GB2300077A - Transformer assembly providing a terminal pin mounting arrangement - Google Patents

Abstract

A transformer assembly has a bobbin having a number of outward extending bosses A. Each boss A includes a hole 21 through which extends part 52 of a terminal pin 55. A portion 58 of the terminal pin 55 is exposed to the exterior of the boss A and is inclined relative to the terminal pin part 52. The portion 58 is also directly engaged by the tip of a rib 40 formed on the inside of a shroud member. The terminal pin 55 may be L-shaped and a trough 22 may be formed in the boss A to partially receive the terminal pin portion 58. The transformer assembly may be mounted on to a printed circuit board 57.

Description

TRANSFORMERS This invention relates to an assembly of a bobbin of a transformer, a shroud for covering the bobbin and a terminal pin, in which the bobbin has a boss extending outwardly and the shroud has a rib projecting inwardly towards the boss and towards the terminal pin, part of which pin fits within a hole through the boss. Such an assembly is referred to below as an assembly as defined.

In a known assembly as defined, the pin is straight but has a local widening which is closely surrounded by a widened region of the hole through the boss so that lengthwise movement of the pin is prevented or hindered.

According to the present invention there is provided an assembly as defined in which the pin has, instead of the widening, a portion which is inclined to, for example substantially perpendicular to, a part of the pin which lies within the hole through the boss and said portion is exposed at the exterior of the boss and is directly engaged by the tip of the rib.

The pin is preferably substantially L-shaped and preferably said portion of it lies in a trough in the boss.

An example in accordance with the invention is described below with reference to the accompanying drawings in which: Figure 1 shows a front elevation of a bobbin of a transformer, Figure 2 shows a view of the bobbin, taken as indicated by the arrow II in Figure 1, i.e. an underneath plan view, Figure 3 shows a side elevation of the bobbin, seen when looking in the direction of the arrow Ill in Figure 1, Figure 4 shows a sectional view, taken as indicated by the arrows IV in Figure 3, of part of the bobbin, Figure 5 shows a front elevation of a shroud, Figure 6 shows a side elevation of the shroud, seen as indicated by the arrow VI in Figure 5, Figure 7 shows an underneath plan view of the shroud, seen as indicated by the arrow VII in Figure 5, Figure 8 shows a side elevation of the complete transformer comprising the bobbin, the shroud, terminal pins and coils, and Figure 9 shows a sectional view of part of a transformer mounted on a printed circuit board.

The bobbin consists of a single moulding of a heat stabilised 30% glass filled nylon 66, preferably black in colour. The bobbin and has two rectangular flanges 11 and 12, between which a coil is wound on a hollow core 13, and two more rectangular flanges 14 and 15, between which a coil is wound on a hollow core 16. There is an empty passageway 10 of rectangular cross-section through the flanges and the cores and through a rectangular part 20 which connects the flanges 1 2 and 14 to each other. The coils are not shown.

They are in the form of tubes of rectangular cross-section, as are the cores 1 3 and 16, and they consist of copper wire with enamel insulation. Projecting outwardly from the remainder of the bobbin at one side are five bosses A, near which the numbers 1 to 5 (shown inverted in Figure 8) are formed during the moulding process, and projecting outwardly from the remainder of the bobbin at the other side are four bosses A near which the numbers 6 to 9 (shown inverted in Figure 3) are likewise formed. The numbers are formed on faces 17 of two strips 18 and 19 which connect the bosses A to the flanges 15 and 11, respectively, and which are thinner between bosses A than they are at the locations from which the bosses project.

The bosses A are each formed with a hole 21, of circular cross-section, through it which opens into a trough 22 in the top of the boss and the lower end of the hole 21 is countersunk at 23. The strip 18, but not the strip 19, is formed with a channel 24 of substantially square cross-section which extends along the entire length of the strip. Between the bosses A numbered 8 and 9 there is a part B which is not formed with a trough 22 (see Figure 3) and does not extend outwardly (see Figure 2).

