Prime-mover dynamo plants – Electric control – Engine control
Reexamination Certificate
2002-11-25
2004-08-31
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Electric control
Engine control
C180S065230
Reexamination Certificate
active
06784563
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid vehicle and a method of controlling the hybrid vehicle. More specifically the invention pertains to a hybrid vehicle with an engine that outputs power through combustion of a fuel, a generator that generates electric power with at least part of the power output from the engine, and a motor that outputs power to a drive shaft of the vehicle, as well as a method of controlling such a hybrid vehicle.
2. Description of the Related Art
A diversity of hybrid vehicles have been proposed. The hybrid vehicle has a motor that outputs electric power as a driving force, in addition to an engine that outputs power through combustion of a fuel, such as gasoline. The hybrid vehicle uses the engine as the final energy source and thus requires only the supply of gasoline or another fuel. It is accordingly not required to socially provide new facilities and equipment, for example, power stations for charging batteries.
The hybrid vehicles are mainly classified into series hybrid vehicles and parallel hybrid vehicles. The series hybrid vehicle uses all the power output from the engine to drive a generator, accumulates the electric power generated by the generator in a battery, and obtains the required driving force to be output to the drive shaft from a motor, which is driven with the electric power accumulated in the battery. The parallel hybrid vehicle has a three shaft-type power distributing mechanism or a pair-rotor motor to distribute the power of the engine, for example, a gasoline engine, and causes the power output from the engine to supply part of the driving force to be output to the drive shaft. In the parallel hybrid vehicle, the residual power that is not output to the drive shaft is used for power generation by the generator. The generated electric power is generally accumulated in a battery or a high-capacity capacitor.
The electric power accumulated in the secondary battery or the high-capacity capacitor is used to drive the vehicle while the engine is at as top. When the engine is driven but the driving force of the engine does not satisfy all the required torque, the motor utilizes the accumulated electric power to supplement the insufficient torque.
In the hybrid vehicle of the above structure, in the case of malfunction of the secondary battery or the high-capacity capacitor that accumulates the electric power therein or in the case of malfunction of a charging circuit for charging the secondary battery or the high-capacity capacitor, operation of the generator is not allowed. This makes a further drive of the vehicle difficult According to the principles of the hybrid vehicle, the vehicle can be driven by directly connecting the generator with the motor and driving the motor with the generated electric power. The drive mode in this state is called the battery-less drive mode. In the case where the vehicle is actually driven in the direct connection of the generator with the motor, however, expected abrupt variations in loading on the motor during a drive cause a diversity of problems and troubles. There is a possibility that the loading or the required power of the drive shaft during a drive abruptly decreases within a very short time, due to racing of wheels or any braking operation. In such cases, the electric current to be flown into the motor also abruptly decreases within a very short time. The abrupt decrease in required electric current causes a high impedance in the generator that is driven in stationary state by the engine. This abruptly raises the voltage between terminals of the generator and causes an unexpectedly high voltage to be applied to the circuit and exceed the rated power of the circuit.
In the actual state, these problems make the battery-less drive mode substantially unpractical. It is difficult to actualize the limp home capability that enables the vehicle to be anyway driven to a gas station while the battery or its charging circuit malfunctions. Especially in the case of malfunction of a switching element included in an inverter that is connected to the generator to form the charging circuit, even when the engine, the generator, and the motor are all normally operable, the vehicle is driven only with the electric power accumulated in the battery. This undesirably leads to a restricted driving distance or a limited vehicle speed.
The secondary battery used in the hybrid vehicle is a high voltage battery. Positive and negative power lines respectively have contacts to cut off the connection of the power lines with the secondary battery in the inactive state. These contacts are kept open when the vehicle is not used or when some abnormality is detected in the battery. The open position of the contacts prevents the high voltage of the secondary battery from being applied to the power lines when not required. These contacts are used to allow and forbid a large flow of electric current and are thereby often subject to troubles like welding. The prior art arrangement accordingly connects the power line with a standard contact in parallel via a resistor for restricting the electric current and an auxiliary contact. The procedure first closes the auxiliary contact to allow a restricted flow of electric current and then closes the standard contact.
In this prior art arrangement, however, there is still a possibility that the contact welds. In response to detection of a weld of the contact in either one of the positive and negative power lines, the prior art arrangement prohibits the use of the secondary battery. If the continuous use of the secondary battery is allowed in the welding state of one contact, the connection of the secondary battery with the power lines can not be cut off in case of a weld of the other contact.
SUMMARY OF THE INVENTION
The object of the present invention is thus to attain a drive of a hybrid vehicle with an engine, a generator, and a motor mounted thereon without using a secondary battery.
At least part of the above and the other related objects is actualized by a first hybrid vehicle with an engine, a generator, and a motor mounted thereon, wherein the engine outputs power through combustion of a fuel, the generator provided with permanent magnets generates electric power with at least part of the power output from the engine, and the motor outputs power to a drive shaft of the hybrid vehicle. The first hybrid vehicle includes: an engine control unit that feedback controls a quantity of the fuel injected to the engine to attain a specified target revolving speed of the engine; a power generation control unit that causes the generator to carry out power generation utilizing a counter electromotive force; a loading detection unit that specifies a loading applied to the hybrid vehicle; a generator rotational speed variation unit that varies a rotational speed of the generator, based on the specified loading; and a motor driving unit that drives the motor with the electric power generated by the generator at the varying rotational speed.
There is also a method of controlling the hybrid vehicle, which corresponds to the arrangement of the first hybrid vehicle. The present invention is accordingly directed to a first method of controlling a hybrid vehicle, wherein an engine outputs power through combustion of a fuel, a generator provided with permanent magnets generate electric power with at least part of the power output from the engine, and a motor is driven with at least part of the electric power generated by the generator, so as to output power to a drive shaft of the vehicle. The first method includes the steps of: feedback controlling a quantity of the fuel injected to the engine to attain a specified target revolving speed of the engine; causing the generator to carry out power generation utilizing a counter electromotive force; specifying a loading applied to the hybrid vehicle; varying a rotational speed of the generator, based on the specified loading; and driving the motor with the electric power generated by the generator at
Gonzalez R. Julio
Oliff & Berridg,e PLC
Ponomarenko Nicholas
LandOfFree
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