What are Hybrid Cars

WHAT ARE HYBRID CARS

Basically, a hybrid drive vehicle concept is used for vehicles that takes energy from two separate energy sources; for either series or parallel drive configurations or any combination of these. Sincerely, explaining the hybrid drive concept appears in many forms depending on the mix of the different energy sources as determined by the specified manufacturer and propulsion systems used on the vehicle. To some manufacturers, this is the solution considered to be a short-term remedy to the various pollution problems. There are two forms of hybrid vehicles which are parallel and series hybrid. The major difference between the both is the conditions in which they are both used, a parallel hybrid drive is used in lower power electric vehicles where both drives can be operated in parallel to enhance high power performance. While the series hybrid drive cars are used in high power systems.
In pollution and in fuel economy terms, the hybrid technology should be able to deliver two-thirds fuel consumption and one-third noxious emission levels of the internal combustion engine vehicles. This technology can help to maintain the emission status of automobiles for at least 10 years. Technically, there have been a neat description of problems of the hybrid-drive after a 3-year HYZEM research program undertaken by the European manufacturers. Confirmation was also given to such empirical assessments that parallel hybrids give particularly good fuel economy because of the inherent efficiency of transferring energy direct to the wheels as against the series hybrids relatively inefficient energy conversion from mechanical to electrical drive. The need for a battery which can cope with much more frequent discharge/charge cycles than one for a pure electric drive vehicle and was also confirmed. Although electric energy capability requirement is less stringent, a need to reduce weight is paramount in overcoming the problem to the redundant drive in hybrid designs.

HYBRID PASSENGER CARS

There was a recent method of construction for permanent magnet motors by Fichtel & Sachs and Magnet Motor Gmb H, exploits the relationship that specific motor torque, on the basis of weight and bulk, is proportional to the product of magnetic field in the air gap, radius of the air gap squared and the axial length of the motor. The requirement for maximum air gap focuses on the construction of the outside of the rotor. On the inside, tangentially magnetized permanent magnets are fitted to the circumference.

TOYOTA HYBRID SYSTEM OF TOYOTA PRIUS

The Toyota hybrid system [THS] has two motive power sources, which are selectively engaged, depending on the particular driving conditions of which the first 1.5 liter petrol engine, developing 42.5KW at 4000 rpm and a peak torque of 102Nm at 4000 rpm and the second is a battery powered permanent magnet synchronous electric motor with a maximum output of 30KW over the speed range of 940-2000 rpm and peak torque of 305Nm from standstill to 940 rpm. But nevertheless, the petrol engine is the hybrid’s main power source. It is a 1.5 liter dual overhead cam 16 valve with a compression ratio of 13.5:1, the engine also has a variable valve timing intelligent (VVT-I) {is a continuously variable valve mechanism} and electronic fuel injection, using the highly heat-efficient Miller cycle that in turn, is a further development of the high expansion Atkinson cycle. Now in this cycle, the expansion continues longer than in the conventional 4-stroke engine, thereby extracting more of the thermal energy of the burning gases than can be achieved in either 2 stroke or 4 stroke engine of conventional design.

Engine revolutions are restricted to 4000 rpm maximum and the engine is electronically controlled to run always within a relatively narrow band of engine speed and load, corresponding to optimum fuel efficiency. Toyota as a whole claim that this sacrifice of a wide span of engine is more than made up for by the greater flexibility of the epicyclic drive system and the power split between the two motive-power units. The Toyota hybrid system functions as a continuously variable transmission and combines power from the petrol engine and the electric motor, to give smooth power delivery with little lag between the driver depressing the accelerator pedal and vehicle response. The innovative features of the prius are in the design details of the power sources and the power split device in the hybrid transmission that allocates power from the petrol engine either directly to the vehicle’s front wheels or to the electric generator. The power-split device employs a planetary gear system, which can steplessly affect the optimum power flow to suit the driving conditions encountered at any one moment. One of the output shafts of the power-split device is linked to the electric generator, while the other is linked to the electric motor and road wheels.
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