family
ID: |
22538468 |
Appl.
No.: |
05/151,372 |
Filed: |
June 9, 1971 |
Current U.S.
Class: |
604/33 |
Current CPC
Class: |
A61M
1/774 (20210501); A61M 1/7411 (20210501); A61M
1/85 (20210501) |
Current International
Class: |
A61M
1/00 (20060101); A61m 003/00 () |
Field of
Search: |
;128/240,276,239,224
;32/33 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Yasko; J.
Claims
What is claimed is:
1. A combination surgical instrument having a readily detachable
and replaceable work tool for applying vacuum and delivering fluid
to a work area, said instrument comprising:
a. a work tool having first and second tubular members for
delivering fluid and applying vacuum, respectively, to a work area
with each member having an entrance end and an exit end, the
entrance end of the second member being located on an extension of
the second tubular member that projects beyond the entrance end of
the first member, and said first and second members being
interconnected to form a unitary work tool; and
b. an elongated tubular handle resistant to sterilizing
temperatures and conditions and having a first enclosed passage
extending the length of the handle which slidably and detachably
receives at a first end of the handle the entrance end of the first
tubular member of the work tool and communicates with a supply of
fluid; and a second passage spaced from the first passage and
communicating with a source of vacuum, said second passage having
an enclosed portion rearwardly spaced from said first handle end
which slidably and detachably receives the entrance end of the
extension of the second tubular member and a cutaway portion
between the enclosed portion and said first handle end exposing an
elongated section of the passage along an exterior surface of the
handle which slidably and detachably receives the extension of the
second tubular member while leaving exposed a portion of the
extension of the second tubular member so that a vacuum relief hole
can be provided in the extension of the second tubular member of
the replaceable work tool for control by the operator when the
handle is gripped to permit control of the amount of vacuum applied
to the work area.
2. The instrument of claim 1, wherein said cutaway portion is
defined by two opposed side walls which partially wrap around and
grip the extension of the second tubular member.
3. The instrument of claim 1, wherein said handle includes a slot
connecting the first passage with the elongated section of the
second passage at said handle end, and the first and second tubular
members are interconnected by a brace adjacent the entrance end of
the first member which is received in said slot for preventing
rotation of the work tool with respect to the handle.
4. The instrument of claim 1, including a valve means in said
handle intersecting said first passage and operable by a finger of
the operator for controlling the flow of fluid through said first
tubular member.
5. The instrument of claim 4, wherein the valve means comprises a
valve housing having a conically divergent surface which serves as
a valve seat, a valve plunger positioned in said housing, a plastic
valve seat resistant to sterilizing temperatures and conditions
attached to the plunger and having an external configuration to
seat to said conically divergent surface, an actuator connected to
one end of said plunger, and a coil spring contacting the actuator
to bias the valve seal against said conically divergent surface in
a fluid flow preventing position.
6. The instrument of claim 5, wherein a valve cap is secured to an
end of said housing, said cap having a bore to slidably receive one
end of the plunger opposite the end connected to the actuator, said
valve cap being removable to expose internal surfaces of the valve
means to permit cleaning of these surfaces.
7. The instrument of claim 5, including a shaft seal surrounding
said plunger to seal the end of the housing adjacent to said
actuator.
8. The instrument of claim 6, wherein said shaft seal comprises an
annular stem and a head having an internal annular void which
imparts flexibility to the shaft seal, said coil spring being
interposed between the actuator and said head.
9. The instrument of claim 1, wherein said second member is spaced
vertically below said first member and the exposed portion of the
extension of the second tubular member extends along the bottom of
the handle.
10. The instrument of claim 9, including a relief hole in the
exposed portion of the extension of the second tubular member.
11. The instrument of claim 1 wherein the first and second tubular
members gradually expand in diameter from their entrance ends.
Description
The present invention relates to surgical apparatus, and more
particularly to a combination surgical instrument for delivering
fluid and supplying vacuum to an operating area.
