CA2207902C - Rectifier assembly for automotive alternator - Google Patents
Rectifier assembly for automotive alternator Download PDFInfo
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- CA2207902C CA2207902C CA002207902A CA2207902A CA2207902C CA 2207902 C CA2207902 C CA 2207902C CA 002207902 A CA002207902 A CA 002207902A CA 2207902 A CA2207902 A CA 2207902A CA 2207902 C CA2207902 C CA 2207902C
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- heat sink
- diodes
- stator
- rectifier assembly
- heat
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Abstract
A poly-phase rectifier assembly (100) for an alternating current generator includes five heat sinks, three of which are compression spring-loaded (130) to form series electrical circuits to the poly-phase stator windings. The other two heat sinks (101, 102) are separated by a crush-proof, phenolic type, insulating gasket (103), and carry a plurality of semiconductor button-type diodes. The stator sinks are cupped (121) to position compression springs, and are slotted (170) for heat transfer. The stator sinks extend above the slotted positive heat sink into the cooling air flow area. A second embodiment utilizes back- to- back diodes, compression spring-loaded into a positive heat sink and a negative heat sink. A cupped stator heat sink forms a nest and provides series connection for the stator poly-phase windings. A plastic assembly supports a capacitor. I
Description
WO 96119032 PC'~'~ITS95116340 1ZECTIFIER ASSEMBLY FOR AUTC?1V~0'I~VE ALT)rRNATOR
Back ound of the Invention Field of the Invention The present invention relates to the hold of automotive-type rectifier s assemblies used to canvest naulti-phase al~rn~ating cvaront to direct currant using semiconductors located in the rear housing of the alternator, More particularly, the invention deals with the high power requirements and high under-hood temperatures associated wifih modern day automotive elect!ronics..- Further, the invention relates to the complex manufacturing problems Qeated by the high ~ o power and high tanperattue requ'uements, and also relates to the extreme sensitivity of semiconductors to heat, thermal stress, compression and mechanical forces created during the manufacturing process and generated during long-term operation of the alternator.
Descrintion_f the Related Apt ~ s It should be understood that the power requirements for charging a storage battery alone are approximately 50 amperes or greater. In addition, power is needed to run the air conditioning, the head lamps, an onboard computer, a stereo system, and fins in the engine compartment and in the passenger compartment.
Thus, the overall power consumption can exceed 70-90 amperes. Tlxe heat 20 generated by the rectifier assembly in producing this much power must be rapidly dissipated in order to avoid breaking down the semiconductor material in the rectifier assembly. 'fl~is is particularly true during the summer when the ambient temperatures are quite high so that the ambient air does not provide a significant cooling effect. insu~'tciout cooling of the rectifier assembly typically causes 2s short-term life of the rectifier assembly and ultimately results in high cost repairs or replacement of the alternator.
The present invention is also concerned with automated manufacturing and installation of rectifier assemblies using semiconductor diodes and stamped-out heat sinks, terminals, gaskets and molded parts. The semiconductor diodes are ao extremely sensitive to thermal and mechanical stresses and forces typically wo ~l9osz PGT/I1S951~634p
Back ound of the Invention Field of the Invention The present invention relates to the hold of automotive-type rectifier s assemblies used to canvest naulti-phase al~rn~ating cvaront to direct currant using semiconductors located in the rear housing of the alternator, More particularly, the invention deals with the high power requirements and high under-hood temperatures associated wifih modern day automotive elect!ronics..- Further, the invention relates to the complex manufacturing problems Qeated by the high ~ o power and high tanperattue requ'uements, and also relates to the extreme sensitivity of semiconductors to heat, thermal stress, compression and mechanical forces created during the manufacturing process and generated during long-term operation of the alternator.
Descrintion_f the Related Apt ~ s It should be understood that the power requirements for charging a storage battery alone are approximately 50 amperes or greater. In addition, power is needed to run the air conditioning, the head lamps, an onboard computer, a stereo system, and fins in the engine compartment and in the passenger compartment.
Thus, the overall power consumption can exceed 70-90 amperes. Tlxe heat 20 generated by the rectifier assembly in producing this much power must be rapidly dissipated in order to avoid breaking down the semiconductor material in the rectifier assembly. 'fl~is is particularly true during the summer when the ambient temperatures are quite high so that the ambient air does not provide a significant cooling effect. insu~'tciout cooling of the rectifier assembly typically causes 2s short-term life of the rectifier assembly and ultimately results in high cost repairs or replacement of the alternator.
The present invention is also concerned with automated manufacturing and installation of rectifier assemblies using semiconductor diodes and stamped-out heat sinks, terminals, gaskets and molded parts. The semiconductor diodes are ao extremely sensitive to thermal and mechanical stresses and forces typically wo ~l9osz PGT/I1S951~634p
-2-associated with high vohime manufacfi>ring techniques, whereas the invention described herein avoids the stresses by gently placing and Ioekxng the sensitive semiconductors in place for a one-time riveting end soldering operation, while never exceeding the technical and handling specif rations set forth by the ~n~s of the semiconductors.
The prior art teaches that poly phase alten~ating current can be converted to direct current suitable for automotive use- by using six semiconductor chips or button type diodes, and by connecting the cathodes of three of the diodes to $
positive D_C. heat sink, and by connecting the anodes of the remaining three ~ o diodes to a negative D.C. heat sink. The anode of one of the diodes on the positive heat sink is connected by a copper terminal to a cathode of a diode on the negative heat sink, thereby forming a set of diodes in series with the positive and negatirre D.C. heat sinks. A wire lead extending from phase one of tho alternator poly phase stator wording is connected to the series copper terminal of s s the fast sat of diodes. A phase taro lead and a phase three lead also extend fronx the poly phase stator windings and ate similarly connected to the next two sets of diodes to complete the poly-phase series circuit through the positivelnegative D.C. po~uver output terminals and the storage battery charging system, ~ as seen, for example, in Figure 10.
zo Most rectifier assemblies use semiconductor diodes in their chip form, as illustrated by U.S. patent No. 4,606,000, assigned to General Motors Corporation.
The chips are only O.I80" x 0.012" in size in the ceramic form with glass passivated edges. The chips are extrdnely difficult to handle. Nickel-plated copper tabs, which are slightly larger than the chips, are soldered to the anodes zs and cathodes to strengthen theta fox the manufacturing process and for the thermal stresses which arc incurred during norms! operation.
',t'lxe anodes of three of these chips are affixed to the selnicirculax copper negative D.C. heat sink. The cathodes of three other chips are affvced to an aituninvm carted positive D.C, heat sink. The positive b,C. heat sink is much 3o thicker than the negative heat sink and has a series of cooling slots which are extended out into the alternator's cooling airflow area. The positive heat sink is WO 96/19032 ~ ~'CTlUS95/16340 mounted above the negative heat sznk, and separated by a very thin siliconelfiberglass woven insulation gasket Three flat thin copper complex-formed terminal strips are formed to connect the stator leads to the diodes.
Frach ternninal strip has three legs extending mufti-directionally out of a plastic molded s dove-tailed insulating support member. The insulating support member is press-fit into the three matching slots which are machined on the peripheral surface of the aluminum heat sink. The support members are then staked into position, Six of the thin copper legs are "r?"-formed to align with and be affixed to the three sets of diodes located on the positive and negative heat sinks, respectively.
The t o remaining three legs connect to the stator windings during alternator installation to form a series circuit through the polyphase stator windings and the diodes.
Prior to the alternator installation, the rectifier assembly is processed through multiple solder applications and solder furnace temperature stages to solder the semiconductors to the heat sinks. During this process, the semiconductors axe ~ s held in position by a slight axial force from the copper "U" stator terminal above them. After the multiple stages of soldering are completed, and the noise suppressant capacitor is staked into position, a plastic cover is pushed into positioa and silicone xubber is injected around the senuconduotor chips and capacitor to protect them from enviroximental hazards, such as salt spray, dust and 2o metal particles. The rectifier assembly is then tested and installed into the alternator.
1 he prior art devices cannot transfer the heat generated by the diodes to the cooling air flow air rapidly enough to prevent thermal damage during high amtbient temperatures because the conventionally used aluminum heat sink has 2s approximately half the thermal conductivity of copper. Aa alternate thermal cooling _ path through the copper heat sink under the alum~imun is further decreased by the silieonelfibergl2~ss woven "insulator" gasket.
The top stu~faces of the semiconductor chigs soldered to the stator "U"
tettninals also cannot dissipate the heat of the semiconductor chips to the cooling 3o air because the semiconductor chips are encapsulated in an insulating silicone after the plastic cover is instahed. 'thus, during high ambient sumnner .
WO 96119032 PCTtiTS95/16340 tomperahues and power loads, the semiconductors are thermally overloaded, causing prematczte alternator failures.
The prior art also presents high volume manufacturing problems associated with placing, locating and holding the extremely sensitive semiconductors in s position for the soldering operation. The semiconductors are extremely light, and they tend to float up and arotmd because the thin copper "U"-shaped stator terminals required to hold the saniconductors in position have minimal. or no axial force. There is also a high cost associated with the ultrasonic welding process requirai to weld the copper diodes tabs to the aluminum heat sink because copper cannot be soldered to aluminum.
The thin siticone/fiberglass woven insulator gasket under the aluminum also presents major problems during iastaIlation of the rectifier assembly into the alternator. If the installation bolts are slightly over-torqued, the sharp edges of the aluminum heat sink will cut through the thin gasket to create a direct short circuit to the negative heat sink. The over-torquing may resctlt in the positive plate shorting out to the negative plate. The gasket under the alumit~,um roust be both thermally conductive aad "thin" to allow the heat generated by the positive diodes on the aluminum to rapidly conduct into the copper heat sink and alternator housiuag, and ultimately into the ambient sir.
zo If slightly under-torqued, the loss of thermal conductivity will cause the reo 'trfrer to overheat or become loose and to fail in the field. Even if the rectifier is installed at. the recommended torque, the alternator will pzematurely fail because of the high coefficient of expansion of the aluminum. The aluminum expands each time the engine is stetted and the temperature rises above 300° F, zs and the aluminuru contracts where the engine is fumed off and the temperature retvnn~s to the ambient temperature, which could be below 0° F. The repeated expansion and contraction of the aluminum positive heat sink also causes the rectifier assembly and. the positive electrical output connection on the alternator housing to become loose. Once loose, the rectifier assembly begins to overheat, ao and the overheating results in the premature failure of the alternator.
w0 96lI903Z ~CTlUS95I16340 Electrical problems inherent with aluminum have bees well documented in the building industry. Most electrical codes have banned aluminum wiring because the terminal co~ections on the aluminum wire become loose, overheat and cause fires. Similar problems can occur with the use of aluminum s connections in automotive rectifier assemblies. .
