Patent Application
20070206363
The present invention relates to the field of voltage regulators, and more particularly, the present invention relates to voltage regulators for controlling voltage and current supplied from a generator or alternator used in maritime, automobile, motorcycle or small engine charging systems.
The charging system for an automobile, truck, boat, motorcycle or small engine typically includes an alternator or generator with appropriate windings, armature and stator components. A voltage regulator regulates the charging voltage and output current to provide consistent alternator or generator operation during varying loads that would create voltage drops and other operational problems. Many different regulator designs are commercially available, including discrete transistor, custom integrated circuit systems using application specific integrated circuits (ASIC), or hard-wired circuits that define a specific function for a specific type of application. These voltage regulators typically require the use of a heat sink for drawing heat away from the active and passive voltage regulator components, which in many prior art devices, are mounted on a conventional printed circuit board (PCB) or printed wiring board (PWB) and sometimes included on a heat sink or ceramic material. The heat sink radiates excessive heat generated because of the voltage regulator operation into the atmosphere or mounting system.
Typically, many of the voltage regulator designs include a voltage regulator body having a component receiving cavity and a lead frame embedded within the voltage regulator body. This lead frame forms external lead frame connectors and may include some type of terminal connections positioned on the inside surface of the component receiving cavity such as disclosed in commonly assigned U.S. patent application Ser. No. 10/982,176, filed Nov. 5, 2004, the disclosure which is hereby incorporated by reference in its entirety. This type of voltage regulator includes a substrate with active and passive components mounted on the substrate and wire stand-up leads that are soldered and connected to the housing terminals or internal lead frame terminals by soldering. Other designs include resistance welding any stand-up leads to internal lead frame terminals, but with the different active and passive components and stand-up leads still soldered to a substrate.
Another approach replaces a substrate with a printed circuit board in which some printed circuit board components are soldered to a ceramic. Some components and connectors are soldered to the board and other terminals are welded.
These proposals, however, have a number of soldered connections or junctions that can fail from shock, vibration or reflow melting. Every junction in the voltage regulator is a potential problem arising from both manufacturing and component use. It is believed that other proposals have used integrated circuits and complicated tuning circuits and welded connections, but these types of designs were complicated in circuit designs and not amenable for packaging in certain voltage regulator applications such as CS130 applications.
In accordance with one non-limiting aspect of the present invention, a voltage regulator controls voltage supplied from a generator or alternator and includes a voltage regulator body having at least one component receiving cavity. A lead frame is embedded within the voltage regulator body and forms external lead frame connectors on the voltage regulator body that are adapted to be connected to devices controlled by the voltage regulator. The lead frame also forms internal lead frame connectors within the component receiving cavity. The internal lead frame components expose connection paths to optimize the use of space in the at least one component receiving cavity. A voltage regulator integrated circuit (IC) and passive components are mounted within the component receiving cavity and each connected to selected internal lead frame connectors at a connection, such as a welded or mechanical connection, such that the voltage regulator IC and passive components form a voltage regulating circuit. Each connection is preferably formed as a welded connection, for example, a resistance welded connection. The lead frame is configured such that one or more passive components are positioned over or under at least a portion of the voltage regulator IC.
In yet another aspect, the lead frame extends into the at least one component receiving cavity and includes one of a raised or lowered portion or a combination of raised or lowered portions allowing one or more passive components to be mounted over, under or a combination of both to a portion of the voltage regulator IC. A heat sink can be connected to the voltage regulator IC in yet another aspect.
In yet another aspect, the voltage regulator IC is formed as an All Silicon Voltage Regulator (ASVR). The passive components can include a varistor operative with the voltage regulator IC. The varistor could be connected between a battery sense input terminal and the ground terminal of the voltage regulator IC. A diode could be connected between the lamp output terminal and the ground terminal of the voltage regulator IC. The voltage regulator, in one non-limiting example, is adapted for use in B-circuit (high-side) vehicle system applications.
In yet another aspect, the lead frame connectors are not necessarily configured to allow passive components to be positioned over or under or a combination of both to at least a portion of the voltage regulator IC, but typically would include at least a varistor and a diode.
