U.S. patent application number 15/091263 was filed with the patent office on 2016-08-18 for rim board connector rod.
The applicant listed for this patent is Eric W. Johnson, Gary H. Koblasz. Invention is credited to Eric W. Johnson, Gary H. Koblasz.
Application Number | 20160237674 15/091263 |
Document ID | / |
Family ID | 56620864 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160237674 |
Kind Code |
A1 |
Koblasz; Gary H. ; et
al. |
August 18, 2016 |
Rim Board Connector Rod
Abstract
A connector for connecting an add on building structure to a rim
board of an original building structure, including a connector rod
including an elongated hollow intermediate portion and smaller
breadth externally threaded extensions extending from ends of the
hollow intermediate portion. The first externally threaded
extension is a length to extend through an opening in the rim board
that aligns with an opening in the ledger board, and internally
threaded sockets are threaded onto the externally threaded
extensions at a positions straddling the rim board at one end and a
supportive member within the joists of the add on building
structure at the other end for holding add on building at a desired
distance from the rim board and preventing rotation of the
connector rod.
Inventors: |
Koblasz; Gary H.; (Roswell,
GA) ; Johnson; Eric W.; (Atlanta, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Koblasz; Gary H.
Johnson; Eric W. |
Roswell
Atlanta |
GA
GA |
US
US |
|
|
Family ID: |
56620864 |
Appl. No.: |
15/091263 |
Filed: |
April 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14643472 |
Mar 10, 2015 |
|
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|
15091263 |
|
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61995770 |
Apr 21, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04B 1/003 20130101;
E04B 5/10 20130101; F16B 5/0275 20130101 |
International
Class: |
E04B 1/00 20060101
E04B001/00; E04B 1/19 20060101 E04B001/19; E04B 1/48 20060101
E04B001/48; E04B 1/61 20060101 E04B001/61; E04B 1/58 20060101
E04B001/58 |
Claims
1. A retrofit connector bracket for supporting an add on building
structure with a ledger board to a rim board of original building
structure, including an elongate intermediate connector rod with
opposed ends, a threaded bolt extending from each end of the
connector rod of a length for extending through the rim board and
through a supportive member spanning between joists of the add on
building structure a first internally threaded socket for
surrounding the threaded bolt in a position for bearing against the
rim board of the original building structure, and a second
internally threaded socket for surrounding the threaded bolt in a
position for bearing against the supportive member spanning between
floor joists of the add on building structure a third socket for
surrounding the connector rod in a position for bearing against the
ledger board.
2. The retro fit connector of claim 1, wherein the first internally
threaded socket includes a cylinder defining a cylindrical opening,
and a disk mounted to the cylinder, the disk defining an opening in
alignment with the cylindrical opening.
3. The retrofit connector of claim 2 wherein the third socket is
flexible and includes a slot allowing the socket to expand and
enlarge its diameter.
4. The retro fit connector of claim 1 wherein the bolts are formed
of a breadth smaller than the elongate hollow intermediate
connector rod.
5. The retro fit connector of claim 1, wherein a cylindrical spacer
is mounted on the elongate hollow immediate connector rod for
fitting an enlarged opening in the ledger board.
6. A connector for connecting the joists of an add on building
structure to a rim board of an original building structure, the
connector comprising a connector rod including an elongated hollow
intermediate portion and a first externally threaded extension
extending from an end of the hollow intermediate portion, a first
externally threaded extension being of a length to extend through a
hole in the rim board that aligns with a hole in the ledger, a
second externally threaded extension being of a length to extend
through a supportive member attached to the joists of the add on
building a first internally threaded socket threaded onto the
externally threaded extension at a position for bearing against the
rim board, and a second internally threaded socket threaded onto
the externally threaded extension at a position for bearing against
the supportive member for holding the add on building at a desired
distance from the rim board.
7. The connector of claim 6, wherein a third socket is moved
laterally on the connector rod to a position to facilitate contact
between the connector rod and ledger board.
8. The connector of claim 7, wherein the first and second
internally threaded sockets are of a smaller diameter than the
elongated hollow rod.
