DE1638588A1 - Variable autotransformer and process for its manufacture - Google Patents

Description

DR. ISTG. ERNST MAIER PATEIiTANTVAI ₁ T

8 MUNICH SS

BTJr. β ■ ΧΧΚΒΙΌΧ »15 90. Ιβ 51 GS

A 30767 July 6, 1967

THE SUPERIOR ELECTRIC COMPANY, 58j Middle Street, Bristol,

(Conn.,

Variable autotransformer and process for its manufacture

The present invention relates to a variable autotransformer with a contact surface on which a brush is relatively movable in electrical contact therewith; in particular, the invention relates to the contact surface and the method of their manufacture.

The German patent application S 92 5θ6 VIIIb / 21d2 describes an adjustable autotransformer with a contact surface. The autotransformer has a coil formed by winding a length of wire onto a magnetic core, while the contact surface is formed by a flared like portion "" to ¹ """of each of most turns of the winding

10 9 8 13/0367

is. The parts are mounted around the trajectory of an electrical, conductive brush, which is opposed by spring force. is pressed. The output voltage can be adjusted by changing the brush position on the contact surface.

The same parts of the turn and those adjacent to them on the spool Winding lengths are covered with a relatively thick hardened epoxy coating, which is used to Tie the same parts together to reduce their propensity for physical movement and thereby protect the autotransformer make it possible to handle more electricity than was previously possible. Although such a coating proves to be extremely satisfactory has proven; the contact area was formed so that it was just a tiny bit above the area of the epoxy coating between the parts and therefore foreign bodies could easily penetrate between the brush and the contact surface, which the Possibility of interference. The amount of coating was also those at the completion of manufacture after deposition

i remained on the coil, in itself limited and was only a fraction of the total deposited amount, which is the structural Diminished bond between the turns? the manufacturing cost however increased.

ν ■

109813/0357 bathroom original

Accordingly, the present invention seeks to provide a variable autotransformer with one of conductive sectors formed contact surface where a relatively thick, hardened epoxy coating is deposited on the coil., at however, the surface of the epoxy coating in the spaces between the sectors is sunk below the contact surface will.

Another purpose of the present invention is to achieve the above objective while increasing it the amount of hardened coating that is present in the spaces between the sectors and on the terminating parts of these sectors in order to bind them more tightly to each other and to the core.

Furthermore, the creation of a variable autotransformer is intended, which fulfills the above-mentioned purposes and which is more economical to manufacture, by not only having a small exe Amount of hardened coating is applied to the coil, but also less during the manufacturing process is to be removed from it.

When carrying out the method according to the invention, there is a feature in the creation of a coil that is made by winding

109813/0357

a length of conductive wire is formed on a closed core of magnetic material. When shown here ' th special embodiment, the core is ring-shaped, the winding is toroidal and the contact surface here is arcuate is formed at one end of the coil. At least this end of the coil is covered with a relatively thick hardened epoxy ^ layer coated, e.g. deposited by heating the coil, exposing it to the epoxy powder, which melts after contact with the heated coil and adheres to it. The then coated coil becomes powder pulled away and cooled, this is how the molten powder hardens, becomes coherent and adherent and binds the parts together, who have touched.

The present invention not only includes the above-mentioned

»Ten, in the German patent application pending at the same time S 92506 a, but also the measure that consists in a compliant organ against the part to To press the coil on which the contact surface is formed, during the period in which the coating is still in its semi-liquid State is - and even before it hardens. The pressing, process serves to apply the coating to the corresponding To force parts into the gaps between the sectors, thereby increasing the amount of coating therein, and this pressing

10 9 813/0 35 7

also displaces the excess coating material the corresponding parts radially away from these parts, so that thicker coating edges arise around their ends.

During the pressing process, the end face of the cover is sunk in the interstices in most of these below the plane in which the contact surface is formed and it therefore comes to lie under this after this contact surface has been formed. Of course, the distance by which the end face of the coating comes to lie below the plane of the contact surface in the interstices depends on many factors, such as the wire thickness, the width of the interstices and other factors. However, although the end face of the coating is deeper in the gaps than in the subject of the above-mentioned German patent application, it was found that forcing the material on the contact surface into the gaps between the sectors results in the coating generally on the core in sticks firmly to the gaps, whereby the bond between the sectors at the contact surface generally weakens, but the bond between the characters increases at the ends of the contact sections, the result is a single bond of the Sskto ^ ®rs ₀ --- the snindestsnsca is complete, like those in the above gsnarsntsn P

101 (113/035?.

described. In addition, the coating leaves the bond at the gaps at the core there is an inhibiting effect on the sectors, which counteracts the inclination of these sectors, to rise above their normal position, eliminating this tendency decreases to lift.

