Patent Publication Number: US-4927379-A

Title: Electrical connector

Description:
SUMMARY OF THE INVENTION 
     The present invention seeks to mitigate this drawback not only in commutator segments, but also in other types of electrical connector 
     According to the present invention there is provided an electrical connector having two overlying parts, each part being provided with a slot open at one end and the two slots being arranged so as to be only partly in register with one another so that the resulting slot in the connector is narrower than each of the slots in the two overlying parts and is open at one end for receiving and gripping a wire, non-aligned regions (as considered in a direction perpendicular to the plane of each overlying part) bordering the slots of the two overlying parts being offset, e.g. part sheared, out of the plane of the respective part towards the other part. 
     Preferably, the two overlying parts are integrally connected at a fold line extending transversely of the longitudinal extent of the said resulting slot. 
     Advantageously, said non-aligned regions are half-sheared out of the plane of the respective part and the two overlying parts are in contact or closely adjacent to one another so that said regions lie in, or substantially in, a common plane. 
     Other preferred and/or optional features of the invention are set forth in claims 5, 6 and 7. 
     Conveniently, the connector forms a terminal portion of a commutator segment and serves to connect an armature winding portion to the commutator segment. However, the connector could take other forms. For example, it could slidably connect with a terminal to connect a wire thereto. 
     The invention will now be more particularly described by way of example with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a commutator provided with commutator segments (only one shown) embodying the invention, 
     FIG. 2 is an enlarged plan view of one embodiment of a commutator segment embodying the invention, in blank form, 
     FIG. 3 is an enlarged plan view of part of the commutator segment of FIG. 2 shown partly formed, and 
     FIG. 4 is a section taken along line IV--IV of FIG. 3 on an enlarged scale. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1 of the drawing, there is shown therein a commutator base 10 and a commutator segment 11. The segment 11 has an electrical connector in the form of an integral terminal portion 12 at one end and an integral lug 13 at its other end with a brush contacting portion 9 therebetween. The base 10 has at one end an integral rose-like arrangement of five housings 14 each provided internally with a central boss (not shown) upstanding from the base of the housing. 
     In assembling this commutator, an armature winding portion is located in an aligned pair of slots 15 in each housing so as to be supported by the closed ends of the slots 15 and a respective boss. The commutator segments (only one shown) are then moved in a direction parallel to the axis of the base 10 so that the terminal portions 12 move into respective housings 14 and the lugs 13 move into respective recesses in the end of the base remote from the housings. Slots 16 in parallel arms 17 of the terminal portions 12 have cutting edges which strip insulation from the winding portions as the slots 16 move thereover and the slots then straddle and grip the core of the winding portions to establish and maintain electrical contact between the winding portions and respective terminal portions 12. 
     Each arm 17 comprises two overlying parts as more particularly shown in FIGS. 2, 3 and 4. 
     The terminal portion 12 of the commutator segment blank shown in FIG. 2 is generally rectangular with its minor axis coincident with the longitudinal axis of the brush contacting portion 9 of the commutator segment. The terminal portion 12 comprises a central part 18 and two end parts 19 and 20. The central part 18 has a central cut out portion 8 which reduces from its largest width at the centre to two elongate slots 21 which terminate either end of the cut out. Each end part 19, 20 also has an elongate slot 22 which, when the end part 19, 20 is folded about fold line 23, 24, respectively, to overlie the central part 18 (as shown in FIG. 3), comes only partly into register with the respective slot 21 in the central part 18. 
     Thus, the resulting slot 16 (FIGS. 1 and 3) on each side of the terminal portion is narrower than each of the slots 21 and 22. 
     Non-aligned regions (as considered in a direction perpendicular to the plane of each overlying part) 31 and 32 bordering the slots 21 and 22, respectively, of the two overlying parts 18 and 19 and the two overlying parts 18 and 20 are offset out of the plane of the respective part towards the other of the two overlying parts. This is most clearly seen in FIGS. 3 and 4. The regions 31 and 32 interlock with non offset regions, as best shown in FIG. 4, to prevent movement of the end parts 19 and 20 with respect to the central part 18. 
     The offset of the respective non-aligned regions is effected by a part-shearing operation and preferably the regions 31 and 32 are half sheared out of the plane of the respective part 18, 19, 20 so that when the overlying parts 18 and 19 and the overlying parts 18 and 20 are in contact or closely adjacent to one another as for example shown in FIG. 4 the regions 31 and 32 of each arm 17 lie in a common plane to define the resulting slot 16. 
     Two cutters 26 and 27 having sharp cutting edges project into each slot 16 the cutter 26 being provided on the region 31 of the central part 18 and the cutter 27 being provided on the region 32 of the end part 19, 20. The cutting edges on the cutters 26 and 27 are for stripping insulation from the winding portions as previously described. 
     The closed end of the slot 16 is enlarged to ensure that the edges of the slot 16 have a certain resilience to separation by the winding. 
     A triangular barb 28 is provided on either side of the minor axis of the central part 18 along the edge furthest from the commutator segment. Barbs 29 on the end parts 19 and 20 register with barbs 28 when the end parts 19 and 20 are folded to overlie the central part 18 as shown in FIG. 3 and these barbs 28 and 29 grip the housing 14 (FIG. 1) and therefore retain the terminal portion 12 in the housing 14. 
     The brush contacting portion 9 of the commutator segment is of arcuate form to conform to the external radius of the commutator base 10. The terminal portion 12 is bent upright from the commutator segment 11 and the central part 18 of the terminal portion is bent at 90° in areas 30 to form the arms 17 (FIG. 1) which extend parallel to each other and to the longitudinal axis of the commutator segment 11, and forward along the length thereof. 
     The above embodiment is given by way of example only and various modifications will be apparent to persons skilled in the art without departing from the scope of the invention defined by the appended claims. 
     For example, the terminal portion 12 may be designed with only one arm 17 or may have more than two arms 17. Instead of the barrel commutator shown, the commutator may be a face commutator with the commutator segments arranged in a single plane perpendicular to the axis of the armature. Furthermore, the winding portions may be pre-stripped of insulation thus avoiding the need to provide the cutters 26 and 27. 
     Also the electrical connector could take a form other than an integral terminal of a commutator segment. For example, the connector could be in the form of a device for connecting a wire to a terminal, the device being adapted to slidably connect with the terminal and having a slot formed in the manner described herein which straddles and grips a wire as the device is connected to the terminal.