Description
PRIORITY
[0001] This is a continuation-in-part of U.S. patent application
Ser. No. 14/643,472 filed in the U.S. Patent and Trademark Office
on Mar. 10, 2015. Applicants claim priority to U.S. Provisional
Patent Application Ser. No. 61/995,770, filed in the U.S. Patent
& Trademark Office on Apr. 21, 2014.
SUMMARY OF THE INVENTION
[0002] This invention concerns a method and apparatus for attaching
building structures together. More particularly, this invention
concerns a cantilevered connector rod with a stabilizer extension
that may be used for attaching a deck, patio, porch or other add-on
building structures to a rim board of an adjacent original building
structure. In this invention, the end of add-on building structure
opposite the original building structure is supported. And the
invention also concerns methods of attaching the connector rod
between the structures.
BACKGROUND OF THE INVENTION
[0003] A typical building structure may include a horizontal rim
board that extends about and is supported by the foundation of the
building. The floor, roof, ceiling framing, and exterior cladding
of the building are referred to herein as the "original building
structure". When a deck or other add-on building structure is to be
added to the exterior of the original building structure, the
add-on building structure may include a ledger board that is to
extend adjacent and parallel to the rim board of the original
building structure. The ledger board can be mounted to and
supported by the rim board of the original building structure. In
this arrangement, the ledger board supports the portion of the
add-on building structure that is adjacent the original building
structure.
[0004] Usually both the rim board and ledger board are formed of
wood and the connection of the ledger board of the add-on building
structure to the rim board of the original building structure is
made with dowel type connectors, typically bolts or screws. The
load from the floor of the add-on building structure is transferred
to its ledger board, then from the ledger board to the bolts of the
bracket, then from the bolts to the rim board of the original
building structure.
[0005] The exterior cladding of a typical original building
structure may include, but is not limited to brick masonry, stone
masonry, stucco, exterior insulating finishing system ("EIFS"), or
siding. The exterior cladding usually is removed from the original
building structure at the point of mounting the ledger board of the
add-on building structure to the rim board of the original building
structure, so the ledger board of the deck may be located close to
the rim board, making contact with the wall sheathing or rim
board.
[0006] In some cases, it is desirable to space the ledger board of
the add-on building structure away from the supporting original
building structure to avoid removing the adjacent exterior cladding
of the original building structure. This may be done for water
proofing reasons or to avoid supporting the exterior cladding above
the ledger board.
[0007] Usually, exterior cladding of the original building
structure is not intended to be a load carrying element, and recent
building codes have begun to explicitly address this. If the
exterior cladding is not removed and the ledger board of the add-on
building structure is separated farther from the rim board of the
original building structure to leave space for the exterior
cladding, the connector must span farther through an unsupported
gap between the two buildings. The gap may include a space or the
non-structural wall cladding. This extra length of the connector
and the gap weakens the strength of the connections between the
buildings.
[0008] A conventional "single shear" dowel type connector, or a
dowel type connector with a single failure plane, used to mount a
ledger board to a rim board of joined building structures has two
contact points, one at the rim board and the other at the ledger
board. Pivoting of the connector bracket by the load of the add-on
building applied to the connector bracket is resisted by a
non-uniform compression stress distribution between the connector
bracket and the wood of the rim and ledger boards. This potential
failure mode is known as "mode II" in the National Design
Specification for Wood Construction, as illustrated herein in FIG.
1.
[0009] When the ledger board of the add-on building structure is
attached to the rim board of an original building structure and the
boards are in contact with one another, or very close to one
another, the length of the single shear connector extending between
the rim and ledger boards is relatively short and a high shear load
from the ledger board to the rim board can be transferred through
the connector bracket.
[0010] But when the structures are separated by a wider unsupported
gap, the length of the connector bracket extending between the rim
and ledger boards must be greater and the maximum compression
stress on the wood of the structures by the single shear connector
becomes higher as the connector begins to pivot. The result is the
add-on building structure is not supported at an acceptable
level.
