RU2239220C1 - Automatic pressure control system in pneumatic system of traction rolling stock - Google Patents

Abstract

FIELD: modification of piston compressor plants of traction rolling stock, for example, diesel traction rolling stock, on which the compressors are driven by a thermal engine.

SUBSTANCE: the automatic pressure control system has a pneumatic system connected to a compressor driven by the shaft of a thermal engine by means of a mechanical pressure regulator and a variable filling fluid coupling, whose inlet is connected to a regulating slide valve of oil feed to the fluid coupling, use is made of a continuous-action microprocessor control connected to whose inputs by means of analog-to-digital converters is a pressure transducer, connected through a pipe-line to the pneumatic system of the traction rolling stock, and a compressor shaft rotational speed transducer connected to the compressor shaft, and the output of the microprocessor control is coupled via a digital-to-analog converter to an amplifier connected to the winding of the traction electromagnet directly connected to the measuring spring and the slide valve of oil feed to the fluid coupling.

EFFECT: provided automatic maintenance of pressure in the pneumatic system of the traction rolling stock irrespective of air flow from the pneumatic system, temperature and pressure of free air.

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Description

The invention relates to the field of improvement of reciprocating compressor units of traction rolling stock, for example, diesel traction rolling stock on which compressors are driven by a heat engine. The following compressor drives are used on diesel traction rolling stock: mechanical non-disconnectable from the main heat engine; electric adjustable relay; hydrodynamic with adjustable clutch; hydrodynamic with an unregulated coupling; drive from auxiliary heat engine (non-switching) [1].

The operation of compressor units on locomotives is significantly different from their operation under stationary conditions. Due to the specifics of train work, the design features of locomotives and compressor drive types, this difference is characterized by variable shaft speeds, discharge pressure, temperature conditions, frequent starts and stops or changes of working and idling [2].

It is known that of all the methods used to change the supply Q ₂ and pressure p _{k of} compressors, the method of changing them by changing the speed of rotation of the compressor shaft ω _k is the most effective. However, relay automatic pressure regulating system (ASRD) are widely used to maintain the air pressure p _to the pneumatic system of the traction vehicle, in which the functions of executive-control devices (EDM), i.e. actuators (MI) in conjunction with regulatory authorities (RO), perform the drive of the compressor and the actual compressor (figure 1). The pneumatic system of the traction vehicle itself is an object of pressure regulation (ARD). The automatic pressure regulator (ARD) contains, in addition to the executive-regulating device, a control body (UO), consisting of a measuring device (IU), a master (ZU), a comparing (SU) and an amplifier-converting (UU) device [3].

In the pressure control object acted upon by external disturbance variables: air flow rate Q of the compressed air system ₁ (λ _1), the temperature T _a (λ ₂₎ and _a pressure p (λ ₃₎ outside (intake) air. To maintain an adjustable value - pressure p _k (φ) in a given range, the automatic pressure regulator changes the regulatory effect - air supply Q ₂ (μ) in the pneumatic system. Relay automatic pressure regulator has a static characteristic in the form of a loop (Figure 2), and if the automatic pressure regulating system _for the value of p varies from p to p _{k1 k2.} The increase in pressure, the value of p _to from p _k1 to p _{k2 is} carried out during operation of the compressor with a maximum shaft rotation speed ω _{to max} and a maximum supply of Q _{2 max} . At the same time, the maximum wear rate of parts of the cylinder-piston group of the compressor and increased lubricant consumption are observed. Thus, a decrease in ω _k from 1450 to 710 rpm leads to a decrease in the wear rate of compression and oil scraper rings (from improved special phosphorous cast iron) of the first and second stages by 1.3–3 times, and cylinders by 2.5–3 times [4 ]. The test results show that the wear rate of the compressor parts increases both with an increase in ω _k and with an increase in p _k , and the pressure p _k has a stronger effect on the increase in the wear rate. By increasing p _to 1.4 times (from 0.7 to 1.0 MPa) the wear rate increased the crankpins 3.2 times, whereas with an increase in p _to 1.4 times (from 1170 to 1640 rev / min ) - only 1.2 times. The most intense wear rate begins to increase at p _to more than 0.6-0.7 MPa [5].

Changing the compressor operating modes has a significant effect not only on the wear rate of the parts of the cylinder-piston group, but also on the lubricant consumption. With an increase in ω _k and a discharge pressure p _{k, the} lubricant consumption increases. For example, when tested at nominal compressor speed mode with serial piston rings _to increase p from 0 to 0.6, 0.8 and 1.0 MPa, resulting in increased grease consumption respectively 1.8, 2.7 and 3.0 times . With a decrease in ω _k from 1450 to 710 rpm, the lubricant consumption decreased by about 6 times [4]. To reduce the wear of parts of the compressor piston group and to reduce the lubricant consumption, it is necessary to apply continuous regulation of p _{to the} most efficient way - a smooth change in ω _k , at which the compressor operating time decreases at ω _{k max} and p _{k max} . Automatic continuous pressure control systems contain automatic pressure regulators, the static characteristics of which are shown in Fig. 3 (1 - when the compressor drive is turned off at ω _to = 0; 2 - when the compressor drive is turned off at ω _to = (0,13- 0.17 ω _{k max} ) .Analysis of the properties of an automatic pressure regulator for relay and continuous operation shows that with continuous pressure control, the compressor works longer with a lower ω _k and a lower p _k , which helps to reduce the speed and wear of cylinder piston parts and a decrease in lubricant consumption (the cost of which is much higher than the cost of diesel fuel).

