TO THE OPERATION OF UNDERCAR GENERATORS IN PASSENGER TRAINS

ABSTRACT

The results of studies on the justification of the value of additional specific resistance to movement from undercar generators in passenger trains are presented, taking into account their speed and the type of cars used. It is proved that an increase in the number of cars with air conditioning leads to an increase in the value of the specified movement resistance from undercar generators, which decreases with an increase in the speed of a passenger train.

АННОТАЦИЯ

Представлены результаты исследований по обоснованию величины дополнительного удельного сопротивления движению от подвагонных генераторов в пассажирских поездах с учётом их скорости движения и типа используемых вагонов. Доказано, что увеличение количества вагонов с кондиционированием воздуха приводит к повышению величины указанного сопротивления движению от подвагонных генераторов, которое с увеличением скорости движения пассажирского поезда снижается.

Keywords: research, passenger train, car, undercar generator, movement resistance, specific, movement speed.

Ключевые слова: исследование, пассажирский поезд, вагон, подвагонный генератор, сопротивление движению, удельный, скорость движения.

Based on a comprehensive program for the development and modernization of the railway industry in Uzbekistan, the forecast for the expected growth in passenger traffic is 26.5% with an average annual growth of 4.4%, which will be provided by more than seven hundred passenger cars.

The above is confirmed by the diagram [1], which characterizes the dynamics of the expected growth in passenger turnover in million passengers. km with the structure of the passenger car fleet of the railway industry, indicated in fig. 1.

One of the main tasks in the development of passenger traffic of Uzbekistan Temir Yollari JSC is to develop measures and recommendations aimed at improving the efficiency of passenger service along the way by improving their travel conditions and increasing comfort in passenger trains. Therefore, studies of the efficiency of using the passenger car fleet on the sections of the Uzbek railways under operating conditions are very timely and relevant.

The organization of the process of movement of passenger trains is significantly affected by external forces, the effects of which on the train, in the physical model adopted by the authors [2], are shown in Fig. 2, where it is indicated: F_k - tangential traction force of the locomotive; W_k - resistance to train movement; B_br is the braking force of the train; Q is the weight of the train; Q' - "reaction" of the track (rails). The specified forces affecting the controlled movement are considered to be applied to the rims of the wheels of the locomotive and train cars.

Figure 1. The structure of the passenger car fleet of the railway industry

Figure 2. Physical model of the train

Depending on the combination of the considered forces, taking into account the unevenness of the transportation process (refers to the movement of the train), the following train driving modes are distinguished: traction mode, when forces act (F_k - W_k - T), braking mode, when forces act (B_br ± W_k - T) and idle mode, when forces (T - W_k) act. Here, T are the inertia forces of translationally moving masses m and rotating masses m into the train, overcoming of which the work of the traction force or braking force is expended.

The movement resistance force Wк participates in all three modes of train driving and consists of the forces of the main and additional movement resistances.

In passenger train cars, autonomous power supply systems are predominant [3], in which the main power source is an undercar generator driven from the axle of the wheelset through a gearbox mounted on the middle part of this axle and a cardan shaft.

According to the purpose, two groups of electrical equipment of passenger train cars are distinguished - those that provide power supply to the cars and consumers of electrical energy, and at the location they are divided into intracar, which includes devices for lighting, air conditioning, ventilation and heating of the car, as well as household appliances and undercarriage, that is, electrical equipment , located outside the train car body and the undercar generator belongs to one of them. The latter operates in a wide temperature range from -50ºС to +40ºС and is exposed to atmospheric (rain, snow, icing), as well as dust and dirt.

This complicates the operating conditions and necessitates the use of a specially designed undercar generator with the adoption of protective measures to ensure its stable and reliable operation.

During the operation of undercar generators of passenger cars, forces temporarily acting in operation arise, which are attributed to additional resistance to movement and which should be taken into account in passenger trains at speeds of 20 km/h and above.

