INFORMATION-MEASURING TEST SYSTEM OF DIESEL LOCOMOTIVE HYDRAULIC TRANSMISSIONS

Dep. «Electronic Computing Machines», Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan, Lazaryan St., 2, Dnipropetrovsk, Ukraine, 49010, tel. +38 (056) 373 15 89, e-mail ivzhuk@mail.ru, ORCID 0000-0002-3491-5976 Dep. «Electronic Computing Machines», Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan, Lazaryan St., 2, Dnipropetrovsk, Ukraine, 49010, tel. +38 (056) 373 15 89, e-mail klugran@i.ua,, ORCID 0000-0001-9939-0755 Dep. «Locomotives», Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan, Lazaryan St., 2, Dnipropetrovsk, Ukraine, 49010, tel. +38 (056) 733 19 61, e-mail oalexander@mail.ru, ORCID 0000-0002-7719-7214 Dep. «Locomotives», Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan, Lazaryan St., 2, Dnipropetrovsk, Ukraine, 49010, tel. +38 (056) 733 19 61, e-mail koroman@ua.fm, ORCID 0000-0003-1416-4770


Introduction
Most locomotives with hydraulic power transmission used in Ukraine need the overhaul repair or reconditioning.When performing the overhaul repair one of the complex and responsible diesel locomotive units is hydraulic transmission.After overhauls of locomotive hydraulic transmissions one conducts their running-in testing without load as well as testing with load to check the basic parameters.Specifications of companies that repair hydraulic transmission recommend performing a certain amount of evaluation and adjustment tests to monitor their post-repair condition.According to the repair rules in the non-load and load running-in process mainly there is controlled the level of noise, tightness, temperature, pressure in the oil system, turbine shaft acceleration, triggering of blocking devices, reverse clutch and modes engagement, body vibration magnitude, reliability and accuracy of the automatic control system [12].The quality of these tests affects the transmission resource and its efficiency.

Purpose
In Ukraine today for hydraulic transmission testing, particularly at locomotive repair plants and other repair enterprises of the equipment with hydraulic transmission, there are used out-of-date stands developed in the USSR.These stands do not allow capturing the measured test parameters in dynamics and therefore drawing a full conclusion as to the repair flaws of the tested device.That often resulted in returning of not properly repaired hydraulic transmission for revision after such tests.Also there are no production standards for these stands.
Today in Ukraine there are almost no informationmeasuring test systems of diesel locomotive hydraulic transmission.Hence it is necessary to create a unique system of its kind that has no analogues in Ukraine based on the experience and development of foreign scientists.So the important is a detailed review of existing foreign information-measuring test systems of diesel locomotive hydraulic transmission and problem statement to create a national test system, based primarily on the automation capabilities of the existing test stand of locomotive hydraulic transmission at Dnipropetrovsk Diesel Locomotive Repair Plant «Promteplovoz».