In surgery, it is important that the operating area be kept free of
blood and other fluids and debris that could obstruct the surgeon's
vision, and the contaminating influence of bacteria and dirt as in
wounds that can cause serious infections. It is also generally
important that the operating areas be maintained in a moist or
lubricated condition and that overheating be prevented to avoid
damage to or deterioration of the exposed tissues during
surgery.
It has, therefore, been necessary to provide surgical instruments
that facilitate the cleaning and sterilization of surgical wounds
and prevent the drying out or overheating of the tissues, as occurs
in cutting bone, to properly prepare and maintain the operating
area during the operative procedure and to reduce post-surgical
morbidity and suffering.
In the past, many separate and combination devices have been
provided to perform these functions. Controlled vacuum or
aspirating devices, for example, have been used to remove debris
and suck fluids from surgical wounds. Irrigating or lavage devices
for spraying the surgical area with the necessary sterilizing and
cleansing fluids have also been provided and sometimes in
combination with the aspirating devices to increase the
effectiveness of the suction action.
The surgical equipment presently available, however, to perform the
necessary suctioning and lavaging functions during an operative
procedure has generally proven to be awkward and cumbersome in use
as it is often provided in separate instruments; requires more than
one hand to operate; requires special containers for the fluids; or
does not facilitate rapid and convenient replacement of the work
tools, depending upon the type of surgery being performed.
Another disadvantage of prior aspirating and suction instruments
concerns increasing the degree of an iatrogenic disease, that is,
disease which is initiated or results from the activity of a
physician or surgeon. Such disease is inherent in any surgical
procedure, but can be minimized through sterilization of the
surgical instruments used during surgery, observance of good
surgical technique and meticulous removal of debris and foreign
material. While a number of surgical instruments now in use
comprise a hand piece and detachable work tool, so that the work
tool can be detached from the hand piece and replaced with a
sterile one, the hand piece generally must be reused without
sterilization, leaving an undesirable source of contamination.
Accordingly, it is a primary object of this invention to provide a
new and improved combination surgical instrument that delivers
fluid and supplies vacuum to an operating area during surgery, that
is easy and convenient to handle and operate, and that is reliable
and readily maintainable in a sterile condition.
A further object of this invention is to provide a surgical
instrument for applying suction and selectively delivering an
appropriate sterile fluid to a limited area that can be operated by
one hand, readily detached from its source of suction and fluid,
and readily adaptable to a wide variety of applications.
Additional objects and advantages of the invention will be set
forth in part in the description which follows, or in part may be
learned by practice of the invention.
To achieve the foregoing objects and in accordance with its
purpose, this invention provides a combination surgical instrument
for applying vacuum and delivering fluid to a work area. The
instrument comprises a work tool having a first tubular member for
delivering fluid and a second tubular member for applying vacuum,
respectively, to a work area, with each member having an entrance
end and an exit end, the entrance end of the second tubular member
being located on an extension of the second tubular member that
projects beyond the entrance end of the first member; and an
elongated tubular handle resistant to sterilizing temperatures and
conditions and having a first enclosed passage for detachably
receiving the entrance end of the first tubular member of the work
tool and communicating with a supply of fluid, and a second passage
spaced from the first passage and having a cutaway portion exposing
an elongated section of the passage along an exterior surface of
the handle for detachably receiving the extension of the second
tubular member and an enclosed portion for receiving the entrance
end of the second tubular member of the work tool and communicating
with a source of vacuum.
Preferably, the cutaway portion is defined by two exposed side
walls which partially wrap around and grip the extension of the
second tubular member to provide increased rigidity to the
instrument.
It is also preferred to provide a valve means in the handle for
controlling the flow of fluid through the first tubular member. The
valve means intersects the first passage and preferably comprises a
valve housing having a conically divergent surface which serves as
a valve seat, a valve plunger positioned in the housing, a plastic
valve seal resistant to sterilizing temperatures and conditions
attached to the plunger and having an external configuration to
seat the conically divergent surface, an actuator connected to one
end of the plunger, and a coil spring in contact with the actuator
to bias the valve seal against the conically divergent surface in a
fluid flow preventing position.
It is to be understood that both the foregoing general description
and the following detailed description are exemplary and
explanatory, and are not restrictive of the invention.
