Planetary gear transmission systems or components – Input from independent power sources – Including electric motor input
Reexamination Certificate
2001-04-02
2003-03-04
Bonck, Rodney H. (Department: 3681)
Planetary gear transmission systems or components
Input from independent power sources
Including electric motor input
C475S317000, C475S319000
Reexamination Certificate
active
06527658
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to vehicular transmissions. More particularly, the present invention relates to electrically variable transmissions with selective operation that can be tailored to the specific use, or uses, to which the vehicle in which the transmission is incorporated is intended to be used. Specifically, the present invention relates to a transmission having only two differential gearing components, typically planetary gear subsets, and two clutches in the nature of torque transfer devices and yet may be selectively operated in an input split mode, a compound split mode, a neutral mode or a reverse mode.
BACKGROUND OF THE INVENTION
Air quality, the possibility of climate change, and dependency on fossil fuels are great public concerns today. Vehicles now produce roughly a third of air pollutants and consume roughly a third of fossil fuels. A novel transmission system, for use primarily in vehicles, which can help to reduce emissions and fuel consumption may be of great benefit to the public.
Internal combustion engines, particularly those of the reciprocating piston type, currently propel most vehicles. These engines are soundly criticized by public figures and groups as the most flagrant source of air pollution, energy consumption, and climate change. However, internal combustion engines are relatively efficient, compact, lightweight, and inexpensive mechanisms by which to convert fossil fuel into useful mechanical power, so that with the exception of their negative environmental impact they are very suitable for vehicle propulsion. One of the primary reasons that internal combustion engines are a major source of pollution and fuel consumption is their success and widespread use.
The flexibility with which reciprocating piston internal combustion engines operate is another reason for their pollution and energy consumption. Typically, a vehicle is propelled by such an engine, which is started from a cold state by a small electric motor and relatively small electric storage batteries, then quickly placed under the load of effecting propulsion and operating accessory equipment. Such an engine is also operated through a wide range of speeds and a wide range of loads and typically at a fifth of its maximum power. These wide ranges of engine operation require that clean, efficient combustion be maintained through extremes in operating conditions—an elusive goal.
A vehicle transmission can deliver mechanical power from an engine to the remainder of a drive system, typically fixed gearing, axles, and wheels. A transmission allows some freedom in engine operation, usually through alternate selection of five or six different drive ratios, a neutral selection that allows the engine to operate accessories with the vehicle stationary, and clutches or torque converters that allow smooth transitions between driving ratios to start the vehicle from rest and accelerate to the desired highway speed with the engine turning. Transmission gear selection typically allows power from the engine to be delivered to the rest of the drive system with a ratio of torque multiplication and speed reduction, with a ratio of torque reduction and speed multiplication known as overdrive, or with a reverse ratio.
An electric generator can transform mechanical power from the engine into electrical power, and an electric motor can transform that electric power back into mechanical power at different torques and speeds for the remainder of the vehicle drive system. This arrangement allows a continuous variation in the ratio of torque and speed between engine and the remainder of the drive system, within the limits of the electric machinery. An electric storage battery used as a source of power for propulsion may be added to this arrangement, forming a series hybrid electric drive system.
The series hybrid system allows the engine to operate relatively independently of the torque, speed, and power to propel a vehicle, so as to be controlled for improved emissions and efficiency. This system also allows the electric machine attached to the engine to function as a motor to start the engine and allows the electric machine attached to the remainder of the drive train to act as a generator, recovering energy into the battery by regenerative braking. A series electric drive suffers from the weight of the electric machinery necessary to transform all engine power from mechanical to electrical and from electrical to mechanical, and from the useful power lost in this double conversion.
A power split transmission can use what is commonly understood to be a “differential gearing” to achieve a continuously variable torque and speed ratio between input and output without sending all power through the variable elements. An electrically variable transmission can use differential gearing to send a fraction of its transmitted power through a pair of electric motor/generators and the remainder of its power through another, parallel path that is all mechanical and direct, of fixed ratio, or alternatively selectable. One form of differential gearing, as is well known to those skilled in this art, may constitute a planetary gear subset. In fact, planetary gearing is usually the preferred embodiment employed in differentially geared inventions, with the advantage of compactness and different torque and speed ratios among all members of the planetary gearing subset. However, it is possible to construct this invention without planetary gears, as by using bevel differential gears or other differential gears.
For example, a set of bevel differential gears found in a typical automobile axle consists of three or four bevel pinions on a carrier and a meshing bevel gear for each axle. To replace the first subset of planetary gearing in the first embodiment of the invention, the carrier of a first set of bevel differential gears would be connected to the input, one bevel gear that would normally be connected to an axle would instead be connected to the first motor, and the other such bevel gear would be connected to the central shaft. Bevel differential gears could likewise replace the second subset of planetary gearing, and so the invention could be embodied without any planetary gears.
A hybrid electrically variable transmission system for a vehicle also includes an electric storage battery, which allows the mechanical output power to vary from the mechanical input power, engine starting with the transmission system and regenerative vehicle braking.
An electrically variable transmission in a vehicle can simply transmit mechanical power. To do so, the electric power produced by one motor/generator balances the electrical losses and the electric power consumed by the other motor/generator. A hybrid electrically variable transmission system in a vehicle includes an electrical storage battery, so the electric power generated by one motor/generator can be greater than or less than the electric power consumed by the other. Electric power from the battery can sometimes allow both motor/generators to act as motors, especially to assist the engine with vehicle acceleration. Both motors can sometimes act as generators to recharge the battery, especially in regenerative vehicle braking.
One of the most successful substitutes for the series hybrid transmission is the variable, two-mode, input-split, parallel, hybrid electric transmission. Such a transmission utilizes an input means to receive power from the vehicle engine and a power output means to deliver power to drive the vehicle. First and second motor/generators are connected to energy storage devices, such as batteries, so that the energy storage devices can accept power from, and supply power to, the first and second motor/generators. A control unit regulates power flow among the energy storage devices and the motor/generators as well as between the first and second motor/generators.
Operation in a first or second mode may be selectively achieved by using clutches in the nature of torque transfer devices. In one mode the output speed of the transmission i
Holmes Alan G
Klemen Donald
Schmidt Michael Roland
Bonck Rodney H.
General Motors Corporation
Hodges Leslie C.
Williams Eric M.
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