Other rectifter manufactiuers have attempted to solve the prior art manufacturing problems using the same saniconductor chips on the same aluminum and copper heat sinks with the same thin silicone/fiberglass insulator gasket separating the heat sinks. The other manufacturers merely xeplaced the t o dove-tailed, complex beat copper stator terminals with short 0.032" round copper molded into the plastic cover and extending dovvnwaxd witb, a thin, flat copper "S" ter~mit~on instead of a "L1~ termination to apply an axial force against the ve~~aaaivo~i~~r Wlp~ to hold. ~u°~ ua'~i~ iu plave fa'1r- i~.
lillilLiplG soidCIlIl~ SaQ
encapsulation process. Consequently, the rectifier assemblies overheat, become ~ s loose and fail in the same matmer as prior rectifier assemblies.
Still other manufactururs have tried replacing the glass passivated semiconductor chips (which were soldered on top of the aluminum and copper heat sinks) with "button"-type diodes. The three positive diodes were placed in three wells in the same type of aluminum heat sink with their respective anodes 2o protruding above the top of the wells. The other three buuon diodes were placed on the same type of copper heat sink with their respective cathodes in alignment with the anodes of the diodes in the aluminum wells.
The cathode and anodes of the diode sets are secured in position by three thin, flat copper stator terminal strips which apply little or no axial force to hold zs the diodes down during the soldering process and during alternator operation in the field. As the solder begins to liquify, the molten liquid flows under the diodes to cause the diodes to float up and even tilt. The diodes thus loss approximately SO% of the thermal conductivity to the heat sinks.
Placing the diodes deep within the wells restricts the cooling air from 3o flowing around the diodes. The use of the same silicone insulating gasket 'WO 96119032 PCTlITS9511634p bctvt~,ea the heat sinks creates the sarae inherent failure mode as in U.S.
Patent No. 4,606,000.
Other patents, such as ~ U.S. Patent No. 3,959,676, describe the use of button diodes which require an insulated circuit board and a complex "U"-shaped s stator terminal. Still other patents, such as U.S. Patent No. 4,065,686, describe sY~s r~r~,g precision holes sad computerized presses to ge~y ~e~ f-lt diodes into cavities because of the extreme sensitivity of the diodes to shock, stress and compx~ssion forces.
The xlew and novel invention described herein eliminates all of.the above a o problems and reduces manufacturing costs and failures by using compression springs to apply a predetermined farce to the diode. 'Three extra stator heat sinks are added with slotted air cooling fins and slots extending into the alternator's cooling air supply area A copper positive heat siltk with high conductivity and 50% more surface area rapidly transfers the heat generated out of the diodes, thus ~ s lowering the operating temperature by approximately 15%, as shown, fox examples in Figure Z.
The presernt invention also replaces the complex manufacturiztg process with a simple riveting and soldering operation to produce a rectifier having an extended life and which is simple to install in the alternator.
2o Summary of the Invention The preset invention provides a rectifier assembly which is manufactured in a simplified productive manner, using stamped and molded parts in a new and novel form to extend the life and to decrease the manufacturing failures ~d casts. In its present foam, the rectifier is manufactured using five metal heat sinks. One heat sink is a negative D.C. heat sink and ore heat sink is a positive D.C. heat sink. The other three heat sinks are stator heat sinks which are compressed against six semiconductor button-type diodes by six compression springs which preferably comprise stainless steel. The compression springs are nested within a pheaolic cover which is riveted into a compact a~r..cooled 3o package. Three of the six semiconductor "button"-type diodes are nested against the negative A.C. heat sink with the anodes down. The positive D.C. heat sink VVO 96119032 pGTNS95116340 _7_ has three accurately registered clearance holes allowing the cathodes of the xiegative heat sink diodes to extend through the holes. The positive r3.C.
heat sick is placed above and against the negative best sink, and is electrically insulated from the negatirre heat sink by a phenolic/fiberglass woven, electrically s insulating gasket to allow maaamum torquing during installation without crashing the gasket or shorting out betv~reen the heat sinks. The three retraining button diodes are nested against the positive D.C, heat sink with their xespective cathodes contacting the positive D.C. heat sink. The rogistration and placement of these diodes are not random. Rather, the diodes are strategically placed to z o rapidly dissipate the tremendous heat generated by each diode while rectifying the alternating current to ~D.C, current. The two heat sinks and gasket are sandwiched together and aligned using a riveting fixture with disappearing anvil guide pins. The six diodes are then merely placed in their proper registration by polarity and with solder paste applied to their electrically conductive contact 15 SllrfaCe areas. Hecause of the above-described registration, the diodes are automatically aligned into three separate cathodelanode series circuits which are completed when the three stator heat sinks are applied and connected to their respective stator windings to complete the poly-phase electrical circuit The three stator heat sinks are specially formed and extended with air ventilating slots. The 2o three stator heat sinks nest to align each set of series diodes so as to rapidly dissipate the generated heat into the cooling air flow opposite the stator winding tez~mination area. 'fhe stator heat sinks add thxee heat-dissipating sources to the xloraial two-heat sink rectifier system to allow each diode to dissipate heat out of both the cathode and anode surface areas, thus decreasing expensive diode 25 failures.
The three stator heat sinks are held in position for soldering by sit high temperatiae, stainless steel compression springs located in six cavities of the phcnolic cap. The springs are adjusted so as snot to exceed the critical compression force of 32 pounds recommended by lvtotorola, a Principal ao manufactures of the diodes. Some rectifier assemblies use computerized presses so as not to damage the diodes during insmllation, but the_ present invention _8_ merely uses the compression springs to secure the diodes in position for soldering and to extend the life of the rectifier assembly constricted in accordance with the present invention.
Once the molded phenolic cap is riveted into position, the six compression S springs force the diode contact surface areas against the stator and against the D.C. heat sinks to create an excellent parallel surface-to-surface heat dissipating and electrical contact connection.
The molded cap also provides three slots to lock the stator termination ends into position to prevent accidental short circuiting during the crimping and soldering of the poly-phase windings to the stator termination during final assembly and during service installations.
A further object of an aspect of the present invention is to affix the capacitor used for electrical noise suppression into a firm vibration and heat protected position with the simplicity and ease of high volume productivity.
This 1 S is accomplished using a plastic bushing with two formed brass terminals affixed to both ends to accept the capacitor leads for soldering or crimping. The bushing assembly is press-fit into the positive D.C. heat sink mounting hole which aligns the capacitor onto a cushioned bed of silicon rubber which insulates it from vibration and which provides a heat barrier from the negative heat sink. As the hold-down bolt is torqued down during installation, the capacitor is firmly looked into position and the bolt automatically causes a positive and negative electrical circuit to be completed through the positive and negative D.C. heat sinks. A
copper spacer bushing is press-fit into the positive heat sink to provide an electrical connection for the voltage regular and the positive output stud when the 2S rectifier installation nut is torqued down during installation. A centrally located plastic spacer bushing is also provided to allow the rectifier assembly to be evenly torqued down during installation to provide an excellent thermal and electrical connection in the alternator rear housing.
Another object of an aspect of the present invention is to allow the semiconductor surface temperatures to exceed the solder melting temperatures while still maintaining excellent electrical and thermal conductivity for diode operation, and, as the temperature returns to normal, the surfaces re-solder themselves into their normal position.
Still another object of an aspect of the present invention is to use all components which are pry-punched, formed and molded so as to be riveted in place using high volume, proven manufacturing processes and methods.
A further object of an aspect of the present invention is to provide a rectifier assembly which operates under load at cooler temperatures than prior art rectifier assemblies. Comparative tests of various rectifier assemblies, including an OEM manufactured assembly, verify that the lower operating temperatures of the present invention meets and exceeds the objectives. Measurements of the temperature versus time have shown that while operating at 3600 r.p.m. using a 45-50 ampere load at 12.8 to 13.5 volts D.C., the present invention operates approximately 15% cooler than an OEM unit, and up to 50% cooler than competitive conventional type rectifiers. The higher operating temperatures and the failure to hold the semiconductor chips in a fixed position against the heat sinks are the primary causes for the exceptionally high failure rate of OEM
rectifier assemblies due to arcing and the eroding away of the chips. This ultimately causes the entire alternator to be replaced with another unit which will also fail under the same conditions. By using the present invention, the components are permanently held in position during manufacturing and during long-term usage, to create a better, cheaper and longer lasting alternator which addresses and corrects these costly problems. This saves the money for consumers and decreases the usage of manufacturing power, which ultimately reduces air pollution into the atmosphere and environment.
In another object of an aspect of the present invention is a rectifier assembly mountable to the housing of a multi-phase alternating current generator to rectify A.C. current produced by the alternator into D.C. current, said rectifier assembly comprising: a positive heat sink positioned in a first plane; a negative heat sink positioned in a second plane parallel to said first plane; a finned heat sink positioned in a third plane parallel to said first and second planes, said finned heat sink comprising a plurality of electrically isolated heat sink portions, each of said electrically isolated heat sink portions including a terminal electrically connectable to a respective stator winding of said alternator, at least a portion of said heat sink portions positioned in an air flow caused by the operation of said alternator; a plurality of power diode pairs, each diode pair comprising a first -9a-diode and a second diode, each diode having an anode and a cathode, one diode of each pair having its anode connected to said negative heat sink and having its cathode connected to a respective one of said heat sink portions, the other diode of each pair having its anode connected to said respective one of said heat sink portions and having its cathode connected to said positive heat sink; an electrically insulating cover; and a plurality of compression springs positioned between said cover and said finned heat sink portions to apply pressure to said finned heat sink portions to thereby apply pressure to said diodes to provide secure mechanical and electrical contact between said diodes and said heat sinks.
A further object of an aspect of the present invention is a rectifier assembly for an alternator having stator windings, said rectifier assembly comprising:
a plurality of finned, air-cooled stator heat sinks, having respective stator terminals formed thereon; a negative polarity heat sink; a copper positive polarity heat sink extending into the cooling air flow, said positive polarity heat sink having air cooling slots for heat dissipation, said positive polarity heat sink having a plurality of holes formed therein; a first plurality of diodes supported by and connected to said positive polarity heat sink, said first polarity of diodes formed to fit parallel and above said negative polarity heat sink; a second plurality of diodes supported by said negative polarity heat sink, said second plurality of diodes extending through said holes in said positive polarity heat sink and connecting electrically and thermally to said plurality of stator heat sinks; and a plurality of compression springs forcing said first plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said positive polarity heat sink and forcing said second plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said negative polarity heat sink.
