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Thursday, 5 June 2014


                "Future cars offer good, clean fun: Hydraulic Hybrids are engines of tomorrow”
                            Depletion of conventional energy sources and increase in pollution are the two main problems of this era. Vehicles are the largest consumers of this conventional energy sources results in increase in pollution. In order to overcome these problems new concepts like Hybrid Technology has emerged. This article discusses the new upcoming Hybrid technology

                                                              HISTORY OF HYBRID VEHICLE

Robert Anderson of Aberdeen, Scotland built the first electric vehicle
Sir David Salomon developed a car with a light electric motor and very heavy storage batteries. Driving speed and range were poor
1890 – 1910
Period of significant improvements in battery technology, specifically with development of the modern lead-acid battery by H. Tudor and nickel-iron battery by Edison and Junger.The German Dr. Ferdinand Porsche, built his first car, the Lohner Electric Chaise. In 1905, H. Piper filed a patent for a petrol-electric hybrid vehicle.
With the advent of the self-starter (making it easy for all drivers to start gas engines), steamers and electrics were almost completely wiped out. In this year, sales of electric cars dropped to 6,000 vehicles, while the Ford Model T sold 182,809 gasoline cars.
 1920 – 1965
Dormant periods for mass-produced electric and hybrid cars. So-called alternative cars became the province of backyard tinkerers and small-time entrepreneurs
1977 – 1979
General Motors spent over $20 million in electric car development and research, reporting that electric vehicles could be in production by the mid-1980s.
Toyota released the Toyota Prius, the first hybrid four-door sedan available in the United States. The Toyota Prius II won 2004 Car of the Year Awards from Motor Trend Magazine and the North American Auto Show. Toyota was surprised by the demand and pumped up its production from 36,000 to 47,000 for the U.S. market

                   Hydraulic Hybrids..:                              

                   A hydraulic-diesel hybrid power train allows for the use of a less powerful and more fuel efficient diesel engine operating at its optimal setting and less frequently to obtain the same power as a less efficient engine directly powering the wheels. There are two accumulators; one high-pressure and the other low-pressure. Inside the accumulators are nitrogen bladders. When hydraulic fluid accumulates, the nitrogen bladders are compressed, and energy is stored. The low pressure accumulator acts like a reservoir containing hydraulic fluid.
                                            During braking, energy that is usually dissipated through heat is used to operate a pump that takes hydraulic fluid from the low-pressure accumulator to
pressurize the high pressure accumulator. This energy stored in the high-pressure nitrogen bladder is then used to accelerate the vehicle. During acceleration, the pressurized fluid leaves the high pressure accumulator and powers the pump/motor. The fluid then returns to the low pressure accumulator. The diesel engine is used when the high-pressure accumulator is depressurized and the vehicle is running at steady state


          Types of Hydraulic Hybrid vehicle systems   
                             Parallel hydraulic hybrid system           
                             Series hydraulic hybrid system

How Does a Parallel Hydraulic Hybrid System Work?
       A pump/motor is used to pump the hydraulic fluid from the low pressure accumulator to the high pressure accumulator during braking and also it acts as a motor during acceleration driving another motor connected to the wheels by a shaft. During acceleration, the pressurized fluid leaves the high pressure accumulator and powers the pump/motor which in turns acts as a motor to drive the motor connected to the wheels, during this process the hydraulic fluid is returned back to the reservoir.


How Does a Series Hydraulic Hybrid System Work?

          A pump is used to pump the hydraulic fluid from the low pressure accumulator to the high pressure accumulator during braking. During acceleration the energy stored in the accumulator is used to power the pump/motor. The fluid then returns to the reservoir. Hence the fluid from the reservoir moves to the accumulator through the pump and it returns to the reservoir through the motor.
Advanced Hydraulic Hybrid control systems derive their fuel economy improvement from the use of four design and control strategies:
1) Recovery and reuse of over 70% of braking energy (known as regenerative braking).
2) Optimization of engine operation at the “sweet” spot.
3) Reduction of engine operation (e.g. engine is shut-off when the vehicle isn’t moving, so there is never any engine idling).
4) Improve engine efficiency from enabling new innovative efficient engine concepts.

The Parallel Hydraulic Hybrid System utilizes only design strategy of recovery and reuse1). The Series Hydraulic Hybrid System takes advantage of all four strategies.


                                      Future of Hydraulics 
                    Hydraulic hybrid systems create a unique opportunity to optimize engine operations.   EPA has produced research concept vehicles that demonstrate the hydraulic technology.  One concept vehicle is an urban delivery truck that uses hydraulic "launch assist."  This delivery truck retains its conventional engine and transmission, but adds on a hydraulics package optimized for fuel economy. The next generation of hydraulic vehicles involves fully integrating hydraulic technology.  In this configuration, the "full" hydraulic hybrid replaces the conventional drivetrain with a hydraulic drivetrain and eliminates the need for a transmission and transfer case. Using the full hydraulic drive in conjunction with EPA's clean diesel combustion technology is projected to improve fuel economy even more.

                       EPA also has achieved major breakthroughs in designing hydraulic accumulators and pump/motors to be more efficient, smaller, and lighter for motor vehicle applications, which will help improve fuel efficiency.  EPA currently has cooperative research and development agreements with several private sector partners to further the development of hydraulics.


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