Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02222647 1997-11-27
GR 95 P 3383 IN
Description ~~~ ~
Universal modular guide rail for printed circuit boards
DE 36 24 839 C2 disclones a guide rail for
printed circuit boards in which a side wall of the guide
groove is separated in sections from the base of the
groove by means of slots. These free parts of the side
wall of the guide groove are each configured as leaf
~pringfi curved in a bell ~hape, in such a way that the
width of the guide groove is tapered in each case. These
leaf springs curved in a bell shape constrict the guide
groove in such a way that not only are printed circuit
boards having a very small thickness still guided at both
sides, but also it is still possible to push in printed
circuit boards having a very large thickness.
A further boundary condition occurring in
practice with guide rails is that they must have, if
appropriate, different lengths correspo~;ng to the
respective depth of a printed circuit board. To date it
has been customary and necessary to provide a
speci~ically matched, 6eparate type of guide rail for
each printed circuit board depth. This has entailed an
increa~e in the outlay on components and production and
an increase in the cost~.
The invention is based on the object, then, of
~pecifying a universal guide rail for printed circuit
boards which can be matched modularly, without a
relatively high outlay, to printed circuit boards w~ich
may have nGt only a different thickness but also a
different edge length or depth.
The o~ject is achieved by meaIls of the guide rail
specified in Claim 1. Further advantageous r~finements
thereof are specified in the subclaimR.
One advantage of the modular guide rail accordins
to the in~ention is manife~t in the fact that, fir~tly,
the matching of the length cf the ~lide rai~ to the
current edge length of a plug-in a~sembly i~ faciiitated
by the capability of latchl.lg or plugging the groove
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segment parts onto the supporting rail in the manner of
a head. To this end, the length of the supporting rail is
correspo~;ngly matched to the respective plug-in
assembly. Subsequently, groove segment parts are
modularly fitted onto the supporting rail until the
region on the top side of the supporting rail between the
two end pieces is covered as completely as possible with
groove segment parts, consequently producing a flush
guide groove which is as continuous as possible over the
entire length of the edge of the plug-in assembly.
A further advantage is moreover manifest in the
fact that the matching of the guide rail to plug-in
assemblies of different thicknesses is also considerably
assisted by the configuration according to the invention.
By virtue of fitting the groove segment parts onto the
supporting rail in the manner of a head, the prime
functional importance of the supporting rail is its
action purely as a support; the supporting rail in no way
constricts the guide groove segments on the top side of
the groove segment parts with regard to their cross-
sectional extent. In this way, on the one hand, it is
possible to fit different groove segment parts which are
provided for printed circuit boards of differing
thickness with regard to the width of the guide groove
segments. On the other hand, however, the two side walls,
which bound a guide groove segment on the top side of a
groove segment part, are also completely free and can
yield laterally, according to their material properties,
when a thick printed circuit board i~ introduced into the
guide groove.
It i8 particularly advantageous if, in accordance
with the configuration disclosed in DE 36 24 839 C2, in
the case of a groove segment part, a side wall of the
guide groove segment there is separated in sections from
the base of the groove by mean~ of a 810t and this free
part of the side wall is in each case configured as a
leaf spring curved in ~ bell shape, such that the width
of the guide gr~ove segme.lt cn the top ~ide of the
respective groove segment part is tapered.
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The invention is explained further using the
examples illustrated in the figures which are referred to
briefly below and in which
Figure 1 shows a cross-sectional representation of a
guide rail according to the invention, the
supporting rail of which has, by way of
example, a rectangular cross-section and onto
which a groove segment part is fitted in the
manner of a head,~0 Figure 2 shows a perspective plan view of a preferred
embodiment of an end piece and of a supporting
rail of the guide rail according to the
invention with a groove segment part fitted on
by way of example,~5 Figure 3 shows a cross-sectional representation of the
preferred embodiment of the guide rail of
Figure 2 in the region of the supporting rail,
Figure 4 shows a plan view of the coupling region of the
end piece of the guide rail of Figure 2, and~0 Figure 5 shows a cross-sectional representation of a
further embodiment of the guide rail, the
underside, in particular, of the supporting
rail having a preferred boat-shaped outer
contour which is favourable in terms of flow.
