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(11) | EP 1 233 430 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Magnetic lamination core for monophasic low-power Transformers |
| (57) From a continuous strip of plate (1) by stamping are obtained the parts (2-2'), which
are identical in shape and size to each other, and which form two longitudinal and
marginal alignments in which said parts are opposite each other, each part adopting
an asymmetrical E-shape with its outer legs (3-4) having equal widths and also equal
to the width of the common leg (2), but half the length of its middle leg (5), and
with said legs (3-4) having clearly different lengths while the middle leg (5) has
an intermediate length, and with the separation between said middle leg (5) and the
outer legs (3-4) equal to the width of the latter legs. |
OBJECT OF THE INVENTION
[0001] The present invention relates to a core of the type used as magnetic circuits in monophasic low-power transformers, comprising several stacked laminations of magnetic steel on which are mounted the various coils or electric circuits which correspond to the input voltage (primary coil) and the output voltage (secondary coil) of the transformer.
[0002] The object of the invention is to achieve a construction of the core from two half-cores which are identical in size and shape, formed by the aforementioned stack and which are created in the same stage of the stamping process and with the stack configuration required for each case, with an ideal use made of the materials in order on one hand to facilitate the assembly of the core on the transformer and in addition, essentially, to obtain a uniform electrical response.
BACKGROUND OF THE INVENTION
[0003] It is known that a low-power monophasic transformer comprises a core made from magnetic steel formed by a number of superimposed laminations which configure a single or double ring, generally rectangular, on the sides of which are established the corresponding coils, so that the inducing current which passes through one of them becomes an induced current in the other, with the same or different voltage.
[0004] Obviously, these rings must be initially open so that the coils can be inserted inside them, with each layer of the core formed by engaging two laminations, so that stacking of several layers produces the transformer core.
[0005] Specifically in the scope of armoured cores in which two adjacent rings are defined, a common solution is to begin from a rectangular lamination in which two long rectangular openings are stamped, which have a length equal to that of the width of the base lamination so that in the same process as the openings are made two I-shaped strips are obtained which are later used, after breaking the base lamination into two halves, each half having an E shape that is later closed by one of the I-strips, forming the required double ring, and thereby making an optimal use of the material, with 100% of the metal plate being used.
[0006] Along this line can be mentioned, with differences in detail but having the same basic structure, European Patent 671,750, Japanese Patent 61-35.505 and US Patent 4,827,237.
[0007] All of these patents have as an objective a maximum use of the available material, but however have two basic drawbacks mainly centred on the following aspects:
- The different configuration of the parts which form the armoured core makes the electrical response not uniform.
- The presence in each armoured core of two types of parts with different configuration and size requires a selection and matching of these parts as each half-core is different, with a resulting cost in time and lower productivity in assemblies using both manual or automatic machinery.
[0008] In addition, English Patent 1543567 and standard E-I type configurations have the following problem:
- The transformer core must be made by the transformer manufacturer, stacking the laminations one by one and alternating E's and I's on either side of the coil, resulting in longer times and a slower manufacturing process, and thereby greater production costs.
[0009] In addition to this most common solution which uses E-shaped and I-shaped parts there are others such as that of European Patent 196,406, in which C-shaped and T-shaped half-cores are obtained, but which still have the object of making a full use of the material and in which the same aforementioned drawbacks are present in the same sense as described.
DESCRIPTION OF THE INVENTION
[0010] The core for low-power monophasic transformers disclosed solves the aforementioned problems in a fully satisfactory manner, so that in exchange for a small waste of material which has little relevance each layer of the armoured core is formed by laminations identical in size and shape, and thus naturally stacking several layers will give rise to two also identical half-cores, which on one hand considerably simplifies their assembly process as no part selection and pairing is required, and in addition and more importantly a uniform electrical response is achieved and a greater speed in constructing the core, as the corresponding half-cores are obtained with the required dimensions from the stamping process.
[0011] For this purpose and more specifically, as is conventional a continuous strip of a given width is stamped, also as is conventional, obtaining two longitudinal and marginal alignments of identical parts, each of which is approximately E-shaped, with the middle leg being twice the width of the outer legs, which outer legs are unequal in length with one shorter and one longer than the middle leg and with a common leg having the same width as the outer legs, which are in turn separated from the middle leg by a distance equal to their width.
[0012] In this manner and using as mentioned above a continuous strip of a suitable width opposing parts are obtained, longitudinally out of phase, in which the larger outer leg of each is obtained from the empty space left in the opposite part between its own larger outer leg and its middle leg, and where the middle leg of each part is obtained from the space left in turn by the shorter outer leg of the opposite part.
