Patent Application
20120000721
1. Field of the Invention
The present invention relates generally to the field of vehicle propulsion systems and, more particularly, to an electrical propulsion system that may be easily retrofitted to a conventional gasoline or diesel-powered vehicle.
2. Background
There is widespread concern about the continued use of fossil fuels to provide power for automobiles and other vehicles. Numerous alternative energy sources have been proposed. One alternative that has met with considerable success is the “hybrid” vehicle that uses a conventional gasoline engine to mechanically power the vehicle's wheels and to also generate electrical power for one or more electric motors. Hybrid vehicles have a relatively large array of batteries to store electrical power so that they can operate for extended periods using only the electric motors. If additional power is required, as when the vehicle is under heavy load or when the batteries are discharged, traditional vehicle propulsion is provided by the gasoline engine.
Hybrid vehicles and other alternative energy vehicles are built from the outset with their respective power trains. To date, there has been no practical system for converting a conventional gasoline or diesel-powered vehicle to utilize electrical power for propulsion.
Embodiments of the present invention provide a supplemental propulsion system for a vehicle that can be retrofitted to a conventional gasoline or diesel-powered vehicle. The system includes an electrical generator coupled to the vehicle's engine. At least one electric motor is coupled to one or more road wheels. Electrical power from the generator is supplied to an electronic control unit (ECU) that then supplies electric power to the electric motor.
In a certain specific embodiment, a supplemental propulsion system is adapted for use with a conventional front-wheel drive automobile. An electrical generator is coupled to the vehicle's engine and the ECU is installed in a convenient location. The rear wheels of the vehicle, which are unpowered in a conventional front-wheel drive vehicle, are powered by electric motors. The motors may be installed inboard of the rear wheels with an appropriate mechanical drive mechanism coupled to the stock vehicle wheels. Alternatively, the motors may be installed integrally with the vehicle's rear wheels.
Other embodiments of the invention are adapted for use with other types of vehicles, including trucks, buses, motor homes, motorcycles, rail vehicles, aircraft and watercraft.
In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail.
Electrical energy produced by generator 18 is delivered to electronic control unit (ECU) 20 on bus 22. Electrical power from ECU 20 is delivered to electric motors 24 and 25 on buses 26 and 27, respectively. Motors 24 and 25 are coupled to drive wheels 28 and 29, respectively.
The ECU 20 is configured to operate with the particular characteristics of generator 18 and motors 24 and 25. In one embodiment, ECU 20 may be of the type disclosed in U.S. Pat. No. 6,700,214. With reference to
The generator drive 40 is responsive to the amplitude- and frequency-variant signal produced by the generator 18 and is controlled by a processor 50 to maintain the DC power supply bus 42 at a desired DC voltage level. The AC inverter 44 produces AC output power by converting the DC voltage supplied by the power bus 42 into an AC power signal.
When the vehicle engine is running and the generator 18 is generating electrical power, the generator drive 40 attempts to regulate the electrical power produced by the generator such that a desired voltage level across the power supply bus 42 is achieved. The generator drive 40, responsive to control signals received from the processor 50, attempts to regulate the electrical power produced by the generator 18 such that the DC power bus 42 is maintained at a constant nominal voltage. The AC inverter 44 converts the DC power into a plurality of AC output power signals, such as for example, two 120 VAC, 60 Hz signals, 180° out of phase. The AC inverter 44 supplies the plurality of output AC power signals to the AC load, i.e., motors 24 and 25.
The ECU may be configured to automatically activate the AC inverter 44 to produce AC power immediately upon start-up of the vehicle engine. At initial start-up of the system, there exists no voltage on the DC power supply bus 42. In the described embodiment, the generator 18 is an induction-type generator and lacks self-excitation. The lack of DC voltage on the power supply bus 42 precludes the generator drive 40 from developing or applying any current for the generator stator field coils. Thus, shortly after initial start-up, the system draws electrical power from the vehicle battery (not shown) to the generator drive 40 to enable the generator drive to apply sufficient current to drive the generator. Once the generator drive 40 has been supplied with adequate power, the generator drive develops a current for the generator stator field coil windings. The electrical power generated by the generator 18 then charges the power supply bus 42. When the voltage of the power supply bus 42 is sufficient for the generator drive 40 to develop current for the generator stator field coils, the system may disable the flow of electrical power from the vehicle battery.
A driver control unit 52 is coupled to processor 50 and is located on the dashboard of the vehicle or otherwise within reach of the driver. Control unit 52 allows the driver to activate the supplemental propulsion system and to manually control its output. In a manner similar to a conventional cruise control device, the driver can regulate the supplemental propulsion system to set the vehicle speed, to accelerate, to coast or to resume a previously set speed. Under most driving conditions, the vehicle's gasoline or diesel-powered engine need only be idling to supply sufficient electrical power to the electric drive motors.
Motors 24 and 25 may be mounted inboard of drive wheels 28 and 29 and drive the wheels through suitable mechanical couplings. Alternatively, motors may be mounted integrally with the drive wheels. In a further alternative, the electric motors may be motor/generators so that kinetic energy of the vehicle may be captured and stored as electrical energy. Thus when the vehicle is not being powered by the electric motors, such as when the vehicle is coasting or braking, the motor/generators are mechanically driven by their respective road wheels and act as electrical generators to deliver electrical energy to a battery or other suitable storage device.
Although the invention has been described in connection with certain embodiments for use with an automobile, it will be recognized that the invention also finds application to any type of motorized vehicle, including, without limitation, trucks, buses, motor homes, motorcycles, locomotives and other rail vehicles, aircraft and watercraft.
It will be recognized that the above-described invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the disclosure. Thus, it is understood that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.
