COIL FORMER AND COIL BODY FOR AN ELECTROMAGNETIC RELAY

The present invention relates to a coil former for an electromagnetic relay which is configured to include a core and upon which a coil winding can be fixed. The coil former thus comprises a first coil flange and a second coil flange, between which a cylindrical winding area for fixing a coil winding is arranged.

The present invention also relates to a coil body for an electromagnetic relay which comprises a base and a coil former which are integrally connected to one another.

In order to achieve a particularly simple manufacturing process and compact construction in electromagnetic relays, it is known for the base and the coil former of such an electromagnetic relay to be produced in one piece from a plastic material. DE 19718985 C1 shows, for example, a relay with a combined coil body of this type. The relay disclosed in said document consists of a coil former, a T-shaped or almost M-shaped core, a U-shaped armature, a card-shaped slider, a fixed contact spring, a mobile contact spring, a casing and two coil terminals fixed in the coil former. The double plate which comprises plug-in slots for the connector elements of the contact springs is integrally moulded on the coil former.

A further known configuration of a relay with a coil body of this type is known from EP 1 271593 A2. The decisive drawback, however, of the known coil bodies is that, in the known configuration, they are conceived in such a way that, in the case of production by a master mould, that is to say generally by means of an injection-moulding process, it is always necessary to have four de-moulding directions. This is based on the fact that the known coil bodies correspondingly comprise many undercuts. Of course, this also applies to known coil formers which are produced separately without the base. In addition, the required master mould tools for producing such a coil former or coil body are comparatively expensive, and the production method is correspondingly lengthy, in particular with regard to de-moulding.

The object of the present invention is to improve a coil former for an electromagnetic relay of the known type so the coil body can be produced more quickly and in a more cost-effective manner.

Said object is achieved by the subject-matter of the independent claims. Advantageous developments of the present invention are the subject-matter of the dependent claims.

The invention is therefore based on the idea that one of the two coil flanges of the coil former is configured in such a way that a portion of its periphery ends so as to be flush with the winding area. This omission of part of the flange allows the outer side of the coil former to be de-moulded in the same direction as the core. In this manner, it is possible to construct the undercuts of a coil former in such a way that a minimum number of de-moulding directions must be provided, even only two in the appropriate construction. This reduces the complexity of the master mould and accelerates de-moulding during the production process. For an integrated coil body which has such a coil former with an integral base, said reduction according to the invention of the necessary de-moulding directions may be used in a particularly advantageous manner.

In particular, the construction according to the invention has a particularly advantageous effect with regard to injection moulding. Said method is characterised in that the plasticized material (the injection-moulding compound) is, in the case of thermoplastic polymers, injected into a cooled master mould tool (the injection-moulding tool) at a high pressure and, in the case of thermosets, is injected into a heated master mould tool at a high pressure and solidifies under the influence of pressure. After the substance used has solidified, the injection-moulding tool is opened and the moulding (the injection-moulded part) is removed.

Opening the injection-moulding tool is a multiple-stage process, of which the complexity depends on the number of undercuts in the moulding. The advantage of this production method is that the vast freedom of shape means it is possible to implement a particularly wide range of constructional ideas.

According to the invention, by omitting undercuts which would necessitate an excessive number of de-moulding directions, the de-moulding process is systematically simplified and made more efficient.

According to an advantageous embodiment of the present invention, a coil former with only two de-moulding directions may be produced in that the flange moulded integrally on the end region of the coil former does not occupy the entire periphery but is only present at approximately less than three quarters of the periphery. A part of the periphery of the coil former facing the region of the base, in which part the contacts are arranged, is configured without an undercut so no coil flange is provided there. In this manner, the master mould can be removed from the finished coil former in only two de-moulding directions.

The present invention is therefore based on the idea that in order to reliably fix and hold the coil winding it is not necessary for the first coil flange to be circumferential. This basic principle may of course also be used for any type of coil which comprises a coil former with a coil winding wound thereupon.

In particular, the coil former may either have a rectangular cross-section or a circular cross- section. In the first case, the two-step de-moulding process according to the invention is achieved by omitting the coil flange one of the sides of the rectangle. If the cross-section of the coil former is circular, i.e. generally in the case of a round coil tube, a substantially semicircular flange may be provided instead of the conventional circumferential flange provided in the prior art.

The above-mentioned advantages of a coil former according to the invention may be advantageously used for assembling an electromagnetic relay. In this case, both a separate coil former and base as well as a combined coil body, in which the coil former is configured according to the principles of the present invention, may be used in an electromagnetic relay of this type.

Combined coil bodies comprise a base and a coll former which are produced in one piece and of which the longitudinal axes extend substantially transversely to one another. The flanges required for fixing the coil winding are conventionally produced, on the one hand, in an end region of the coil former and, on the other hand, are formed so as to be integrated by a corresponding face of the base (see, for example, Fig. 14 of EP 1271593). In contrast to a base and a coil former produced separately, said single-piece embodiment is characterised by low production and assembly costs and by high mechanical strength.

