GB2221089A

GB2221089A - Rectifier bridge

Info

Publication number: GB2221089A
Application number: GB8912641A
Authority: GB
Inventors: Pierluigi May; Luciano Buschi; Ernesto Roverselli
Original assignee: Industrie Magneti Marelli SRL; Magneti Marelli SpA
Current assignee: Industrie Magneti Marelli SRL; Marelli Europe SpA
Priority date: 1988-06-22
Filing date: 1989-06-02
Publication date: 1990-01-24
Also published as: TR24679A; FR2633463B1; IT8867582A0; GB8912641D0; FR2633463A1; ES2013570A6; DE3918767A1

Description

1 i 1 - 229,5n,4

DESCRIPTION

The present invention relates to a rectifier bridge for an electrical generator, particularly an alternator associated with the engine of a motor vehicle, including two vaned or partially-vaned dissipator bodies which face each other so as to define a space for the mounting of two rows of diodes of the rectifier bridge.

The two rows of diodes have f irst terminals which are connected electrically to the dissipator bodies, for example, by means of soldering, and second terminals which face and are in contact with each other and have projecting appendages which act as connectors for connection to the electrical generator.

The dissipator bodies, which are normally made of aluminium or alloys thereof, are currently produced by drawing and the subsequent treatment of the drawn pieces by copper-zinc plating, nickel plating, tin plating, etc, in correspondence with the portion to which the diodes of the recitifer bridge are to be soldered. The drawn and treated aluminium bars are then cut in order to produce vaned dissipator bodies of the desired width.

The galvanic surface treatment of the drawn bars intended for the production of dissipator bodies with soldered diodes is difficult to achieve and has a considerable effect on the final cost of the rectifier bridge. In fact, in a typical treatment cycle, seven stages are necessary: cleaning of the surface in an alkaline bath, cleaning in an acid bath, alkaline bronze plating, alkaline copper-zinc plating, copper plating, tin plating, and the polishing of the surface 2 by the melting of the tin.

The object of the present invention is to provide a rectifier bridge of the type specified at the beginning of the description which enables the surface treatment of the dissipator bodies to be eliminated, whilst ensuring that the diodes can be soldered properly to the dissipators.

This is achieved by virtue of the fact that each dissipator body has an easily-solderable insert -to which the diodes of one row are connected electrically.

The insert can conveniently be made of copper or alloys thereof since this material presents no problem for the soldering of the diode terminals.

Moreover, the dissipator bodies are preferably produced, for example, by the pressure casting of aluminium or another suitable metal or alloy,. the inserts being inserted in the pressure-casting dies so as to be comoulded with the dissipator bodies, ensuring a proper electrical connection between them.

Further characteristics and advantages of the present invention will become clear from the detailed description which follows with reference to the appended drawings, provided by way of non-limiting example, in which:

Figure 1 is a front view of a rectifier bridge according to the invention, Figure 2 is a section taken on the line II-II of Figure 1, 3 Figure 3 is an exploded perspective view of the bridge of Figure 1, Figure 4 is a section taken on the line IV-IV of Figure 3 j, Figure 5 is a section taken on the line V-V of Figure 3, Figure 6 is a plan view of a detail of Figure 3, Figure 7 is a view taken on the arrow VII of Figure 6, Figure 8 is a view taken on the arrow VIII of Figure 6, and Figure 9 is a detail of Figure 2 according to another embodiment of the rectifier bridge.

With reference. to the drawings, a rectifier bridge of an alternator mounted in a motor vehicle is generally indicated 1. The rectifier bridge 1 includes two vaned or partially-vaned dissipator bodies 2, 3 (in case heat must be dissipated by conduction) coupled together frontally with the interposition of an insulating element 4, by means of screws 5, so as to form an arcuate segment which can be connected frontally to or within the alternator casing (not shown).

The bodies 2 and 3 are made of aluminium and are provided with external vanes 2a and 3a, the individual vanes varying in length so as to give the assembly the aforementioned appearance of an arcuate segment. The dissipator bodies 2 and 3 have respective f lat surfaces 6 and 7 which face each other so as to def ine a space 4 for the mounting of the diodes of the rectifier bridge.