The accompanying drawings illustrate an example of a preferred
embodiment of the invention and together with the description serve
to explain the principles of the invention.
Of the drawings:
FIG. 1 is a side view of a surgical instrument constructed in
accordance with the teachings of the present invention.
FIG. 2 is a top plan view of the surgical instrument of FIG. 1.
FIG. 3 is a bottom view of the surgical instrument of FIG. 1.
FIG. 4 is a vertical sectional view taken along the lines 4--4 of
FIG. 2, and shows a detailed view of the assembled instrument
according to the teachings of the present invention, but without
the valve means illustrated in FIG. 2.
FIG. 5 is a horizontal sectional view taken along lines 5--5 of
FIG. 1 and shows the valve means constructed in accordance with the
teachings of the present invention.
FIG. 6 is a vertical sectional view taken along lines 6--6 of FIG.
1.
FIG. 7 is a vertical sectional view taken along lines 7--7 of FIG.
1.
FIG. 8 is a vertical sectional view taken along lines 8--8 of FIG.
2.
FIG. 9 is a vertical sectional view taken along lines 9--9 of FIG.
2.
In accordance with the invention, the surgical instrument includes
a work tool having integrally connected first and second tubular
members, with one of said members being longer than the other. As
here embodied, and as shown in FIG. 1, a work tool, generally 10,
comprises a first tubular member 12 for carrying an irrigating
solution, and a second tubular member 14 vertically aligned below
and integrally connected with member 12 for drawing suction.
Irrigating member 12 has an exit or work end 16 and an opposite
entrance or connector end 18. Suction member 14 has an exit or work
end 20 abutting work end 16 of irrigating member 12, and an
entrance or connector end 22 (See FIG. 4).
Work ends 16 and 20 of members 12 and 14 generally have a
downwardly curved shape as illustrated in FIG. 1 to facilitate
their placement in the area where surgery is occurring. Work ends
16 and 20 are joined together as with solder to provide a unitary
structure to be inserted into the work area.
At its outermost portion, work end 16 is provided with an outlet
opening 24, and work end 20 is provided with an outlet opening 26.
Work end 20 extends past work end 16 so that outlet opening 26 of
suction member 14 is several millimeters beyond outlet opening 24
of irrigating member 12. This arrangement permits the irrigating
solution to be projected past outlet opening 26 of suction member
14, and insures that the solution is allowed to contact the work
area and is not immediately drawn into outlet opening 26 upon
issuance from its outlet opening 24. A relief hole 28 is provided
adjacent outlet opening 26 of suction member 14 on its bottom
surface, as best seen in FIGS. 1 and 3. Preferably, and as best
shown in FIGS. 1, 3 and 4, a second relief hole 29 is provided on
the bottom surface of suction member 14. Relief hole 29 is used to
increase temporarily the amount of suction when necessary, while at
the same time preventing an undue amount of vacuum to be present
when delicate tissues are in contact with work tool 10.
Generally, suction and irrigating members 12 and 14 of work tool 10
gradually expand in diameter from narrow work ends to wider
entrance ends to provide relative freedom from accidental clogging
of the suction member, and to reduce the flow resistance in the
irrigating member. If clogging should occur, the work tool is
easily removed and replaceable with an identical new tool. The
caliper or diameter of the work end and size and shape of suction
member 14 is, of course, related to the type nasal surgery for
which it is to be used. Thus, abdominal, masal or sinus work tools
are usually provided with tubular members of constant diameter
throughout because, in abdominal surgery, the suction tubular
members of such work tools require a large diameter at its work end
and in nasal or sinus surgery it is impractical to make the
remainder of these tubular members larger than their work ends
because the increased size of such a member can interfere with good
visibility of the work area.
As best seen in FIG. 1, a vertical brace 30 joins the tubular
members to each other near entrance end 18 and provides rigidity to
this end of work tool 10 as well as to prevent rotation of the work
tool by engaging in a slot 33 (FIGS. 4 and 9), in the handle 32,
described in greater detail hereafter. Work ends 16 and 20
gradually diverge from each other so that the entrance ends are
vertically spaced and parallel to each other. In accordance with
the invention, and as best shown in FIG. 4, the entrance end 18 of
irrigating member 12 terminates shortly beyond brace 30, whereas
the entrance end 22 is located on an extension 31 of suction member
14 and projects beyond the end of irrigating tube 12.
