Door seal

A door seal has a base portion comprising straight sections joined at their ends to form corner joints with another section, at least four first seal sections each of which are disposed at a respective one of the corner joints, and a plurality of second seal portions each having a length that extends between a spaced pair of the first seal sections. The first seal sections comprise a pair of spaced lip seals, whereas the second seal sections comprise a lip seal and a compression seal. The seal avoids the problem of undesirable compression seal distortion at the corners joints.

TECHNICAL FIELD 
This invention relates generally to a seal for sealing around the perimeter 
of a door, and more particularly to such a seal having lip and compression 
seal components. 
BACKGROUND ART 
There has been a long-felt need for an effective and durable seal around 
the rear doors of a semitrailer. In the course of transporting cargo over 
long distances, semitrailers are exposed to severe weather and other 
environmental conditions that cause deterioration of door seals. The 
semitrailers are also prone to the buildup of dirt and road salt, 
resulting in abrasive wear of the seals, and are constantly subjected to 
door frame movement, or racking, that causes movement between the door 
seals and adjoining surfaces. Heretofore, semitrailer door seals have 
typically been lip-type seals formed of polyvinyl chloride or similar 
thermoplastic material. 
In an attempt to provide better seals, some arrangements have proposed the 
use of a compression seal in addition to a lip seal. For example, U.S. 
Pat. No. 5,107,622 issued Apr. 28, 1992 to Fuchs et al describes a door 
seal assembly that has two elements. The outer element is a double lip 
seal, whereas the inner element, in one embodiment, is a compression seal. 
Compression seals provide a biased seal against an adjacent opposed surface 
that is generally better, and tighter, than that provided by a lip seal. 
However, because of their inherent construction, compression seals tend to 
be undesirably displaced, or distorted, at their corners when the door 
they are sealing is closed. The excessive distortion of the compression 
seal at the corners leads to early failure of the seal, requiring 
replacement. 
The present invention is directed to overcoming the above problems. It is 
desirable to have a door seal that has a lip seal that overlays adjoining 
outer surfaces, and a compression seal that is compressed against an 
adjacent opposed surface. Furthermore, it is desirable to have such a seal 
that avoids the problem of undesirable compression seal distortion at the 
seal corners. It is also desirable to have such a seal that is formed of a 
abrasion- and weather-resistant, long wearing elastomeric material. 
SUMMARY OF THE INVENTION 
In accordance with one aspect of the present invention, a seal for sealing 
the perimeter of a door having at least four edge surfaces, includes a 
base portion consisting of at least four straight sections each having a 
length corresponding with a respective one of the door edges. Each one of 
the straight base portions are joined at their respective ends to another 
one of the sections to form a corner joint. The seal also includes at 
least four first seal sections, one of each being disposed at a respective 
one of the corner joints of the base portion. Each one of the first seal 
sections have a pair of lip seals extending outwardly from the base 
portion and spaced from each other. The first of the pair of lip seals 
overlays a starface adjacent and aligned with the outside surface of the 
door when the door is in the closed position, and the second lip seal of 
the pair abuts an opposed surface spaced from, and generally parallel 
with, a respective edge surface of the door when the door is in the closed 
position. The seal also includes a plurality of second seal sections each 
having a length that extends between a spaced pair of the first seal 
sections with one of the second seal sections being disposed along at 
least three of the straight sections of the base portion. Each of the 
second seal sections have a lip seal that overlays an adjacent surface 
planarly aligned with the outer surface of the door when the door is in 
the closed position, and a compression seal having a deformable wall that 
defines, in cooperation with the base portion, a hollow chamber that 
extends the length of each second seal section. 
Other features of the seal embodying the present invention, include the 
first seal section having a length that is greater than the height of the 
compression seal, and less than the width of the base portion.

BEST MODE FOR CARRYING OUT THE INVENTION 
A seal 10 embodying the present invention is shown in the drawings with 
particular application to sealing the rear doors 12 of a semitrailer 14. 
