Regenerative Braking

In Traditional braking systems, brake pads produce friction with the brake rotors to slow or stop the vehicle. Additional friction is produced between the slowed wheels and the surface of the road. This friction is what turns the car's kinetic energy into heat.

With regenerative brakes, on the other hand, the system that drives the vehicle does the majority of the braking. When the driver steps on the brake pedal of an electric or hybrid vehicle, these types of brakes put the vehicle's electric motor into reverse mode, causing it to run backwards, thus slowing the car's wheels. While running backwards, the motor also acts as an electric generator, producing electricity that's then fed into the vehicle's batteries.

The regenerative braking effect drops off at lower speeds; therefore the friction brake is still required in order to bring the vehicle to a complete halt. Physical locking of the rotor is also required to prevent vehicles from rolling down hills. The friction brake is a necessary back-up in the event of failure of the regenerative brake.

The GM EV-1 was the first commercial car to do this. Engineers Abraham Farag and Loren Majersik were issued two patents for this brake-by-wire technology.

IMG Ref: http://auto.howstuffworks.com/auto-parts/

Reference:

http://en.wikipedia.org/wiki/Regenerative_brake
http://auto.howstuffworks.com/auto-parts
GM patent 5775467 – Floating electromagnetic brake system.
GM patent 5603217 – Compliant master cylinder.

MPFI (Multi Point Fuel Injection)

MPFI Petrol Injectors with the fuel lines
IMG Ref: http://dieselpumpservice.com/services

MPFI means Multi Point Fuel Injection system. In this system each cylinder has number of injectors to supply/spray fuel in the cylinders as compared to one injector located centrally to supply/spray fuel in case of single point injection system. MPFI system injects fuel into individual cylinders after receiving command from the on board engine management system computer or Engine Control Unit (ECU).

Advantage of M. P. F. I.

1. More uniform A/F mixture will be supplied to each cylinder, hence the difference in power developed in each cylinder is minimum. Vibration from the engine equipped with this system is less, due to this the life of engine components is improved.
2. No need to crank the engine twice or thrice in case of cold starting as happens in the carburetor system.
3. Immediate response, in case of sudden acceleration / deceleration.
4. Since the engine is controlled by ECM* (Engine Control Module), more accurate amount of A/F mixture will be supplied and as a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level.
5. The mileage of the vehicle will be improved.
   

ECM (Engine Control Module) and its function

The function of ECM is to receive signal from various sensors, manipulate the signals and send control signals to the actuators. Sensors; Sensing different parameters (Temperature, Pressure, Engine Speed etc.) of the engine and send signal to ECM. Actuators; Receives control signal from ECM and does function accordingly (ISCA, PCSV, Injectors, Power Transistor etc.)

Reference:

http://www.automobileindia.com/consumer-guide/automobile-technology.html