Elastomeric sectional strip for expansion joints

An elastomeric sectional strip, for sealing an expansion joint on a building. Each edge of the strip is thickened for engagement in a corresponding one of a pair of grooves bordering the joint edges and is characterized by a three-point mounting of its thickened edge region inside each of said grooves. Each three point mounting is constituted by: PA0 (a) a bulge on an upper side of the edge region, in which case said bulge is located inside said groove adjacent its opening; PA0 (b) a shoulder projecting in the form of a wedge into said groove in the opposite direction to the insertion direction on an underside of said edge region, in which case after complete insertion, said shoulder bears against a corresponding stop face of the groove and PA0 (c) a camber on said upper side of said edge region close to its outer end.

FIELD OF THE INVENTION 
The invention relates to an elastomeric sectional strip for sealing 
expansion joints on buildings, the edges of which strip are respectively 
thickened for connection in corresponding grooves in the edges of the 
joint. 
Sectional strips of this type are known with varied constructions. They are 
distinguished inter alia as regards their folding principle, the method of 
attachment, the materials used or the like. For their construction, for 
example the area of use is an essential influence. A sectional strip in 
expansion joints of public roads is clearly subject to quite different 
requirements to a sectional strip provided for sealing expansion joints in 
building construction. 
DESCRIPTION OF THE PRIOR ART 
A known sectional strip for expansion joints (Swiss Patent Specification 
No. 520 823) comprises attachment edges constructed as a hollow profile. 
The hollow profiles fold together in a satisfactory manner, but are 
difficult to insert and inadequately prevented from being torn out. 
In another known sectional strip for sealing expansion joints (German GM 
No. 6 605 223), the attachment edges are provided with barb-like 
projections, which spread out in a groove cavity adjacent the edge of the 
joint. Sectional strips of this type can only be mounted with difficulty 
and in particular on account of the related work of squeezing and 
deformation. This work is frequently made more difficult due to the fact 
that in narrow joints, the lateral grooves for receiving the attachment 
edges of the sectional strips are not easily accessible. 
In another known sectional strip (German OS No. 30 47 904), for 
facilitating the assembly, cleats which can be bent back are formed on the 
free ends of the attachment edges. When the attachment edges are inserted 
in the corresponding grooves, these cleats bear against the sectional 
strip in the region of the attachment edges and after complete insertion 
they spread out against support surfaces constructed on corresponding 
cavity extensions of the attachment grooves. On the other hand, the 
aforementioned cleats prevent a desirable thickening of the attachment 
edges. 
Finally, sectional strips also exist (U.S. Pat. No. 3,888,599) in which the 
edge thickening is squeezed into the corresponding attachment groove by 
utilizing the elasticity of a solid rubber part. In this case also, 
assembly is made more difficult and there is little to prevent tearing 
out. 
It is the object of the present invention to provide a sectional strip with 
increased protection against tensile stress, which can be assembled with 
little expenditure, but nevertheless has a simple profile which is 
particularly advantageous for the extrusion method. 
BRIEF STATEMENT OF THE INVENTION 
This object is achieved according to the invention on a sectional strip of 
the aforementioned type due to the fact that 
(a) a bulge on the upper side of the edge region, in which case the bulge 
is located inside the groove adjacent to its opening, 
(b) a shoulder on the underside of the edge region projecting in the form 
of a wedge into the groove in the opposite direction to the insertion 
direction (F1), in which case after the complete insertion, the shoulder 
is supported against a corresponding stop face in the groove and 
(c) a camber on the upper side of the edge region on or close to its outer 
end. 
According to feature (a) the upper bulge serves as an abutment and as a 
sealing lip, i.e. when the edge region is inserted completely in the 
attachment groove, the bulge is located within the groove, where it is 
pressed with a sealing effect against the adjacent inner wall. 
Furthermore, the bulges on both sides may contribute to facilitating 
fitting due to the fact that they form shoulders for fitting tools (FIG. 
4). 
The projection present on the underside serves for limiting the insertion 
travel when fitting the sectional strip. In this way, exact limiting of 
the depth of the groove is not necessary. 
According to feature (b), the wedge-shaped shoulder projecting downwards 
serves for preventing the edge region of the sectional strip from being 
drawn out of the corresponding attachment groove. In conjunction with 
features (a) and (c) it is sufficient to construct this shoulder in a 
relatively weak manner, so that the deformation work at the time of 
fitting is slight. The wedge shape of the shoulder facilitates 
installation. When the edge region is completely inserted, a support face 
of the shoulder pointing towards the expansion joint comes to bear against 
a corresponding stop face of the groove, constructed as an inner extension 
of the groove. 
The interaction of features (a), (b) and (c) occurs so that in the final 
fitted position, the camber provided towards the upper side of the 
sectional strip, on the outer end of the edge region, abuts against the 
adjacent groove wall to such an extent that the outer edge region is 
deflected as a whole away from the groove wall, which one could also 
describe as a type of pitching motion of the outer edge region of the 
sectional strip. As a result of the aforedescribed deflection of the outer 
edge region, produced with corresponding material deformation, the 
wedge-shaped shoulder on its underside is pressed in an increased manner 
behind the corresponding stop face of the groove in the direction 
increasing the stop effect. 
In this case, the bulge on the upper side of the sectional strip (sealing 
lip) acts as an abutment for the deflection of the outer edge region. The 
fitted condition is thus characterised by a braced three point mounting 
between the support points of the camber, bulge and wedge-shaped shoulder 
(FIG. 3). 
The concave fillet present on the opposite side of the camber or a 
corresponding concave shape of the outer edge region is necessary in order 
to deflect the latter in a corresponding manner into the attachment groove 
at the beginning of insertion, which takes place in a particularly 
advantageous manner with the assistance of a fitting tool. Furthermore, 
despite the head-like thickening of the outer edge region, the hollow 
fillet allows its unforced introduction through the narrowed outer groove 
section and serves as a stop face for the sectional strip, when it is 
placed in the joint gap (FIG. 4). 
Naturally, within the framework of the invention, a certain construction of 
the attachment groove, adapted to the sectional strip, in particular to 
its edge region, is essential. For this purpose the invention proposes 
that the grooves each have a hollow cross-section adapted to the 
cross-sectional shape of the thickened edge regions, but which does not 
comprise the upper camber of the sectional strip and the height of which 
is less in the inlet region than the sectional thickness of the edge 
region, measured through the lower shoulder.