[0011] Prior art U.S. Patents of Jewell U.S. Pat. No. 4,953,339 and
Eldeen U.S. Pat. No. 7,254,926, and Smith Patent Application
Publication 2014/0215956 A1 disclose devices that span through a
pre-assembled structure to a rim board with an unsupported gap
there between. However, none of the known prior art could be easily
installed as a retrofit in an application where the ledger board
and framing of the add-on building structure are already assembled
and existing. Additionally, the structural mechanics of these prior
art devices are not adequately addressed or realized, including
whether each contact point is designed as: "Roller", whereby
translation is resisted in one direction but rotation is not
significantly resisted; "Pinned", whereby translation is resisted
in all directions but rotation is not significantly resisted (which
is characteristic of most conventional screwed or bolted
connection); or "Fixed", whereby translation is resisted in all
directions and rotation or moment is resisted. As a result, some
prior art devices include complex features that are not necessary
for structural purposes.
[0012] U.S. Pat. No. 7,254,926 to Eldeen discloses a connector
composed of a rod with a sleeve at the end of a rod. The nature of
the sleeve design and its use in an application with only two
contact points suggests that a fixed connection at the sleeve was
intended and realized. However, in an application where the rod has
three contact points, fixity at the sleeve connection is redundant
and unnecessary. Eldeen describes an option where the rod has a
third contact point, but apparently fails to realize that fixity at
this third contact point is unnecessary. Resisting moment at this
connection point requires the sleeve to be of thick material,
highly specialized, difficult to install, and expensive.
[0013] Additionally, Eldeen locates the third contact point on the
side of the supporting structure opposite the ledger board. This is
undesirable for several reasons. The space within the floor system
of the original building structure is typically difficult to
access. Additionally, when gravity loads are applied on the add-on
building, an uplift load is imposed on the third contact point.
This load must be transferred to the floor joists of the original
building structure. Resisting an uplift load requires there to be
an adequate amount of dead load to resist it, and the add-on
building contractor is most often not aware of the design of the
original building's floor system.
[0014] U.S. Pat. No. 4,953,339 to Jewell and U.S. Patent
Publication 2014/0215956 A1 to Smith disclose larger devices with
two contact points. The large custom size of these devices is
necessary to facilitate a fixed connection at the rim board. This
moment transfer appears to cause rotation of the rim board when
vertical loads are applied on the deck. Preventing rotation of the
rim board is dependent on the connection at the top and bottom of
the rim board, which may be existing and impossible to reasonably
verify. Additionally, the large size of these devices appears to
require significant removal of exterior cladding to install.
[0015] Eldeen, Jewell, and Smith disclose a vertical plate behind
the ledger board as a component of the connector device. These
plates serve to transfer lateral load from the ledger board through
the connector, via compression, to the rim board. Without these
plates, it appears that the ledger board could move freely into the
gap when subjected to a lateral load towards the supporting
structure. In a retrofit application, it would be difficult to
install these components without rebuilding the deck.
[0016] Thus, it is an object of this invention to provide an
improved connector to support a ledger board of an add-on building
structure on a rim board of an adjacent original building structure
that can span through an unsupported gap between the buildings.
Other objects of this invention include providing a cantilevered
connector rod with a stabilizer extension that can transfer load
about all space axes between joined buildings, can avoid or reduce
significant removal of exterior cladding, can be installed in both
retrofit and new construction applications, uses readily available
materials of readily available shapes, does not require
unconventional support of the joists attached to the ledger board,
and does not require access to the floor system of original I
building structure.
SUMMARY OF THE INVENTION
[0017] A connector and method of attaching an add-on building
structure with joists perpendicular to a ledger board to a
supporting structure are disclosed. The connector is described as a
cantilevered rod with a stabilizer extension located within the
add-on building structure that is constructed to span through an
unsupported gap between building structures and transfer loads
about all three space axes from the ledger board to the supporting
structure. The unsupported gap may consist of air or material not
designed to support a load. Typically, the material not intended to
support a load would consist of exterior cladding, including, but
not limited to, siding, stucco, exterior insulating finishing
system (EIFS), or masonry veneer.
[0018] The cantilevered rod is used for mounting through openings
in a rim board of an original building structure and openings in a
ledger board of an adjacent add-on building structure, so that the
facing portion of the add-on building structure is supported by the
original building structure. The stabilizer extension maintains the
bracket in its desired attitude, usually in a horizontal
attitude.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is an example of a single shear failure mode II from
National Design Specification for Wood Construction. (Prior
art.)
