Enamelled wire connection for circuit boards

Abstract

Disclosed is an arrangement for providing an electrical connection to the enamelled wire of a coil of an electrical motor. The arrangement includes a circuit board carrying at least one conductive component such as an electrical trace on the surface of the circuit board. A conductive pin-type contact, also carried by the circuit board, is electrically connected to the conductive component. An insulating body is carried by the electrical motor and includes passageways for receiving at least two pin-receiving receptacle terminals. The receptacle terminals have inwardly-extending rib members for engaging the enamelled wire when the enamelled wire and the pin-type contact are inserted therein. The rib members are operative to penetrate the enamel covering to establish electrical contact with the wire.

Description

The invention concerns a device for producing an electrically conductive connection between the enamelled wire ends of one or several stator coils of an electrical motor, especially a direct current motor without a collector, and electrical conductors with contact pins, each of which, individually and in common with one or several of the enamelled wires to be contacted, is, by producing a radial compression, through which the enamel casing of the enamel wire is in places penetrated or removed in a contacting manner, inserted in the axial direction into the hollow space of an insulating body.

With increased use of electronic components for the control or power supply of devices which have electromagnetic enamelled wire coils, such as, for example, relays, transformers, motors and the like, the use of circuit boards also increases, and therewith as well the technical problem of how to connect the Cu-enamelled wire ends of the coils of these electromagnetic devices to the circuit boards in serial sequence and with adequate contact security. In this, the insulating enamel layer should, for reasons of cost, be removed from the Cu-wire at the connecting place, and a firm connection with the conductor track be produced at the same time. Previously, this was done in such a way that the enamelled wire section to be attached was soldered directly onto a conductor track with a soldering bit. In this, the insulating enamel layer is removed from the wire, and it is necessary that the hot soldering bit be repeatedly guided with a certain bearing pressure over the individual wire, so that the insulating enamel melts, and the exposed wire surface has direct contact with the fluid soldering material. This method is not only very time-consuming, but also entails the danger that, particularly with very thin enamelled wires, the wire section to be joined breaks, or that no electrical contact occurs.

It is, of course, known to provide electrical circuit boards with contact pins which are closely pressed into the borings of the circuit boards, and soldered together with the other construction elements of the circuit boards. These known contact pins are, however, only used where a metallic plug socket which accommodates the contact pin in a clamping manner is present as a fixed contact element.

It is also already known (U.S. Pat. No. 3,014,140) to connect the enamelled wire ends of the coil of a shaded pole motor in a contacting manner with individual contact pins, through the fact that a contact pin section provided with a threading is pressed into a boring of an insulating casing together with an enamelled wire section. Through this, the sharp-edged threads burrow into the enamel casing up to contact with the wire. Connecting strands are joined to the contact pins by means of attachable clamping plates.

Apart from the fact that this manner of producing a contacting connection is only suited for relatively thick enamelled wires, the danger that the wire end, upon insertion of the contact pin into the boring, will break is very great, since the end of the wire is also drawn into the boring.

This task is, in accordance with the invention, solved through the fact that, in circuit boards provided with electronic control elements and attached to the insulating body, several contact pins provided with smooth casing surfaces are attached in a contacting manner, and that the plastic body has, in several borings, axially parallel receptacle terminals of metal, each of which, serves to accommodate one of the contact pins, the inner surfaces of which slightly taper conically in the direction of insertion, and/or are provided with riblike elevations which run essentially laterally to the axial direction.

The principal advantage which is to be obtained through this is to be seen in the fact that the electrical contact between the coil wires and the conductive tracks of the printed circuit board and the mechanical attachment of the circuit board occurs in the same work process on the plastic body, and that the danger of breaking or shearing is prevented by the fact that either no sharp-edged parts come into contact with the wire, or that the elevations are positioned on the part which does not move relative to the insulated wire.

28 28'), which then penetrate the enamelled wire layer, and produce a conductive connection to the metal wire. Approximately the same result also appears during the driving of the contact pin (30) into the receptacle terminal (27), with the difference that the annular reinforced corrugations (28) penetrate the enamelled casing of the wire in less a cutting manner than in a squeezing manner, in order to contact the wire, since they are blunter.

