IES81164B2 - Electric motor comprising simplified elements for connection to the electrical supply - Google Patents

Abstract

An electric motor of the type comprising at least one stator winding and at least two elements (5) for electrically connecting the ends of the stator winding to an external electrical supply; the connection elements (5) each comprise a portion of electrical conductor (3) integral with the enamelled wire of the stator winding, in order to avoid the use of further connection elements in place of said conductor portions (3).

Description

Electric Motor Comprising Simplified Elements ter Connection to the Electrical Supply This invention relates to an electric motor in accordance with the precharacterising part of the main claim.

In known electric motors, in particular in induction motors, the stator windings are connected to the electrical supply by supplementary cables of suitable cross-section insulated electrically by a sheath of various types depending on its thermal class and its specific use. These supplementary cables generally have a core formed from copper strands so as to be flexible and be able to withstand bending and flexure.

To connect these supplementary cables to the stator wires, one end of each of the supplementary cables has to be bared from the insulating sheath and then joined, for example by soldering or crimping, to the wire or wires, for example of copper, of the stator winding (the winding can comprise several wires in parallel). Both that part of the supplementary cable which has remained uninsulated and the soldered region have to be covered with an insulating tube, this tube possibly being heat-shrunk to prevent its movement. The supplementary cable or cables are then positioned on and fixed to the top of the winding. A specific terminal of the type required for the connection to the external supply is then connected to the suitably bared other end of the supplementary cables. The aforesaid operations are relatively difficult, lengthy and complicated, and influence the motor construction time and cost.

An object of this invention is to provide a motor in which the operations required to connect the stator winding or windings to an external electrical supply are simplified and facilitated. This and further objects which will be apparent to the expert of the art are attained by a motor in accordance with the characterising part of the main claim.

The invention will be more apparent from the accompanying drawing, which is provided by way of non-limiting example and on which: Figures 1 and 2 are a schematic view from above of a stator for a motor of the - 2 invention, shown during construction and when finished respectively.

With reference to said figures, these show a conventional stator 1 for a conventional induction motor. The stator 1 in the illustrated example is of the type comprising three windings, the six ends of which have to be connected to the electrical supply.

To achieve this, a portion 3 of the copper wire 2 at the ends of the stator windings is made to emerge from the stator by a length L sufficient to allow connection to the external electrical supply. To make this connection, a conventional insulating sheath 4 is mounted on the wire portions 3, to extend from the stator winding as far as the free end 3A of the wire portion emerging from the stator.

A conventional terminal 6 is rigidly secured to the free end 3A, preferably by crimping, for connection to the electrical supply. Advantageously, the terminal 4 clamps both the copper wire and one end of the sheath, to prevent sheath movement.

By virtue of the invention it is no longer necessary to provide supplementary connection elements between the ends of the stator windings and the terminals 6, these connection elements (indicated overall by 5) being formed by using the conductor (enamelled wire) of the stator windings themselves. A direct connection is consequently formed between the electrical supply and the motor windings. The invention results in a decrease both in the motor assembly time and in the number of components required to make the connection to the external supply.

As is conventional to the expert of the art, a first part 7A of the conductor portion 3 and relative sheath 4 is secured to the stator body, whereas a second part 7B projects from the stator (Figure 2). The part 7A is secured to the stator body by conventional tie wires 6A.

To enable the connection elements 5 to be secured, yet have the terminals 6 uniformly spaced apart, if as in the illustrated example the stator has more than one winding the connection elements 5 must be of different lengths, implying that the length L of the wire portions extending from the stator windings must be different one from another.

It should be noted that besides providing further electrical insulation, the sheath 4 also protects the copper wire extending from the windings, and also increases its mechanical strength.

The motor of the invention is not suitable for use where the connection elements are subjected to continuous and frequent movement, because in such a case the wire 3 could break. However the motors of the invention are well suited to all applications in which once the connection has been made to the external supply, the connection elements are no longer subjected to handling or movement.

Finally, it should be noted that the aforedescribed embodiment has been provided by way of non-limiting example and that the invention can be used on electric motors of any type with one or more windings.

Claims (5)

1. An electric motor of the type comprising at least one stator winding and at least two elements (5) for electrically connecting the ends of the stator winding to an external electrical supply, characterised in that the connection elements (5) each comprise a portion (3) of electrical conductor having a sheath (4) of electrical insulation, the portion (3) being integral with the enamelled wire of the stator winding, in order to avoid the use of further connection elements in place of said conductor portions (3).

2. A motor as claimed in claim 1, characterised in that the ends of the stator winding are prolonged by a portion (3) having a length (L) such as to enable a first part (7A) of the portion to be rigidly secured to the stator, and a second part (7B) of the portion to be used for connecting a terminal (6) for connection to the external electrical supply, said stator winding prolongation portions (3) comprising a sheath (4) which electrically insulates them, said connection elements (5) comprising said portions (3) of the stator winding, said sheath (4) and said terminal (6) for the element connection.

3. A motor as claimed in claim 3, characterised in that the terminals (6) are rigidly secured both to one end (3A) of the electrical conductor portion (3) extending from the stator windings and to one end of the insulation sheath (4).

4. An electric motor substantially as described herein with reference to and as illustrated in the accompanying drawings.

5. An electric motor stator substantially as described herein with reference to and as illustrated in the accompanying drawings.