Abstract:
An electric fuse holder of the modular kind, i.e. formed by combining a plurality of identical fuse holder units. The fuse holder units are shaped in such a way that they can be joined together under pressure of wedge action merely by virtue of their geometry or configuration into a composite or multipolar fuse holder, i.e. in the absence of any additional fastener means.

Description:
BACKGROUND OF THE INVENTION 
     It is well known to assemble single identical fuse holders to form multipolar, or composite, fuse holders. 
     A multipolar or composite fuse holder is shown, for instance, in U.S. Pat. No. 3,171,002 to J. D. Kinnear, 02/23/65 ELECTRICAL FUSE MOUNTING. In the instance of Kinnear the units are nested into composites secured to a mounting panel. The mounting panel is the means for joining the individual fuse holder sections to a unitary structure. This structure is not modular since it comprises two different kinds of sections, namely end sections having lugs for fastening screws and normal sections without such lugs. 
     U.S. Pat. No. 3,810,077 to E. Salzer 05/07/74 for FUSE HOLDERS relates to a truly modular multipolar fuse holder, i.e. one wherein the individual fuse holder units are identical. This fuse holder requires, however, special fastener means, e.g. cement, for integrating several separate fuse holder units into a unitary structure. 
     The present invention refers to a modular fuse holder structure, i.e. one consisting of identical sub-units, which are capable of being assembled under pressure of wedge action into a multi-polar or composite structure without additional fastener means of any sort. 
     SUMMARY OF THE INVENTION 
     This invention relates to a modular fuse holder unit comprising a substantially prismatic fuse clip supporting block of synthetic resin. Said block is planar at two opposite sides thereof except for a planar projection on one of said sides and a planar recess on the other of said sides. Said projection converges in upward direction and defines a first pair of grooves open at one of the lower longitudinal edges of said block. Said first pair of grooves, or the depth thereof, slightly increases in upward direction and said recess converges likewise in upward direction and defines a second pair of grooves open at one of the lower longitudinal edges of said block. Said second pair of grooves, or the depth thereof, decreases in upward direction. Said recess and said second pair of grooves and said projection and said first pair of grooves are complementary positives and negatives of each other. As a result of this geometry, or configuration, said block is capable of being joined under pressure of wedge action with other identical blocks in the absence of any additional fastener means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 and FIG. 1a are an end view and a side view, respectively, of two separate blocks embodying this invention; 
     FIG. 2 and FIG. 2a are an end view and a side view, respectively, of two blocks embodying this invention in the process of being joined; 
     FIG. 3 and FIG. 3a are an end view and a side view, respectively, of two fuse clip supports upon having been fully joined; 
     FIG. 4 is a top plan view of two joined blocks or fuse clip supports; and 
     FIG. 5 is an isometric view of the structure of FIG. 4. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawings and particularly to FIGS. 1, 1a and 2, 2a and 3, 3a thereof, FIGS. 1, 2 and 3 show end views of a fuse holder, or fuse clip support, embodying this invention in three different positions, and FIGS. 1a, 2a and 3a are side elevations of the structure shown in FIGS. 1, 2 and 3. In FIGS. 1-3 two fuse holder elements 1 and 1&#39; are shown which are intended to fit together at the longitudinal surfaces 2, 2&#39; of the sockets thereof. The surfaces 2 and 2&#39; of fuse holder elements 1 and 1&#39; are strictly planar except at a single point of each of said surfaces 2, 2&#39; of said socket situated immediately adjacent a lower lateral edge 3, 3&#39; thereof. As shown in FIG. 1 surface 2&#39; has a projection 4&#39;. Projection 4&#39; is wider at its lower end situated adjacent edge 3&#39; than at its upper end 5&#39;. Projection 4 is wider at its front than at its base. Hence, a pair of grooves 6&#39; is formed, one on each side of projection 4&#39;. Said pair of grooves 6&#39; are open at their lower ends adjacent edge 3&#39;. They are also open at their upper ends remote from edge 3&#39;. The geometry of projection 4&#39; is also fully apparent from FIG. 5. As shown in the latter figure the width &#34;a&#34; at the bottom of projection 4&#39; slightly exceeds its width&#34;b&#34; on the top thereof. The depth &#34;c&#34; of groove 6&#39; at the top thereof exceeds their depth &#34;d &#34; of grooves 6&#39; at the bottom thereof. In other words, projection 4&#39; is a double wedge, or is capable of performing a double wedge action since its front surface decreases -- a &gt; b -- and its grooves 6&#39; have an increasing cross-section from the bottom 3&#39; to the top thereof. Arrow R indicates the direction which will hereafter be referred-to as upward direction. 