Another object of an aspect of the present invention is a rectifier assembly for an alternator, comprising: a negative heat sink; a positive heat sink; a plurality of pairs of diodes; a plurality of heat sink tabs electrically and mechanically connected to said negative heat sink, each of said tabs having a respective cavity which receives a first terminal of a respective first diode of one of said pairs of diodes; a plurality of cavities formed in said positive heat sink in alignment with said cavities of said plurality of tabs, said cavities each receiving a respective first terminal of a respective second diode of said one of said pairs of diodes; a -9b-plurality of stator tabs, each stator tab electrically and mechanically connected with respective second terminals of said first diode and said second diode in said one of said pairs of first and second diodes; and a plurality of compression springs, each compression spring positioned proximate to a respective one of said stator tabs, each said compression spring applying force against said respective stator tab to force said first and second diodes in said one of said pairs of diodes in secure electrical and mechanical contact with said respective one of said stator tabs, said heat sink tabs and said negative heat sink.
In another object of an aspect of the present invention is a rectifier assembly for an alternator, said rectifier assembly comprising: a first heat sink which provides an electrical interconnection for a positive voltage; a second heat sink which provides an electrical interconnection for a negative voltage; a plurality of diodes electrically interposed between said first heat sink and said second heat sink; a crush-proof gasket interposed between said first and second heat sinks, said crush-proof gasket providing electrical insolation between said first heat sink and said second heat sink; and a plurality of compression springs which apply force to hold each of said plurality of diodes in electrical and thermal contact with one of said first heat sink and said second heat sink.
Brief Description of the Drawings Figure 1 illustrates the thermal comparison of various rectifier assemblies, including original equipment manufacturer (OEM) assemblies, competitive aftermarket assemblies, and the present invention.
Figure 2 illustrates a completed rectifier assembly in accordance with one embodiment of the present invention.
wo 9sr~9o3z Pcrms~ms~to -IO-Figure 3, comprising Figures 3A and 3B, ihustrates an exploded view of the embodiment of Figure 2, showing the simplicity of maaufactiuing. ' Figure 4 illush'ates a cross-sectional view of the assembled rectif er assembly in accordance with the present invention, taken along the lines 4-4 in s Figure 2, showing the position of the hcat sinks and the diodes, and showing the housing and air flow for cooling.
Figcaes SA and 5>3 illustrate the capacitor mounting assembly witb~ an installation bolt completing the electrical connection from ono terminal of the capacitor to the negative ground potential of the alternator housing. ' ~ o Figures tiA and 6B illustrate the nesting of the compression springs in the phenolic cover and the assembly hole layout of the embodimeat of Figures 2-5.
Figure ? illustrates an exploded view of another embodiment of the invention with back-to-back button diodes, with cooling air flowing around the diodes and between the heat sinks and further showing the simplicity of ~ s manuf, Figuxe 8 illustrates a partial cross-sectional view of the embodiment of Figure 7 pictorially iliustraiing the cooling air flowing around the diodes and between the heat sinks, ' Figure 9 illustrates a partial cross-sectional view similar to Figure 8 with ' 2o semiconductor chip diodes instead of button diodes.
Figure 10 illustrates an electrical schematic of the rectifier stator connections, capacitor co~ections and battery charging system from positive and negative boat sinks using cathodes from positive diodes and anodes from negative diodes.
25 Detailed -Description of the Preferred Embodiment As illustrated in Figures 2-6, a rectifier assembly 100 in accordance with one embodiment of the present invention comprises a negative D.C. copper heat sink 101, a positive D.C. heat sink 102, and a phenoIicJfiberglass woven WO 96!19032 PCTlU595/16340 -lI-iz>sulatixlg gasket 103. The gasket 103 is used to electrically separate the negative and positive heat sinks, and is appro~amately 0.017 inches thick. The negative heat sink 101 has three nesting cavides 106a c to nest semiconductor button-type diodes 104a~ having resp~ive anodes 105a-c and having respective cathodes s 107a-c. The positive heat sink 102 has th~rec nest~g cavities 114a c to nest semiconductor button-type diodes 118a-c having respective cathodes 119a-c and having respective anodes 120a-c. Before the button diodes 104a-c are set in Place, the negative heat sink 101, the gasket 103 and the positive heat sink are stacked upon each other using a ~xxture (not shown) with aligiunent pins io 131a-c to locate the proper hole registration in cozresponding holes in the heat sinks and gaskets. Solder paste or solder tabs 117 are dispensed into the nest cavities 106a-c of the heat sink 101 and the nest cavities 114a-c of the heat sink 102. The button diodes 104a-c are then placed into the respective nest cavities lOba a with their respective anodes 105a-c against the negative heat sink 10I, and the button diodes 118a-c are placed into the nest cavities 114a-c of the positive heat sink 102 with the respective cathodes 119a-c of the diodes 118a-c positioned into the nests 114a-c. The bodies of the diodes 104a-c pass through the positive heat sink 102 through reeve clearance holes 109a-c, and pass through clearance holes 108 of the gasket 103.
zo Three stator heat sinks 122, 123, 124 have respective nesting cavities 121a-b, 121o-d and 121e-f. The nesting cavity 121a receives the anode I20a of the diode 118a. The nesting cavity 121b receives the cathode 107a of the diode 104x, The nesting cavity 121c receives the anode 120b of the diode 118b. The nesting cavity 121d receives the cathode 107b of the diode 104b. The nesting is cavity 121e receives the cathode 107c of the diode 104c. 'The nesting cavity 121f receives the anode 120c of the diode 118c. It is particularly preferable at this time that the solder paste or solder tabs 117 be dispensed onto the anodes 120a-c and onto the cathodes 107a-c, or, alternatively, dispensed into the nest cavities 121a-f prior to installing the stator heat sinks 122, 123, 124 onto the anodes ao 120a-c and onto the cathodes 107a-c of the positive heat sink lOZ and the negative heat sick 101, wo 9srmi pcrmsasrls3ao The stator heat sink 122 is shown with a wire crimping tab 125 in its normal stamped position, which allows a phcnolic cap 129 to be dropped over the ' tabs. A tab I26 of the stator heat sink 123 and a tab I2? of the stator heat sink 124 are shown in their formed positions after the phenolic cover 129 has been s iastalIed and riveted The tab 126 is.fiuther shown partially bent in preparation for the crimping process. A further tab I28 of the stator heat sink I24 provides an electrical contlection to a voltage regulator (not shown), Tile three stator heat sinks 122, 123, 124 ere plar.,cd an top of the diodes l0~ls a nasd ~o diodoo llQshe u~aieh have bees pre_reg~ctvrod EsY p~3~~,.
to diodes 104a-c and I1$a-e are thus ready to be locked into position by a set of rivets 132a-c which secure the phenoIic cover 129 with the tops of six compression springs 130 located in respective cavities 161a-f in the phenolic cover 129. The compression springs preferably comprise stainless steel.
As illustrated in more detail in Figure 3A, the compression springs I30 i s are maintained in alignment during the manufacturing steps by raised portions of the three stator heat sinks I22, 123, 124 formed on opposite sides of the heat sinks from the cavities 121a-f. The phenoIic cover 129 is then placed onto the disappearing anvil pin guides 131 which were previously used to guide and align tlae negative heat sink 101, the gasket 103 and the positive heat sink I02 into Zo position for assembly. The tabs 125, 126 and I27 are passed through slots 160a-c in the phenolic cover 129. The compression springs 130 are received by cavities 161 a-f in the phenolic cover 129 (see Figures 6A and 6H). The rectifier assembly 100, including the diodes 104a c, 118a c, the stator heat sinks 122, 123, I24 and the cover I29, call now be riveted and sent through a soldering or curing 2s fenrace operation. Note that the slots 160a-c may be open dovetailed slots, as illustrated in Figure 3A, or the slots 160a-c may be oval . Waped SlOt9, Ss illustrated in Figure 6A.
After cooling, the rectifier assembly I00 is tested, and the tabs 125, 126, 127 are foamed and aligned to accept the stator wire leads to present accidental ao shorting when the rectifier assembly is installed into the alternator. The tabs 125, 126, 127 are then crirzzped and soldered to the stator winding to complete the three series electrical circuits for the poly-phase stator.
As shown in more detail in Figures SA and 5>3, an electrically insulating capacitor stapd-o~ bushing 133, comprising plastic, for example, and having a s pair of brass terminals 134, 135 mounted thereon, is pressed into a mounting hole 136 of the positive heat sink 102. A capacitor 137 is affixed in an open area on the negative heat sink 101 usung siIicoue rubber adhesive 111 (shown schematically in Figure SB). First and second leads 147, 148 of the capacitor 13? are soldered or crimped to the terminals 134, 135, respectively; to complete t o the positive electrical connection 102 and the negative electrical connection 10I
for the capacitor 137 when the rectifier assembly is installed and a bolt 146 is torqucd down to the housing 143. The bolt 146 completes the electrical connection between the brass terminal 135 and the negative heat sink 101 and the brass terminal 134 is in fixed electrical contact with the ~sitive heat sink 102.
~ s A copper spacer bushing 142 completes the electrical connection to the positive polarity components of the alternator when a nut 138 is tordued down onto a positive voltage stud 150 located through the housing 143 to a positive output connector I52 (see Figure SB which illustrates a cross-sectional view of a portion of the alternator housing 143). A plastic spacer bushing 139 insulates 2o the stud 150 from the housing 143. The nut 138 and bolts 140 and 146 are used to toxquc the rectifier assembly 100 down to the housing 143 to create a good thermally conductive path for the negative heat sink 101 without introducing au electrically conductive path ~rom the positive hcat sink 102.
The alternator cooli»g fan system supplies cooling air flow (indicated by 2s an arrow 145 in Figure 4) through air ported windows 144 on the back side of the housing 143 to cool the copper positive heat sink 102 which has a series of vented slots 110 extending above the windows 144. The three stator heat sinks ' 122, I23, 124 include slots 170. '1 he three stator heat sinks 122, 123, 12.4 extend above the positive heat sink 102 and are cooled by the same cooling air flow ao through the slots 170 to create a rapid and an efficient heat transfer system to ~CTlIJS951163~0 dissipate the heat generated by the diodes while converting alternating curt to direct current in an automotive electrical system.