Such doors are generally rectangular and open 270.degree. to provide full 
access to the interior of the semitrailer. As best shown in FIG. 3, each 
of the doors 12 have a top edge surface 16 and a bottom edge surface 18. 
In a similar manner, as shown in FIG. 2, each of the doors 12 have left 
and right side edge surfaces 20, 22 that extend between the top and bottom 
edge surfaces 16, 20. Also, each of the doors 12 have an inside surface 24 
facing the enclosed interior of the semitrailer 14 when the door 12 is at 
a closed position, as shown in FIG. 1, and an outside surface 26 facing 
away from the enclosed interior when the door is at the closed position. 
A seal retainer 28 extends completely along, and is removably attached to, 
each of the edge surfaces 16, 18, 20, 22. The seal retainer 28 is 
preferably an H-shaped extruded aluminum channel having an interior width 
substantially equal to the thickness of the door 12, a relatively longer 
pair of legs extending over the inner and outer surfaces 24, 26 of the 
door 12, and a shorter pair of legs extending outwardly from the 
respective edge surface of the door with an inwardly extending flange 30 
disposed at each end. Optionally, the seal retainer 28 may have a 
protective shroud 32, as shown in dashed lines at the right seal member in 
FIG. 2, that extends outwardly from the external short leg of the retainer 
28 and covers the seal 10. 
As best illustrated in FIGS. 4 and 5, the seal 10 embodying the present 
invention, has a base portion 34 having a width equal to the interior 
width of the seal retainer 28 and a pair of opposed notches 36 that, when 
installed in the seal retainer 28, receive the inwardly extending flanges 
30 of the retainer 28. The base portion 34 of the seal 10 comprises four 
straight sections each having a length that is substantially equal to the 
length of a respective one of the door edge surfaces 16, 18, 20, 22. Each 
section is joined perpendicularly at each of its ends with another one of 
the sections to form four right angle corner joints at the joined ends of 
the straight sections. Thus, the base portion 34, when viewed on edge, has 
a rectangular shape comprising four straight sides intersecting at four 
corners. 
The seal 10 embodying the present invention has four first seal sections 
38, the cross section of which is shown in FIG. 5. The four first seal 
sections 38 are respectively disposed at the four right angle corner 
joints of the base portion 34 and, in that they extend only a relatively 
short distance along each of the straight sections of the base portion 34, 
are spaced apart from each other. Preferably, the length of each of the 
first seal sections 38, as measured along the base portion 34, is less 
than its width. Each of the first seal sections 38 has a first lip seal 40 
that extends outwardly from the base portion 34. When the door 12 on which 
it is mounted is closed, the first lip seal 40 overlays a surface 42 of 
the semitrailer 14 that is adjacent to the respective door 12 and 
substantially aligned in a plane parallel with the outer surface 26 of the 
door 12. Each of the four first seal sections 38 also has a second lip 
seal 44 that extends outwardly from the base portion 34 in spaced 
relationship with the first lip seal 40 and is deformed by, and thereby 
biasedly abuts, an opposed surface 46, either of the semitrailer 14 or 
other structure, when the door 12 on which it is mounted is closed. 
The seal 10 also includes a plurality of second seal sections 48 each 
having a cross section as shown in FIG. 4, and a length that extends 
between a spaced pair of the first seal sections 38. In a single door 
system, and on at least one door 12 of a double door system, one of the 
second seal sections 48 is desirably disposed along each of the four 
straight sections 16, 18, 20, 22 of the base portion 34. Each of the 
second seals sections 48 have a lip seal 50 that extends outwardly from 
the base portion 34 and overlays the surface 42 that, as described above, 
is adjacent and planarly aligned with the outer surface 26 of door 12. 
Importantly, the second seal section 48 also has a compression seal 52 that 
is spaced from the lip seal 50. The compression seal 52 has a U-shaped 
deformable wall 54 that is connected at each end of the U to the base 
portion 34 and there forms, in cooperation with the base portion 34, a 
hollow chamber 56 that extends the entire length of the second seal 
sections 48. When the door 12 on which the seal 10 is mounted is closed, 
the compression seal 52 is deformed as shown in FIGS. 2 and 3, so that it 
biasedly abuts the respective opposed surface 46, and provides a tight, 
water and dust resistant seal around the door 12. 