The latter are arranged in two rows of three diodes, indicated 8 (on the body 2) and 9 (on the body 3) respectively.

The surfaces 6 and 7 of the dissipator bodies 2 and 3 have rectangular recesses 10 in which inserts 11 of copper or alloys thereof are housed. The dissipator bodies 2 and 3 are produced by pressure casting and the inserts 11 are inserted by co-moulding with the bodies, so as to ensure proper adhesion and proper electrical connections.

Each insert 11, which is in the form of a rectangular plate, has a first surface lla provided with a plurality of ribs 12 for improving adhesion to the respective dissipator body, and a second flat surface llb to which the first terminals A of the rows of diodes 8 and 9 are soldered. According to solutions already known in the art. the latter have second terminals B which face each other and are connected together electrically by blade connectors 13 intended to be connected to the electrical generator.

In the most usual situation of use, the latter is constituted by a triphase alternator. Each of the rows 8 and 9 therefore comprises three diodes, each of which has its free terminal B which extends into contact with the free terminal of a corresponding diode of the other row joined to the respective connector 13 which is intended to be connected to one of the three phases of the alternator.

With this arrangement of the electrical connection of 1 the diodes, a pseudo-direct voltage (that is, one achieved by the rectification of the three phases of the alternator) is established between the dissipator bodies 2 and 3, with the positive pole in the body 2 and the negative pole in the body 3. The electrical connection between the dissipator bodies and the electrical system of the motor vehicle is achieved by means of rivets or bolts inserted in suitable seats 14 provided in the sides of the dissipator bodies.

With the use of the copper or alloy inserts 11,, the soldering or brasing of the diodes of the bridge is not difficult and the galvanic treatment of the flat surfaces 6 and 7 of the dissipators is no longer necessary. The production process is therefore simplified and the cost of the rectifier bridge thus obtained is consequently reduced. Moreover, with the use of the copper inserts 11, a better and more uniform distribution of the temperature of the dissipator bodies is achieved, ensuring better heat exchange between the diodes and the vaned dissipator bodies. The reliability and life of the rectifier bridge is consequently increased.

In a second embodiment (Figure 9), at least one of the inserts 11, preferably that associated with the dissipator 3 which has negative polarity, has a portion llc flush with the side wall of the dissipator so that it can be placed in contact with the casing of the alternator in order to increase the dissipation of heat.

In order to increase the surface of the copper insert 11 which is in contact with the alternator casing, or the cooling air flow, the portion llc of the insert has 6 a bent, L-shaped configuration.

Naturally, it is understood that the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated in the drawings, without thereby departing from the scope of the present invention.

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Claims

1 A rectifier bridge for an electrical generator, particularly an alternator associated with the engine of a motor vehicle, comprising two vaned or partially-vaned dissipator bodies which face each other so as to def ine a space f or the mounting of the two rows of diodes of the rectifier bridge, characterised in that each dissipator body has an insert to which the diodes of one row are connected electrically.

2. A rectifier bridge according to Claim 1, characterised in that each dissipator body is produced by pressure casting, and in that each insert is co-moulded with the respective dissipator body

3. A rectifier bridge according to Claim 2, characterised in that each insert is made of copper or an alloy thereof.

4. A rectifier bridge according to Claim 2, characterised in that each insert is formed substantially as a rectangular plate with a first flat face to which first terminals of a row of diodes are soldered and a second face which is provided with a plurality of ribs for improving adhesion between the insert and the dissipator body.

5. A rectifier bridge according to Claim 2, characterised in that at least one insert is in the form of a rectangular plate with a side portion which is substantially flush with a side wall of the respective dissipator body.

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6. A rectifier bridge substantially as described and illustrated and for the purposes specified.

1 Published 1990 at The PatentOffice. State House. 6671 llighHolborn, LondonWC1R4TP.Further copies maybe obtainedfrom, The Patent Office. Sales Branch, St Maiy Cray. Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. L'87