Figure 10 illustrates an electrical schematic of the completed assembly I00 which receives the electrical outputs from the stator windings 180 of a s conventional alternator and which provides a D.C. output current to charge a conventional battery 182.
Figure 7 illustrates an exploded view and Figure 8 illustrates a peal cross-sectional view of a new or an existing rectifier assembly 200, such as the well known CS130, which is rebuilt in accordance ysil~ ~e pre~~ iny~hon using modified heat sinks only. In particular, the rebuilt rectifier assembly includes a positive heat sink 2I0 and a negative heat sink 212 which form part of the existing rectifier assembly. Three phenoliclfiberglass woven insulator ring gaskets 214 are nested under the mounting hole locations 2I5, 2I6 and 136 for the bolts 13$, I40 and 146 to electrically and. mechanically separate the positive heat sink 210 from the negative heat sink 2I2, The ring gaskets 2I4 are approximately 0.020" thick and allow heat transfer and air circulation between the two heat sinks (represented by an arrow 145 in Figure 8) for cooling. The ring gaskets 2I4 will not crush or loosen after being torqued down during installation. The positive heat sink may advantageously include recesses 217 zo (shown as dashed lines m Figures 8 and 9) to receive a portion of the ring gasket's 214 to hold the zing gaskets 214 in fixed positiozts until the rivets or bolts are secured. The ring gaskets 2I4 may also be used in the embodiment of Figures 2-6 in place of the continuous gasket 103.
An L-shaped br~.ss tab ?.20 is press fit into each of three existing 2s dovetailed slots 22Z of the positive heat sink 2I0 such that a horizontal portion 224 of each tab 220 overlies a portion 226 of the negative heat sink 212 when assembled. The horizontal portion 224 of the brass tab 220 includes a cavity 230, and the underlying portion 226 of the negative heat sink 212 includes a cavity 232 in substantial alignment with the cavity 230 when assembled.
so A diode 240 having an anode 242 and a cathode 244 is positioned with thc cathode 244 in the cavity 230. Similarly, a diode 250 having an anode 252 w0 96I19U3Z . ~CTIITS95116340 and a cathode 254 is positioned with tht anode 252 in the cavity 232. A
flexible brass tab 260 has a first offset or depressed portion 262 and a second offset or depressed portion 264, Each offset portion 262, 264 forms a respective depression on one side of the tab 260 and bump on the opposite side of the tab 260. The tab 260 is formed around a compression spring 270 so that the compression spring 270 is constrained between the two bumps caused by the o#Set portions 262, 264. The depression caused by oNe offset portion 262 is positioned to receive the anode 242 of the diode 240, and the depression caused by the offset portion 26~ is positioned to receive the cathode 254 of the diode ~ 0 250. While being held in these relative positions, the positive heat sink 210 is secured to the negative heat sink 21z by a pair of rivets 318 through holes in the positive heat sink 210 and holes 320 in the negative heal sink 212. The rivets 318 are electrically is°labed from the negative heat sink 212 by tapered insulators 321 which spread beneath the lower heads of the rivets when they are z s formed. The compression springs 270 are thus compressed to hold the diodes in fixed electrical and, mechanical contact with the positive heat sink 210, the txgative heat sink 21.2 and the flexible tab 260. Preferably, as discussed above m connection with the exnbod~~t of Figures 2-6, the solder paste or solder tabs are positioned on the anodes and cathodes o~ the tyvo diodes or in the receiving zo cavities and depressions prior to assembly to enhance the electrical contact between the components- It should be understood that the assembly of Figure 6 is used for each of the three diode pairs for each stator winding. Xn alternative ~~~ ~. ding slots can be out between, under or on top of the positive heat sink 2I0 as illustrated by a dashed liuo 218 is Figure 9.
~s Figure 9 illustrates an altemaflve embodiment of an existing rectifier assembly rebuilt in accordance with the present invention. The embodiment of Figure 9 is similar to the embod~c~at of Figures 7 at~d 8, and like compoNents are identified with Iike numbers; however, semiconductor chips are used in Figure 9 instead of the button-type diodes of Figures 7 and 8. In particular, a ao first semiconductor chip 300 has a pair of nickel-plated copper tabs 302, 304, which are slightly larger than the chip 300, soldered to the lower anode surface w0 96/19032 s ~I'1US95/1G340 anti upper cathode surface of the chip 300 in a conventio~nal~ manner.
Although the edges of the semicoriduetor chip 300 are preferably glass psssivated, a silicon O-ring or adhesive 304 is positioned on the outer perimeter of the chip 300 betuve~ the extend perimeters of the tabs 302, 304 to seal the exposed edges from dust, humidity, and the like. The nickct-plated copper tabs 302 aad 304 are respectively positioned in the cavity z62 of the flexible tab 260 and in the cavity 230 of the brass tab 220. A second semiconductor chip 310 is formed in like manner with a pair of nickel-plated copper tabs 31Z and 314 soldered to its lower anode surface and its upper cathode suxface, respectively. A silicon-O-ring i o seals the glass passivated edges of the chip 310. The second semitconductor chip 3I0 is positioned with the lowex brass tab 3I2 nested in the cavity 232 of the negative heat sink 212 and with the upper brass tab 314 nested in the cavity of the flexible tab 260. After positioning the semiconductor chips 300, 310 and the other semiconductor chips {ant slaovm}, the assembly is completed as before to compress the spring 270 and provide secure electrical and mechanical contact.
Again, solder paste or tabs (not shown) are applied to the brass tabs 302, 304, 3I2, 3I4 or to the respective cavities (shows in Figvm 7} before assembly.
' As discussed above, the embodiments of the present invention provide a substantial improvement over the conventional rectifier assemblies by increasing zo the heat dissipation and thus reducing the operating temperature of the rectifier ' assembly. Figure 1 illustrates graphs which compare the thermal characteristics of various rectifier assemblies. Line A illustrates the thermal profile of an OEM
rectifier asseatnbly. Line B illustrates the thermal profile of a competitive after-market rectifier assembly. Line C illustrates the thenaal profile of the present 2s invention without a fumed stator heat sink (e.g., such as when implemented on a rebuilt rectifier assembly as illustrated u1 Figures 6 and ~. Line D
illustrates the therrzlal profile of the present invention with a finned stator heat sink, as illustrated in Figures 2-5. Line E illustrates the thermal profile of a fwrther eom~petitive rectifier.
ao As described herein, this preferred embodiment of the prtsent irtventiou merely shows the simplicity, cost savings and reliability of the present invention.
WO 96119032 PC'ffUS95I16340 . -I7-There are many other applications of the prrscat invention which could deviate from the intent of the prascnt invention; however, .the irrttnt of using the compression spring-loaded embodiment with nested stator heat sinks or other heat sinks which are slotted and extended into the cooling air flout to extend the life s of the diodes because of the springs forcing a better contact system, and the intent of simplifying manufacturing and iastallatioa using phenolic type, Grush-proof gaskets, is within the scope of the present invention as defined in the clans appended hereto.
The prior art teaches that poly phase alten~ating current can be converted to direct current suitable for automotive use- by using six semiconductor chips or button type diodes, and by connecting the cathodes of three of the diodes to $
positive D_C. heat sink, and by connecting the anodes of the remaining three ~ o diodes to a negative D.C. heat sink. The anode of one of the diodes on the positive heat sink is connected by a copper terminal to a cathode of a diode on the negative heat sink, thereby forming a set of diodes in series with the positive and negatirre D.C. heat sinks. A wire lead extending from phase one of tho alternator poly phase stator wording is connected to the series copper terminal of s s the fast sat of diodes. A phase taro lead and a phase three lead also extend fronx the poly phase stator windings and ate similarly connected to the next two sets of diodes to complete the poly-phase series circuit through the positivelnegative D.C. po~uver output terminals and the storage battery charging system, ~ as seen, for example, in Figure 10.
zo Most rectifier assemblies use semiconductor diodes in their chip form, as illustrated by U.S. patent No. 4,606,000, assigned to General Motors Corporation.
The chips are only O.I80" x 0.012" in size in the ceramic form with glass passivated edges. The chips are extrdnely difficult to handle. Nickel-plated copper tabs, which are slightly larger than the chips, are soldered to the anodes zs and cathodes to strengthen theta fox the manufacturing process and for the thermal stresses which arc incurred during norms! operation.
',t'lxe anodes of three of these chips are affixed to the selnicirculax copper negative D.C. heat sink. The cathodes of three other chips are affvced to an aituninvm carted positive D.C, heat sink. The positive b,C. heat sink is much 3o thicker than the negative heat sink and has a series of cooling slots which are extended out into the alternator's cooling airflow area. The positive heat sink is WO 96/19032 ~ ~'CTlUS95/16340 mounted above the negative heat sznk, and separated by a very thin siliconelfiberglass woven insulation gasket Three flat thin copper complex-formed terminal strips are formed to connect the stator leads to the diodes.
Frach ternninal strip has three legs extending mufti-directionally out of a plastic molded s dove-tailed insulating support member. The insulating support member is press-fit into the three matching slots which are machined on the peripheral surface of the aluminum heat sink. The support members are then staked into position, Six of the thin copper legs are "r?"-formed to align with and be affixed to the three sets of diodes located on the positive and negative heat sinks, respectively.
The t o remaining three legs connect to the stator windings during alternator installation to form a series circuit through the polyphase stator windings and the diodes.
Prior to the alternator installation, the rectifier assembly is processed through multiple solder applications and solder furnace temperature stages to solder the semiconductors to the heat sinks. During this process, the semiconductors axe ~ s held in position by a slight axial force from the copper "U" stator terminal above them. After the multiple stages of soldering are completed, and the noise suppressant capacitor is staked into position, a plastic cover is pushed into positioa and silicone xubber is injected around the senuconduotor chips and capacitor to protect them from enviroximental hazards, such as salt spray, dust and 2o metal particles. The rectifier assembly is then tested and installed into the alternator.
1 he prior art devices cannot transfer the heat generated by the diodes to the cooling air flow air rapidly enough to prevent thermal damage during high amtbient temperatures because the conventionally used aluminum heat sink has 2s approximately half the thermal conductivity of copper. Aa alternate thermal cooling _ path through the copper heat sink under the alum~imun is further decreased by the silieonelfibergl2~ss woven "insulator" gasket.
The top stu~faces of the semiconductor chigs soldered to the stator "U"
tettninals also cannot dissipate the heat of the semiconductor chips to the cooling 3o air because the semiconductor chips are encapsulated in an insulating silicone after the plastic cover is instahed. 'thus, during high ambient sumnner .