P Other features and benefits can be seen from the description below emerged.

Illustrated in the drawing:

Fig. 1 is a partial sectional view of a variable autotransformer according to the present invention;

Fig. 2 is a top plan view taken along line 2-2 of Fig. 1 |

Fig. 3 is a section along the line 3-3 of Fig. 2, the has a larger scale to show construction details}

Fig. 4 a view similar to dsr ίίψ _ο 3, 3Tsit a Bs r-2 division around section ainendsr e ^ t & pDSi ^ snüj ¹ :? Ts ^ e ₁ se v; ^ s si © themselves

BATH

FIG. 5 is a view similar to FIG. 4, with the cover has already been applied, but is still in the semi-liquid state;

6 is a view similar to FIG. 5 (but reversed), showing the pressing process for the coating on the corresponding parts;

FIG. 7 is a view similar to FIG. 6, with the coating already is hardened;

Fig. 8 shows a detail on a somewhat larger scale along the Line 8-8 of Figure 2;

FIG. 9 shows a detail on a somewhat larger scale along the line 9-9 of FIG. 2;

10 is a pictorial representation of a type of coating pressing,

As can be seen from the drawing, the autotransformer is general denoted by 10 and has an annular core 11 formed by a thin strip of magnetic Metal is wound spirally. At the ends of the core there are end caps 12 and 13 and a length of circular, Electrically conductive wire is wrapped over it to get in

109813/0357

the embodiment described here a single layer a toroidal winding 14 to form. The core 11 that Winding 14 and the end caps 12 and 13 represent the coil mentioned here and it is between a base part 15 and a retaining part 16 mounted. The parts 15 and 16 also serve as a guide for a shaft 17, which is around the The axis of the bobbin rotates. The shaft IT carries a disk-shaped one Heat radiator 18 on which a brush 19 is mounted. The rotation of the shaft 17 by means of a knob 20 or a another, firmly resting on the shaft 17 organ causes an arcuate movement of the brush 19 around the end of the coil.

The upper end cap 12 is provided with a curved, raised portion 21 and a contact surface generally designated 22 is formed by having an equal part 23 of most, if not all, of the outer turns of the winding 14 is stripped.

Fig. 3 illustrates a wire section on a larger scale along the contact surface 22 on the curved portion 21. The length of the conductive wire forming the winding 14 has a length Insulating covering and thus each has the corresponding Parts 23, as can be seen from Fig. 4, an insulation layer after the wire is wound and before the contact

1098 13/0357

area is formed. The turns of the winding 14 are fairly close to one another but between the corresponding ones Parts are spaces 25 provided which run transversely to the contact surface.

In the formation of the contact surface there is a vein cut each the same parts with inclusion of the insulation layer removed e.g. by grinding to one end face 26 of the conductor to be provided on that of the same parts and a plating material 27 is applied to this surface, so, that the top surface of the cladding material is equal to each other Part represents the contact surface 22 which is swept by the brush.

As set out in the above-mentioned pending patent application, a relatively thick, hardened coating or covering 28 is deposited on the spool, which comprises the same parts 23 and the winding parts adjacent to them. This consists of epoxy material and is preferably deposited by heating the coil and exposing it to a certain amount of epoxy powder so that the heated coil melts after touching the epoxy powder and then the melted powder flows into one another. The end of the coil where the contact surface is to be formed will be like this over a length of about 2 1/2 cm

- ίο -

coated and thus the coating extends over such a length on both the inner and outer circumference of the bobbin, the deposition of substantially of constant thickness. As can also be seen from FIG. 5, the semi-liquid coating partially penetrates into the Interstices 25 between the same parts of the Windings a.