     Grooves 6&#39; are bounded by straight ribs or overhangs 6a&#39;. The cross-sectional area of these ribs changes inversely to that of grooves 6&#39;, i.e. it is larger near edge 3&#39; and decreases in upward direction. Projections 4&#39; are supposed to engage negatives thereof, i.e. recesses 4. Each recess 4 is, therefore, planar, wider at its lower than at its upper end, has a pair of lateral grooves 6 bounded by a pair of ribs or overhangs 6a. The cross-sectional area of grooves 6 is widest at their lower ends near edge 3&#39;, and decreases in upward direction, while that of ribs or overhangs 6a changes inversely to that of grooves 6. 
     Fuse clips 7 and 7&#39; are arranged between the side walls 2&#39;. These clips have not been shown in FIGS. 1a, 2a and 3a since they are not relevant to what these figures intend to show. FIGS. 4 and 5 show fuse clips 7 and 7&#39; in considerable detail. 
     Fuse holder element 1 has a planar lateral surface 2 which is only interrupted by a recess 4. Recess 4 is narrower at the front than at the base thereof, so as to form a pair of grooves 6, one on each side thereof. Grooves 6 are open at their lower ends adjacent edge 3 and closed at their upper end remote from edge 3. The cross-sectional area at the lower ends of grooves 6 adjacent edge 3 is larger than their cross-sectional area at the end thereof remote from edge 3. In other words, grooves 6 converge in upward direction. 
     Recess 4 and grooves 6 are negatives of projection 4&#39; and grooves 6&#39;. When fuse holder element 1&#39; is moved upwardly from the position shown in FIGS. 1 and 1a through the position shown in FIGS. 2 and 2a to the position shown in FIGS. 3 and 3a both fuse holder elements interlock mutually and take the appearance of one single double pole fuse holder, as shown in FIG. 4 and FIG. 5. This interlocking action is effected under pressure of wedge action and in the absence of any additional fastener means. 
     It will be apparent from all the figures that each fuse holder element 1, 1&#39; is provided with one projection 4&#39; and one recess 4. This makes it possible to stack an indefinite number of fuse holder elements to form an integral multipolar fuse holder structure. 
     As shown in FIG. 2 each fuse holder element or fuse clip carrier is provided with a pair of holes 8 and 8&#39; intended to receive screws for attaching the fuse holder to an appropriate support. 
     It will be apparent from the figures that each of the fuse clip carriers is provided with four congruent partitions whose cross-sectional area decreases toward the exposed edges thereof. Partition between phases have twice the thickness as partitions at the end of a stack. 
     The materials of which parts 1 and 1&#39; are made must have a certain give since each projection 4&#39; is compressed in two directions at right angles when it is inserted into one of recesses 4. When the right material is used there is no visible gap between the constituent parts of a fuse holder according to this invention. Glass filled hardened polyester resins have been successfully tried. 
     As mentioned above, the geometry described is capable of exerting two wedge actions which are at right angles to each other. How these wedge actions are obtained will again be described in more detail. 
     It will be apparent that each of grooves 6&#39; is bounded by a first pair of ribs or overhangs 6a&#39; which form wedges increasing in cross-section from edge 3&#39; in upward direction (FIG. 5). Similarly, each of grooves 6 is bounded by a second pair of ribs or overhangs 6a which form wedges increasing in cross-section from lower edge 3 in upward direction (FIG. 1). 
     A first wedge action occurs on account of the fact that both the planar front surfaces of projections 4&#39; and the recesses into which they enter, converge in upward direction. A second wedge action at right angles to said first wedge action is achieved on account of the fact that the cooperating surfaces of the ribs or overhangs 6a&#39; and 6a are wedges, i.e. that 6a&#39; decreases and 6a increases in cross-section in upward direction. In FIG. 3 arrows S have been applied to indicate the directions of the wedge action effected by engagement of groove 6 by ribs or overhangs 6a&#39; and engagement of groove 6&#39; by ribs or overhangs forming part of recess 4. FIG. 3 shows also that ribs or overhangs 6a&#39; decrease in cross-section from edge 3&#39; in upward direction and that ribs or overhangs 6a increase in cross-section in upward direction.