WO 96119032 PCTtiTS95/16340 tomperahues and power loads, the semiconductors are thermally overloaded, causing prematczte alternator failures.
The prior art also presents high volume manufacturing problems associated with placing, locating and holding the extremely sensitive semiconductors in s position for the soldering operation. The semiconductors are extremely light, and they tend to float up and arotmd because the thin copper "U"-shaped stator terminals required to hold the saniconductors in position have minimal. or no axial force. There is also a high cost associated with the ultrasonic welding process requirai to weld the copper diodes tabs to the aluminum heat sink because copper cannot be soldered to aluminum.
The thin siticone/fiberglass woven insulator gasket under the aluminum also presents major problems during iastaIlation of the rectifier assembly into the alternator. If the installation bolts are slightly over-torqued, the sharp edges of the aluminum heat sink will cut through the thin gasket to create a direct short circuit to the negative heat sink. The over-torquing may resctlt in the positive plate shorting out to the negative plate. The gasket under the alumit~,um roust be both thermally conductive aad "thin" to allow the heat generated by the positive diodes on the aluminum to rapidly conduct into the copper heat sink and alternator housiuag, and ultimately into the ambient sir.
zo If slightly under-torqued, the loss of thermal conductivity will cause the reo 'trfrer to overheat or become loose and to fail in the field. Even if the rectifier is installed at. the recommended torque, the alternator will pzematurely fail because of the high coefficient of expansion of the aluminum. The aluminum expands each time the engine is stetted and the temperature rises above 300° F, zs and the aluminuru contracts where the engine is fumed off and the temperature retvnn~s to the ambient temperature, which could be below 0° F. The repeated expansion and contraction of the aluminum positive heat sink also causes the rectifier assembly and. the positive electrical output connection on the alternator housing to become loose. Once loose, the rectifier assembly begins to overheat, ao and the overheating results in the premature failure of the alternator.
w0 96lI903Z ~CTlUS95I16340 Electrical problems inherent with aluminum have bees well documented in the building industry. Most electrical codes have banned aluminum wiring because the terminal co~ections on the aluminum wire become loose, overheat and cause fires. Similar problems can occur with the use of aluminum s connections in automotive rectifier assemblies. .
Other rectifter manufactiuers have attempted to solve the prior art manufacturing problems using the same saniconductor chips on the same aluminum and copper heat sinks with the same thin silicone/fiberglass insulator gasket separating the heat sinks. The other manufacturers merely xeplaced the t o dove-tailed, complex beat copper stator terminals with short 0.032" round copper molded into the plastic cover and extending dovvnwaxd witb, a thin, flat copper "S" ter~mit~on instead of a "L1~ termination to apply an axial force against the ve~~aaaivo~i~~r Wlp~ to hold. ~u°~ ua'~i~ iu plave fa'1r- i~.
lillilLiplG soidCIlIl~ SaQ
encapsulation process. Consequently, the rectifier assemblies overheat, become ~ s loose and fail in the same matmer as prior rectifier assemblies.
Still other manufactururs have tried replacing the glass passivated semiconductor chips (which were soldered on top of the aluminum and copper heat sinks) with "button"-type diodes. The three positive diodes were placed in three wells in the same type of aluminum heat sink with their respective anodes 2o protruding above the top of the wells. The other three buuon diodes were placed on the same type of copper heat sink with their respective cathodes in alignment with the anodes of the diodes in the aluminum wells.
The cathode and anodes of the diode sets are secured in position by three thin, flat copper stator terminal strips which apply little or no axial force to hold zs the diodes down during the soldering process and during alternator operation in the field. As the solder begins to liquify, the molten liquid flows under the diodes to cause the diodes to float up and even tilt. The diodes thus loss approximately SO% of the thermal conductivity to the heat sinks.
Placing the diodes deep within the wells restricts the cooling air from 3o flowing around the diodes. The use of the same silicone insulating gasket 'WO 96119032 PCTlITS9511634p bctvt~,ea the heat sinks creates the sarae inherent failure mode as in U.S.
Patent No. 4,606,000.
Other patents, such as ~ U.S. Patent No. 3,959,676, describe the use of button diodes which require an insulated circuit board and a complex "U"-shaped s stator terminal. Still other patents, such as U.S. Patent No. 4,065,686, describe sY~s r~r~,g precision holes sad computerized presses to ge~y ~e~ f-lt diodes into cavities because of the extreme sensitivity of the diodes to shock, stress and compx~ssion forces.
The xlew and novel invention described herein eliminates all of.the above a o problems and reduces manufacturing costs and failures by using compression springs to apply a predetermined farce to the diode. 'Three extra stator heat sinks are added with slotted air cooling fins and slots extending into the alternator's cooling air supply area A copper positive heat siltk with high conductivity and 50% more surface area rapidly transfers the heat generated out of the diodes, thus ~ s lowering the operating temperature by approximately 15%, as shown, fox examples in Figure Z.
The presernt invention also replaces the complex manufacturiztg process with a simple riveting and soldering operation to produce a rectifier having an extended life and which is simple to install in the alternator.
2o Summary of the Invention The preset invention provides a rectifier assembly which is manufactured in a simplified productive manner, using stamped and molded parts in a new and novel form to extend the life and to decrease the manufacturing failures ~d casts. In its present foam, the rectifier is manufactured using five metal heat sinks. One heat sink is a negative D.C. heat sink and ore heat sink is a positive D.C. heat sink. The other three heat sinks are stator heat sinks which are compressed against six semiconductor button-type diodes by six compression springs which preferably comprise stainless steel. The compression springs are nested within a pheaolic cover which is riveted into a compact a~r..cooled 3o package. Three of the six semiconductor "button"-type diodes are nested against the negative A.C. heat sink with the anodes down. The positive D.C. heat sink VVO 96119032 pGTNS95116340 _7_ has three accurately registered clearance holes allowing the cathodes of the xiegative heat sink diodes to extend through the holes. The positive r3.C.
heat sick is placed above and against the negative best sink, and is electrically insulated from the negatirre heat sink by a phenolic/fiberglass woven, electrically s insulating gasket to allow maaamum torquing during installation without crashing the gasket or shorting out betv~reen the heat sinks. The three retraining button diodes are nested against the positive D.C, heat sink with their xespective cathodes contacting the positive D.C. heat sink. The rogistration and placement of these diodes are not random. Rather, the diodes are strategically placed to z o rapidly dissipate the tremendous heat generated by each diode while rectifying the alternating current to ~D.C, current. The two heat sinks and gasket are sandwiched together and aligned using a riveting fixture with disappearing anvil guide pins. The six diodes are then merely placed in their proper registration by polarity and with solder paste applied to their electrically conductive contact 15 SllrfaCe areas. Hecause of the above-described registration, the diodes are automatically aligned into three separate cathodelanode series circuits which are completed when the three stator heat sinks are applied and connected to their respective stator windings to complete the poly-phase electrical circuit The three stator heat sinks are specially formed and extended with air ventilating slots. The 2o three stator heat sinks nest to align each set of series diodes so as to rapidly dissipate the generated heat into the cooling air flow opposite the stator winding tez~mination area. 'fhe stator heat sinks add thxee heat-dissipating sources to the xloraial two-heat sink rectifier system to allow each diode to dissipate heat out of both the cathode and anode surface areas, thus decreasing expensive diode 25 failures.
The three stator heat sinks are held in position for soldering by sit high temperatiae, stainless steel compression springs located in six cavities of the phcnolic cap. The springs are adjusted so as snot to exceed the critical compression force of 32 pounds recommended by lvtotorola, a Principal ao manufactures of the diodes. Some rectifier assemblies use computerized presses so as not to damage the diodes during insmllation, but the_ present invention _8_ merely uses the compression springs to secure the diodes in position for soldering and to extend the life of the rectifier assembly constricted in accordance with the present invention.
Once the molded phenolic cap is riveted into position, the six compression S springs force the diode contact surface areas against the stator and against the D.C. heat sinks to create an excellent parallel surface-to-surface heat dissipating and electrical contact connection.
The molded cap also provides three slots to lock the stator termination ends into position to prevent accidental short circuiting during the crimping and soldering of the poly-phase windings to the stator termination during final assembly and during service installations.
A further object of an aspect of the present invention is to affix the capacitor used for electrical noise suppression into a firm vibration and heat protected position with the simplicity and ease of high volume productivity.
This 1 S is accomplished using a plastic bushing with two formed brass terminals affixed to both ends to accept the capacitor leads for soldering or crimping. The bushing assembly is press-fit into the positive D.C. heat sink mounting hole which aligns the capacitor onto a cushioned bed of silicon rubber which insulates it from vibration and which provides a heat barrier from the negative heat sink. As the hold-down bolt is torqued down during installation, the capacitor is firmly looked into position and the bolt automatically causes a positive and negative electrical circuit to be completed through the positive and negative D.C. heat sinks. A
copper spacer bushing is press-fit into the positive heat sink to provide an electrical connection for the voltage regular and the positive output stud when the 2S rectifier installation nut is torqued down during installation. A centrally located plastic spacer bushing is also provided to allow the rectifier assembly to be evenly torqued down during installation to provide an excellent thermal and electrical connection in the alternator rear housing.
Another object of an aspect of the present invention is to allow the semiconductor surface temperatures to exceed the solder melting temperatures while still maintaining excellent electrical and thermal conductivity for diode operation, and, as the temperature returns to normal, the surfaces re-solder themselves into their normal position.
Still another object of an aspect of the present invention is to use all components which are pry-punched, formed and molded so as to be riveted in place using high volume, proven manufacturing processes and methods.
A further object of an aspect of the present invention is to provide a rectifier assembly which operates under load at cooler temperatures than prior art rectifier assemblies. Comparative tests of various rectifier assemblies, including an OEM manufactured assembly, verify that the lower operating temperatures of the present invention meets and exceeds the objectives. Measurements of the temperature versus time have shown that while operating at 3600 r.p.m. using a 45-50 ampere load at 12.8 to 13.5 volts D.C., the present invention operates approximately 15% cooler than an OEM unit, and up to 50% cooler than competitive conventional type rectifiers. The higher operating temperatures and the failure to hold the semiconductor chips in a fixed position against the heat sinks are the primary causes for the exceptionally high failure rate of OEM
rectifier assemblies due to arcing and the eroding away of the chips. This ultimately causes the entire alternator to be replaced with another unit which will also fail under the same conditions. By using the present invention, the components are permanently held in position during manufacturing and during long-term usage, to create a better, cheaper and longer lasting alternator which addresses and corrects these costly problems. This saves the money for consumers and decreases the usage of manufacturing power, which ultimately reduces air pollution into the atmosphere and environment.