Work tool 10 can be made of metal, such as stainless steel, or
plastic, such as polyvinyl chloride, polyethylene, polypropylene,
or the like. When using metal work tools, the tools are preferably
sterilized after use so that they can be reused. When using plastic
work tools, the tools are preferably disposed of and replaced with
new sterile work tools. The work tools, of course, are easily
removed, and tools used for the same purpose are made identical in
size and shape so that they are readily interchangeable. Further,
the work tools can be provided in a wide variety of configurations,
diameters and lengths to satisfy particular surgical requirements.
For example, the work tools used for gross procedures are larger in
all respects than the delicate type tools used in ear surgery.
In accordance with the invention, the surgical instrument further
includes an elongated plastic tubular handle having a first
enclosed passage for detachably receiving the fluid supplying tube
of the work tool and a second passage vertically spaced from the
first passage for detachably receiving the vacuum tube of the
tool.
As here embodied, and as best shown in FIGS. 1 and 4, the handle
comprises an elongated tubular handle grip, generally 32, having a
first axially extending passage 34 for supplying irrigating
solution, and a second axially extending passage 36, for drawing a
vacuum, vertically spaced below passage 34. An end plate 38 is
attached to a supply end 40 of handle 32 and has vertically spaced
fittings 42 and 44 which are aligned with and communicate with
first and second passages 34 and 36, respectively, of handle
32.
Fitting 42 is a coupling for a hose unit connected to a supply of
sterile irrigating solution. Sterile isotonic salt solutions of
diverse compositions are commonly available in convenient packaging
for cleaning surgical wounds. It is well known that tap water
should not be used because of its chemical composition,
contamination, and hypotonicity, and that sterile water is also
unsatisfactory because of its hypotonicity. Sterile normal saline
solutions or .9 normal solutions are most commonly used.
Fitting 44 serves as a connection for a suitable source of vacuum.
Fittings 42 and 44 have irregular exterior surfaces to facilitate
sealed coupling of hose units thereto, but the hose units can be
quickly disconnected from the fittings to disconnect the entire
surgical instrument from the source of the vacuum and irrigating
fluid.
As best seen in FIG. 4, irrigating passage 34 extends from supply
end 40 of handle 32 to its opposite tool receiving end 46 of the
handle and is completely enclosed by the material of the handle.
Irrigating passage 34 includes a uniformly cylindical main section
48 that extends the greater length of handle 32, and a shorter
enlarged cylindrical tool receiving section 50 at end 46 of the
handle for detachably receiving entrance end 18 of irrigator member
12. The maximum inward movement of entrance end 18 into section 50
is limited by interior shoulder 49 formed at the point where
irrigator passage 34 expands from main section 48 to tool receiving
section 50. A transverse bore 52 perpendicularly intersects main
section 48 of passage 34 at a point closely adjacent tool receiving
section 50. As seen in FIG. 2, bore 52 extends from a first side 51
of handle 32 completely through to the opposite second side 53 of
the handle. As best seen in FIGS. 2, 3, 5, and 8, a valve means,
generally 54, described in greater detail hereafter, is positioned
in bore 52 for controlling the flow of irrigating fluid through
handle 32 and to work tool 10.
As seen in FIGS. 1, 3, 4, and 7-9, second passage 36 of handle 32
has a cutaway portion that exposes an elongated section 56 of the
passage along the bottom exterior surface of the handle for
receiving the extension 31 of the member 14 of the work tool and an
enclosed portion 58 adjacent supply end 40 of handle 32, which
receives entrance end 22 of member 14. As seen in FIGS. 3 and 7-9,
opened section 56 is defined by two opposed side walls 60 and 62
which are joined together by a bottom curved surface 64. Side walls
60 and 62, as best seen in FIGS. 3 and 8, partially wrap around
extension 31 of suction member 14 and provide a snap or
friction-type fit when the work tool is inserted into handle 32.
