Positive coupling structure

In a positive coupling structure for interconnecting a first element having a T-shaped projection with a neck and a head portion which extends from the neck portion in opposite directions and a second element which has a cut-out shaped corresponding to the T-shaped projection of the first element for snugly receiving the T-shaped projection, the opposite ends of the head portion are widened to form recesses in which the adjacent areas of the second element are firmly engaged.

BACKGROUND OF THE INVENTION 
The invention relates to a positive coupling structure between two 
elements, wherein the first element has a T-shaped projection with at 
least a first neck portion and a head portion, which is wide in comparison 
with the neck portion. The second element has a cut-out corresponding in 
shape to the projection of the first element. 
Such coupling structures are known for example for use with relatively long 
gaskets as they are used for example in very large internal combustion 
engines. Very long gaskets are generally formed by providing various 
gasket sections, which are combined by coupling structures to a full area 
gasket structure. 
Although the known couplings have very good properties with regard to 
pulling forces on the various components in the longitudinal direction of 
the gasket, they have the disadvantage that the edge areas defining the 
recesses have a relatively small material width. As a result, the edge 
areas can bend apart whereby the outer dimensions of the gasket change and 
the gasket protrudes from the respective machine elements in an 
undesirable manner. Under adverse conditions, the edge areas can bend 
apart to such a degree that the projection slides out of the recess in 
which it is received. This happens especially with relatively thin 
gaskets. 
It is the object of the present invention to provide a positive coupling 
arrangement in such a way that edge areas do not bend apart when the 
elements to be joined are subjected to pulling. 
SUMMARY OF THE INVENTION 
In a positive coupling arrangement for interconnecting a first element 
having a T-shaped projection with a neck and a transvers head portion 
which extends from the neck portion in opposite directions and a second 
element which has a cut-out shaped corresponding to the T-shaped 
projection of the first element for snugly receiving the T-shaped 
projection, the opposite ends of the head portion are widened to form 
recesses in which the adjacent areas of the second element are firmly 
engaged. 
The widened areas at the opposite ends of the transverse head portions 
provide for a recess in which the resective areas defining the cut-out are 
received which prevents the edges forming the cut-outs from bending apart. 
Similarly, the widened area prevents the edges delimiting the recess to 
move away from one another as the element with the projection is 
prevented, by the jointure of projection and recesses, to move out of 
engagement with the element having the cut-out. 
Preferably, the T-shaped projection has a first and second transverse head 
portions of which the second is connected to the first by way of a second 
neck portion. With the second transverse head portion the surface area 
where the projection and the cutout are in engagement is substantially 
increased whereby the forces which are effective when the elements are 
pulled apart are more widely distributed. 
In another particularly advantageous embodiment of the invention the 
projections and cutouts are formed by stamping with oppositely directed 
stamping action. 
In this way, the cutting edges are rounded and the rounded end areas are 
directed against one another when the elements are assembled. Also, the 
elements can be assembled more easily as the projection is funnel-like 
guided into the cut-out. 
Further features and advantages of the present invention will become 
apparent from the following description of a particular embodiment thereof 
on the basis of the accompanying drawings.

DESCRIPTION OF A PREFERRED EMBODIMENT 
As shown in FIG. 1, a first element 1 which is to be positively coupled 
with a second element 2 is provided with a projection 3, 4, 5, 6, 7 which 
is essentially T-shaped. The projection has a first neck 3 and a 
transverse head area 4, 5 wherein the neck 3 is formed by the vertical 
part of the T and the head 4, 5 is formed by the transverse beam of the T. 
The head portion 4, 5 has at its lateral ends, widened areas 5. The 
widened areas 5 extend the transverse beam of the T in a direction 
parallel to the neck 3. Above the transverse beam of the head portion 4, 
5, there is provided a second transverse beam 7 which is centrally 
connected to the first beam 4, 5 by means of a second neck 6 and which 
extends about parallel to the first beam 4, 5. 
The second element 2 includes a cutout 8, which has the same shape as the 
projection 3, 4, 5, 6, 7. The cutout 8 has marginal side areas 9, which 
are relatively narrow because of the cutout 8. Because the marginal side 
areas 9 are relatively narrow, they can be easily bent apart. This 
movement, however, is prevented when the projection 3, 4, 5, 6, 7 is 
received in the cutout 8. Then the marginal side areas 9 are held in place 
as portions thereof are received and engaged in the recess formed by the 
widened areas 5 of the beam 4, 5. As a result, the marginal side areas 9 
are prevented from being bent apart. 
As shown in FIG. 3, the cutting edges 10 have rounded areas 11 which are 
formed during stamping. Preferably, the projection and cut-out are formed 
by oppositely directed stamping action so that the rounded edges are 
formed as shown in the example given in FIG. 3; the elements 9a represent 
the edges of the element 2. The cut-out is stamped into the element 2 by a 
downwardly directed stamping action, so that the rounded edge areas 11 are 
formed on top. The element indicated in FIG. 3 by the reference numeral 5a 
is part of the element 1, that is, it is a section taken through the head 
4, 5. It is formed by stamping in a direction from bottom to top so that 
the rounded edge areas 11 are formed at the bottom. With the rounded edges 
formed in this manner into the rims of the projection and the cutout, the 
projection 3, 4, 5, 6, 7 can be easily inserted into the cutout 8.