[0020] FIG. 2 is a side cross sectional view of the adjacent
portions of an original building structure and an add-on building
structure, such as a deck, joined by the cantilevered connector rod
with the stabilizer extension and a plate-insert assembly at the
end of the road at the rim board
[0021] FIG. 3 is an expanded view of the plate-insert socket
assembly of FIG. 2
[0022] FIG. 4 is an expanded view of the both ends of the connector
rod of FIG. 2
[0023] FIG. 5 is an expanded view of the spacer assembly of FIG.
2
[0024] FIG. 6 is a side cross sectional view of the adjacent
portions of an original building structure and an add-on building
structure, such as a deck, joined by the cantilevered connector rod
with a bolt at the end of the rod at the rim board (not a
plate-insert assembly)
[0025] FIG. 7 is a side cross sectional view of the adjacent
portions of an original building structure and an add-on building
structure, such as a deck, joined by the cantilevered connector rod
with a screw at the end of the rod at the rim board (not a
plate-insert assembly)
[0026] FIG. 8 is an expanded view of the connector rod of FIG. 2
with the spacer assembly
DETAILED DESCRIPTION
[0027] FIG. 2 illustrates an original building structure 28 and an
add-on building structure 29 that is to be connected to the
original building structure. A cantilevered connector rod 9
connects the original building structure to the add-on building
structure.
[0028] A conventional original building structure may include
parallel floor joists 14, rim board 13, and flooring 21 mounted on
a foundation wall 18. A sheathing 19, such as plywood or OSB, may
be applied to the stud wall 28 of the building structure, and an
exterior cladding 8 such as a brick veneer may be applied to the
original building structure, usually with an internal air space 7
formed between the exterior cladding and the stud walls and the
other exterior wall covering. Rim board 13 surrounds most of the
original building structure and is supported by the foundation wall
18. The rim board 13 supports parts of the building structure above
the lower foundation wall in the conventional structure.
[0029] The add-on building structure 29, that may be in the form of
a conventional outdoor deck, is positioned adjacent the outdoor
cladding of the original building structure, such as the brick
veneer 8. The add-on building structure includes a ledger board 11
that is placed parallel to the rim board 13 of the original
building structure, and parallel joists 3 are mounted to the ledger
board with conventional joist hangers 10. Flooring 20 is supported
by the joists 3, in the usual manner.
[0030] The connector rod 9 is used to support the add-on building
structure 29 and attach it to the rim board 13. The connector rod 9
includes a cantilevered portion 30 and a back span or stabilizer
extension 31. Multiple connector rods may be used to attach the
add-on building structure. The connector rods are located between
floor joists 3 of the add on. The spacing between the connector
rods is primarily based on the span of the joists 3 and the
associated loads at the ledger 11, the length of the cantilever and
the length of the stabilizer extension 31.
[0031] As shown in FIG. 4, the connector rods 9 may be comprised of
a hollow pipe made of steel or aluminum. Preferably the rod is
comprised of 11/4'' Schedule 40 steel pipe, which has an outer
diameter of 1.66'' and a wall thickness of 0.14''. This diameter
and wall thickness is selected based on a rod spacing of
approximately 2'-0'', assuming a 15'-0'' floor joist span and the
associated structural demand to cantilever approximately 6''
through a gap composed of brick veneer while having 14'' stabilizer
extension.
[0032] FIG. 4 illustrates an expanded view of one end of the
connector rod 9. A bolt 25 with external spiral threads 77 has its
head 73 inserted into the end of the rod 9. Preferably the bolt has
a diameter of 3/4'' making the inside face 71 of the pipe in close
contact with a standard hexagonal head 12 of the 3/4'' diameter
bolt. The bolt head 12 is welded at 72 and 73 to the inside face 71
of the rod. The weld 73 may be a continuous butt weld made around
the circumference of the rod 9. This single plane weld may not
alone provide significant resistance to bolt rotation within the
pipe 70. Therefore, six equally spaced holes are drilled around the
circumference of the pipe 70 aligning with the external points of
the hexagonal head 12 of the bolt 25. A plug weld 72 is made in
each of these holes creating an additional plane of welds.