Figure 1 shows a cross-sectional representation
of a first embodiment of the guide rail according to the
invention, in which the supporting rail TS has, by way of
example, a rectangular cross-section. According to the
invention, a groove segment part FSn is fitted or latched
or plugged onto the supporting rail in the manner of a
head. For this purpose, the groove segment part FSn has
latching elements starting at its underside. In the
example of Figure 1, these latching element~ are embodied
in the form of two edge strips RLTl and RLT2, which lead
downwards from the sides of the supporting body TR of the
groove segment part and have a respective projecting
latching edge RRTl, RRT2 at their end. Said latching
edges project inward~ in the example of Figure 1 and
consequently form, behind them, a respective groove
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region HNT1, HNT2, into which the rectangular supporting
rail TS comes to lie after being latched into place. In
the example illustrated, the supporting rail TS is
consequently ~hraced by the latching elements RLT1,
RLT2. In other designs, one of which will be explained in
more detail below with reference to Figures 2 to 4, it is
possible to provide grooves on the sides of the
supporting rail as well, into which grooves the latching
elements of the groove segment part engage. On the other
hand, the latching elements may also be a component part
of the supporting rail and engage, for example, into
webs, grooves and the like located on the underside of
the supporting body TK of the groove segment part.
It is crucial that the connection between the
groove segment part and the supporting rail take place
underneath the supporting body TR of the groove segment
part FSn, 80 that the head-like top side of the groove
segment part FSn, on which the guide groove segment FSn
serving to accommodate the edge of a plug-in assembly is
formed, bounded by two side walls SW1, SW2, can be
constructed to be completely lln; , cded. The guide groove
segment and the side walls forming it are consequently in
no way restricted, on account of the configuration
according to the invention, with regard to lateral
extension or expansion, in particular for the purpose of
accommodating printed circuit boards having a relatively
large thickness. Thus, in the example of Figure 1, the
right-hand side wall SW2 is separated in regions from the
base of the groove and constructed like a leaf spring,
constricting the guide groove segment FSn in sections. In
particular when an especially thick printed circuit board
is pushed in, this leaf spring-like region is deformed in
such a way that it is forced beyond the right-hand
boundary, illustrated in Figure 1, of the ide wall SW2.
Expansions of this type in the tran~verse direction are
easily possible on account of the connection according to
the invention of the supporting rail and guide grooYe
segment by means o~ latching elements Eituated on the
underside of the guide groove segment.
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A further embodiment of the invention is
explained with reference to the perspective plan view of
Figure 2. A preferred design of an end piece R of the
guide rail according to the invention i8 illustrated
there. This is preferably the so-called front end piece
of a guide rail, which additionally has encoding ch~hers
RR in the case which is illustrated. The said encoding
chambers face the printed circuit board to be inserted
and can be filled with encoding pins. By this means, it
can be ensured that only the printed circuit board
intended for an insertion location can actually be pushed
completely into the correspo~;ng guide rail. For reasons
of clarity, that end piece of the guide rail which is
situated at the other end of the supporting rail TS i~
not illustrated. It can advantageously have the same
configuration as the front end piece R which is shown, or
at least the encoding chambers may be omitted, since the
latter are not required on the rear side of a mounting
rack.
The front end piece K illustrated in Figure 2 has
a coupling region RP for connection to an opposite
insertion region ES of a supporting rail TS. Constructed,
by way of example, on the top side of the supporting body
TR of the end piece R, by means of two laterally bollnAing
side walls SW, is a guide groove segment FN for
accommodating the edge of a printed circuit board. On the
underside of the supporting body TR, there are further
securing elements BE, in particular latching hooks and/or
guide pins or insertion knobs, which serve to retain the
end piece R and hence the entire modular guide rail in
correspo~; ng openings or slots of a transverse rail (not
illustrated in Figure 1) of a mounting rack.
In the example illustrated in Figure 2, the guide
groove is ~plit into three, for example, on the top side
of the end piece R. A first region FNl at the end side
has introduction bevels for easier introduction of the
edge of a plug-in asse~bly. Behind this, there follows a
second reyion FN2 of the guide groove, approximately in
the centre of the top side of the supporting body. In the
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case of this second region, perforations for
accommodating a contact spring are provided, to replace
the side walls, on both sides of the base of the groove.
Such a contact spring is described, for example, in
5 DE 36 24 883 C2 and serves to interconnect the earth
potential of the printed circuit board and of the
mounting rack. Finally, there is a third region FN3,
situated above the coupling region KP, of the guide
groove. This third region forms the transition to the
guide groove segments FSn on the top sides of the groove
segment parts FSn which are latched onto the supporting
rail TS.
In the example of Figure 2, by way of example,
only a single groove segment part of this type is latched
on the supporting rail TS. Normally, the entire top side
of the supporting rail, which is matched to the length of
the plug-in assemblies to be pushed in in each case, is
completely occupied by groove segment parts. In this
case, the two end pieces, the supporting rail and the
application-dependent nl~her of groove segment parts are
coordinated with one another in such a way that the guide
groove segments on the individual parts come to lie flush
with one another, that is to say without any edges,
consequently producing a smooth continuous guide groove
from the beg;nning of the front end piece via all of the
groove segment parts right up to the rear end piece.