In another object of an aspect of the present invention is a rectifier assembly mountable to the housing of a multi-phase alternating current generator to rectify A.C. current produced by the alternator into D.C. current, said rectifier assembly comprising: a positive heat sink positioned in a first plane; a negative heat sink positioned in a second plane parallel to said first plane; a finned heat sink positioned in a third plane parallel to said first and second planes, said finned heat sink comprising a plurality of electrically isolated heat sink portions, each of said electrically isolated heat sink portions including a terminal electrically connectable to a respective stator winding of said alternator, at least a portion of said heat sink portions positioned in an air flow caused by the operation of said alternator; a plurality of power diode pairs, each diode pair comprising a first -9a-diode and a second diode, each diode having an anode and a cathode, one diode of each pair having its anode connected to said negative heat sink and having its cathode connected to a respective one of said heat sink portions, the other diode of each pair having its anode connected to said respective one of said heat sink portions and having its cathode connected to said positive heat sink; an electrically insulating cover; and a plurality of compression springs positioned between said cover and said finned heat sink portions to apply pressure to said finned heat sink portions to thereby apply pressure to said diodes to provide secure mechanical and electrical contact between said diodes and said heat sinks.
A further object of an aspect of the present invention is a rectifier assembly for an alternator having stator windings, said rectifier assembly comprising:
a plurality of finned, air-cooled stator heat sinks, having respective stator terminals formed thereon; a negative polarity heat sink; a copper positive polarity heat sink extending into the cooling air flow, said positive polarity heat sink having air cooling slots for heat dissipation, said positive polarity heat sink having a plurality of holes formed therein; a first plurality of diodes supported by and connected to said positive polarity heat sink, said first polarity of diodes formed to fit parallel and above said negative polarity heat sink; a second plurality of diodes supported by said negative polarity heat sink, said second plurality of diodes extending through said holes in said positive polarity heat sink and connecting electrically and thermally to said plurality of stator heat sinks; and a plurality of compression springs forcing said first plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said positive polarity heat sink and forcing said second plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said negative polarity heat sink.
Another object of an aspect of the present invention is a rectifier assembly for an alternator, comprising: a negative heat sink; a positive heat sink; a plurality of pairs of diodes; a plurality of heat sink tabs electrically and mechanically connected to said negative heat sink, each of said tabs having a respective cavity which receives a first terminal of a respective first diode of one of said pairs of diodes; a plurality of cavities formed in said positive heat sink in alignment with said cavities of said plurality of tabs, said cavities each receiving a respective first terminal of a respective second diode of said one of said pairs of diodes; a -9b-plurality of stator tabs, each stator tab electrically and mechanically connected with respective second terminals of said first diode and said second diode in said one of said pairs of first and second diodes; and a plurality of compression springs, each compression spring positioned proximate to a respective one of said stator tabs, each said compression spring applying force against said respective stator tab to force said first and second diodes in said one of said pairs of diodes in secure electrical and mechanical contact with said respective one of said stator tabs, said heat sink tabs and said negative heat sink.
In another object of an aspect of the present invention is a rectifier assembly for an alternator, said rectifier assembly comprising: a first heat sink which provides an electrical interconnection for a positive voltage; a second heat sink which provides an electrical interconnection for a negative voltage; a plurality of diodes electrically interposed between said first heat sink and said second heat sink; a crush-proof gasket interposed between said first and second heat sinks, said crush-proof gasket providing electrical insolation between said first heat sink and said second heat sink; and a plurality of compression springs which apply force to hold each of said plurality of diodes in electrical and thermal contact with one of said first heat sink and said second heat sink.
Brief Description of the Drawings Figure 1 illustrates the thermal comparison of various rectifier assemblies, including original equipment manufacturer (OEM) assemblies, competitive aftermarket assemblies, and the present invention.
Figure 2 illustrates a completed rectifier assembly in accordance with one embodiment of the present invention.
wo 9sr~9o3z Pcrms~ms~to -IO-Figure 3, comprising Figures 3A and 3B, ihustrates an exploded view of the embodiment of Figure 2, showing the simplicity of maaufactiuing. ' Figure 4 illush'ates a cross-sectional view of the assembled rectif er assembly in accordance with the present invention, taken along the lines 4-4 in s Figure 2, showing the position of the hcat sinks and the diodes, and showing the housing and air flow for cooling.
Figcaes SA and 5>3 illustrate the capacitor mounting assembly witb~ an installation bolt completing the electrical connection from ono terminal of the capacitor to the negative ground potential of the alternator housing. ' ~ o Figures tiA and 6B illustrate the nesting of the compression springs in the phenolic cover and the assembly hole layout of the embodimeat of Figures 2-5.
Figure ? illustrates an exploded view of another embodiment of the invention with back-to-back button diodes, with cooling air flowing around the diodes and between the heat sinks and further showing the simplicity of ~ s manuf, Figuxe 8 illustrates a partial cross-sectional view of the embodiment of Figure 7 pictorially iliustraiing the cooling air flowing around the diodes and between the heat sinks, ' Figure 9 illustrates a partial cross-sectional view similar to Figure 8 with ' 2o semiconductor chip diodes instead of button diodes.
Figure 10 illustrates an electrical schematic of the rectifier stator connections, capacitor co~ections and battery charging system from positive and negative boat sinks using cathodes from positive diodes and anodes from negative diodes.
25 Detailed -Description of the Preferred Embodiment As illustrated in Figures 2-6, a rectifier assembly 100 in accordance with one embodiment of the present invention comprises a negative D.C. copper heat sink 101, a positive D.C. heat sink 102, and a phenoIicJfiberglass woven WO 96!19032 PCTlU595/16340 -lI-iz>sulatixlg gasket 103. The gasket 103 is used to electrically separate the negative and positive heat sinks, and is appro~amately 0.017 inches thick. The negative heat sink 101 has three nesting cavides 106a c to nest semiconductor button-type diodes 104a~ having resp~ive anodes 105a-c and having respective cathodes s 107a-c. The positive heat sink 102 has th~rec nest~g cavities 114a c to nest semiconductor button-type diodes 118a-c having respective cathodes 119a-c and having respective anodes 120a-c. Before the button diodes 104a-c are set in Place, the negative heat sink 101, the gasket 103 and the positive heat sink are stacked upon each other using a ~xxture (not shown) with aligiunent pins io 131a-c to locate the proper hole registration in cozresponding holes in the heat sinks and gaskets. Solder paste or solder tabs 117 are dispensed into the nest cavities 106a-c of the heat sink 101 and the nest cavities 114a-c of the heat sink 102. The button diodes 104a-c are then placed into the respective nest cavities lOba a with their respective anodes 105a-c against the negative heat sink 10I, and the button diodes 118a-c are placed into the nest cavities 114a-c of the positive heat sink 102 with the respective cathodes 119a-c of the diodes 118a-c positioned into the nests 114a-c. The bodies of the diodes 104a-c pass through the positive heat sink 102 through reeve clearance holes 109a-c, and pass through clearance holes 108 of the gasket 103.
zo Three stator heat sinks 122, 123, 124 have respective nesting cavities 121a-b, 121o-d and 121e-f. The nesting cavity 121a receives the anode I20a of the diode 118a. The nesting cavity 121b receives the cathode 107a of the diode 104x, The nesting cavity 121c receives the anode 120b of the diode 118b. The nesting cavity 121d receives the cathode 107b of the diode 104b. The nesting is cavity 121e receives the cathode 107c of the diode 104c. 'The nesting cavity 121f receives the anode 120c of the diode 118c. It is particularly preferable at this time that the solder paste or solder tabs 117 be dispensed onto the anodes 120a-c and onto the cathodes 107a-c, or, alternatively, dispensed into the nest cavities 121a-f prior to installing the stator heat sinks 122, 123, 124 onto the anodes ao 120a-c and onto the cathodes 107a-c of the positive heat sink lOZ and the negative heat sick 101, wo 9srmi pcrmsasrls3ao The stator heat sink 122 is shown with a wire crimping tab 125 in its normal stamped position, which allows a phcnolic cap 129 to be dropped over the ' tabs. A tab I26 of the stator heat sink 123 and a tab I2? of the stator heat sink 124 are shown in their formed positions after the phenolic cover 129 has been s iastalIed and riveted The tab 126 is.fiuther shown partially bent in preparation for the crimping process. A further tab I28 of the stator heat sink I24 provides an electrical contlection to a voltage regulator (not shown), Tile three stator heat sinks 122, 123, 124 ere plar.,cd an top of the diodes l0~ls a nasd ~o diodoo llQshe u~aieh have bees pre_reg~ctvrod EsY p~3~~,.
to diodes 104a-c and I1$a-e are thus ready to be locked into position by a set of rivets 132a-c which secure the phenoIic cover 129 with the tops of six compression springs 130 located in respective cavities 161a-f in the phenolic cover 129. The compression springs preferably comprise stainless steel.
As illustrated in more detail in Figure 3A, the compression springs I30 i s are maintained in alignment during the manufacturing steps by raised portions of the three stator heat sinks I22, 123, 124 formed on opposite sides of the heat sinks from the cavities 121a-f. The phenoIic cover 129 is then placed onto the disappearing anvil pin guides 131 which were previously used to guide and align tlae negative heat sink 101, the gasket 103 and the positive heat sink I02 into Zo position for assembly. The tabs 125, 126 and I27 are passed through slots 160a-c in the phenolic cover 129. The compression springs 130 are received by cavities 161 a-f in the phenolic cover 129 (see Figures 6A and 6H). The rectifier assembly 100, including the diodes 104a c, 118a c, the stator heat sinks 122, 123, I24 and the cover I29, call now be riveted and sent through a soldering or curing 2s fenrace operation. Note that the slots 160a-c may be open dovetailed slots, as illustrated in Figure 3A, or the slots 160a-c may be oval . Waped SlOt9, Ss illustrated in Figure 6A.
After cooling, the rectifier assembly I00 is tested, and the tabs 125, 126, 127 are foamed and aligned to accept the stator wire leads to present accidental ao shorting when the rectifier assembly is installed into the alternator. The tabs 125, 126, 127 are then crirzzped and soldered to the stator winding to complete the three series electrical circuits for the poly-phase stator.