In a double door system, as illustrated in FIGS. 1 and 2, one of the doors 
12, for example the left hand door 12, has a second seal section 48 
disposed on only the top edge surface 16, the bottom edge surface 18, and 
the left side edge surface 20. The section of the seal 10 extending along 
the right edge surface 22 of the left door 12 has only a lip seal 58. The 
compression seal along this section is omitted to avoid interference with 
the compression seal 52 on the left hand edge surface 20 of the right door 
12. In this arrangement, the left door 12 is closed first, and then the 
right door 12 is closed. At the center, i.e., the joint between the two 
doors, the lip seals 58 and 50 on the respective left and right doors 12 
cooperate to provide covering protection for the compression seal 52 which 
biasedly abuts, and is deformed by contact with, the base portion 34 of 
the left door seal 10. The outer periphery of the double doors 12 is also 
sealed by the compression seal 52 which extends along each of the straight 
sections of the base portion 34 along the top and bottom edge surfaces 16, 
18, and along the respective outer side edge surfaces 20, 22 of the left 
and right doors 12. 
In an illustrative embodiment of the present invention, a seal 10 is 
described that is suitable for use on a door having a thickness of about 
2.1 cm (0.825 in). Preferably, the seal 10 is formed of EPDM rubber as 
described below in greater detail. In the illustrative example, deformable 
wall 54 of the compression seal 52 has a thickness of 0.20 cm (0.08 in) 
and a height of 1.5 cm (0.590 in) as measured from the exterior surface of 
the base portion 34, i.e., the surface facing away from the door edge 
surface, to the outermost extending surface of the deformable wall 54. 
When the door 12 is in the closed position, the height of the compression 
seal 52 is desirably compressed against the respective opposed surface 46 
to a height of about 1.11 cm (0.438 in), or to about 75% of its 
unrestrained height. The compression seal 52 in the center area between 
the two doors, i.e., between the side edge surface 22 of the left door 12, 
and the side edge surface 20 of the right door, is desirably compressed to 
a height of about 1.27 cm (0.50 in), or to about 85% of its free height, 
when the doors are closed. 
An important feature of the present invention is the relief provided 
against excessive deformation of the compression seal 52 at the corners of 
the doors 12. The compression seal 52, provides a pressure-biased seal 
along the straight edges of the door 12, but does not extend into the 
corners where it would be disadvantageously distorted upon closure of the 
door 12. At each corner, the first seal section 38 of the seal 10 has two 
readily displaceable lip seals 40, 44. Furthermore, sealing is optimized, 
and seal distortion minimized, by controlling the length of each first 
seal section 38 between desirable minimum and maximum values. To assure an 
adequate length of compression seal 52 along the side surfaces, the length 
of each first seal section 38, as measured along the base portion 34 from 
each corner joint, should be not longer than the width of the base portion 
34. In the illustrative example, the width of the base portion 34 is 2.08 
cm (0.820 in). To prevent "corner bunching" and excess deformation of the 
compression seal 52, the seal should not extend any closer to the corner 
than its free height which, in the illustrative embodiment described 
herein, is 1.50 cm (0.59 in). Thus, in the described example, the length 
of each of the first seal sections 38, as measured along each of the base 
portions 34 from their corner juncture, should be no less than 1.50 cm 
(0.590 in), and not greater than 2.08 cm (0.820 in). In the actual 
construction of the seal 10 described above, the length of each of the 
first sections 38 is about 1.9 cm (0.75 in). 