According to the invention, after the epoxy coating has been deposited and while the coil is still hot, the coating still being somewhat liquid, the coil end is then pressed with great force against a flat, flexible sheet material 30. The covering on the same parts, where they are raised by the raised part 21, is pushed away from these same parts, so that they are practically free from the covering. Shortly after the pressing process has started and while the bobbin is still being pressed, the bobbin and sheet 30 are immersed in a liquid bath 29. The bath is located in a container 29 'and is used to cool the spool while the sheet 30 maintains pressure on it. It has been found that water is a satisfactory liquid for the bath 29 at room temperature. As shown in FIG _o 6, the displaced coating -Dur ^ h dpn ^ i ^ vosgang in the interstices hineingsdrüsktp .u "άί ^ -ζ-ζ- ^ £ · L is :. '_, - .. = ζ ■: /■.*. -gsnz to be filled in during the

109813/0

displaced residual coating is displaced radially from the same ones around an inner edge 31 · and an outer edge

32 of a thicker covering material at the ends of the same parts.

Fig. 7 illustrates the same parts and the coating after it has hardened. The spaces in between 25 are practically filled with the covering and the top

33 of the covering in the spaces is generally located approximately in the middle between the same parts. It it will be understood that the relative position of the top 33 depends on many factors, such as the flexibility of the Sheet material 30, on the dimension of the conductor, on the width of the spaces, on the thickness of the semi-liquid covering, the force with which the material 30 is pressed against the spool and the like. In the case of autotransformers with larger wire dimensions and larger spaces can be the Top side lie below the middle of the same parts, while with other autotransformers the top side is somewhat can come to lie higher. Even with one and the same autotransformer, the relative position of the top side can also change change between the individual spaces, as the width of these spaces is generally not constant. According to In the present invention, however, one wants the semi-liquid topping

109813/0357

_ ₁₂ _ 1b38b88

from the same parts and set it up so that the top 33 of the spaces under the End face 26 of the conductor comes to rest.

After the covering 28 has hardened, such as by hardening in a post-heating oven at hardening temperature, is a tangential sector of each of the equal parts removed to create the flat side 26 of the conductor overlying the center of that conductor and it also becomes the layer of insulation 24 removed to create an area 34 of the insulation layer. The plating material 27 is then applied to surface 26, which is preferably a metal such as silver, rhodium, gold, or layers thereof containing do not oxidize as easily as the copper surface 26 of a conductor .

The tangential sector is preferably removed by grinding and is a feature of the present invention lies in the fact that it is no longer necessary to have a very thick, hardened one To grind away the covering on the same parts, since the pressing process, if not all of the covering, then at least most of it from the sectors of the same parts, that are ground away.

1098 137.0367

BATH ORIGINAL

1b38588

As can be seen from FIG. 1, the raised part 21 has the effect that the same parts are lifted slightly above the remaining turns inward of it at the end of the coil and the lengths the turns outward from the same part under the raised part are sunk by making the turns over the edge of the coil. As described in connection with FIG. 6, during the pressing process, the displacement of the amount of deposit on the corresponding part causes the material to break the edges 31 and 32 forms. As can be seen from FIG. 8, the edge 32 is formed on the outer edge of the parts which are identical to one another, wherein this lining edge is noticeably thicker than the lining on the spool side. Also, as can be seen from Fig. 9, the other is on edge 31 formed in the inner part is noticeably thicker than the coating as it was initially deposited.

The sheet material 3G lies on a rigid, flat (not here shown) plate so that the applied force is distributed over the entire surface. A material from which the sheet is made can be is HGch-tßiripsrstursilikongurami, with relative good health and safety,

3eira use can be made between the brush 19 and the contact surface Flowing current, which knows both the output current and the short-circuited Windingsetrom includes reaching such values that

109813/0357

1b38588

the brush and the sectors of the contact surface that it brushes get very hot. This, in turn, can cause the hot sectors to move away from and out of the end cap Level of the contact surface are lifted out. After cooling, the sectors may not return to their original state Position back and if they are outside the plane of the contact surface stay, they create an obstacle that is detrimental to the operation of the autotransformer, as it is difficult for the brush is to move over it. -

The hardened covering described in the aforementioned pending patent application serves to bind all sectors of the turns together. If one or two sectors are heated so much that they are caused to lift, this leads to because of their chaining to one another, the adjacent turns are also raised. Instead of one sudden, just one or two raised turns caused an increase over the contact surface it comes accordingly in the embodiment according to the present invention Invention only to a slight hill-like elevation or to a slightly increasing lift caused by many windings, which is normally required for the operation of the autotrane formatter ksin represents an obstacle.