A method of forming a voltage regulator is also set forth.
Other objects, features and advantages of the present invention will become apparent from the detailed description of the invention which follows, when considered in light of the accompanying drawings in which:
Different embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments are shown. Many different forms can be set forth and described embodiments should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments.
In accordance with one non-limiting example of the present invention, a voltage regulator includes both a voltage regulator integrated circuit (IC) and passive components mounted within at least one component receiving cavity of a voltage regulator body, each connected to selected internal lead frame connectors at a connection, typically formed by resistance welding or in some cases, a strong mechanical bond. The voltage regulator IC and passive components form a voltage regulating circuit. The lead frame is configured in one non-limiting aspect such that one or more passive components are positioned over or under or a combination of both to at least a portion of the voltage regulator IC. It should be understood that lead frame refers to the metallic or other material embedded within the voltage regulator body, and can be formed by one or more sections, connected or separate, and forming internal lead frame terminals in the cavity and external terminals, including terminals in a slot that receives a wiring harness.
In yet another non-limiting aspect of the present invention, the passive components include a varistor operative with the voltage regulator IC and operatively connected between the battery sense input terminal and the ground terminal of the voltage regulator IC. A diode can be operatively connected between the lamp output terminal and the ground terminal of the voltage regulator IC. The voltage regulator is typically adapted for use in B-circuit (high-side) vehicle system applications, for example, CS130 and similar alternator applications.
In another non-limiting example, the voltage regulator IC can be formed as a flip chip or other configuration and connected such as by resistance welding to the internal lead frame connectors. Passive or “discrete” components are connected, for example, resistance welded to the internal lead frame connectors. It should be understood that “discrete” components is a term that can also be synonymously used for the term “passive” components, such as a varistor, resistor and diode as explained below. This type of voltage regulator design in accordance with non-limiting examples of the present invention overcomes the disadvantages from using solder joints that can fail from shock, vibration and reflow (melting). As a result, the voltage regulator, in accordance with non-limiting examples of the present invention, has a longer component life, better cost value and a quality that meets or exceeds the original equipment specifications.
One commercial example of this type of voltage regulator is a D411 voltage regulator sold by Transpo Electronics, Inc. This type of voltage regulator 50 includes a voltage regulator body 52 having a component receiving cavity (not shown in this view), which is typically covered. A lead frame is embedded within the voltage regulator body and forms external lead frame connectors 54 on the voltage regulator body, as illustrated. Details of the different external connectors and their function and internal lead frame connectors will be described relative to an example of a prior art voltage regulator shown in
A prior art voltage regulator 100 such as disclosed in the copending and commonly assigned '176 application is now described relative to
In this particular embodiment, the voltage regulator body 102 is formed from an insulator material with an embedded lead frame shown by dashed lines within the voltage regulator body. The lead frame 162 includes external lead frame terminals 164 that connect to wires and terminals of various devices controlled by the voltage regulator, or receive signals from other devices. The board or component receiving cavity 104 in this example is an open cavity as illustrated (later covered in the final product) and includes internal lead frame terminals 166 extending from the lead frame that connect to the terminal connections 118 formed as conductive pins extending from the substrate board 106, which are bent and soldered onto the internal lead frame terminals 166 as shown in
During assembly, when the substrate board 106 is received into the board receiving cavity 104, all conductive pins 118 are typically bent inward so that they do not interfere with the embedded conductors forming the internal terminals 166. The silicon gel or conductive epoxy or other adhesive can be used to secure the substrate board 106 and later a cavity cover. The conductive pins are bent and soldered to the internal terminals and the component receiving cavity 104 is filled with a silicon gel. The cavity cover is then placed over the cavity and secured using epoxy.
The illustrated voltage regulator 100 is typically used with CS-series voltage regulators, for example, with a CS130 series alternator, but it should be understood that it can be used on different types of alternators. In this prior art example, the voltage regulator circuit could incorporate a field effect transistor having a drain terminal connected to B+ and to an integrated circuit chip, for example, its terminal A. An external sense connector could be connected to terminal 3 of the IC chip, which typically has dual sensing ability, either external or internal. This voltage regulator 100 is a B-circuit as a high-side drive with a voltage set point at about 14.7 volts. This voltage regulator can be light activated and the stator input can turn off the light. It preferably has a soft start feature.
