Electricity: single generator systems – With flywheels or massive moving parts
Reexamination Certificate
2000-09-06
2002-07-23
Ramirez, Nestor (Department: 2834)
Electricity: single generator systems
With flywheels or massive moving parts
C310S153000, C310S254100, C322S016000, C322S014000, C180S065100, C180S065310
Reexamination Certificate
active
06424126
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a propulsion system for a vehicle. More particularly, it relates to a propulsion system for a vehicle, designed for reduced torsional vibration of an engine as well as lighter weight of the system.
BACKGROUND OF THE INVENTION
One known type of propulsion system for a vehicle has an engine provided therein as a power source, and further has a transmission disposed therein in communication with a crankshaft of the engine through a clutch. Another type of propulsion system has both an engine and a motor disposed therein as a power source. The motor has a dual function of driving and electric power generation. The latter propulsion system adds the driving force of the motor to that of the engine in response to an engine operating status in order to achieve increased output, improved fuel efficiency, and a reduced rate of detrimental exhaust emission components.
Such propulsion systems are disclosed in published Japanese Patent Application Examined No. 62-29979, granted Patent No. 2708469, Japanese Patent Application Laid-Open No. 9-215270, and Japanese Patent Application Laid-Open No. 8-233035.
According to Application No. 62-29979, an engine has an electromagnetic retarder mounted on a crankshaft and a flywheel disposed on the output side of the retarder.
According to U.S. Pat. No. 2,708,469, a revolving field pole of a charging and generating apparatus is mounted on a drive plate of an automatic transmission. The apparatus is disposed between an engine crankshaft and an automatic transmission input shaft.
According to Application No. 9-215270, an electric motor having a plate-like rotor formed thereon is disposed between an engine crankshaft and an automatic transmission input shaft. The rotor is mounted on the crankshaft.
According to Application No. 8-233035, a flywheel to be mounted on an engine crankshaft is divided into first and second flywheel elements. The first flywheel element is located on the input side of the engine, while the second flywheel element is positioned on the output side of the engine. The first flywheel element includes a damper.
In some prior art propulsion systems, a first flywheel is provided on a crankshaft of an engine at an output end of the crankshaft; a motor is disposed on the first flywheel on the output side thereof, which motor has a dual function of driving and electric power generation; a second flywheel is disposed on the motor on the output side thereof; and, a transmission is disposed in communication with the output side of the second flywheel through a clutch.
This type of a propulsion system transmits the driving force of the engine to the transmission through the crankshaft, the first flywheel, the second flywheel, and the clutch. At the same time, the propulsion system adds the driving force of the motor to that of the engine in dependence upon an engine operating status in order to provide increased output, improved fuel efficiency, and a reduced rate of harmful exhaust emission components.
The propulsion system suffers from a problem in which torsional vibration occurs in the crankshaft during engine operation. The torsional vibration results from a conflict between forces from a reciprocating portion (or, a piston) of the engine and forces from the flywheel having a great moment of inertia. In view of the torsional vibration of the crankshaft, it is advantageous to position the flywheel near the crankshaft as close as possible.
However, the propulsion system has the motor disposed on the crankshaft through the first flywheel, and further has the second flywheel disposed between the motor and the clutch. Thus, the second flywheel is spaced apart from the crankshaft. This causes an inconvenience in that such positioning of the second flywheel is disadvantageous in view of the torsional vibration of the engine. Further, the propulsion system includes the first flywheel positioned close to the crankshaft and the second flywheel distant from the crankshaft. This brings about another inconvenience in that such flywheel positioning is disadvantageous in view of weight.
In order to obviate or at least minimize the above inconveniences, the present invention provides a propulsion system for a vehicle, having a first flywheel mounted on a crankshaft of an engine at an output end of the crankshaft, the engine being disposed in the vehicle, a motor disposed on the first flywheel on the output side thereof, the motor having a dual function of driving and electric power generation, a second flywheel disposed on the motor on the output side thereof, and a transmission disposed in communication with the output side of the second flywheel through a clutch, the improvement wherein the first flywheel has inertial moment greater than that of the second flywheel.
In the propulsion system according to the present invention, the inertial moment of the first flywheel disposed near the crankshaft is set to be greater than the inertial moment of the second flywheel spaced apart from the crankshaft. As a result, the first flywheel having greater inertial moment is positioned closer to the crankshaft. This is advantageous in view of torsional vibration of the engine. Furthermore, the second flywheel distant from the crankshaft is formed by a raw material having a lesser density in order to provide reduced inertial moment. Consequently, the second flywheel made lighter in weight than the first flywheel is achievable.
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Flynn ,Thiel, Boutell & Tanis, P.C.
Gonzalez Julio C.
Ramirez Nestor
Suzuki Motor Corporation
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