Expandable band and locking mechanism

The expandable band is used to secure a sealing element within a generally cylindrical structure, such as a pipe or manhole, or other round hole. The expandable band includes a band body having a first band end portion and a second band end portion. A plurality of slots are disposed in the first band end portion, and a locking member extends from the second band end portion. The locking member includes a tab for extending through the second band end portion and into one of the plurality of slots to lock the expandable band at the desired diameter. An end section of the second band end portion extends beyond the tab of the locking member to ease the transition between the overlapping first and second band end portions. When the band is expanded, the tab is disengaged from the slots and slides over the slots, allowing the first and second band end portions to move relative to one another. At the desired diameter, the tab engages one of the slots to lock the band at the desired diameter. The locking member is disposed on the outside region of the band with the tab extending inward such that the sealing member provides a resilient backing against the locking member.

FIELD OF THE INVENTION 
The present invention relates to expandable bands and locking mechanisms 
for such bands and more particularly, to an expandable band having slots 
at one end and a locking tab at the other end to engage one of the slots 
and lock the band at the desired diameter. 
BACKGROUND OF THE INVENTION 
Expandable bands are commonly used to secure flexible sealing elements or 
gaskets against an internal surface of a pipe, manhole, or other similar 
structure. Expandable bands typically fit against an annular surface 
within the sealing element and are expanded to apply pressure against the 
sealing element. Various types of locking mechanisms are used to lock the 
band into the expanded position against the sealing element. 
The existing bands and locking mechanisms, however, have a number of 
limitations and disadvantages. Many of the existing expandable bands are 
expandable to only one diameter and therefore have a limited overall 
expansion range. Many of these bands also require a number of steps to 
both expand and lock the band and are not capable of quickly and securely 
locking the band over a range of diameters. Moreover, the existing 
expandable bands are difficult to release or "unlock" and cannot easily be 
removed or adjusted to a smaller diameter. Other existing bands do not 
slide easily or bind being installed or adjusted. Overall, the existing 
bands are not useful with seals of various sizes that need to be installed 
in pipes or manholes having various sizes. 
Accordingly, a need exists for an expandable band that is easily installed, 
adjusted and securely locks over a range of diameters. A need also exists 
for an expandable band that is more easily released from a locking 
position. 
SUMMARY OF THE INVENTION 
The present invention features an expandable band comprising a band body 
having a first band end portion and a second band end portion. A plurality 
of slots are disposed in the first band end portion of the band body. A 
locking member is disposed on the second band end portion and includes a 
tab for extending through an aperture in the second band end portion and 
into one of the plurality of slots to lock the expandable band at a 
desired diameter. The second band end portion of the band body includes an 
end section that extends beyond the tab of the locking member. 
The first and second band end portions of the band body preferably overlap 
to form a generally annular shape with the second band end portion having 
the locking member disposed on an outside region of the band. The tab of 
the locking member preferably extends inwardly with respect to the band to 
engage one of the plurality of slots and forms an obtuse angle with 
respect to a plane tangential to the second band end portion of the band 
body. 
The preferred embodiment of the band b has a generally U-shaped 
cross-section such that the band body includes a base portion and side 
portions extending from the base portion. The plurality of slots are 
disposed in the base portion of the band body. At least part of the first 
and second band end portions also preferably have a generally U-shaped 
cross-section, and the first band end portion has a narrower width than 
the second band end portion such that the first band end portion fits 
within the U-shaped cross-section of the second band end portion. In the 
preferred embodiment, the second band end portion has the U-shaped 
cross-section on each side of the tab. 
The end section of the second band end portion also preferably has a flat 
cross-section extending from and one-piece with the section of the second 
end portion having the U-shaped cross-section. Alternatively, the second 
band end portion can include a separate extension member having the flat 
cross-section and attached to the section of the second band end portion 
having the U-shaped cross-section. 
In one embodiment, the first band end portion having the plurality of slots 
is one piece with the band body. In another embodiment, the first band end 
portion includes a separate piece attached to the band body and having the 
plurality of slots. In one embodiment, the locking member includes a 
semi-rigid strip attached to the second band end portion. 