The preferred design of the supporting rail TS
and of the groove segment parts FSn of the guide rail of
Figure 2 i8 described in more detail below with reference
to a cross-sectional representation in the region of the
supporting rail according to Figure 3. In thi~ case, both
the groove segment parts FNn and the supporting rail TS
have latch~ng elements, which are shaped approximately
inversely with respect to one another and consequently
engage into one another in an optimally po itively
locking manner.
For this purpose, in Figure 2 the latching
elements of the ~upportin~ rail TS a~e e~bo~ied, by Wdy
of example, in the form of two edge ~trips RL51, KLS2
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which protrude at the top of the supporting rail TS and
have projecting, preferably outwardly facing latching
edges RRS1, RRS2. As a result, it i8 possible, on the one
hand, for the edge strips RLTl, RLT2 of the groove
segment parts FSn to engage into the groove regions HNS1,
HNS2 formed by the edge strips RLS1, RLS2 of the
supporting rail TS, and conversely for the edge strips
RLS1, RLS2 of the supporting rail TS to engage into the
groove regions HNTl, HNT2 formed by the edge strips RLT1,
RLT2 of the groove segment parts FSn. Optimum
intermeshing regions VR are consequently produced between
the edge strips RLS1, RLS2 of the supporting rail TS and
the edge strips RLT1, RLT2 of the groove segment parts
FSn.
The guide rail TS advantageously has an
approximately u-shaped cross-sectional profile. In the
example of Figure 2, this is ensured by a longitudinal
slot LS which is preferably expanded in the shape of a
drop in the lower region in the centre of the supporting
rail. The elasticity of the edge strips RLS1, KLS2 of the
supporting rail TS which is also achieved by this means
assists the capability of latching on the groove segment
parts. According to a further embodiment already
illustrated in Figure 3, the underside US, which faces
away from the groove segment parts FSn plugged on in the
manner of a head, of the supporting rail TS has two roof-
shaped bevelled faces AB. As a result, a cooling air
stream which serves to cool components on the top sides
of the plug-in assemblies and is introduced from the
underside US of the guide rail is optimally routed. This
is particularly necessary when, given dense population of
a mounting rack with plug-in assemblies, a large number
of guide rails are arranged closely parallel next to one
another.
Figure 4 finally shows a plan view of the
coupling region RP of the end piece R of the guide rail
of Figure 2. The rear view of the supporting body TR and
the l~tching elements BE of the end piece R are
illustrated on the left-hand side. The coupling region RP
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of the end piece K advantageously has an insertion
opening EO which corresponds to the cross-sectional
profile of the supporting rail TS and is intended for
that end of the supporting rail TS which forms the
insertion region ES. This ensures particularly secure
retention of the inserted supporting rail TS in the end
piece K. That part OT of the coupling region KP of the
end piece K which is situated above the insertion opening
EO advantageously has a cross-sectional shape which
corresponds as far as possible to the groove segment
parts FSn. This is the case in the example of Figure 4.
Thus, the end piece also has edge strips which engage in
an optimally positive locking manner into the
complementary edge strips of the supporting rail. This
has the further advantage that the transition between an
end piece and a groove segment part is completely free of
edges, at the same time avoiding any overhangs. In the
example of Figure 4, the support skid AU for the roof-
shaped bevelled faces AB on the underside of the
supporting rail TS is designed to be particularly robust.
As a result, it is possible to avoid undesired torsion
between the two end pieces and the supporting rail.
Additional latching elements (not visible in
Figure 4) are advantageously provided in the interior of
the coupling region KP of the end pieces R, being for
example let into the interior of the support skid AU. The
said latching elements either latch in a positively
locking manner into correspo~i ng cutouts in the
supporting rail TS or rest flat on the outer sides of the
supporting rail with the application of an appropriate
pressure load. As a result, the retention or clamping
between the insertion region ES of a supporting rail TS
and the coupling region KP of an end piece K can be
considerably improved.
Finally, Figure 5 shows a further cross-sectional
representation through a guide rail TS with a groove
segment part FSn fitted on. In this case, the outer sides
AB, in particular, on ~he under~ide US of the supporting
rail TS are configured to be particularly favourable in
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terms of flow for a cooling air stream supplied from
below. In the example illustrated, the underside has
approximately the shape of a boat hull. According to a
design which is not illustrated, it may also be V-shaped.
This hull shape is extended upwards on both sides right
up to the two downwardly pointing edge strips RLT1, RLT2,
80 that the outer sides, in particular, of the inwardly
projecting latching edges RRTl, RRT2 are likewise
bevelled downwards.