The embodiment according to the present invention holds at least the same effective bond between the same parts

108813/0367

right, thanks to the thicker, stronger bond that creates Rims 31 and 32 at the ends of the sectors, while the latter have a lower penetration force because of the Coating over the center of the wire adhered to a smaller part of the sector. In addition, the topping fills when it is in As the gaps are pushed in, most of these gaps are sufficiently squeezed out so that it generally becomes one Adhesion to the surface of the end cap 12 comes through the resistance of the sectors to stand out from cieser End cap increases.

From this it can be seen that the autotransformer described here is suitable for converting at least as much current as the previously known in the patent application mentioned at the beginning described autotransformers of a similar size. This is achieved by the fact that the hardening covering not only binds the sectors to one another in such a way that their individual movement but that they are also bound to the core in the area where the contact surface is formed. In this way, to prevent individual movements, the sectors are not only held against one another, but also against the core. In addition, the stronger support of the 5ectors was achieved with a simultaneous reduction in production costs, by reducing the amount of topping required and by at

109813/0357

BATH

the formation of the contact surface the removal of larger parts was turned off by the sectors.

Deviations and changes are within the scope of protection of the claims are possible and parts of the improvements can be used without other parts.

109813/0357

Claims (8)

Claims Method of forming a contact surface with spaced apart electrically conductive sectors representing a path which corresponds to the path of movement of a conductive brush which slides over it in electrical contact with it, including the steps which consist in placing a coil therethrough is produced in that a length of electrically conductive wire is wound onto a core to form turns, with equal parts of at least a plurality of turns approaching the track with gaps formed between these parts, characterized in that a relatively thick, liquid coating is deposited on and next to these same parts, pressure is exerted on this coating at least at the point where it covers these parts in order to force practically the entire coating away from these parts and into the spaces between the adjacent parts so that the cavity between these parts and the core is filled, the covering is hardened to make it adhere to the same parts, enough material is removed from the same parts to create exposed surfaces, but in such a way that the covering is in the spaces below these surfaces remains and ultimately by the fact that a conductive material is firmly adhered to the exposed surfaces in order to form conductive sectors with external contact surfaces. 109813/0357 2. The method according to claim 1, characterized in that the pressing process consists in a resilient member against the Press covering on the same parts. 3. The method according to claim 1, characterized in that the area of the core on which the mutually identical parts are mounted are lifted over the other area of the core and that when pressing the covering between the same Parts of the covering to form an edge is also pushed outwards beyond the ends of these parts. 4. The method according to claim 1, characterized in that with the pressing process, the liquid coating in spaces between the same parts on a level below the surface is displaced up to which level the portion of the conductive material is removed from the same parts. 5. The method according to claim 1, characterized in that the coil is heated that an Epoxypulvex is used to form the coating melts together on the spool and. that at least During part of the pressing time, at least the same parts of the coil are immersed in a cooling bath, to reduce the level of fluidity on the surface of the pavement. 109813/0357 ORIGINAL INSPECTED 6 * Variable autotransformer with a contact surface that is designed so that it follows the trajectory of a movable thereon and is in electrical connection with it Brush corresponds to, consisting of a core of magnetic material, a length of electrically conductive wire, which is used to Forming a plurality of turns is wound on the core, with at least some of the turns facing each other have like parts with spaces formed between adjacent parts and each of which is like each other Parts having an end face of the conductive wire, and further consisting of an electrically conductive material, which is adhered to the face of the conductive wire and which has an outer surface which the Contact surface forms, characterized by a hardened, relatively thick covering (28) made of insulating material a region of the coil (14) including the mutually identical parts (23) and adjacent to them, the covering (23) practically completely fills the gaps (25) and the parts (2J) which are identical to one another are next to one another and where this covering (2δ) has a surface which surrounds the end faces of the conductive wire, except for the end faces forms uninterrupted covering and comes to lie below the end faces and with the end faces of the conductive Wire and the coating is in the spaces below the contact surface (22). - 20 109813/0357 7. Autotransformer according to claim 6, characterized in that an outer edge (32) next to the outer edge the contact surface (22) is present and an inner edge (3I) is next to the inner edge of the contact surface (22) located, these edges (31,32) from the hardened coating (28) emerged and are thicker than this coating. 8. Autotransformer according to claim 6, characterized in that that the conductive wire (23) is semicircular Has cross section and the top of the covering (28) in the spaces (25) approximately with the diameter of the wire (23) is at the same height. 109813/0357