Method of making a rectifier and control module for an alternator

A rectifier circuit and control regulator are assembled onto a single plate for integral installation within the housing of an alternator. The method includes fabricating the plate with insulating, masking and conducting layers so as to provide mounting areas for commonly oriented rectifier diodes and efficient cooling for the entire unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is directed to the field of alternators as employed 
to supply D.C. electrical power to automotive vehicles and more 
specifically to the area of alternator construction in which both the 
rectifier assembly and the regulator circuitry are provided within the 
alternator housing. 
2. Description of the Prior Art 
Much work has been done in the past to increase the heat dissipation 
efficiencies of rectifier diode assemblies mounted within alternator 
housings. As part of that work, numerous disclosures have been made for 
both diode construction and mounting techniques. 
U.S. Pat. No. 3,184,625 describes a technique for mounting rectifier diodes 
on metal plates within the housing of an alternator. The metal plates are 
shown to provide electrical interconnection to common terminals for each 
set of diodes. However, numerous wire-to-terminal solder connections are 
required to interconnect the diodes in the rectifier network. 
U.S. Pat. Nos. 3,539,850, 3,925,809, 3,959,676, 4,218,694 and 4,538,169 all 
show various techniques for sandwiching diode elements between 
interconnecting conductors to provide the rectifier network in a manner 
that will facilitate heat dissipation. 
SUMMARY OF THE INVENTION 
The present invention steps beyond the techniques disclosed in the prior 
art by providing an efficient method of fabricating an alternator control 
module. The entire rectifier network is fabricated on a single metal heat 
sink plate and combined with a brush holder, a regulator circuit and an 
electrical connector for installation inside the alternator. The 
fabrication is performed in such a manner that the resultant control 
module becomes a unitary structure; and when assembled with the other 
components of the alternator offer significant cost reductions in that 
assembly process. 
The method of fabricating the rectifier circuit described herein includes 
the steps of: 
(a) Providing an electrically and heat conducting plate member. 
(b) Coating a first predetermined pattern area on the plate member with an 
electrically insulating layer that leaves a second predetermined pattern 
area exposed. 
(c) Masking a predetermined portion of the first predetermined pattern area 
to expose the remainder of the insulating layer. 
(d) Depositing an electrically conducting film on both the exposed surfaces 
of the plate member and the insulating layer in a third predetermined 
pattern to form conductor runs that are respectively and separately bonded 
to the conducting plate or the insulating layer. 
(e) Providing a first predetermined number of like rectifier diode elements 
each having respective anode and cathode terminals disposed on opposite 
sides thereof. 
(f) Bonding the anode terminals of a portion of the predetermined number of 
the rectifier diode elements directly to preselected ones of the conductor 
runs that are bonded to the conducting plate. 
(g) Bonding the anodes of the remainder of the rectifier diode elements 
directly to preselected ones of the conductor runs that are bonded to the 
insulating layer. 
(h) Providing a second predetermined number of electrically conducting 
elements configured to extend from the cathode terminals, of rectifier 
diode elements bonded to the conducting plate, to the preselected ones of 
the conductor runs bonded to the insulating layer. 
(i) Electrically bonding an electrically conducting element to both the 
cathode terminal of each of the rectifier diode elements bonded to the 
conducting plate and to a preselected conductor run onto which the anode 
terminal of a corresponding rectifier diode element is bonded. 
(j) Providing a common bus bar conductor formed to be connected to the DC 
output terminal of the alternator, having exposed portions and being 
mounted within an insulated means. 
(k) Mounting the common bus bar conductor insulating means on the plate so 
that exposed portions of the bus bar conductor are adjacent the cathode 
terminals of the rectifier diode elements bonded to the conductor runs 
bonded to the insulating layer. 
(l) Electrically bonding the bus bar conductor to the adjacent cathode 
terminal of the diode elements. 
Each of the placement and connecting steps are ideally suited to be 
performed by automated machine or robotic apparatus, since the diode 
elements need not be sorted or otherwise segregated by types or 
orientation. Each diode element is of the same orientation as any other 
and has its respective anode terminal bonded to the appropriate position 
containing the electrically conducting film. 
Along with the foregoing steps which result in the formation of the 
rectifier network, a regulator circuit, preferably a multi-leaded 
integrated circuit, is provided and is also bonded onto a conducting film 
area deposited on the insulating layer. Leads from the regulator circuit 
are appropriately bonded to corresponding conductor runs so that it will 
become integral with the alternator. Integrating the regulator circuit 
into the alternator eliminates the need for a wire harness which would 
conventionally interconnect the field and stator windings of the 
alternator and an externally located regulator circuit. 
Following the connection of the regulator circuit to the plate member and 
to the appropriate conductor runs, an electrical connector is permanently 
connected to the plate member and the connector terminals are electrically 
bonded to appropriate conductor runs. 
A brush holder is also provided that contains a plurality of brushes for 
making contact with the alternator rotor slip rings. The brush holder is 
permanently connected to be aligned with the central aperture of the plate 
member and the two brushes are respectively electrically connected to an 
appropriate conductor run and to ground, to provide field current 
connection when the alternator is assembled. 