The preferred embodiment of the expandable band further includes an 
engaging element disposed on an inside surface of the band body, for 
engaging with a band expansive mechanism. In one example, the engaging 
element includes a block attached to the inside surface of the band body. 
The present invention also features a sealing system comprising a resilient 
sealing member for sealing an internal surface of a cylindrical structure 
and one or more expandable bands.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
An expandable band 10, FIG. 1, according to the present invention, is used 
to secure a sealing element 2, such as a rubber seal or gasket, in the 
interior of a round structure 4, such as a pipe or manhole, or a round 
hole through the wall of a structure. The expandable band 10 expands 
outwardly to secure the sealing element 2 against the internal surface of 
the cylindrical structure 4. The expandable band 10 locks in the desired 
expanded position within a range of diameters, as will be described in 
detail below. Although the exemplary embodiment shows a sealing element 2 
and cylindrical structure 4, the present invention contemplates various 
other uses for the expandable band 10 with other types of structures of 
different shapes. 
The expandable band 10 generally includes a band body 12 having a first 
band end portion 14 and a second band end portion 16. The first and second 
end portions 14, 16 of the band body 12 preferably overlap to form a 
generally annular shaped band. In one example, the band body 12 has a 
generally U-shaped cross-section and is made of 304 or 316 stainless steel 
or any other suitable material. When the band is expanded, the first and 
second band end portions 14, 16 move in opposite directions as shown by 
the direction of arrows 18, 20 respectively. 
According to the preferred embodiment, a plurality of slots 22, FIG. 2, are 
stamped, milled, or otherwise disposed in the first band end portion 14. 
In one example, the slots 22 have a generally rectangular shape with a 
radius at each end and preferably have a width of about 0.125 in., a 
length of about 0.688 in. and a spacing of about 0.281 in. The present 
invention contemplates other shapes and sizes for the slots 22. 
A locking member (or latch) 24 (FIG. 1) is disposed at the second band end 
portion 16 and includes a tab 26 that extends through an aperture in the 
second band end portion 14 into one of the slots 22 to lock the expandable 
band 10 at the desired diameter. In the preferred embodiment, the second 
band end portion 16 overlaps the first band end portion 14 such that the 
tab 26 extends generally inwardly with respect to the band 10 (FIG. 1) to 
engage one of the slots 22. The second band end portion 16 also preferably 
includes an end section 28 that extends to a point beyond the tab 26 of 
the locking member 24 to ease the transition at the second end portion 14 
where the second end portion 14 overlaps the first end portion 16. 
In one embodiment, the first band end portion 14 is one piece with the band 
body 12 (FIG. 2). In another embodiment, the first band end portion 14, 
FIG. 3, is a separate piece 30 attached to the band body 12, for example, 
by welding. 
According to the exemplary embodiment, at least part of the first and 
second band end portions 14, 16, FIG. 4, also have a generally U-shaped 
cross-section. The first band end portion 14 includes a base portion 32 
and side portions 34, 36 extending from the base portion 32 to form the 
U-shaped cross section. The plurality of slots 22 are disposed in the base 
portion 32. The first band end portion 14 preferably has a narrower width 
than the second band end portion 16 such that the first band end portion 
14 fits (or nests) within the U-shaped cross-section of the second band 
end portion 16. In the embodiment of FIG. 2, the first band end portion 14 
is "necked down" from the band body 12 to form the narrower width. In the 
embodiment of FIG. 3, the separate piece 30 attached to the band body 12 
to form the first band end portion 14 has the narrower width. 
Alternatively, the present invention contemplates various types of 
cross-sections for the band body 12 and first and second band end portions 
14, 16 including, but not limited to, a C-shaped cross-section, a 
corrugated cross-section, and a flat cross-section. 