The shroud consists of a single moulding of the same material as the bobbin and has an upper, box-like part 30, which is designed to fit over the top and all four sides of the assembly of the bobbin and its coils, and a lower, lid-like part 31 which is connected by a hinge portion 32 to the part 30 and is intended to be swung under that assembly and to be fastened at its left-hand side to the right-hand side (Figure 6) of the part 30. The part 31 does not extend between the bosses A.

In greater detail, the part 30 includes a top panel 35 formed with four rectangular depressed areas 36, which go above the coils on the bobbin. Two opposite side walls 37 each has near its upper end an outwardly-directed flange 38 and at its lower end a skirt portion 39, which extends firstly outwardly and then downwardly so as to cover the bosses A. The outwardly-extending parts have respective ribs 40, one of which, in the assembly of the bobbin and the shroud, extends inwardly towards the bosses A shown on the right-hand side of Figure 1 while the other extends inwardly towards those shown on the left-hand side. One rib 40 is interrupted at a location corresponding to that of the part B of the bobbin. That same rib 40 is adjacent a less deep inwardly-directed rib 41 which is to fit into the channel 24 in the bobbin. The rib 41 is shown in Figure 5 but not in Figure 7.

The part 31 of the shroud has a top panel 45 which is horizontal as shown in Figure 6, and an end panel 46 which is inclined at about 930 to the top panel 45 and is formed with a rectangular aperture 47. That aperture is to receive a plate-like projection 48 on one of the other two opposite side walls 49 of the part 30 of the shroud when the shroud is in its final configuration and surrounds the bobbin and the two coils wound on it, as shown in Figure 8. Then laminations 50 are assembled on a rectangular core formed by the side walls 37 and 49 of the shroud, the laminations 50 being between the flanges 38 and the skirt portions 39.

Each boss A receives part of a terminal pin 55, shown in Figure 9, which has a straight vertical portion, a part 52 of which is a close fit within the hole 21 through the boss (the hole 21 is countersunk at the bottom in the example shown in Figure 9) whereas below that the pin is soldered at 56 to a metallic part fixed to a printed circuit board 57. The pin 55 is in fact substantially L-shaped, having a straight horizontal portion 58, exposed at the exterior of the boss and directly engaged by the tip of the rib 40. Part of the horizontal portion 58 lies within the trough 22 in the boss A whilst an outward part of it has wound around it and soldered to it one end 59 of the wire forming a coil 60 wound on the bobbin. The pin 55 cannot move downwardly, since it has the horizontal portion 58 bearing on the floor of the trough 22, it cannot move upwardly, because the rib 40 of the shroud prevents this, and it cannot rotate about a vertical axis because the side walls of the trough 22 prevent this.

Claims (6)

1. An assembly of a bobbin of a transformer, a shroud for covering the bobbin and a terminal pin, in which the bobbin has a boss extending outwardly and formed with a hole through it, the terminal pin has a part within the hole and a portion which is inclined to said part and is exposed at the exterior of the boss and the shroud has a rib projecting inwardly towards the boss and the terminal pin, the tip of the rib directly engaging said portion of the terminal pin.

2. An assembly according to claim 1 in which said part of the terminal pin and said portion thereof are substantially perpendicular to one another.

3. An assembly according to claim 1 or 2 in which the terminal pin is substantially L-shaped.

4. An assembly according to any preceding claim in which said portion of the terminal pin runs along a trough in the boss.

5. An assembly according to any preceding claim in which said portion of the terminal pin, proceeding from its junction with said part thereof, projects beyond said boss to an outward part to which one end of a coil wound on the bobbin is fastened.

6. An assembly of a bobbin of a transformer, a shroud and a terminal pin, substantially as hereinbefore described with reference to Figure 9 of the accompanying drawings or Figures 1 to 9 thereof.