It is therefore an object of the present invention to provide a unique 
method of assembling a diode element rectifier assembly or use in 
alternator applications. 
It is another object of the present invention to provide an integrated 
alternator control that is efficiently packaged for assembly into an 
alternator housing. 
It is still another object of the present invention to provide a diode 
element rectifier assembly that is both efficiently constructed and allows 
for a high degree of heat dissipation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A preferred embodiment of the invention is illustrated in FIG. 1 as a 
control module 10 for assembly into an alternator housing 100 along with a 
field winding rotor 300. 
In the exploded view of FIG. 1, the housing 100 contains several vent 
apertures, designated 110 and 120, that are distributed around the 
periphery and at the closed end to provide internal access for cooling 
air. The housing 100 also contains an extension 130 which allows for 
attachment of the alternator to a mounting bracket (not shown). Central to 
the housing 100, is a bearing retainer 150 into which the shaft 320 of the 
field winding 300 rotor is mounted. Apertures 132, 134, 136 and 138 are 
located at the end of the housing 100 to provide mounting support for the 
control module 10. An aperture 142 is also located at the end of the 
housing 100 to provide clearance for the electrical output terminal 242 
that is mounted on the control module 10. A large cutout 140 is also 
located at the end of the housing 100 so as to provide clearance and 
access to an electrical connector 290 that is mounted on the control 
module 10. 
In the control module 10, several key elements are illustrated and are 
described in detail below. Those elements, for assembly purposes, are an 
apertured base plate 200, support rods 232, 234, 236 and 238, electrical 
connector 290, output terminal 242, brush holder 287 and bus bar 240. The 
control module 10 is centered so that the field winding rotor 300, 
containing an internal fan 310 and a slip ring shaft 320, is concentric 
with the brush holder 287 and the bearing support 150. When fully 
assembled into the housing 100, the control module 10 is stationary with 
respect to the housing 100 while the field winding rotor 300 and fan 310 
are free to rotate about the concentric axis on the shaft 320. In that 
manner the slip rings (not shown) of the slip ring shaft 320 will contact 
the spring loaded brushes in the brush holder 287. The cooling fan 310 is 
supported spaced apart from the base plate 200 and provides convection 
cooling to the plate and all the components mounted thereon. 
Several process steps are employed in fabricating the control module 10. 
With reference to FIGS. 3A, 3B, 3C and 3D, several of the method steps are 
illustrated. 
In FIG. 3A, the base plate 200 is illustrated and is preferably a metal 
stamping which has the properties of being highly conductive of both 
thermal and electrical energy. In the present invention, an aluminum alloy 
was selected. The base plate 200 has a top surface 201 onto which several 
layers of insulating and conducting materials are deposited. In FIG. 3B, a 
first coating 202 is made onto the surface 201 of the conducting base 
plate 200 in a predetermined pattern. The first coating 202 is of an 
electrically insulating layer, leaving selected areas 201 exposed. In the 
preferred embodiment, the insulating layer 202 is aluminum oxide, selected 
because of its favorable electrical insulating and thermal conducting 
properties. Subsequently, an inert mask layer 204 is shown in FIG. 3C as 
having been deposited to overlay the insulating layer 202 so as to mask a 
large portion of the insulating layer 202 and to expose other 
predetermined portions 203 of the insulating layer 202 and portions of the 
surface 201 of the underlying base plate 200. With the mask layer 204 in 
place, an electrically conducting film is deposited on the separately 
exposed surfaces of the insulating layer 202 (designated as isolated 
conducting films 206); and deposited on portions of the upper surface 201 
of the base plate 200 (designated as conducting areas 208). In the 
preferred embodiment, the step of depositing conducting film on the 
exposed surfaces of the plate member and the insulating layer is performed 
by using a flame or plasma spraying process which deposits copper. With 
such a process step, subsequent bonding of electrical components is made 
easier using conventional soldering techniques. 
In FIGS. 4 and 5, the various patterns of the conducting areas 206 and 208 
are illustrated as deposited on the base plate 200. Corresponding 
numerical designations are employed in the schematic of FIG. 2 wherever 
relevant to facilitate a better understanding of the component 
relationships as placed on the base plate 200. In the exploded view of 
FIG. 4, rectifier diode disks 252, 254, 256 and 258 are shown as deposited 
on isolated conductive pads 206. Rectifier diode die 262, 264, 266 and 268 
are shown as bonded to conductive areas 208. In each case, the diode 
rectifier die are placed so that their respective anodes are being bonded 
to the substrate while their cathodes are exposed for subsequent 
connection. By the use of the fabrication techniques described herein, the 
diode die are all commonly oriented so that automatic placement of such 
diodes on the appropriate conductive areas eliminates any sorting or 
concern over orientation sequencing during installation. In this case, the 
diodes can be supplied to the automatic placement tool in a manner in 
which all of the diodes are commonly oriented. 