The locking member 24, FIGS. 5-7, according to the exemplary embodiment of 
the present invention, includes a semi-rigid strip 40 attached at one end 
to the second band end portion 16, for example, by welding. The tab 26 
extends from the other end of the semi-rigid strip 40 and preferably forms 
an obtuse angle a with respect to a plane 41 tangential to the second band 
end portion 16. The aperture 42 is cut out from the second band end 
portion 16 to receive the tab 26. The preferred material for the 
semi-rigid strip 40 is hard and strong like stainless steel and allows for 
a 60-90 degree bend. The semi-rigid strip 40 forming the locking mechanism 
is preferably about 0.074 in. thick, 0.5 in. wide, and 3.75 in. long. The 
present invention contemplates other suitable materials, shapes and sizes 
for the locking mechanism 24 as well as other ways of attaching the 
locking mechanism 24 to the second band end portion 16. 
The second band end portion 16 preferably has a section 44 with a U-shaped 
cross section extending just beyond the tab 26. The end section 28 of the 
second band end portion 16 extends from and is one piece with the U-shaped 
section 44 of the second band end portion 16 and preferably has a 
generally flat cross-section. Alternatively, the end section 28 (FIG. 5A) 
can be formed by a separate extension member 46 made of a semi-rigid 
material, such as the material of the band, and attached at one end to the 
second band end portion 16, for example, by welding. The separate 
extension member 46 has a cut out region 47 that receives the locking 
member 24 and forms the aperture through which the tab 26 extends. The 
extension member 46 extends beyond the tab 26 to ease the transition where 
the first and second band end portions 14, 16 overlap. 
The expandable band 10, FIG. 8, further includes an engaging element 50, 
such as a block, attached to an inside surface 52 of the band body 12. 
According to one method of use, a band expansion mechanism 54 is used to 
expand the expandable band 10. Expanding members 56, 58 of the expansion 
mechanism 54 are engaged with the engaging element 50 and an end face 60 
of the first band end portion 14 to cause the first and second band end 
portions 14, 16 to move in the direction of arrows 18, 20. The present 
invention also contemplates other types of engaging elements 50, such as a 
hole or aperture in the band body 12. The present invention further 
contemplates other types of band expansion mechanisms. 
As the band is expanded, the deformability of sealing element 2 allows the 
tab 26, FIG. 9, to be disengaged from the slots 22 in the first band end 
portion 14, allowing the first and second band end portions 14, 16 to 
easily slide relative to one another in the directions of arrows 18, 20 
without the necessity of first band end portion having to "lift" out of 
engagement with tab 26. When the desired diameter of expansion is reached, 
the tab 26, FIG. 10, will engage the slot 22a at the desired diameter, 
thereby locking the band 10 by preventing relative movement between the 
first and second band end portions 14, 16. The angle .alpha. of the tab 26 
allows the tab 26 to easily slide out of engagement with the slots 22 when 
the band 10 is expanded and facilitates locking of the tab within the slot 
22a. 
The pressure applied by the sealing element 2 against the locking member 24 
holds the tab 26 in the slot 22a. By having the locking member 24 disposed 
on an outside region of the band against sealing element 2 with the tab 26 
facing generally inwardly, the sealing element 2 provides a resilient or 
spring-loaded backing for the tab 26. This resilient backing allows the 
end portions 14, 16 of the band 10 to slide easily without binding. 
According to one method of disengaging the band, a tool 62, FIG. 8A, 
similar to a screw driver is used. A flat head 64 of the tool 62 is 
inserted into the gap 66 forward of the tab 26 (FIG. 8) and between the 
first and second band end portions 14, 16, for example, between the sides 
that form the U-shaped cross section. The tool is then pivoted generally 
in the direction of arrow 68 such that the flat head 64 lifts the inner, 
first band end portion 14 away from the outer, second band end portion 16 
until the tab is released from engagement with the slot 22a. If necessary, 
additional impact force can be applied to the tool 62, for example, with a 
hammer. 
Accordingly, the expandable band of the present invention is capable of 
expanding to and effectively locking at a wider range of diameters. The 
expandable band of the present invention also facilitates the 
disengagement of the band for removal as well as the installation and 
adjustment of the band. 
Modifications and substitutions by one of ordinary skill in the art are 
considered to be within the scope of the present invention which is not to 
be limited except by the claims which follow.