As shown in more detail in Figures SA and 5>3, an electrically insulating capacitor stapd-o~ bushing 133, comprising plastic, for example, and having a s pair of brass terminals 134, 135 mounted thereon, is pressed into a mounting hole 136 of the positive heat sink 102. A capacitor 137 is affixed in an open area on the negative heat sink 101 usung siIicoue rubber adhesive 111 (shown schematically in Figure SB). First and second leads 147, 148 of the capacitor 13? are soldered or crimped to the terminals 134, 135, respectively; to complete t o the positive electrical connection 102 and the negative electrical connection 10I
for the capacitor 137 when the rectifier assembly is installed and a bolt 146 is torqucd down to the housing 143. The bolt 146 completes the electrical connection between the brass terminal 135 and the negative heat sink 101 and the brass terminal 134 is in fixed electrical contact with the ~sitive heat sink 102.
~ s A copper spacer bushing 142 completes the electrical connection to the positive polarity components of the alternator when a nut 138 is tordued down onto a positive voltage stud 150 located through the housing 143 to a positive output connector I52 (see Figure SB which illustrates a cross-sectional view of a portion of the alternator housing 143). A plastic spacer bushing 139 insulates 2o the stud 150 from the housing 143. The nut 138 and bolts 140 and 146 are used to toxquc the rectifier assembly 100 down to the housing 143 to create a good thermally conductive path for the negative heat sink 101 without introducing au electrically conductive path ~rom the positive hcat sink 102.
The alternator cooli»g fan system supplies cooling air flow (indicated by 2s an arrow 145 in Figure 4) through air ported windows 144 on the back side of the housing 143 to cool the copper positive heat sink 102 which has a series of vented slots 110 extending above the windows 144. The three stator heat sinks ' 122, I23, 124 include slots 170. '1 he three stator heat sinks 122, 123, 12.4 extend above the positive heat sink 102 and are cooled by the same cooling air flow ao through the slots 170 to create a rapid and an efficient heat transfer system to ~CTlIJS951163~0 dissipate the heat generated by the diodes while converting alternating curt to direct current in an automotive electrical system.
Figure 10 illustrates an electrical schematic of the completed assembly I00 which receives the electrical outputs from the stator windings 180 of a s conventional alternator and which provides a D.C. output current to charge a conventional battery 182.
Figure 7 illustrates an exploded view and Figure 8 illustrates a peal cross-sectional view of a new or an existing rectifier assembly 200, such as the well known CS130, which is rebuilt in accordance ysil~ ~e pre~~ iny~hon using modified heat sinks only. In particular, the rebuilt rectifier assembly includes a positive heat sink 2I0 and a negative heat sink 212 which form part of the existing rectifier assembly. Three phenoliclfiberglass woven insulator ring gaskets 214 are nested under the mounting hole locations 2I5, 2I6 and 136 for the bolts 13$, I40 and 146 to electrically and. mechanically separate the positive heat sink 210 from the negative heat sink 2I2, The ring gaskets 2I4 are approximately 0.020" thick and allow heat transfer and air circulation between the two heat sinks (represented by an arrow 145 in Figure 8) for cooling. The ring gaskets 2I4 will not crush or loosen after being torqued down during installation. The positive heat sink may advantageously include recesses 217 zo (shown as dashed lines m Figures 8 and 9) to receive a portion of the ring gasket's 214 to hold the zing gaskets 214 in fixed positiozts until the rivets or bolts are secured. The ring gaskets 2I4 may also be used in the embodiment of Figures 2-6 in place of the continuous gasket 103.
An L-shaped br~.ss tab ?.20 is press fit into each of three existing 2s dovetailed slots 22Z of the positive heat sink 2I0 such that a horizontal portion 224 of each tab 220 overlies a portion 226 of the negative heat sink 212 when assembled. The horizontal portion 224 of the brass tab 220 includes a cavity 230, and the underlying portion 226 of the negative heat sink 212 includes a cavity 232 in substantial alignment with the cavity 230 when assembled.
so A diode 240 having an anode 242 and a cathode 244 is positioned with thc cathode 244 in the cavity 230. Similarly, a diode 250 having an anode 252 w0 96I19U3Z . ~CTIITS95116340 and a cathode 254 is positioned with tht anode 252 in the cavity 232. A
flexible brass tab 260 has a first offset or depressed portion 262 and a second offset or depressed portion 264, Each offset portion 262, 264 forms a respective depression on one side of the tab 260 and bump on the opposite side of the tab 260. The tab 260 is formed around a compression spring 270 so that the compression spring 270 is constrained between the two bumps caused by the o#Set portions 262, 264. The depression caused by oNe offset portion 262 is positioned to receive the anode 242 of the diode 240, and the depression caused by the offset portion 26~ is positioned to receive the cathode 254 of the diode ~ 0 250. While being held in these relative positions, the positive heat sink 210 is secured to the negative heat sink 21z by a pair of rivets 318 through holes in the positive heat sink 210 and holes 320 in the negative heal sink 212. The rivets 318 are electrically is°labed from the negative heat sink 212 by tapered insulators 321 which spread beneath the lower heads of the rivets when they are z s formed. The compression springs 270 are thus compressed to hold the diodes in fixed electrical and, mechanical contact with the positive heat sink 210, the txgative heat sink 21.2 and the flexible tab 260. Preferably, as discussed above m connection with the exnbod~~t of Figures 2-6, the solder paste or solder tabs are positioned on the anodes and cathodes o~ the tyvo diodes or in the receiving zo cavities and depressions prior to assembly to enhance the electrical contact between the components- It should be understood that the assembly of Figure 6 is used for each of the three diode pairs for each stator winding. Xn alternative ~~~ ~. ding slots can be out between, under or on top of the positive heat sink 2I0 as illustrated by a dashed liuo 218 is Figure 9.
~s Figure 9 illustrates an altemaflve embodiment of an existing rectifier assembly rebuilt in accordance with the present invention. The embodiment of Figure 9 is similar to the embod~c~at of Figures 7 at~d 8, and like compoNents are identified with Iike numbers; however, semiconductor chips are used in Figure 9 instead of the button-type diodes of Figures 7 and 8. In particular, a ao first semiconductor chip 300 has a pair of nickel-plated copper tabs 302, 304, which are slightly larger than the chip 300, soldered to the lower anode surface w0 96/19032 s ~I'1US95/1G340 anti upper cathode surface of the chip 300 in a conventio~nal~ manner.
Although the edges of the semicoriduetor chip 300 are preferably glass psssivated, a silicon O-ring or adhesive 304 is positioned on the outer perimeter of the chip 300 betuve~ the extend perimeters of the tabs 302, 304 to seal the exposed edges from dust, humidity, and the like. The nickct-plated copper tabs 302 aad 304 are respectively positioned in the cavity z62 of the flexible tab 260 and in the cavity 230 of the brass tab 220. A second semiconductor chip 310 is formed in like manner with a pair of nickel-plated copper tabs 31Z and 314 soldered to its lower anode surface and its upper cathode suxface, respectively. A silicon-O-ring i o seals the glass passivated edges of the chip 310. The second semitconductor chip 3I0 is positioned with the lowex brass tab 3I2 nested in the cavity 232 of the negative heat sink 212 and with the upper brass tab 314 nested in the cavity of the flexible tab 260. After positioning the semiconductor chips 300, 310 and the other semiconductor chips {ant slaovm}, the assembly is completed as before to compress the spring 270 and provide secure electrical and mechanical contact.
Again, solder paste or tabs (not shown) are applied to the brass tabs 302, 304, 3I2, 3I4 or to the respective cavities (shows in Figvm 7} before assembly.
' As discussed above, the embodiments of the present invention provide a substantial improvement over the conventional rectifier assemblies by increasing zo the heat dissipation and thus reducing the operating temperature of the rectifier ' assembly. Figure 1 illustrates graphs which compare the thermal characteristics of various rectifier assemblies. Line A illustrates the thermal profile of an OEM
rectifier asseatnbly. Line B illustrates the thermal profile of a competitive after-market rectifier assembly. Line C illustrates the thenaal profile of the present 2s invention without a fumed stator heat sink (e.g., such as when implemented on a rebuilt rectifier assembly as illustrated u1 Figures 6 and ~. Line D
illustrates the therrzlal profile of the present invention with a finned stator heat sink, as illustrated in Figures 2-5. Line E illustrates the thermal profile of a fwrther eom~petitive rectifier.
ao As described herein, this preferred embodiment of the prtsent irtventiou merely shows the simplicity, cost savings and reliability of the present invention.
WO 96119032 PC'ffUS95I16340 . -I7-There are many other applications of the prrscat invention which could deviate from the intent of the prascnt invention; however, .the irrttnt of using the compression spring-loaded embodiment with nested stator heat sinks or other heat sinks which are slotted and extended into the cooling air flout to extend the life s of the diodes because of the springs forcing a better contact system, and the intent of simplifying manufacturing and iastallatioa using phenolic type, Grush-proof gaskets, is within the scope of the present invention as defined in the clans appended hereto.
Claims (26)
1. A rectifier assembly mountable to the housing of a multi-phase alternating current generator to rectify A.C. current produced by the alternator into D.C. current, said rectifier assembly comprising:
a positive heat sink positioned in a first plane;
a negative heat sink positioned in a second plane parallel to said first plane;
a finned heat sink positioned in a third plane parallel to said first and second planes, said finned heat sink comprising a plurality of electrically isolated heat sink portions, each of said electrically isolated heat sink portions including a terminal electrically connectable to a respective stator winding of said alternator, at least a portion of said heat sink portions positioned in an air flow caused by the operation of said alternator;
a plurality of power diode pairs, each diode pair comprising a first diode and a second diode, each diode having an anode and a cathode, one diode of each pair having its anode connected to said negative heat sink and having its cathode connected to a respective one of said heat sink portions, the other diode of each pair having its anode connected to said respective one of said heat sink portions and having its cathode connected to said positive heat sink;
an electrically insulating cover, and a plurality of compression springs positioned between said cover and said finned heat sink portions to apply pressure to said finned heat sink portions to thereby apply pressure to said diodes to provide secure mechanical and electrical contact between said diodes and said heat sinks.
a positive heat sink positioned in a first plane;
a negative heat sink positioned in a second plane parallel to said first plane;
a finned heat sink positioned in a third plane parallel to said first and second planes, said finned heat sink comprising a plurality of electrically isolated heat sink portions, each of said electrically isolated heat sink portions including a terminal electrically connectable to a respective stator winding of said alternator, at least a portion of said heat sink portions positioned in an air flow caused by the operation of said alternator;
a plurality of power diode pairs, each diode pair comprising a first diode and a second diode, each diode having an anode and a cathode, one diode of each pair having its anode connected to said negative heat sink and having its cathode connected to a respective one of said heat sink portions, the other diode of each pair having its anode connected to said respective one of said heat sink portions and having its cathode connected to said positive heat sink;
an electrically insulating cover, and a plurality of compression springs positioned between said cover and said finned heat sink portions to apply pressure to said finned heat sink portions to thereby apply pressure to said diodes to provide secure mechanical and electrical contact between said diodes and said heat sinks.