Typically, in this type of voltage regulator application, the substrate board and its mounted active and passive components are covered completely with a conformal coating and cured at room temperature for about 15 minutes. It is possible to inspect with a UV inspection light and further curing can occur at 80° C. for 15 minutes. The insulator material, for example, a voltage encapsulant base with urethane activator, can act as an adhesive and fill the component receiving cavity.
This and other types of substrate board could be mounted to a ceramic, or could be formed as a separate substrate board, for example, such as disclosed in the copending and commonly assigned '176 patent application that includes a metallic base layer, insulator layer on the metallic base layer, and circuit layer typically formed from copper on the insulator layer and defining a printed circuit pattern. Active components, for example transistors, and passive components, for example capacitors and resistors, can be interconnected by a printed circuit pattern formed as a circuit layer. The metallic base layer could be formed from aluminum or copper, but also could be avoided as a base layer altogether. The substrate board as described could avoid a large heat sink and associated mounting hardware or other thermal interface material.
The substrate board is operable to minimize solder joint fatigue and enhance heat spreading, but still uses a large number of soldered joints as illustrated. Although the number of required interconnections that are soldered are reduced because of surface mount technology applications, reflow soldering techniques, and the use of automatic pick and place equipment for inserting the substrate board into the component or component receiving cavity, there is still the drawback of the soldered connections.
Another prior art voltage regulator 200 having a reduced number of soldered connections is shown in
In accordance with non-limiting examples of the present invention,
Although resistance welding is typically used as shown in the examples from
The different terminals of the voltage regulator IC 490d and the passive components such as the varistor 490a, diode 490b and resistor 490c can be connected to the various internal lead frame connectors by wire bonding such as more particularly shown in
After resistance welding, a cover 492 (
In the specific configuration shown in
The varistor 490a could be a surge protection device that could be connected across an AC input, for example, the ground and the internal sense connector for the battery. As typical with varistors, it can create a shunt path. The varistor 490a could be formed as a metal oxide varistor and have significant non-ohmic current-voltage characteristics. The varistor 490a could contain a mass of zinc oxide grains in a matrix of other metal oxides, sandwiched between two metal plates as electrodes. The boundary between each grain and its neighbor could form a diode junction to allow current to flow in one direction. The randomly oriented grains could be electrically equivalent to a network of back-to-back diode pairs in parallel with many other pairs.
An example of a diode 490b could be a 100 volt switching diode and the resistor 490c could be a 0.25 watt, 7.5K ohm, 5% resistor in these non-limiting examples. The use of these three passive components and the voltage regulator IC is a improved and simplified circuit design for this type of voltage regulator and allows efficient and compact packaging.
It should be understood that the voltage regulator 400 as described is illustrated as a voltage regulator for use in B-circuit (high-side) vehicle system applications. The particular resistance welded connections, the circuit configuration, and the bent lead frame as described could be used in other voltage regulators, including those adapted for use in marine engine applications, motorcycle applications, A-circuit (low-side) vehicle applications, and permanent magnet applications as non-limiting examples. It could also be used in a Mercury-Marine engine application in which a regulator body could be formed as a metallic housing or “can” as referred to by those skilled in the art.
An example A-circuit (low-side) voltage regulator could be Mitsubishi voltage regulators, for example, used on Ford Tracer, Probe and Mazda and similar vehicles. Another example is a voltage regulator sold under the designation IM265 by Transpo Electronics, Inc., and has a system voltage of 12 volts as used on the “A” circuit or low-side drive with a trio excitation. It could be indicator light activated, and in one example, could use a 28 millimeter brush ring and have an operating temperature range of about −40° C. to about 125° C. It could have a field current of about 4 amps and a voltage set point at 4000 RPM of about 14.5 volts. It typically would include a B-terminal and a field terminal at the top. The voltage regulator could also be used such as for Harley-Davidson motorcycles sold under the designation H1988 by Transpo Electronics, Inc. Many other non-limiting examples are possible.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