An automatic pressure control system in the pneumatic system of a traction vehicle with an automatic continuous pressure regulator contains a compressor 1 (Fig. 4) driven from a shaft of a turbine wheel 2 of a variable-pressure fluid coupling 3. Through a hollow shaft of a pump wheel 4 of the fluid coupling, oil is supplied with G ₁ feed. The hollow shaft of the pump wheel 4 is connected via a step-up gear reducer 5 to the shaft of the heat engine 6. The spool 7 controls the oil supply G ₁ to the hydrodynamic clutch. In this microprocessor-based automatic pressure regulator, the signal p _k is fed to pressure sensor 13, passing through the first analog-to-digital converter (ADC1) 14, the on-board microprocessor controller 15 and the DAC 16, is amplified by an amplifier 17 and fed to the winding 18 of the traction electromagnet 19, the electromagnetic force of which is measured by a measuring spring 9. From the relation with yl traction spring and the electromagnet depends position of the slide 7. The force of the electromagnet 19 is transmitted traction measuring spring 9 via the pressure washer 8. Power measuring tightening spring 9 can be adjusted using the adjusting nut 10. The position of the spool 7 is dependent on a number _k, but determined by the algorithm of automatic operation of the microprocessor pressure regulator, taking into account the conditions and modes of operation of the pneumatic system and compressor unit of the traction vehicle. To take into account the value of ω _k in the microprocessor-based automatic pressure regulator, an ω _k 20 sensor is used, connected to the on-board microprocessor controller 15 through a second analog-to-digital converter (ADC2) 21.

Automatic pressure control system in the pneumatic system of a traction vehicle operates as follows. When p _to below p _k1 (see figure 3 and 4), the spring 9 holds the spool 7 in its highest position. The hole for supplying oil G ₁ to the hydrodynamic coupling 3 is completely open by the slide valve 7. The working cavity of the hydrodynamic coupling 3 is completely filled with oil and the turbine wheel 2 and the compressor shaft rotate at a speed of ω _{to max} . The compressor has a flow rate of Q _{2 max} and the pressure p _k rises. After reaching p _to p _{k1, the} electromagnetic force of the traction electromagnet 19 becomes greater than the force of the measuring spring 9, Zolotnik 7 begins to move and partially block the hole for oil supply G ₁ to the hydrodynamic clutch 3. This leads to a decrease in the degree of filling of the hydrodynamic clutch 3, to a decrease in speed ω _to and supply compressor Q ₂ . The air flow Q ₁ from the pneumatic system 11 depends on the operating modes of the pneumatic devices of the traction vehicle. When the compressor becomes equal to the supply flow Q ₁ comes steady state of the automatic pressure regulating system and p is _a constant. If p _k becomes equal to p _{k2, the} spool 7 shuts off the oil supply G ₁ to the hydrodynamic clutch 3, the compressor stops and its supply becomes equal to zero. Since the compressor gives a noticeable supply at ω _to > (0.13-0.17) ω _{to max} , the automatic pressure control system can be adjusted so that the hydrodynamic coupling is defrosted when this minimum rotation speed is reached (Fig. 3). Thus, at different air flow rates from the pneumatic system of the traction vehicle, the automatic pressure control system will always maintain a supply of Q ₂ equal to the flow rate of Q ₁ when the pressure changes in the range from p _k1 to p _k2 .

Sources of information

1. Diesel locomotives. Design, theory and calculation. / Ed. N.I. Panova. - M.: Mechanical Engineering, 1976 .-- 544 p.

2. Sharunin A.A. Field tests of locomotive compressors PK-35 and PK-3,5. Proceedings of the Central Research Institute of the Ministry of Railways, 1970, issue 413.

3. Lukov N.M. Fundamentals of automation and automation of diesel locomotives. - M .: Transport, 1989.

4. Bannikov V.A., Manshin A.P. The influence of compressor operating modes on the wear of cylinder-piston parts and lubricant consumption. - Kolomna, Proceedings of VNITI, 1983, issue 58.

5. Tsykunov Yu.I. Wear test results for PK-35 and PK-3,5 compressors. - M.: NIIINFORMTYAZHMASH, Transport Engineering, 1968, issue 13.

6. Tsykunov Yu.I., Lesin V.I. Test results of prototypes of locomotive compressors PK-3.5 and PK-1.75. - M.: NIIINFORMTYAZHMASH. Transport Engineering, 1968, issue 5-67-14.

7. A.N. Logunov and others. The device locomotive TGM6A. M .: Transport, 1989.

8. Manshin A.P. Research of a system of automatic control of compressor rotation speed with a drive through a fluid coupling of variable filling: Dis. can tech. sciences. - M., MIIT, 1970.

9. Manshin A.P. Investigation of a system for automatically controlling the speed of rotation of a compressor with a drive through a fluid coupling of variable filling. - Kolomna, Transactions of VNITI, 1975, issue 41.

Claims (1)

An automatic pressure control system in the pneumatic system of a traction vehicle, comprising a pneumatic system connected to a compressor driven from a shaft of a heat engine by means of a mechanical gearbox and a variable-flow hydrodynamic clutch, the input of which is connected to a regulating oil supply spool to the hydrodynamic clutch, characterized in that it uses a continuous microprocessor control body, to the inputs of which are connected via analog-digital x transducers, a pressure sensor connected by a pipeline to the pneumatic system of the traction vehicle and a compressor shaft speed sensor connected to the compressor shaft, and the output of the microprocessor control unit is connected through a digital-to-analog converter with an amplifier connected to the winding of the traction electromagnet directly connected to the measuring spring and spool of oil supply to the hydrodynamic coupling.

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