Through the fact that the upper ends of the receptacle terminals (27 and 27/1) are expanded in a flared manner, the enamelled wire ends, if they are inserted from above with a loose loop into the receptacle terminals (27), upon insertion of the contact pins (30), execute an axial motion, without the danger of their being damaged at the edges of the receptacle terminals (27).

Since the contact pins (30) used together with the receptacle terminals (27 and 27/1) have a smooth cylindrical casing surface and conically rounded tips, which make an edgeless transition into the cylindrical casing surface, no sharp edges are present on the contact pins (30) themselves, which, in cooperation with the edges (28/1) of the annular corrugations (28') or the reinforced corrugations (28), exert a shearing effect, and can cut the enamelled wire during insertion into the receptacle terminal (27 or 27/1).

While the receptacle terminals (27), with their elevations which consist of reinforced corrugations (28), are suited for thin, as well as for relatively thick enamelled wires, the receptacle terminals (27/1) with the relatively sharp-edged annular corrugations (28') are more advantageous for contacting extremely thin enamelled wires.

It is also possible to use unslotted receptacle terminals, that is, ones which are smooth all around, which have smooth internal wall surfaces, together with likewise smooth contact pins (30), for contacting with enamelled wires, if the diameter tolerances are precisely dimensioned to the wire strength, and an increased insertion force is tolerated. In this it is of advantage if the smooth internal surfaces taper slightly conically in the direction of insertion, and are, for example, on the insertion side, around a wire thickness further than the end of the insertion length.

Claims

1. An arrangement for providing an electrical connection to the enamelled wires of the coil of an electrical motor, comprising, in combination:

a circuit board carrying at least one conductive component;

a conductive pin-type contact carried by said circuit board and electrically connected to said conductive component;

an insulating body carried by said electrical motor, said insulating body defining at least two receptacle-receiving passageways therein; and

conductive-pin receiving terminals having wall means defining a pin-receiving cavity and engaging means associated with said wall for electrical engagement with one said enamelled wire and one said pin-type contact inserted into said cavity, said engaging means operative to penetrate the enamel covering said wire to establish electrical contact with said wire and said pin.

2. The combination of claim 1 wherein said motor further includes latching means carried by said insulating body for latching to said circuit board, said receptacle terminals arranged to mate with said pin-type contacts as said latching means are latched to said circuit board.

3. The combination of claim 1 wherein said engaging means comprise inwardly-extending rib members formed in said receptacle terminal.

4. The combination of claim 1 wherein said receptacle terminal has a pin-receiving end and defines a slot extending from said pin-receiving end along at least two-thirds the length of said receptacle terminal.

5. The combination of claim 1 wherein said insulating body is supported by a stack of plates of the motor.

6. The combination of claim 1 wherein said engaging means comprises an end section of said receiving terminal wall conically tapered in the direction of insertion.

7. The combination of claim 3 wherein each said rib member has a single edge for penetrating the enamel covering said wire.

8. The combination of claim 3 wherein each said rib member has two edges for penetrating the enamel covering said wire.

9. The combination of claim 1 wherein said insulating body includes wall means defining said receptacle-receiving passageways, said wall means slotted along their length to produce a resiliently-expandable passageway which augments the mating contact force of said engaging means with said pin-type contact.

10. An arrangement for providing an electrical connection to the enamelled wires of the coil of an electrical motor, comprising, in combination:

a circuit board carrying at least one conductive component;

a conductive contact pin carried by said circuit board and electrically connected to said conductive component;

an insulating body carried by said electrical motor, said insulating body defining at least two receptacle-receiving passageways therein; and

at least one conductive pin-receiving receptacle terminal having wall means defining a pin-receiving cavity and engaging means conductively associated with said wall means for electrical engagement with one of said enamelled wires, said engaging means operative to penetrate the enamel covering said wire to establish electrical contact with said wire. 11. The combination of claim 10 wherein the motor is a brushless direct current motor. 12. The combination of claim 10 wherein said receptacle terminal has a pin-receiving end and defines a slot extending from said pin-receiving end along at least two-thirds the length of said receptacle terminal.