ULTRA-EFFICIENT HYBRID TRANSPORT SYSTEM

Fig. 1

1. INTRODUCTION

Vehicles, such as buses and trucks, have become indispensable tools of transportation for people and goods. However, pollutants derived from automobile operation have posed serious environmental problems. Based on different energy sources, vehicles were divided into three main categories: electrical vehicles, fuel-powered vehicles or hybrid vehicles. 

It is known that usually electric vehicles named trolleybuses (fig. 2) can circulate on ways shared by general urban traffic, but that they will have to follow imperatively the trajectory imposed by their source of energy supply, a feeder usually named catenary (dual overhead line) system. This “in motion charging system” limits the vehicle speed at 70 Km/h and consequently the trolleybus can not be used in highways. It is known also a solution which can be named “hybrid” trolleybus that uses an APU (auxiliary power unit) to act the vehicle from the garage or in some portion of the way. In this case, the main problem becomes to put in connection the trolleybus with the overhead lines. This operation is often very delicate and must be made usually with the vehicle stopped.

Fig. 2

The transport by bus, with its flexibility is the means of transport nearest to individual transport or the taxi. Certain informed mediums know that a large fleet of bus, having important portions of way on well protected reserved roads, can, like the trams, to generate great flows of travelers. It is today the mode of connection for the transport of the people between suburbs which require less investment, without relationship with all the current electric solutions. At present, it is thus the public transport considered the most economic. The quality and the flexibility of transport by bus do not make unfortunately disappear the fact that this transport means use thermal engines, that they are with diesel oil, gasoline or gas, generating an air and sound pollution incompatible with the new requirements of environmental protection of the cities and especially of the centers town.  A variant is represented by the purely electric vehicles of which only the automation and the flexibility of the controls allows a smoothness  of accelerations and brakings taking part largely in the comfort of the passengers.

At present the concept of the clean bus is represented by that which functions on electrochemical batteries. Cities try to use it. They are based on infrastructure, which is much reduced compared to that used by the tram, but must have docking stations.  This type of traveling material remains however of a limited availability by times of refill and extraction of the batteries (in the case of removable pack). The best financial compromise and of minimum investment is obtained there by selecting the best battery economically, generally with lead, for a use from five to ten hours continued some, with a slow complete refill each day and some fast refills in the period of the regular work.  Unfortunately this transport means have a limited autonomy and them garages must to be near to them journey.  For the moment, this type of electrochemical battery bus is regarded as a marginal product adapted for an everyday usage and is retained only in the form of minibus, for centers town.

To solve these problems are necessary some major/radical solutions and in this case the time is not our friend. Consequently, the primary object of the proposed solution is to provide an improved transportation system including an electrically operated vehicle and an electrified roadway including means for supplying electric energy to the vehicle operating thereon, and which vehicle includes other means for operating the vehicle when off the electrified roadway.

2. DESCRIPTION OF THE SOLUTION

The proposed ultra-efficient and clean hybrid transport system can be used for urban or transit buses, passenger cars, trucks or other vehicle types without discrimination. It is a "bi" or “tri” modal system which uses mainly a clean external electric source of power to charge an accumulating device coupled with a regenerative brake transmission.  The hybrid transport system, conformable with this concept has two main components the infrastructure and the hybrid vehicles. The infrastructure supply with energy a street network built as a single overhead line containing the both polarities. So, the vehicles are charged in motion by an interrupted grid system (fig. 1 and 3).    

Fig. 3

The main source of power is represented by an accumulating device that is charged by a converter coupled from time to time with the docking station located in each vehicle stand, in city roads, at each crossroad having traffic lights or in general on dedicated roadways. The accumulating device delivers the energy through a reversible machine coupled with the vehicle transmission or directly with the differential (Fig. 4).

Fig. 4

The quantity of energy supplied by the hybrid propulsion system is enough to drive the vehicle between two docking stations. This captured electrical energy is then used as well to power the vehicle in acceleration phase. The system utilizes also, as a secondary or back-up source of power, a small fuel cell associated with the same transmission (or a small internal combustion engine supplied with hydrogen or natural gases). This secondary source with limited power works exclusively when the accumulating device cannot be charged by the docking station, respectively out of the normal way. Dedicated roadways can realize an energy supplying system that charges the vehicle propulsion system while moving. These roadways may be readily and relatively inexpensively electrified in accordance with the present proposal. Also the intermittent charging system of the vehicle is very simple and reliable, and can be adapted for all vehicle types or sizes.

3. INNOVATIVE ASPECTS  

A) As General Transport System:

The Ultra-Efficient Transport System (UETS) creates the possibility to achieve at present an extended high-efficiency zero-pollution transport system for goods and passengers. This transport system can be used both in the city and in the highways. The intermittent charging system can be safely coupled with the supplying system at high speed. Also the charging of the accumulating device can be made in motion at high vehicle speed. The charging system is not influenced by the bad weather and can work at all latitudes. It is a system which does not increase the electromagnetic pollution in the vehicle interior or in the external area.   

The UETS has five major advantages: compatibility with current technologies, effortlessly adaptable infrastructure, reduced energy consumption, zero emission in normal conditions, and lower operating and life cycle costs.

a) Compatibility with current technologies. All the technologies used to develop this new system are well known and are already proved separately in different applications. Some hybrid vehicles are already in use. With a few small modifications these systems can be transformed in UETS vehicles.

b) Effortlessly adaptable infrastructure. The current infrastructure will be easily modified to be compatible with UETS. After the conversion, the infrastructure remains compatible with the usually unmodified vehicles.

c) Reduced energy consumption. The total propulsion efficiency of the UETS vehicle in normal conditions is equal with the multiplication of few factors being around 0.7 - 0.82 for this hybrid system. This value is superior to a fuel cell’s total efficiency. It is another motif to use the main propulsion system preponderantly and the fuel cell only in the case. The regenerative braking operates with a total efficiency up to 70%.

 d) Zero emission. In normal working conditions is a zero-emission vehicle. "Greenhouse" gas emissions, believed to contribute to global warming, are completed eliminated. Consequently the estimated reduction in pollutant emissions (CO2 in special) would be 180 kg/day in case of the urban buses.

 e) Lower operating and life cycle costs. This hybrid system results in lower operating costs due to reduced stress and maintenance on mechanical components.

Other advantages of this system are the very low level of  NVH which reduce also the environmental noises pollution and the easiness to recycle the components at the end of the life time. In the table 1 is described a comparison between different types of urban transport modalities.

Table 1

B) As a solution proposed to replace the trolleybus:

a) The intermittent charging system can be safely coupled with the supplying system at high speed (even at 100 Km/h or more) and the hybrid bus, conformable with this invention, will be no more stopped to make this operation. Consequently this vehicle will not block the traffic behind it.

b) The speed limit can increase without problem because the charging of the accumulating device can be made in motion at high vehicle speed much (more than 70 Km/h). Consequently the new hybrid bus can be used as suburban and interurban means of transport.

c) Using a single overhead line without cross passages the electric supplying network is simplified at maximum and the cost will be reduced.

C) As an alternative solution at the actual propulsion system of the interurban (transcontinental) heavy trucks:

a) This concept creates a real world alternative to the actual propulsion system of the heavy vehicles. It is not need to make so many researches to develop such a system because all the components are already used separately in some applications.

b) The total efficiency is improved and consequently the cost reported to km will be diminished.

c)  It maintains the same flexibility of the actual transport system based on the diesel trucks.

BIBLIOGRAPHY

***, www.tbus.org.uk

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