[0033] The connector rod 9 includes a cantilevered portion and a
stabilizer extension portion 31. Preferably the stabilizer
extension portion is at least 12 inches long. However, the
stabilizer extension may be shortened if desired, thereby
increasing rod shear forces, increasing rod bearing forces, and
decreasing rod deflection, or lengthened if desired, thereby
decreasing rod shear forces, decreasing rod bearing forces, and
increasing rod deflection.
[0034] The stabilizer extension portion 31 of the connector rod
extends through a supportive or "blocking" structure 5 that is
displaced from the rim board and ledger board, out between adjacent
joists of the add-on building structure 29. The supportive
structure 5 can be wood blocking, such as 2.times.8 lumber, mounted
at its ends to adjacent joists 3 with conventional framing clips 4.
The blocking 5 includes an opening with the bolt 1 extending
through the opening and attached thereto with a suitable nut.
[0035] The supportive structure 5 at the stabilizer end of the
connector rod maintains the connector rod 9 at a fixed height. This
tends to avoid any pivoting movement of the connector rod 9. It is
of importance to calculate the load imposed on the joists 3 by the
blocking 5. This load can be determined by first solving for the
load at the rim board 13 (considering a free body diagram of the
add-on building) and then by solving for the loads at the ledger 11
and blocking 5 (considering a free body diagram of the connector
rod 9). Given that the stabilizer extension 31 is located on the
side of the add-on building structure 29, this load is a downward
force when a gravity loads are applied on the deck. This downward
force must be considered in the design of the floor joists 3 and
floor joist hangers 10.
[0036] FIG. 3 illustrates an expanded view of the plate-insert
assembly 26. A hollow cylindrical steel insert 50 includes internal
spiral threads 51 that match and engage the spiral threads of the
bolt 25. The length of the insert is preferable 2 inches, or a
length sufficient to create a moment resistant connection between
the bolt 25 and the insert 50. This insert 50 is welded to a round
steel plate 52, preferably 5 inches diameter with a thickness of
1/4 inch. At least four holes 53 are spaced about the perimeter of
the plate are made for passage of four wood 1/4'' diameter screws
27 that are to be driven into the rim board 13. Compared to a
scenario in which the end of the bolt 25 has a conventional
washer/nut as shown in FIG. 6, this plate-insert assembly can
resist moment or rotation.
[0037] Resisting rotation is beneficial at this connection point
for two reasons. It decreases deflection of the rod (a failure mode
determined to be a controlling factor based on testing and
analysis), and it creates a stable condition without the stabilizer
extension 31 attached to blocking 5. In a new constriction
application, wherein the add-on building has not yet been built and
floor joists are not installed prior to the ledger being installed,
a moment resistant connection at this location here eliminates the
need for temporary shoring. It should be noted that this applied
moment on the rim board is less during construction (under a
typical 20 pounds per square foot construction live load compared
to service conditions (under a typical 40 PSF live load).
[0038] The plate-insert assembly 26 of FIG. 3 could also be
installed in a mirrored position about the rim board 13, wherein
the screws 27 are driven from within the original building floor
system. This would be beneficial in a retrofit application where
the exterior cladding 8 is already installed.
[0039] As shown in FIG. 2, in order to avoid load being transferred
from the rod 9 to the exterior cladding 8 (when loads are applied
to the add-on building structure 29 and the rod 9 deflects) the
hole in the exterior cladding 8 would ideally be made of larger
breadth than the breadth of the connector rod 9. However, if the
add-on building and original building already exist, it would be
difficult to only over-drill the hole in the exterior cladding 8,
without also over-drilling the holes in the ledger board 11.
[0040] As shown in FIG. 5, the spacer assembly 17 provides a means
to over-drill the hole through the ledger board and exterior
cladding, while facilitating contact between the connector rod 9
and ledger 11.
[0041] In most deck applications the connector rod 9 would be hot
dipped galvanized steel. This zinc coating can be damaged and
removed, thereby exposing the bare steel and increasing risk of
corrosion. For this reason the spacer assembly 17 would is made of
a polymer sufficiently soft to avoid damaging the zinc coating on
the rod 9, ideally this polymer would be polyvinyl chloride
(PVC).
