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Introduction
A hybrid car is a car used to drive the drive wheels more than one source of energy.
Modern car manufacturers often resort to sharing of the internal combustion engine and an electric motor, which avoids the mode of the internal combustion engine in low loads, and also to realize the recovery of kinetic energy, increasing the fuel efficiency of the power plant. Another common type of hybrids is vehicles, in which ICE is combined with engines running on compressed air.
It should be distinguished from hybrids vehicles with electro-mechanical transmission, such as locomotives, some tractors and tanks.
As it written in the Analysis of Hybrid-Electric Vehicles as the Car of Future “Hybrid Electric Vehicles (HEV) are neither fully electric nor fully gas-powered, but contain benefits of both components”.
The General Principle
The original idea of the "electric transmission" that is replacing the manual transmission electric wires, was embodied in rail transport and heavy- Haul trucks. Using this scheme caused great difficulties significant mechanical transmission, and wherein the variable torque on a vehicle wheel. Internal combustion engines have a certain load characteristic (dependent on the power output shaft speed), which has optimum performance only within a narrow range, which is typically biased toward the high speed. Partially compensate for this deficiency by applying manual transmissions, which, however, degrade the overall efficiency of the system for their own losses. An additional difficulty is the inability to change the direction of rotation of the shaft engine for reversing car. The load characteristic of the motor is almost uniform throughout the range of operating frequencies, it can be instantly started, stopped and reversed, and does not require idling, eliminating transmission of the clutch mechanism - and in some cases, completely get rid of it by putting motors directly in the wheels (motor- wheel).
In the application of electric transmission engine that runs on regular fuel, rotates an electric generator, produces a current is passed through a control system for electric motors, which are driven vehicle. In this case, the appropriate comparison with the placed in an electric power plant generating electricity for its movement. The scheme of the hybrid vehicle is generally similar, but significantly modified, primarily by addition of the intermediate energy storage - typically battery having less than "clean" electric vehicle, the capacity and therefore the weight).
A hybrid car combines the benefits of an electric vehicle and the internal combustion engine : higher efficiency of electric vehicles (80-90 % compared to 35-50 % for vehicles with internal combustion engines) and a large range of the one filling the car with the engine.
Typical Schemes
- Sequential : essentially a modification of electromechanical transmission with the addition of the intermediate storage. An internal combustion engine mechanically coupled with an electric generator only, and traction motor - with only wheels.
- Parallel : the internal combustion engine and an electric motor mechanically coupled to the wheels through a differential that enables their work individually and together. This scheme is used in vehicles with Integrated Motor Assist (Honda). Characterized by simplicity (use of together with the manual transmission) and low cost.
- Serial-parallel : an internal combustion engine and a motor generator mechanically connected with each other and with the wheels via a planetary gear unit that allows arbitrary change the power flow between the nodes. The scheme is implemented in vehicles with Hybrid Synergy Drive (Toyota), for example, Toyota Prius. According to the Analysis of Hybrid-Electric Vehicles as the Car of Future, “In the spectrum of the transportation history, hybrid vehicles only recently broke nto the industry with the widespread popularity of the Toyota Prius”.
According to the types of drives:
- electrical:
- Based on electrochemical batteries
- On the basis of the inertial drive
- mechanical:
- On the basis of pneumatic accumulators, pneumatic accumulators drive.
- On the basis of inertial drives.
As intermediate storage, in addition to the batteries can also be used capacitor and electric double layer capacitors (supercapacitors). In the case of large energy storage capacity of the hybrid car has the ability to move without the inclusion of an internal combustion engine - in " electric mode » (Chevrolet Volt). If the charge storage device can be made not only on the main engine, but also on the electrical network, talk about the " plug-in hybrids ".
The main advantage of a hybrid car - reducing fuel consumption and exhaust emissions, achieved full automation of the engine control with the on-board computer - from timely switching off the engine when stopped in traffic, with the possibility of immediate resumption of movement without executing it exclusively stored in the storage energy, to the more complex mechanism of recovery - the use of the kinetic energy of a moving vehicle during braking to charge the accumulator when the motor in an electric mode. As in the case with an electromechanical transmission, an internal combustion engine typically operates at optimum conditions.
Reasons for Development
The main reason for the start of production of passenger hybrids become the market demand for these cars, caused by high oil prices and the constant tightening of requirements for environmental vehicles. With improved technology and tax incentives to producers or purchasers of hybrids such cars are sometimes even cheaper than usual. A number of countries are available to owners of hybrids and other benefits - in particular, exemption from road tax, the right to use dedicated speed on the highway, and free parking lots, etc.
Hybrid cars are a compromise solution such drawbacks of electric vehicles as a significant mass of the batteries and the need for time to charge, lack of infrastructure charging stations and the lack of distance run.
The first car with hybrid drive is Lohner-Porsche, developed by designer Ferdinand Porsche in 1900 - 1901 years.
In the United States began to develop hybrid cars Victor Wouk in the 60s - 70s.
In 1980, Volvo has been experimenting with the flywheel is accelerated diesel engine and used for the recovery of braking energy. Subsequently, the project was abandoned in favor of hydraulic accumulators.
So, is hybrid car is a car of the future? There is no exact answer. The development and using hybrid cards have both pros and cons.
Advantages
- Economical operation
The main motive for the development of hybrid cars was the desire to improve their efficiency as possible without sacrificing other performance characteristics - speed, throttle response, mileage on one tank, etc. And, according to the Analysis of Hybrid-Electric Vehicles as the Car of Future, “this trend has been slowly going towards safety, quality and dependability”. The savings were achieved, including :
- an internal combustion engine using less power and, accordingly, the volume ;
- the engine in the optimal mode ;
- its full stop instead of idling
- the use of regenerative braking to charge the battery (which incidentally reduces brake pad wear).