Subsequent to deploying the diode rectifier die onto the appropriate 
positions on the plate 200, interconnect tabs 282 are deposited on the 
isolated conducting areas 206 adjacent diode rectifier die 252, 254, 256 
and 258. Each of those interconnect tabs 282 are soldered to the isolated 
pads 206 along with the adjacent diode rectifier die. The interconnect 
tabs 282 contain upright U-shaped portions 284 for receiving a stator wire 
(YN, Y3, Y2 or Y1) and adjacent upright portions 286 that will be 
interconnected with the cathodes of respectively corresponding diode 
rectifiers (262, 264, 266 or 268). Terminal pins 280, containing expanded 
pads 281, are each electrically bonded to the exposed cathodes of the 
diode rectifier die and, in the case of rectifier diodes 262, 264, 266 and 
268, the upright pins 280 are also electrically bonded to the upright 
portion 286 on each associated interconnect tab 282. 
A bus bar 240, shown embedded in a molded insulator 246, is structured to 
have exposed areas which correspond to the location of terminal pins 280 
extending from the cathodes of rectifier diodes 252, 254, 256 and 258. 
Each of those pins 280 are also bonded to the bus bar 240. 
The bus bar 240 serves as the A+ output having a terminal 242 which, upon 
assembly, extends out of the alternator housing 100. An insulator 243 is 
illustrated as a cylinder which when assembled, provides electrical 
insulation between the terminal 242 and the housing 100. 
The various sized apertures 247 and 248 formed in the bus bar support 246 
serve to provide for adequate clearance for the pins 280 and the tabs 282 
during assembly. Those apertures are subsequently filled with a potting 
material after assembly is completed to protect the electrical connections 
from corrosion and provide mechanical support for U-shaped portion 284 of 
interconnecting tabs 282. Apertures 251 in the bus bar insulator 246 are 
spaced to correspond to apertures 253 in the base plate 200 so that 
appropriate fasteners (rivets) can be used to attach the insulator to the 
plate 200. 
A brush holder 287 is also shown having a pair of spring biased brushes 288 
and 289. This brush holder 287 contains a pair of electrical leads, also 
designated 288 and 289 (see FIG. 5), which extend from the brushes and are 
respectively electrically bonded to conducting areas 208 and 206 shown t 
be adjacent apertures 285 and the base plate 200. The apertures 285 are 
located to accept the fasteners that attach the brush holder 287 to the 
base plate 200. Apertures 231, 233, 235 and 237 respectively serve to 
support subsequently inserted mounting rods 232, 234, 236 and 238. These 
mounting rods also provide a thermal cooling path to the housing 100 when 
assembled. 
A regulator circuit IC 270 is also mounted on the base plate 200 at the 
enlarged conductive area 206 between the apertures 295. The 8 pins and 
heat sink 271 which extend from the regulator circuit IC 270 are 
designated F, A+, R, S, D, L, G.sub.S and G.sub.P. The F terminal provides 
for control of the field current and is internally interconnected to the 
heat sink 271 and connected through connector terminal 294 to a field 
control (FC) for external control, if desired. The A+terminal is the 
sensing terminal for monitoring the alternator voltage output at the 
alternator. The R terminal is connected through connector terminal 293 for 
monitoring the battery "B" voltage level. The S terminal is connected to a 
stator winding S.sub.1 through stator winding lead wire Y.sub.1. The D 
terminal is for external control through connector terminal 292 for 
controllably disabling the regulator circuit. The L terminal is for 
providing energization of the regulator and the warning lamp L-1 through 
connector terminal 291 for normal operation and when there is a failure in 
the regulator or alternator output. The G.sub.P and G.sub.S terminals are 
power ground and signal ground, respectively. 
Subsequent to bonding the regulator integrated circuit 270 to the 
appropriate pads formed on the base plate 200, an electrical connector 
socket is permanently attached to the base plate 200 so that its fastening 
apertures 296 are superimposed and aligned with apertures 295 for the 
acceptance of an appropriate attachment fastener. Connector terminals 291, 
292, 293 and 294 as viewed through an aperture in the base 290 of the 
connector 295, are positioned so that when that connector is permanently 
attached to the base plate 200, the terminals 291-294 correspond to and 
may be electrically bonded to the pads adjacent to those of the regulator 
circuit IC 270 (see FIG. 5). 
In referring to FIG. 5, the interconnection of the aforementioned elements 
is shown as an assembled unit in which the regulator, the brush holder and 
the diode regulator form an integral unit suitable for installation within 
the alternator. The stator winding lead Y1 is shown as connected to the 
tab 282 at the junction between the anode of diode rectifier disk 258 and 
the cathode of diode rectifier disk 268. Connections of stator winding 
leads Y2, Y3 and YN are also shown in accordance with the schematic shown 
in FIG. 2. 
By employing the above described method of assembling a rectifier circuit 
on a conductive plate, the diode anodes are each in an intimate thermal 
conducting relationship with the base plate. Therefore, the resulting 
structure has been found to have highly efficient heat dissipation 
characteristics, as compared to rectifier assemblies of other commercially 
available alternators. 
It will be apparent that many modifications and variations may be 
implemented without departing from the scope of the novel concept of this 
invention. Therefore, it is intended by the appended claims to cover all 
such modifications and variations which fall within the true spirit and 
scope of the invention.