This construction adds support and rigidity to the assembled
instrument when work tool 10 is inserted into the handle, yet
permits the tool to be readily removed and interchanged with any
other type of tool. As shown in FIG. 6, extension 31 extends the
length of exposed section 56 and the entrance end 22 on extension
31 of suction tube 14 is received in the enclosed portion 58 of
suction passage 36 to provide a closed path for the drawing of
vacuum.
Thus, by providing a work tool in which the tubular members 12 and
14 of the tool are of different lengths and a compatible handle as
described above for receiving the tool, it can be seen that the
combination surgical instrument of this invention can be easily,
quickly and reliably assembled, without any chance of incorrectly
aligning the work tool in the handle and without fear of accidental
disjoining during use.
Further, the provision of a cutaway portion in suction passage 36
of handle 32 is particularly important in reducing the enclosed
area of suction passage 36 that must be thoroughly cleaned and
sterilized, thus reducing the chance of infections due to improper
sterilization. Another advantage is that the cutaway portion
permits relief hole 29 in suction member 14, to be located adjacent
the tool receiving end 46 of handle 32 and in a convenient position
for operation by the user of the present device.
In a preferred embodiment of the invention, and as best seen in
FIGS. 4 and 9, a vertically extending slot 33 connects tool
receiving section 50 of first passage 34 with opened section 56 of
second passage 36 at the tool receiving end 46 of handle 32. Slot
33 receives vertical brace 30 of work tool, and this construction
of the instrument prevents rotation of work tool 10 when it is
positioned within handle 32.
In accordance with the invention, handle 32 is formed from plastic
materials which are highly resistant to heat so that the handle can
withstand all commonly used forms of sterilizing equipment
including the steam autoclave. A preferred plastic for use in the
present invention is polytetrafluoroethylene such as that sold
under the tradename Teflon. Teflon is substantially impervious to
fluid penetration, does not readily discolor, and can be cleaned as
easily as more expensive stainless steels. In fact, because of
their lower density, plastic pieces reach sterilizing temperature
and cool far more rapidly than stainless steels and thus can be
reused quicker than stainless steel.
The plastic handles are easily molded by conventional molding
techniques, to a shape to which a person's hand can easily conform,
so that he can easily grip and hold the instrument by the handle in
one hand.
The shape of handle 32 tends to properly preposition the instrument
in the hand and thereby automatically correctly direct the
extending work tool 10.
In accordance with a preferred embodiment of the invention, a valve
means 54 is provided to control the flow of irrigating solution
through irrigating passage 34. As best seen in FIGS. 2 and 5, valve
means 54 includes a tubular valve housing 66 which is positioned in
transverse bore 52 and extends past the opposing sides 51 and 53 of
handle 32.
A central passage, generally 68, in valve housing 66 intersects
passage 34 of handle 32 and extends the full length of the housing
transversely of the handle. Passage 68 includes a first cylindrical
section 70 adjacent side 53 of handle 32 and a reduced cylindrical
shaft receiving section 72 spaced immediately inwardly of section
70. A shoulder 74 is formed at the point where first cylindrical
section 70 meets shaft section 72. Spaced inwardly of shaft section
72, passage 68 is conically expanded in cross section to provide a
conically divergent surface 76 which serves as a valve seat. The
conically expanded portion of passage 68 is followed by a
cylindrical section 78 having the same diameter as cylindrical
section 70, and then by a threaded section to provide an internally
threaded end 80 for valve housing 66.
A valve plunger 82 is movably positioned in passage 68 of valve
housing 66 and a conically shaped valve seal 84 is attached to the
plunger. Valve seal 84 has an external configuration to seat in
conical surface 76. An annular fin 90 and a larger diameter annular
flange 92 abutting the divergent end of seal 84 are provided on
valve plunger 82 to secure and retain the valve seal to the valve
plunger.
Valve seal 84 is preferably made of a plastic material that can
repeatedly withstand sterilization temperatures and procedures.
Silicone rubbers, such as those sold by General Electric under the
tradenames RTV 632A and RTV 63 2B are suitable for use in the
present invention. Valve seal 84 is molded to valve plunger 82 by
using conventional molding conditions well known to those of
ordinary skill in the art.