In order to better understand the present invention, it will be explained in greater detail with reference to the embodiments illustrated in the figures hereinafter. Like parts will be provided with like reference numerals and like component designations. Furthermore, solutions which are independent, inventive or in accordance with the invention may be represented by specific features or combinations of features of the various embodiments shown and described, in which:

Fig. 1 is a perspective view of a coil former according to a first embodiment;

Fig. 2 is a perspective view of the coil former shown in Fig. 1 rotated about 180 degrees;

Fig. 3 is a perspective view of a coil former according to a further embodiment;

Fig. 4 is a perspective view of the coil former shown in Fig. 3 rotated about 180 degrees;

Fig. 5 is a perspective view of a coil body for an electromagnetic relay;

Fig. 6 is an exploded perspective view of an electromagnetic relay with the coil body according to the invention.

Fig. 1 is a perspective view of a first embodiment of a coil former 104 according to the invention. Fig. 2 shows a view of the coil former 104 shown in Fig. 1 , rotated about 180 degrees. The coil former 104 shown in this case is a substantially rectangular coil tube comprising a first coil flange 108 and a second coil flange 110, between which a cylindrical winding area 116 for a coil winding 124 (see Fig. 6) is arranged. In an interior 113 of the coil former 104, a substantially u-shaped core 126 (see Fig. 6) may be arranged as shown, for example, in Fig. 6. According to the invention, the first coil flange 108 does not occupy the entire periphery of the winding area 116, but is omitted in a region of a fourth side of a rectangular cross-section. Because the first coil flange 108 thus ends so as to be flush with the winding area 116, an outer side of the coil former 104 may be de-moulded at this face in the same direction as the interior 113. In this embodiment, the second coil flange 110 is integrated with a base 106 (see Fig. 6), through which coil terminals 115 (see Fig. 6) are guided through openings 114.

An alternative embodiment of the coil former 104 according to the invention is shown in Figs. 3 and 4. In this embodiment, the second coil flange 110 remains substantially unchanged, however, the winding area 116 is cylindrical and has a circular cross-section. In order to achieve the same effect as the embodiment shown in Figs. 1 and 2 when de-moulding the coil former 104, the first coil flange 108 is produced in this case as a semi-circular collar in an end region of the winding area 116.

Of course, in principle, the first coil flange 108 must not necessarily be provided in order to reliably fix and hold the coil winding 124 (see Fig. 6). In order to save material, further gaps could also be provided so only one type of collar plate adopts the function of the first coil flange 108. The main advantage of the configuration according to the invention of the coil former 104 is that it is easy to produce.

With reference to Fig. 5, the basic principle of the present invention when using an

integrated coil body 102 will be explained hereinafter in greater detail. The coil body 102 according to the invention combines, in an integrated construction, a coil former 104 and a base 106 functioning as a base for an electromagnetic relay 100 (see Fig. 6). The coil former 104 and the base 106 are integrally connected to one another and are made of an electrically insulating material using injection-moulding techniques. The coil former 104 is configured as a cylindrical hollow body and has a rectangular inner cross-section which corresponds to a cross-section of the core 126 (see Fig. 6).

At a free end of the coil former 104 a collar is arranged so as to form a first coil flange 108. A second coil flange 110 is produced by a corresponding flange region of the base 106. Plug- in slots 112 for inserting contact springs of a contact system are provided in the base 106. Openings 114 are formed in the second coil flange 110 and are used for fixing coil connector pins (see Fig. 6).

According to the invention, the first coil flange 108 between which the coil winding 124 (see Fig. 6) is fixed, is not integrally moulded circumferentially at an end region of the coil former 104. Only a region facing the openings 114 of the coil former cross-section and a part of the respective shorter side extending transversely thereto of the rectangular cross-section is provided with the first coil flange 108.

The first coil flange 108 formed as a partial flange is adequate for securely fixing and holding the coil winding 124 (see Fig. 6) but, on the other hand, also allows the winding area 116 facing the base 106 with the plug-in slots 112 to be configured so as to be flush and with no undercutting collar. As can be seen in Fig. 1 and as is shown by arrows 118, 120 and 122, this constructive measure means that, during production, the coil body 102, which has been cured, can be de-moulded by removal of a master mould in three de-moulding directions.

The reduction according to the invention of the first coil flange 108 in such a way that the fourth side of the cross-section remains free, allows the coil body 102 to be de-moulded in a substantially simplified manner and also simplifies production and allows for a simplified tool. In particular, the coil body 102 of this type may be particularly advantageously used in the field of electromagnetic relays.

Fig. 6 shows an exploded perspective view of an example of the electromagnetic relay 100. The electromagnetic relay 100 comprises the coil body 102 which integrally combines the coil former 104 and the base 106. The coil winding 124 is fixed and securely held between

the first coil flange 108 and the second coil flange 110 of the base 106 configured as the second coil flange 110.

The core 126 is inserted into the coil former 104 and arranged in such a way that a yoke 128 can cooperate with an armature 140. The coil winding 124 is supplied with current via the coil terminals 115. A fixed contact spring 132 and a mobile contact spring 130 are arranged in the plug-in slots 112 (see Fig. 5).

When the current flows, the armature 140 is attracted to the yoke 128 and the mobile contact spring 130 is pressed onto the fixed contact spring 132 via a slider 134, which may occasionally also be referred to as a ridge, and electrical contact is produced.

A casing 136 protects the electromagnetic relay 100 from dust and disruptive environmental influences. However, by removing a protruding lug 138, the relay may be ventilated if desired.