Metal working – Method of mechanical manufacture – Converting
Reexamination Certificate
1999-08-26
2001-12-25
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Converting
C475S005000, C074S335000
Reexamination Certificate
active
06332257
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to a powertrain system for hybrid electric vehicles and, more particularly, to an automated manual transmission powertrain system for a hybrid electric vehicle having input shaft synchronization using an electric motor.
BACKGROUND AND SUMMARY OF THE INVENTION
Since the invention of power vehicles, many different powertrain systems have been attempted, including a steam engine with a boiler or an electric motor with a storage battery. It was, however, the discovery of petroleum in 1856 and the four-stroke internal combustion engine invented by Otto in 1876, that provided the impetus for the modern motor vehicle industry.
Although fossil fuel emerged as the fuel of choice for motor vehicles, recent concerns regarding fuel availability and increasingly stringent federal and state emission regulations have renewed interest in alternative fuel powered vehicles. For example, alternative fuel vehicles may be powered by methanol, ethanol, natural gas, electricity, or a combination of these fuels.
A dedicated electric powered vehicle offers several advantages: electricity is readily available, an electric power distribution systems is already in place, and an electric powered vehicle produces virtually no emissions. There are, however, several technological disadvantages that must be overcome before electric powered vehicles gain acceptance in the marketplace. For instance, the range of an electric powered vehicle is limited to approximately 100 miles, compared to approximately 300 miles for a similar fossil fuel powered vehicle. Further, the acceleration is significantly less than that of a comparable fossil fuel powered vehicle.
A hybrid powered vehicle, powered by both a renewable and non-renewable energy source, overcomes the technical disadvantages of a dedicated electric vehicle while still offering an environmental benefit. The performance and range characteristics of the hybrid powered vehicle is comparable to a conventional fossil fuel powered vehicle. Thus, there is a need in the art for a hybrid powertrain system for a motor vehicle that is energy efficient, has low emissions, and offers the performance of a conventional fossil fuel powered vehicle. In particular, there is a need for a transmission system to complement the combined electric and gas power plants.
There are presently two typical powertrains for use on the conventional automobile. The first, and oldest, type of powertrain is the manually operated powertrain. These powertrains are typically characterized in that vehicles having manually transmissions include a clutch pedal to the left of a brake pedal and a gear shift lever which is usually mounted at the center of the vehicle just behind the dash board. To operate the manual transmission, the driver must coordinate depression of the clutch and acceleration pedals with the position of the shift lever in order to select the desired gear. Proper operation of a manual transmission is well known to those skilled in the art, and will not be described further herein.
In a vehicle having an automatic transmission, no clutch pedal is necessary, and the standard H configuration of the shift lever is replaced by a shift lever which typically moves back and forth. The driver need only select between park, reverse, neutral, drive, and 1 or 2 low gears. As it is commonly known in the art, the shift lever is placed in one of several positions having the designator P, R, N, D, 2, AND MAYBE 1, which corresponds to park, reverse, neutral, drive, and 1 or 2 low gears, respectively. Vehicle operation when the gear shift lever is placed in one of these positions is well know in the art. In particular, when in drive mode, the transmission automatically selects between the available forward gears. As is well known, older systems typically included first, second, and third gears, while newer systems include first through third gears as well as a fourth and possibly a fifth overdrive gear. The over drive gears provide an improved fuel economy at higher speeds.
As is well known, early transmissions were almost exclusively manually operated transmissions. With a steady development of automatic transmissions, drivers increasingly gravitated toward the easy operation of automatic transmissions. However, in the mid 1970's, rising concerns about present and future fossil fuel shortages resulted in implementation of corporation average fuel economy regulations prorogated in several countries. These fuel economy requirements necessitated the investigation of increasing the fuel economy of motor vehicles in order to meet government regulations. These government regulations prompted a gradual return to manual transmissions which are typically more efficient than automatic transmissions.
In the ensuing years, many mechanically operated vehicle systems were replaced or at least controlled by electronic control systems. These electronic control systems greatly increase the fuel efficiency of vehicle engines and enabled a gradual return to the convenience of automatic transmissions. In addition, electronic controls placed on automatic transmissions, greatly improved the shift schedule and shift feel of automatic transmissions and also enabled implementation of fourth and fifth overdrive gears, thereby increasing fuel economy. Thus, automatic transmissions have once again become increasingly popular.
Automatic and manual transmissions offer various competing advantages and disadvantages. As mentioned previously, a primary advantage of a manual transmission is improved fuel economy. Conversely, automatic transmissions first and foremost offer easy operation, so that the driver need not burden both hands, one for the steering wheel and one for the gear shifter, and both feet one for the clutch and one for the gas and break while driving. When operating a manual transmission, the driver has both one hand and one foot free. In addition, an automatic transmission provides extreme convenience in stop and go situations, as the driver need not worry about continuously shifting gears to adjust to the ever changing speed of traffic.
With respect to a hybrid vehicle, however, manual transmissions prove to be particularly advantageous to increasing efficiency, thereby improving fuel economy. The primary reason for the superior efficiency of the manual transmission for the hybrid vehicle lies in the basic operation of the automatic transmission. In most automatic transmissions, the output of the engine connects to the input of the transmission through a torque converter. Most torque converters have an input turbine that is connected to the output shaft of the engine and an input impeller that is connected to the input shaft of the transmission. Movement of the turbine at the input side results in a hydraulic fluid flow which causes a corresponding movement of the hydraulic impeller connected to the input shaft of the transmission. While torque converters provide a smooth coupling between the engine and the transmission, the hydraulic fluid results in a parasitic loss, thereby decreasing efficiency of the powertrain. Further, the shift operation in an automatic transmission also requires hydraulic fluid pressure, thereby introducing additional parasitic losses of efficiency in the powertrain.
Even with the more efficient manual transmissions, there are substantial losses of kinetic energy due to the friction losses that occur during engagement of the synchronization mechanisms typically used in a manual transmission.
Before a shift between the gear ratios of a manual transmission can occur, it is necessary to synchronize the rotational speed of the drive shaft with the rotational speed of the driven shaft. Typically, synchronization is obtained in a manual transmission by way of a synchronizing mechanism such as a mechanical synchronizer which is well known in the art. The mechanical synchronizer varies the speed of drive shaft to match the speed of the driven shaft to enable smooth engagement of the selected gear set.
Boberg Evan S.
Castaing Francois J.
Lawrie Robert E.
Reed, Jr. Richard G.
Bryant David P.
Chrysler Corporation
Cozart Jermie E.
Mack Lisa K.
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