Conically divergent surface 76 of valve housing 66 contains an
inlet opening 77 which is aligned with an upstream section 79 of
main section passage 48 of passage 34, and an outlet opening 81
which is aligned with a downstream section 83 of main section 48 of
passage 34. As best seen in FIGS. 4 and 5, the upstream and
downstream sections 79 and 83 are axially aligned along the axis of
passage 34. Valve seal 84 is normally seated in sealing relation to
conical surface 76 and completely intercepts the inlet and outlet
openings 77 and 81 of conically divergent surface 76 and thereby
intercepts passage 34 in a fluid flow preventing position as
illustrated in FIG. 5.
A valve cap, generally 94, is removably secured to threaded end 80
of valve housing 66 and comprises an externally threaded stem 96
and an internal bore 98 for receiving and supporting one end 88 of
valve plunger 82. As shown in FIG. 5, the maximum amount of axial
movement of plunger 82 is defined by the depth of bore 98. An
O-ring 108 is positioned between cap 94 and valve housing 66 to
seal the cap to the valve. After repeated use and sterilization,
minerals sometimes precipitate and deposit on the inner surfaces of
the valves and removable valve cap 94 is therefore provided to
allow access to these surfaces so that they can be periodically
cleaned.
A cup shaped actuator, generally 114, is threadably secured to the
opposite threaded end 86 of valve plunger 82. A shaft seal 116 is
positioned within cylindrical section 70 of passage 38 of valve
housing 60 and abuts against the external surface of valve plunger
82 and shoulder 74. Shaft seal 116 comprises a head portion 118
having an internal annular void 122 and a stem portion 120. Void
122 imparts flexibility to the shaft seal 116 and permits easier
movement of plunger 82 within the seal and more positive sealing of
the valve.
A coil spring 124 is interposed between the inner surface of
actuator 114 and head 118 of shaft seal 116 to bias valve seal 84
against conical surface 76. Coil spring 124 presses against head
118 of shaft seal 116 so that a positive seal is formed in
cylindrical section 70 around plunger 82 adjacent shoulder 74 of
valve housing 66.
To operate the valve means, pressure is applied to actuator 114 to
overcome the bias of coil spring 124 and move plunger 82 toward
valve cap 94. Movement of plunger 82 toward the valve cap displaces
valve seal 84 from conical surface 76 of valve housing 66 and
enables inlet opening 77 of the valve housing to communicate with
outlet opening 81 of the valve housing and thereby permits fluid
under pressure to pass out through irrigating tube 12.
In using the apparatus of the present invention, the surgeon of his
assitant can easily and naturally grip handle 32 in one hand using
his thumb or a finger to operate the valve and another finger to
operate the vacuum relief hole 29. Where incisions have been
previously made and the lips thereof spread to expose the area of
the operation, the surgeon or this assitant with one hand can
manipulate the apparatus and selectively flush, wash or cleanse the
operating area and continuously and immediately such away fluids
and debris from the operating area while he continues uninterrupted
with the operative procedure. The apparatus is therefore extremely
flexible and efficient to use. It obviates the need for
interference and delay occasioned by the many hands normally
employed to maintain an operating area in a safe condition during
surgery.
Thus, an extremely simple and effective structure is provided which
may be applied to many other cleansing or lubricating applications
as well. Such other applications are clearly contemplated and will
be understood by those versed in the art as within the scope of the
invention.
After use, the entire surgical instrument is disconnected from the
hose units. Work tool 10 is then detached from handle 32, and if it
is made of a material that can withstand sterilization procedures,
both it and the handle are sterilized. After sterilization is
completed, handle 32 is again connected to the appropriate hose
units and a sterilized work tool 10 is inserted into tool receiving
end 46 of the handle to provide a sterilized surgical instrument
that can be immediately used with a minimum likelihood of
transmitting iatrogenic disease to a patient.
The invention in its broader aspects is not limited to the specific
details shown and described and departures may be made from such
details without departing from the principles of the invention and
without sacrificing its chief advantages.
* * * * *