[0013] This allows to obtain parts which are identical in size and shape to each other, with a minimal waste of material which can be perfectly assumed in view of the advantages obtained from a functional and assembly point of view by this new arrangement.
[0014] In addition, and as is also conventional, the aforementioned outer and middle legs of this single asymmetrical E-shaped part can be provided on their ends with complementary recesses and protuberances which facilitate and ensure the engagement of the two half-cores.
DESCRIPTION OF THE DRAWINGS
[0015] The characteristics of the present description will be better understood in view of the accompanying drawings of a preferred embodiment which are an integral part of the description and where for purposes of illustration only and in a non-limiting sense the following is shown:
Figure 1 shows a plan schematic view of a continuous plate strip duly marked for stamping, from which is obtained a core in accordance with the object of the present invention, where the various lines show the different laminations obtained from said stamping and the wasted material.
Figure 2 shows an isolated plan view of one of the laminations which form part of the core obtained from the continuous plate of the previous figure.
Figure 3 shows, finally, two plates such as those of the previous figure, suitably interlocked to form part of the transformer core.
PREFERRED EMBODIMENT OF THE INVENTION
[0016] In view of the above described figures it can be seen that a lamination core for low-power monophasic transformers is obtained, in accordance with the invention, from a continuous strip (1) from which are stamped a number of parts (2-2') which will create two longitudinal and marginal alignments from the continuous strip (1), longitudinally out of phase and interlocked in order to make a better use of the material, with each part (2-2') having an asymmetrical E-shape with one of the outer legs (3) considerably longer than the other outer leg (4) but with the same width, with a middle leg (5) having a length in between those of the outer legs but with double the width, and having between said middle leg (5) and the outer legs (3-4) spaces (6) of a width equal to that of the outer legs (3-4), so that each greater outer leg (3) of these parts is obtained from the empty space (6) defined in the opposite part (2'), between its greater outer leg (3') and the middle leg (5'), while the shorter outer leg (4) is simultaneously obtained opposite the middle leg (5') of the opposite part (2'), as can be seen clearly in Figure 1, so that small rectangular sectors (7) and (8) are left as waste material, one between each two marginally aligned parts (2-2') and the other when obtaining the space (9), joint, defined between the smaller outer leg (4) and the middle leg (5) and the legs (4'-5') of the transversely opposite part (2').
[0017] As the common leg of each part (2-2'), labelled with the same numbers, has the same width as the outer legs (3-4), it is obvious that in order to obtain these parts one must begin with a continuous strip (1) with the same width as the sum of the length of one of the greater legs (3) and the width of the common leg (2) of these parts.
[0018] In addition, in the stamping process, on the free end of the greater leg (3-3') of these parts are obtained corresponding centred grooves (10), similar corresponding widenings (11), also centred, and on the free end of the middle leg (5-5') are obtained a groove (10) and a projection (11) so that when engaging any of these parts, as shown in Figure 3, a male-female engagement is obtained between them which improves the stability of the armoured core.
1. Magnetic lamination core for monophasic low-power transformers, of the armoured type
in which two half-cores are defined, which after receiving the corresponding coils
are interlocked to form a double ring, characterised in that said half-cores are formed from parts (2-2') which are identical in size and shape
to each other, embodied as an E-shaped asymmetrical lamination with its outer legs
(3-4) identical in width and having the same width as the common leg (2), but being
clearly unequal in length, while the middle leg (5) has a length which is in between
those of the aforementioned legs, and a width twice as large as theirs, with said
middle leg (5) separated from the outer legs (3-4) by a distance which is equal to
the width of the latter legs.
2. Magnetic lamination core for monophasic low-power transformers, as claimed in claim
1, characterised in that said laminations or parts (2-2') obtained by stamping of a continuous strip of plate
(1) are positioned on said plate such that the greater outer leg (3) of one part is
contained in the space (6) defined between the greater outer leg (3') of the part
(2') which is laterally opposite and its middle leg (5'), while said middle leg (5)
of either part (2) is left opposite the shorter outer leg (4') of the laterally opposite
part (2'), defining two marginal alignments of parts (2-2') which are partially interlocked,
with said parts longitudinally out of phase and separated from each other in the alignment
by small discardable segments (7) which have the same size as the smaller outer leg
(4) of one of such parts, while between two such parts (2-2') that are laterally adjacent
is defined another rectangular waste segment (8) which is slightly greater than the
previous one.
3. Magnetic lamination core for monophasic low-power transformers, as claimed in above
claims, characterised in that both the outer legs (3-4) and the middle leg (5) of the aforementioned parts (2-2')
incorporate on their free end grooves (10) and projections (11) which allow a male-female
coupling of the half-cores in order to obtain the final armoured core.