2. The rectifier assembly as defined in Claim 1, wherein said compression springs are stainless steel.
3. The rectifier assembly as defined in Claim 1, wherein said cover is a molded plastic cover.
4. The rectifier assembly as defined in Claim 3, wherein said molded plastic cover is phenolic.
5. The rectifier assembly as defined in Claim 1, wherein said positive and negative heat sinks support a plastic-type bushing having brass terminals which locate and position a capacitor for assembly and actual operation to decrease vibration damage to capacitor leads.
6. The rectifier assembly as defined in Claim 1, further including a crush-proof, phenolic type, electrically insulating gasket positioned between said positive heat sink and said negative heat sink.
7. A rectifier assembly for an alternator having stator windings, said rectifier assembly comprising:
a plurality of finned, air-cooled stator heat sinks, having respective stator terminals formed thereon;
a negative polarity heat sink;
a copper positive polarity heat sink extending into the cooling air flow, said positive polarity heat sink having air cooling slots for heat dissipation, said positive polarity heat sink hurting a plurality of holes formed therein;
a first plurality of diodes supported by and connected to said positive polarity heat sink, said first polarity of diodes formed to fit parallel and above said negative polarity heat sink;
a second plurality of diodes supported by said negative polarity heat sink, said second plurality of diodes extending through said holes in said positive polarity heat sink and connecting electrically and thermally to said plurality of stator heat sinks; and a plurality of compression springs forcing said fast plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said positive polarity heat sink and forcing said second plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said negative polarity heat sink.
a plurality of finned, air-cooled stator heat sinks, having respective stator terminals formed thereon;
a negative polarity heat sink;
a copper positive polarity heat sink extending into the cooling air flow, said positive polarity heat sink having air cooling slots for heat dissipation, said positive polarity heat sink hurting a plurality of holes formed therein;
a first plurality of diodes supported by and connected to said positive polarity heat sink, said first polarity of diodes formed to fit parallel and above said negative polarity heat sink;
a second plurality of diodes supported by said negative polarity heat sink, said second plurality of diodes extending through said holes in said positive polarity heat sink and connecting electrically and thermally to said plurality of stator heat sinks; and a plurality of compression springs forcing said fast plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said positive polarity heat sink and forcing said second plurality of diodes in secure mechanical and electrical contact with said stator heat sinks and said negative polarity heat sink.
8. A rectifier assembly as defined in Claim 7, further including a plastic-type cover with molded slots, said plurality of stator terminals extending through said slots to be affixed to said stator windings of said alternator, said molded slots holding said stator terminals in fixed spaced apart relationship to preclude electrical connections between said stator terminals.
9. A rectifier assembly as defined in Claim 8, wherein which said plastic-type covering includes a plurality of rivet holes, a plurality of spring cavities and a plurality of air flow openings, said plastic cover further including alignment holes to receive a plurality of alignment pins to align said rivet holes, said cavities and said air flow openings during manufacture of said rectifier.
10. A rectifier assembly as defined in Claim 7, further including a plastic-type bushing which connects and supports a capacitor, said bushing having brass-type formed terminals to locate said capacitor in position for assembly and operation while also electrically connecting said capacitor to said positive polarity heat sink and said negative polarity heat sink.
11. A rectifier assembly for an alternator, comprising:
a negative heat sink;
a positive heat sink;
a plurality of pairs of diodes;
a plurality of heat sink tabs electrically and mechanically connected to said negative heat sink, each of said tabs having a respective cavity which receives a first terminal of a respective first diode of one of said pairs of diodes;
a plurality of cavities formed in said positive heat sink in alignment with said cavities of said plurality of tabs, said cavities each receiving a respective first terminal of a respective second diode of said one of said pairs of diodes;
a plurality of stator tabs, each stator tab electrically and mechanically connected with respective second terminals of said first diode and said second diode in said one of said pairs of first and second diodes; and a plurality of compression springs, each compression spring positioned proximate to a respective one of said stator tabs, each said compression spring applying force against said respective stator tab to force said first and second diodes in said one of said pairs of diodes in secure electrical and mechanical contact with said respective one of said stator tabs, said heat sink tabs and said negative heat sink.
a negative heat sink;
a positive heat sink;
a plurality of pairs of diodes;
a plurality of heat sink tabs electrically and mechanically connected to said negative heat sink, each of said tabs having a respective cavity which receives a first terminal of a respective first diode of one of said pairs of diodes;
a plurality of cavities formed in said positive heat sink in alignment with said cavities of said plurality of tabs, said cavities each receiving a respective first terminal of a respective second diode of said one of said pairs of diodes;
a plurality of stator tabs, each stator tab electrically and mechanically connected with respective second terminals of said first diode and said second diode in said one of said pairs of first and second diodes; and a plurality of compression springs, each compression spring positioned proximate to a respective one of said stator tabs, each said compression spring applying force against said respective stator tab to force said first and second diodes in said one of said pairs of diodes in secure electrical and mechanical contact with said respective one of said stator tabs, said heat sink tabs and said negative heat sink.
12. The rectifier assembly as defined in Claim 11, wherein said diodes comprise button type diodes.
13. The rectifier assembly as defined in Claim 11, further including a crush-proof, phenolic type, electrically insulating gasket positioned between said positive heat sink and said negative heat sink.
14. A rectifier assembly for an alternator having a plurality of stator windings, said rectifier assembly comprising:
a plurality of stator terminals, each stator terminal electrically connectable to a respective stator winding of said alternator;
a first heat sink and a second heat sink, said first heat sink electrically positive with respect to said second heat sink when said alternator is operating;
a plurality of diodes electrically connected between said first heat sink and said second heat sink, said diodes further connected to said plurality of stator terminals; and a plurality of compression springs, said compression springs applying force to said plurality of diodes to force said plurality of diodes into secure electrical and mechanical contact with said first heat sink, said second heat sick and said stator terminals.
a plurality of stator terminals, each stator terminal electrically connectable to a respective stator winding of said alternator;
a first heat sink and a second heat sink, said first heat sink electrically positive with respect to said second heat sink when said alternator is operating;
a plurality of diodes electrically connected between said first heat sink and said second heat sink, said diodes further connected to said plurality of stator terminals; and a plurality of compression springs, said compression springs applying force to said plurality of diodes to force said plurality of diodes into secure electrical and mechanical contact with said first heat sink, said second heat sick and said stator terminals.
15. The rectifier assembly as defined in Claim 14, wherein said stator terminals are formed as a third heat sink, and wherein said compression springs are positioned between said third heat sink and respective terminals of said plurality of diodes.
16. The rectifier assembly as defined in Claim 14, further including a crush-proof; phenolic type, electrically insulating gasket positioned between said first heat sink and said second heat sink.
17. The rectifier assembly as defined in Claim 14, wherein said diodes are positioned in back-to-back configuration.
18. The rectifier assembly as defined in Claim 17, wherein metal diode holders are staked into dovetailed grooves in said first heat sink.
19. The rectifier assembly as defined in Claim 18, further including an air gap positioned between said first and second heat sinks.
20. The rectifier assembly as defined in Claim 19, further including a crush-proof insulator positioned between said first and second heat sinks to space said first and second heat sinks apart to form said air gap.
21. The rectifier assembly as defined in Claim 20, wherein said first and second heat sinks are secured together by rivets, said rivets electrically insulated from at least one of said first and second heat sinks.
22. A rectifier assembly for an alternator, said rectifier assembly comprising:
a first heat sink which provides an electrical interconnection for a positive voltage;
a second heat sink which provides an electrical interconnection for a negative voltage;
a plurality of diodes electrically interposed between said first heat sink and said second heat sink;
a crush-proof gasket interposed between said first and second heat sinks, said crush-proof gasket providing electrical insolation between said first heat sink and said second heat sink; and a plurality of compression springs which apply force to hold each of said plurality of diodes in electrical and thermal contact with one of said first heat sink and said second heat sink.
a first heat sink which provides an electrical interconnection for a positive voltage;
a second heat sink which provides an electrical interconnection for a negative voltage;
a plurality of diodes electrically interposed between said first heat sink and said second heat sink;
a crush-proof gasket interposed between said first and second heat sinks, said crush-proof gasket providing electrical insolation between said first heat sink and said second heat sink; and a plurality of compression springs which apply force to hold each of said plurality of diodes in electrical and thermal contact with one of said first heat sink and said second heat sink.
23. The rectifier assembly as defined in Claim 22, wherein said crush-proof gasket comprises a phenolic/fiberglass woven, electrically insulating gasket.
24. The rectifier assembly as defined in Claim 22, wherein said crush-proof gasket comprises a plurality of spaced apart gaskets having air gaps therebetween, said air gaps permitting cooling sir to flow between said first heat sink and said second heat sink.
25. The rectifier assembly as defined in Claim 22, wherein said first heat sink and said second heat sink comprise heat sinks in a conventional rectifier assembly, and wherein said crush-proof gaskets are inserted between said first heat sink and said second heat sink to provide an electrical insulator which maintains electrical isolation between said first heat sink and said second heat sink when said first heat sink and said second heat sink are forced toward each other.
26. The rectifier assembly as defined in Claim 22, further comprising a plurality of compression springs which apply force to hold each of said plurality of diodes in electrical and thermal contact with one of said first heat sink and said second heat sink.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/357,419 | 1994-12-16 | ||
| US08/357,419 US5659212A (en) | 1994-12-16 | 1994-12-16 | Rectifier assembly for automotive alternator |
| PCT/US1995/016340 WO1996019032A1 (en) | 1994-12-16 | 1995-12-14 | Rectifier assembly for automotive alternator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2207902A1 CA2207902A1 (en) | 1996-06-20 |
| CA2207902C true CA2207902C (en) | 2006-02-07 |
Family
ID=35891648
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002207902A Expired - Fee Related CA2207902C (en) | 1994-12-16 | 1995-12-14 | Rectifier assembly for automotive alternator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2207902C (en) |
-
1995
- 1995-12-14 CA CA002207902A patent/CA2207902C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2207902A1 (en) | 1996-06-20 |
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| EEER | Examination request | ||
| MKLA | Lapsed |