[0042] As shown in FIG. 5, the spacer 17 is in the form of a
cylinder 200 and a flange 130 that together form a slot 133 that
extends along the cylinder to enable the spacer to open and
surround the connector rod 9 and form an increase in outside
diameter along the portion 130 of the threaded end of the of the
connector rod 9. When the spacer is installed around the connector
rod 9, the installer could push the spacer too far into the hole
drilled in the ledger 11. This increase in outer diameter of the
plate 52 prevents an installer from rotating the spacer 17 too far
into the ledger 11. The entire spacer assembly could be injection
molded or the main shaft 200 could be made of 1/2 inch Schedule 40
PCV and the lip 130 could be made from 2 inch Schedule 40 PVC
adhered to shaft 200. 1/2 inch Schedule 40 PCV has wall thickness
of 0.145''. When snuggly fitting surrounding a 1.66'' OD 11/4''
Schedule 40 connector rod, total outside diameter of the PVC spacer
is 1.95 inch, making a standard 2 inch diameter hole saw bit
acceptable for creating the hole in the ledger 11.
[0043] The gap between the connector rod 9 and the ledger board 11
eventually gets filled with spacer assembly 17. But before the
spacer assembly is pushed into place, an impermeable material, such
as caulk or silicon, is injected between the rod 9 and exterior
cladding 8 to prevent leakage of air or water into the interior of
the original building structure.
[0044] FIG. 6 illustrates an optional installation where the end of
the connector rod does not include the plate-insert assembly.
Instead, a conventional nut and washer is installed on the end of
the bolt 93. FIG. 6 would be used in a retrofit application, where
the entire add-on building structure is already installed, and also
in municipalities where building officials do not allow screws to
attach ledger boards to rim boards.
[0045] FIG. 7 illustrates an optional installation where the end of
the connector rod does not include the plate-insert assembly.
Instead, a wood lag screw 112 with external spiral threads 113 and
a hexagonal head 110 is inserted and welded into the end of the
connector rod 9, similar to the application of FIG. 4. FIG. 6 would
be used in a retrofit application, where the entire add-on building
structure is already installed, and also in municipalities where
building officials do allow screws to attach ledger boards to rim
boards.
[0046] FIG. 8 illustrates the connector rod 9 composed of 1% inch
Schedule 40 pipe. The PVC spacer assembly 200 includes a sleeve and
a rim 130. The sleeve 200 is free to slide along the rod 9. The
slot 133 allows the spacer assembly to expand and fit snuggly
around the connector rod 9. After the rod is installed in a
building structure, the PVC spacer assembly 200 is moved with the
installer's hands or with a hammer a small hammer if required) in
the hole drilled in the ledger 11 until the flange 130 prevents it
from moving any further.
[0047] As shown in FIG. 4, the diameter of the bolt 12 of the
connector rod 9 is less than the connector rod 9. The connector rod
9 should have a large diameter to cantilever through the brick 8.
The maximum moment occurs at the ledger 11 and decreases linearly
closer to the ends of the rod. Therefore, the structural demand of
the rod 9 at its ends is less than at its center. The smaller bolt
12 require only smaller nuts/washers and are therefore less
expensive (compared to a scenario in which the outer surface of the
connector rod is threaded). Additionally, the surface at the end of
the rod 9 with the weld 73 bears against the rim board 13 at one
end and blocking 5 at the opposite end. This enables the user to
tighten a nut 92 on the opposite side of the rim board as shown in
FIG. 6 and a nut 2 on the opposite side of the blocking. The rod is
prevented from passing through the rim board and blocking because
of the difference in outer diameter of the rod 9 and the bolts 25
and 1.
[0048] While the expressions "rim board" and "ledger board" have
been used to describe the structural features of the connection
points of the add-on building structures and original building
structures, these expressions are to include other supporting
structures that are suitable for connection together by the
inventions disclosed herein.
[0049] Although preferred embodiments of the invention have been
disclosed in detail herein, it will be obvious to those skilled in
the art that variations and modifications of the disclosed
embodiments can be made without departing from the spirit and scope
of the invention as set forth in the following claims.
* * * * *