The continuous monitoring of the operation of all systems, hybrid car at their optimum conditions is a very complex task, which was not possible before the advent of on-board computers.
- Environmental cleanliness
Ecological purity of hybrid cars is due, on the one hand, the reduction in consumption of fossil fuels, further enhances its blackout internal combustion engine when the vehicle is stopped - particularly in traffic jams. On the other hand, the use of batteries smaller than in electric capacitance - and, accordingly, the sizes - alleviating the problem of disposing of used batteries.
- Improved handling characteristics
Engines for conventional vehicles are selected on the basis of peak loads, bringing the total power used relatively rarely, and is redundant for much of the time of their operation. In hybrid vehicles is not necessary - when the tensile load is increased by the energy generated by the combustion engine power is added the energy stored in the batteries - so they set a smaller motor, which in this work in the most favorable regime for yourself. This reallocation of capacity in some models of hybrid cars is releasing directly in the electric transmission, and in others - in the transmission of a direct transmission of torque (" hybrid- joint drive ").
- The increase in driving range
Exception half the races on the gas stations, and even more of these races, in city driving, the car owner releases in some time.
- Save and re-use of energy
Eliminated one of the main disadvantages of the engine on the carbon fuels - the inability to return energy back into hydrocarbon fuels. Transport Engineers have long sought to keep the energy of motion during deceleration to use it again. For example, special design with a large flywheel. But only the electrical and hydraulic power can not save with minimal losses and cheap enough. As the storage batteries used in hydraulic accumulators and special capacitors.
- Normal refueling
In electric vehicles until there is one big drawback - the need to charge the battery. The process is long and requires a specially equipped charging points. Thus, it becomes unsuitable for long-term and longer trips. But already developed technologies to charge the lithium-ion batteries with electrodes from nanomaterials to 80% of capacity for 5-15 minutes.
A hybrid car this disadvantage is eliminated. Refilling is carried out according to the usual pattern typically a hydrocarbon fuel, if necessary, and further movement may continue immediately.
In urban operating a hybrid vehicle 80% of the time operates in an electric vehicle. In February 2006, motorists in the U.S. were able to crack the electronic control system of Toyota Prius and learned to forcibly switch the car in electric mode. The French company PSA Peugeot Citroen will start by 2010 mass production of hybrid versions of the Peugeot 307 and Citroen C4. The engine has a mode electric vehicle at speeds below 50 km / h The driver can optionally include electric mode.
Disadvantages
- High Complexity
Hybrid cars are relatively more weight they are more complex and more expensive than conventional vehicles with internal combustion engines. Rechargeable batteries have a small temperature range, are subject to self-discharge. Furthermore, they are expensive to repair. The U.S. experience says that auto mechanics are taken for the repair of hybrid vehicles with great reluctance. The U.S. is trying to solve the problem of the high cost of tax benefits.
Porsche has abandoned attempts to self-production hybrid vehicle. Mitsubishi has not initially tried to create a hybrid car, and concentrated all its efforts on the development of electric vehicles.
The most successful to date (2008) Continuous development - Hybrid Synergy Drive Toyota's.
- Lack of transmission
The most promising, mechanical, hybrids can not at this stage to compete with electric hybrids. The main problem is the inability to create adaptive transmission that can operate in a wide range of gear ratios (over 20).
- Battery Disposal
Although to a lesser extent than electric cars, hybrid cars are subject to the problem of waste batteries. Effect of emitted accumulators on the environment, apparently, no one investigated. Some hybrid cars batteries are not provided.
- Heating interior
High efficiency determines the low incidental generation of waste heat. In conventional cars in the winter, this heat is used to heat the passenger compartment. In hybrid cars engine does not stall until it heats the cabin to the desired temperature, which, of course, increases fuel consumption. In the American model Toyota Prius also uses electric heating elements, which are powered by a high-voltage battery. They not only provide warmth without too much of ICE, but also allow interior heat immediately after a cold start the car, allowing you to always maintain the average temperature in the cabin.
- The danger for pedestrians
According to research by the American Institute for the assessment of damage to roads (born Highway Loss Data Institute), hybrids represent an increased risk to pedestrians than conventional cars because of their low noise when driving on electricity. In particular, impact of hybrid cars on pedestrians occur in 20% more likely, and the extent of damage above. To prevent this, hybrid cars can be equipped with a generator sound when driving at low speeds warning pedestrians of the approach of the vehicle. These generators are equipped with a 2010 hybrid Toyota Prius, but the legal requirement of a sound generator in hybrid and electric cars currently exist only in Japan. In late 2011, the U.S. President had instructed the National Highway Traffic Safety Administration in the three-year period to develop a similar legislative initiatives.
Conclusions. Modern Application
Toyota leads in the number of hybrids and actively produces these cars since 1997, and in both versions of conventional cars series Prius, parquet SUVs Series Lexus RX400h, and the luxury car class - Lexus LS 600h.
In 2006, the world has sold over half a million only model Prius. Hybrid drive technology licensed by Toyota HSD Ford (Escape Hybrid), Nissan (Altima Hybrid).
Mass production of hybrid cars is constrained by shortage of nickel-metal-hydride batteries.
In 2006, Japan has sold 90,410 hybrid vehicles, up 47.6% more than in 2005.
In 2007, sales of hybrid cars in the United States rose by 38% in comparison with 2006. Hybrid cars in the U.S. has 2.15% market share of new passenger cars. Total for the year 2007 in the United States has sold about 350,000 hybrid vehicles (excluding sales corporation GM).
Totally from 1999 to the end of 2007 the U.S. has sold 1,002,000 hybrid cars.
