New concept of an electric motor car and electrobus

Prof. Dr. Techn. Sci. N. GULIA, Dipl. Eng. S. YURKOV

Briefly about the authors of the article:

N. Gulia – Prof. Dr. Techn. Sci., Moscow State Industrial University, Automobile Faculty, Machine Design Chair (Head of the Chair), Moscow, Russia. The author has more than 500 scientific works in Russian and foreign issue, 20 monographies, more than 200 inventions, including the first patent for superflywheel with a priority of 1964, and several patents for Automatic Continuously Variable Transmission (ACVT). Researches – flywheels and ACVT. He carries on scientific and practical work in association with a number of Russian and foreign corporations.

Moscow State Industrial University, Russia, Moscow, 109280, Avtozavodskaja street 16, Fax: (095) 275-2256, E-mail: gulia@mail.msiu.ru (for Prof. N. Gulia).

S.Yurkov – Dipl. Eng., the Principal of CVT Group, ZIL plant, Moscow, Russia. Research – ACVT. A young specialist, the author 10 scientific works, designer of ACVT for urban buses of medial and high capacity, and also for industry purposes.

A new concept of the automobile discussed below, in which the basic power unit represents the source of electric power. Such automobile is usually called an electric motor car. This source can be a fuel cell or an electrical accumulator. This concept generally allows us to increase power output of this electric power source and efficiency of the power aggregate, to lower its mass, or to increase run of the vehicle having the same mass of an aggregate. Small volume and mass of an obtained power aggregate allow us to mount it on the conventional automobile and bus chassis, after removing the existing aggregates.

Let's consider the traditional concept of a electric motor car (fig. 1). The source of electric power of the electric motor car should not be an accumulator, but fuel cell, because in order to charge this mass of accumulators the energy worked out in the whole world would not be sufficient. For example, such sources as the modern fuel cells, have high specific energy, about 400 W/kg, at a small effective specific power – about 60 W/kg at maximum efficiency. The fuel cells are most perspective for electric motor cars.

Fig. 1. Traditional scheme of a electric motor car

Such sources of electric power should be selected taking into account specific power, because power sources selected on specific energy can not supply required power of the vehicle.

For an electric motor car having power of an energy aggregate equal about to 100 kW and for urban electrobus with power of an energy aggregate – about 200 kW, fuel cells mass are 1670 kg and 3330 kg, accordingly. At additional masses of tractive electromotors (approximately 150 and 400 kg), control systems and reduction gears are becoming completely unacceptable, they are about 2000 and 4000 kg accordingly. Therefore the constructors of electric motor cars either reduce the power of the vehicle, or use extra accumulators with high specific power (hybrid circuits). But to reduce mass of the power aggregate, slightly especially taking into account high mass of tractive drive calculated at maximum torque. The power efficiency of such aggregate is insignificant because of small opportunities recuperation of energy and its low efficiency at high rates of specific power.

The characteristic features of the new concept of the electric motor car (fig. 2), offered by Prof. Dr. N. Gulia are discussed below.

Fig. 2. New scheme of a electric motor car

1. The source of the electric power of the vehicle is selected only by specific energy criterion, that much more reduces a mass of this source. For this case for an electric motor car run of 600 km and electrobus of 400 km, accordingly, these masses are equal 150 and 1000 kg.

2. The energy takeoff is carried out from a source of electric power with a small specific power, which is optimum taking into account its efficiency. It can be realized by means of low-power velocity electromotor, having powers 10 and 20 kW and masses 15 and 30 kg, accordingly.

3. On the vehicle the intermediate accumulator of a mechanical energy – superflywheel is provided. Such accumulators are now used for vehicles with experimental hybrid circuits, and they are not the problem. The energy accumulated in a superflywheel is very small it corresponds to energy of conventional hybrid circuits of automobiles, and for both cases is approximately equal to 1...2 kW·h. The mass of a superflywheel from modern materials, for example, filaments of graphite, can be no more than 10 kg, and all accumulators with a drive of about 30...50 kg. It is necessary to note such feature of accumulators as ability to develop rather high powers, restricted only by mechanical strength of shafts. Thus this accumulator is the great concentrator of power.

4. The shaft of the superflywheel is linked to driving wheels of the vehicle by means of mechanical variable-speed drive, which controls the vehicle speed.

Generally the technical solution discussed above is the conventional automobile circuit where the function of the engine is executed by the source of electric power together with superflywheel. Variable-speed drive as a gearbox on automobiles is not more rarity. The combination of a multidisk variable-speed drive and superflywheel establishes especially favourable conditions for a development rather high vehicle power. This combination ensures effective recuperation of energy and eliminates necessity ABS and retarders, that is especially valuable for buses.

The masses and volumes of aggregates for the new concept are practically equal to masses of eliminated aggregates on the automobiles and buses – engine, cooling system, starting system and others. The installation of an electric power source with the superflywheel in the motor hood space of existing vehicles instead of the engine, therefore, makes it possible to receive an electric motor car or electrobus of the new concept. As the output shaft of an accumulator rotates, as well as the drive output shaft, so it is necessary only to connect it with the transmission of an automobile type.

It should be noted, that variable-speed drive, suitable for the mentioned purposes is developed at the Moscow State Industrial University (MSIU) together with the ZIL plant. The construction of ACVT is licensed.

Fig. 3 shows the scheme of city electrobuses of new concept.

Fig. 3.  Scheme of city electrobuses of new concept:
1 – fuel cell; 2 – small electromotor; 3 – reverse; 4 – reduction gear; 5 – ACVT; 6, 7 – cardan shafts; 8 – axle gear; 9 – cone gear; 10 – superflywheel.

We should like to find business partners having appropriate engineering, industrial and material possibilities, in order to realize this project.

Date of the publication:

January 18, 2000