DESCRIPTION OF A PREFERRED EMBODIMENT 
The assembly is illustrated in three stages in FIGS. 1 to 3, in which case 
the sectional strip itself is shown solely in each case as a partial 
cross-section, namely in FIG. 1 as a half section and in FIGS. 2 and 3 
solely a cross-section through the edge region is shown. On the other 
hand, FIG. 4 shows the two joint edges 3, 4 limiting an expansion joint 2 
and between the latter the complete sectional strip 1 in the initial 
position for assembly. 
In the embodiment chosen in this case, the joint edges 3,4 are illustrated 
substantially as U-profiles, the sides of which define a groove 5 for 
receiving an edge region 6 of a sectional strip 1. The groove 5 has a 
narrowed inlet cross-section or on the inside an enlarged groove cavity 
15, which is limited inter alia by an inwardly pointing stop face 7 of the 
lower side of the U-shaped profile. 
Each edge region of the sectional strip 1 comprises a bulge 8 on the upper 
side and a camber 9 at the outer end of the edge region 6. On the 
underside, the edge region 6 comprises a projection 10 approximately 
opposite the said bulge 8, as well as a wedge-shaped shoulder 11. Opposite 
the camber 9, the underside of the profile comprises a hollow fillet 12. 
Moreover, in the edge region 6, the profile cross-section is somewhat 
thicker than in the remaining cross-sectional region of the sectional 
strip 1. The axis a extends vertically through the central bend 13 of the 
sectional strip 1. 
According to FIG. 2, the edge section 6 has been inserted into the inside 
of the groove 5 by only approximately half. As will be seen in this figure 
the height of groove 5 in its inlet region is less than the thickness of 
the end portion of the sectional strip 1 measured through its shoulder 11. 
In the region of the narrowed inlet cross-section, the wedge-shaped 
shoulder 11 provided on the underside of the strip bears against the 
underside of the sectional strip at the time of insertion in the direction 
of arrow F1. The insertion may take place by means of a tool fitted on the 
bulge 8 in the direction of arrow F1 and which is not itself illustrated. 
According to FIG. 3, the edge region 6 has been completely inserted in the 
groove 5. The bulge 8 thus bears against the associated wall of the groove 
5. The bulge 8 forms the abutment and a sealing lip to prevent the 
penetration of water. The groove cavity 15 has dimensions such that when 
the edge region 6 is completely inserted, the camber 9 is deflected 
downwards by the wall of the groove, thus the wedge-shaped shoulder 11 is 
pressed firmly against the stop face 7 of the groove cavity 15. The lower 
projection 10 to a certain extent forms a stop to prevent the edge region 
6 from being pushed too far into the groove 5. An equalization space 14 
for equalizing tolerance variations is produced on the upper side of the 
completely inserted edge region 6. The position of the camber 9 and of the 
bulge 8 relative to the wedge-shaped shoulder 11 is characterised by the 
lever arms h.sub.1 and h.sub.2. 
In conjunction with FIG. 3, it becomes clear that the secure retention of 
the edge region 6 inserted in the groove 5, achieved with the 
aforedescribed sectional strip, is brought about substantially by a 
controlled deformation of the edge region 6 inside the groove 5. As a 
result of the downwardly directed deflection of the outer end of the edge 
region 6, comprising the camber 9, (according to arrow F2), the lower 
shoulder 11 is braced against the stop face 7 of the groove wall. Thus, 
the entire cross-section of the edge region 6 including the shoulder 11 
becomes active at the time of tensile stress, that is to say the tensile 
load may be correspondingly great. 
FIG. 4 shows diagrammatically an assembly tool 16 with flaps 17 which fold 
out at the lower end. If the assembly tool is raised in the directon of 
arrow F3, then the ends of the flaps 17 underpin the bulges 8 directed 
inwards in the illustrated position of the sectional strip, so that the 
sectional strip is raised as a whole. The hollow fillets 12 on the 
underside of the edge region 6 bear against the lower sides of the 
respective edge profile 3,4 and in this way bring about a deflection of 
the ends of each edge region in the direction of arrow F4 into the inside 
of the grooves 5. After completed deflection into the horizontal position 
of the edge regions 6, the latter are likewise inserted completely into 
the grooves 5 with a tool, by further pressing on the bulges 8 in the 
direction of arrow F1 (FIG. 2).