The above dimensions are presented herein as examples representative of the 
preferred embodiment of the present invention. The values are based on a 
seal 10 formed of a thermoset elastomer such as ethylene propylene with an 
added diene monomer (EPDM rubber) having a shore A hardness of about 60 
durometer. This material is preferred because of its excellent resistance 
to wear and abrasion, long life, weatherability, low compression set, and 
retention of flexibility over a wide temperature range. These 
characteristics provide a superior seal, particulary during racking, or 
shifting non-parallel movement, of the rear frame of the semitrailer. 
Other materials, and other hardness values, may require more or less 
allowance in the length of the first seal sections 38 to avoid corner 
distortion of the compression seal 52. 
Preferably, the seal 10 is formed of extruded EPDM rubber having a cross 
section corresponding to that of the second seal section 48. The 
extrusions are cut to desired lengths corresponding to the length of a 
selected door edge surface minus the length of the first seal section 38 
at each end of the edge surface. The ends of two cut-to-length second seal 
sections 48 are then placed in a right angle mold having a cavity 
corresponding to the preselected shape and dimensions of the first seal 
section 38. The mold cavity is then injected with an uncured liquid, but 
highly viscous, EPDM rubber compound. The injected material is maintained 
in the mold until it has cured and bonded to the respective ends of the 
second seal section 48. This operation is carried out, either 
simultaneously or sequentially, at each of the corner joints. Upon 
completion of mold forming a first seal section 38 at each of the four 
corners, the seal 10 is removed from the molds whereupon it has the shape 
of a continuous rectangular member with four straight sides corresponding 
in length with the four sides of the door on which the seal 10 is to be 
mounted. 
Another method of forming the seal 10, although less desirable than that 
described above, is to make 45.degree. miter cuts at each end of straight 
sections of extruded seal, each having a length corresponding to the full 
length of a corresponding edge of a door. The mitered ends are then joined 
together by a suitable bonding method to form a rectangular structure 
having both compression and lip seals extending completely around the 
structure. The corner portions are then formed by cutting away a portion 
of the deformable wall 54 at each corner to form the second lip seal 44 of 
the first seal sections 38. 
Alternatively, the seal 10 may be formed by premolding the first seal 
sections 38 and then bonding them to the respective ends of the second 
seal section 48. However, the earlier described process is preferred over 
the later described methods because of the better bond achieved between 
the first and second seal sections 38, 48 during in-mold curing of the 
first seal section 38. 
The seal 10 is secured in the seal retainer 28 by inserting one of the 
flanges 30 of the retainer 28 in a respective one of the notches 38 formed 
in the base portion 34. The base portion 34 is then deformed, preferably 
by an appropriate tool, to engage the opposite flange 30 into the notch 38 
on the opposite side of the base portion 34. If it is desired to remove 
the seal 10, the installation procedure is simply reversed. An important 
feature of the seal 10 embodying the present invention is that if the seal 
10 should become torn or damaged, it can be replaced without removing the 
retainer 28 or other hardware from the door. This replaceability advantage 
avoids disturbing the factory seal between the retainer and door. 
While the seal 10 embodying the present invention has been described is 
association with the rear doors of a semitrailer, it should be realized 
that the seal 10 is suitable for use on doors in other fields of 
application and use, with corresponding appropriate changes in dimension 
and material. Also, while described in association with a rectangular 
door, the seal 10 embodying the present invention is adaptable for use in 
doors of other geometric shapes having more or less than four side surface 
edges. 
INDUSTRIAL APPLICABILITY 
The seal 10 embodying the present invention is particularly useful for 
sealing around the perimeter of the rear doors of a semitrailer. The seal 
10 provides a tight weatherproof, wear resistant, long life seal that is 
not disadvantageously deformed at the door corners when the door is 
closed. 
The seal 10 embodying the present invention has a lip seal that overlays 
the surface of the semitrailer that is adjacent and planarly aligned with 
the outer surface of the door when the door is closed. Furthermore, the 
seal 10 provides a compression seal between each edge of the door and an 
opposed surface adjacent the door to prevent the intrusion of foreign 
matter into the interior of the semitrailer when the doors are closed. 
Other aspects, features and advantages of the present invention can be 
obtained from a study of this disclosure together with the appended 
claims.