The undercar generator, being a source of electrical energy during the movement of passenger trains, fully ensures the operation of power supply systems and consumers of electrical energy of passenger cars, which leads to an increase in resistance to the movement of rolling stock, and as a result, to an increase in the consumption of fuel and energy resources for train traction.

Therefore, in the calculation of the movement of passenger trains, it is necessary to take into account the additional resistance to movement from the action (operation) of undercar generators, based on the recommendations [2].

Additional specific resistance to movement from undercar generators is determined by the following formula:

                                        N/kN                                                 (1)

where P' is the average nominal power of the undercar generator per one passenger train car, kW; V - speed, km/h; qo is the load from the wheelset on the rails, kN/axle.

The P' values are determined from the following expression:

                              kW                                        (2)

where P_пг is the actual power of the undercar generator consumed for service needs, kW. P_пг =2 kW; n_бк - the number of passenger train cars without air conditioning; Р_гк is the actual power of the undercar generator consumed for air conditioning, kW. Р_гк = 9 kW; n_кв - number of wagons with air conditioning; m_п is the total number of cars in the train.

To assess the effect of additional specific resistance to movement from undercar generators on the transportation process of passenger trains, we perform a series of numerical calculations based on such initial data.

Passenger trains consisting of three sets of 15, 20 and 25 cars, each of which sixty percent are air-conditioned cars. Travel speed in the range from 20 km/h to 100 km/h with a change interval of ΔV = 20 km/h and load from the wheelset on the rails qо = 150 kN/axle. Preliminary calculations using formula (2) found that the average nominal power of the undercar generator per each car of a passenger train is equal to a constant value - Р' = 7.4 kW and does not depend on their total number in these trains.

Then, substituting the values of Р' = 7.4 kW/car and qо = 150 kN/axle into equation (1), we obtain simple formulas for determining the additional specific resistance to movement from undercar generators for the trains considered by the authors with differents of percentages of train cars airconditioned air, namely:

·                        for n_кв = 60 percent,  62,9 ^-1, N/kN                                               (3)

·                        for n_кв = 80 percent,  78,2 ^-1, N/kN                                               (4)

·                        for n_кв = 40 percent,  47,6·^-1, N/kN                                               (5)

In table 1 shows the results of numerical calculations to determine the additional specific resistance to movement from undercar generators for different options for the process of movement of passenger trains.

Table 1.

Additional specific resistance to movement from undercar generators in passenger trains

On fig. 3 shows the nature of the change in the additional specific resistance to movement from undercar generators in passenger trains, where: 1,2,3 - respectively, the number of cars with air conditioning is 80, 60 and 40 percent.

Thus, the operation of undercarriage generators leads to a decrease in additional specific resistance to movement from them with an increase in the speed of passenger trains.

Figure 3. Performance indicators of undercar generators in passenger trains

In addition, an increase (decrease) in cars with air conditioning by 20 percent will provide, respectively, an increase (decrease) by 24.30-24.33 percent of the additional specific resistance to movement from the operation of undercar generators, in the range of changes in the speeds of passenger trains considered by the authors.

Reference:

1. Ablyalimov O. S. To the analysis of the work of undercar generators in passenger trains [Text] / O. S. Ablyalimov, Zh. D. Khodzhiev // Republic of ilmiy - amaly anzhumani "Talimning uzviyligi va uzliysizligini ta'minlash - soҳa taraққiyotining muhim mezoni". – Tashkent׃ ToshDYU, 2015. – pp. 41-45.
2. Ablyalimov O. S. Fundamentals of train traction [Text] / O. S. Ablyalimov, D. N. Kurilkin, I. S. Kamalov, O. T. Kasimov // Textbook for higher educational institutions of railway transport. Under the general editorship of O. S. Ablyalimov. - Tashkent: "Complex Print" nashriyoti, 2020. - 662 p.
3. Rolling stock and train traction [Text] / A. P. Tretyakov, V. V. Deev, A. A. Perova et al. Ed. V. V. Deeva, N. A. Fufryansky // Textbook for higher educational institutions of railway transport. - M.: Transport, 1979. - 368 p.