Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-05-05
2001-10-16
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S064000, C310S089000
Reexamination Certificate
active
06304012
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to alternators and methods for producing alternators, and more particularly, but not by way of limitation, to an improved alternator having a higher electrical current output at low speeds of revolutions and having an improved battery terminal assembly and to methods of producing such an improved alternator.
2. Brief Description of the Prior Art
Alternators for vehicles are well known in the art. The prior art alternators, such as the CS-130 alternator manufactured by General Motors, are presently provided with a housing defining an alternator interior space adapted to receive a rotor having a rotor coil. The rotor coil is rotated by the vehicle's engine and generates a moving magnetic field which induces an alternating current in three-phase stator windings disposed near the rotor coil. The speed at which the rotor coil rotates and the intensity of the rotor coil's magnetic field determine the voltage and current characteristics of the electricity generated by the prior art alternator.
Because the vehicle's engine speed varies considerably under normal driving conditions, the prior art alternators are provided with a voltage regulator which controls the intensity of the magnetic field generated by the rotor coil so that the alternator's output voltage remains within predefined limits. However, as the engine speed varies, the current of the electricity produced by the alternator also varies. That is, as the engine speed is reduced the electrical current produced by the prior art alternators is also reduced, and as the engine speed is increased the electrical current produced by the prior art alternators is also increased.
The output of the prior art alternators is electrically connected to the battery and electrical system of the vehicle to recharge the battery and to meet the current demands of the electrical system. However, if the prior art alternators are not generating a sufficient amount of electrical current to meet the demands of the electrical system then such electrical system draws electrical current from the battery to meet this deficiency. Because excess use of the battery shortens the useful life of same, it is undesirable for the battery to supply electrical current to the electrical system except during starting.
The prior art alternators typically produce a sufficient amount of electrical current to effectively charge the battery and to meet the demands of the electrical system when the prior art alternators are operating at high speeds. However, when the prior art alternators are operating at idle or low speeds, the prior art alternators produce an insufficient amount of electrical current to meet the demands of the electrical system. Thus, the battery supplies electrical current to the electrical system when the engine is operating at low speeds which shortens the useful life of the battery.
The voltage regulators of the prior art alternators are typically disposed in the alternator interior space of the housing where they are subjected to both external and internal heat. It should be noted that the number one cause of alternator failure is an overheated voltage regulator. The external heat described above is supplied to the voltage regulator by the engine and the internal heat described above is supplied to the voltage regulator by the electric current flowing through the voltage regulator.
While these prior art voltage regulators maintain the alternator's output within predefined limits, heat sinks provided on the back plate of the regulator do not effectively transfer the external and internal heat away from the voltage regulator. Thus, the voltage regulator overheats and is either destroyed or caused to malfunction.
To supply electricity to the rotor coil of the prior art alternators so that the rotor coil can generate the moving magnetic field, the rotor is provided with a pair of slip rings which are adapted to mate against a pair of corresponding brushes. The prior art alternators are provided with a brush assembly which includes a brush housing having a pair of brush chambers formed therein. A cylindrically shaped brush spring and one of the brushes is disposed in each of the brush chambers such that the spring force of each brush spring forces one of the brushes against the corresponding slip ring of the rotor.
Upon assembly of the prior art alternators, a portion of the brush may be inadvertently locked between one of the loops of the brush spring and the brush housing thereby preventing the brush spring from forcing the brush against the slip ring of the rotor coil. Thus, electricity is not supplied to the rotor coil and the alternator malfunctions.
The brushes in the prior art alternator are electrically connected to their respective electrical field circuits provided externally of the brush housing by flexible braided wires extending from the respective brushes to the field circuit connections. Because the brush housings of the prior art alternators provide no guarding or channeling mechanisms for the braided wires, these wires can be pinched, trapped, severed or otherwise damaged. If any of these conditions occur, the electrical connection to the field circuit can be lost and the prior art alternator will fail.
In addition, the prior art alternators are provided with a rectifier which rectifies the output of the alternator. The rectifier has a conductive surface with an opening formed therethrough. The voltage regulator of the prior art alternators is provided with a conductive surface which has an opening formed therethrough. The conductive surface of the voltage regulator is adapted to mate against the conductive surface of the rectifier such that the opening in the voltage regulator is aligned with the opening in the rectifier and such that electrical current flows between the conductive surfaces.
The voltage regulator and the rectifier are disposed in the alternator interior space of the housing of the alternator and a bolt is inserted through a plastic insulator, an opening formed in the housing of the alternator and the aligned openings in the voltage regulator and the rectifier such that a threaded end of the bolt extends from the voltage regulator into the alternator interior space. A nut is disposed on the threaded end of the bolt and is tightened to clamp the voltage regulator and the rectifier to the housing and to simultaneously clamp the mating conductive surfaces of the voltage regulator and the rectifier together.
However, the clamp formed from the nut and the bolt must be maintained at a precise predetermined tension. When the clamp is too loose, a gap forms between the mating conducting surfaces of the voltage regulator and the rectifier. Electricity arcs across the gap and generates heat which can overheat the voltage regulator, the rectifier and/or the battery. When the clamp is too tight, the plastic insulator can break or crack and then the clamp becomes too loose and excess heat is generated as previously discussed.
The voltage regulator of the prior art alternator is provided with an electronic switch for controlling the field current in the rotor of the alternator. If a fault such as a short circuit occurs in the rotor, the current through the electronic switch increases significantly. This increased current can destroy the electronic switch and generate excess heat.
Finally, the prior art voltage regulators control a lamp in the automobile's dash for communicating an alternator failure to a driver. Conventionally, the means for controlling the lamp was disposed internally in the logic control unit. The logic control unit was destroyed in the event of a lamp short caused by the insulation being rubbed off a wire, or the incorrect wiring of the automobile or in the event that the ignition key was left in the lamp on-engine off position for an extended period of time, for example. This was costly in terms of dollars and i
Ballard Michael D.
Chen Jianing
Dunlap Codding & Rogers P.C.
Nguyen Tran
Unit Parts Company
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