Previous studies analysis
Analogues of test systems for locomotive hydraulic transmission and other vehicles exist in Russia [6,14,15] and some other countries [9].The research works reviewed in [1,3,7] are dedicated to the problem of improvement of hydraulic transmission locomotive testing.Industry research laboratory «Technical maintenance and diagnostics of locomotives» of Dnepropetrovsk National University of Railway Transport named after Academician V.Lazaryan is working to improve testing of locomotive hydraulic transmissions under the conditions of Diesel Locomotive Repair Plant [2,16,5,8].
At the Ukrainian enterprises, which repair the hydraulic transmission for tests, they use typical stands most of which were designed and have been used since 1980-s.
The Dnipropetrovsk Diesel Locomotive Repair Plant «Promteplovoz» uses UGP750-1200 stand for testing the unified hydraulic transmission.The hydraulic transmission of this type is installed on most locomotives with hydraulic transmission that operate at the industrial transport enterprises and «Ukrzaliznytsia».
Of course, the number of control parameters and measurement accuracy of the above stand (with analogue pointed indicators) do not correspond to the current level of computing.The stand does not to record the process dynamics.The absence of automatic fixing of measured parameters and test protocol reduces the opportunities for analysing test results and those of the test stand.
The closest modern analogue of the stands existing in Ukraine (without computerized recording of parameters) is the test stand used by Special-purpose Equipment Plant «Standard» for testing the unified hydraulic transmission UGP 230 [15].
The stand is designed for acceptance testing of unified hydraulic transmission UGP 230 after repair for inspection and setting of the basic performance data.
While testing the hydraulic transmission there are checked build quality, tightness, oil system pressure, temperature control, reverse switch, assembly and operation quality of friction clutches, drive shaft speed.
Tests are conducted in two modes: train and shunting.
Hydraulic transmission test stands are used not only at the locomotive repair plants, but also at the enterprises that perform repair of quarry vehicles, track vehicles and other vehicles.For example, RDC «Technical diagnostics and precision measurement» created a computerized stand for hydraulic transmission testing and running-in (HMT) [6].This stand is used to test hydraulic transmission of BelAZ earthmovers, aircraft tugs, slag cars, trucks, BelAZ wheel dozers, some brands of tractors, etc. Fig. 1 shows a block diagram of such a stand.The stand performs testing of HMT using an asynchronous electromotor.Data from the sensors are transmitted to the computer via ADC.The asynchronous electromotor has a feedback from the computer through the rotary speed converter that allows adjusting the motor rotary speed.
The considered stand controls the torque fixing the rotary speed of the input and output shafts, temperature and flow rate in the cooling system, the pressure in HMT oil systems (main passage, torque converter, lubrication system, lock friction clutch engagement channel).Also the test time is fixed.
Test is performed on this stand automatically by a computer: software selection of HMT type, selection and shifting of transmission, setting of running-in modes for each HMT transmission, setting of running-in time and automatic maintenance of speed mode.The measured parameters are monitored and displayed on the computer monitor.There is an option of emergency stop when the measured parameters exceed the set value.Furthermore there are options of documentation and archiving of test results, protocol printing.
The disadvantages of the stand include the absence of brake load (generator unit for hydraulic transmission testing in load mode).
The next development of the aforementioned plant is a stand for hydraulic transmission runningin and testing [14], which is in fact an improved version of the previously considered one.
Block diagram of the stand is shown in Fig. 2.
The main distinguishing feature of the stand is the use of asynchronous electromotors (AEM) paired with frequency converters, both as driving and braking load devices, and the use of the braking load generator.Herewith, the frequency converters are connected by means of DC bus that allows to transmit the power from braking AEM to drive AEM, and thus to provide power recuperation.Rotary speed and load are programmable.Sensor readings are recorded in the program and displayed on the screen in real time.After the test completion the report is formed.
The stand allows to check HMT build quality, the pressure in HMT oil systems in different temperature regimes, reverse clutch engagement in different temperature regimes, turbine shaft spinup at different temperatures, the stability of the feed pump, transients, operation in stop mode.

Methodology
The measuring tools of the existing hydraulic transmission test stand at the plant DLRP «Promteplovoz» are analogue control devices that are obsolete.Control devices do not correspond to the current level of computing.The equipment has low accuracy and cannot collect and analyze data on the technical condition of hydraulic transmission.Thus information content of hydraulic transmission test is decreased and creation of a holistic view of the hydraulic transmission technical condition is complicated.
In order to eliminate these shortcomings the authors are working on development and implemen-tation of information-measuring test system of locomotive hydraulic transmission [13] under the conditions of Diesel Locomotive Repair Plant DLRP «Promteplovoz.»Based on the experience of the above mentioned systems and hydraulic transmission test technology there are selected the types of sensors and their installation place.In the first stage of development according to the plant test program there were selected the most essential and critical 13 process parameters, which include: -Oil temperature in circulation circle of the first and second torque converters, and oil temperature before and after hydraulic transmission (0-120°C, scale division -1°C); -Oil pressure in circulation circle of the first (see.Fig. 3) and the second torque converters (0 … 0.25 MPa, scale division -0.01 MPa); -Rotary speed of the turbine shaft of hydraulic transmission, drive motor and generator (up to 1500 min -1 , scale division -1 min -1 ); -Current and voltage of drive motor and load generator (current -500 A, scale division -(according to plant test program and expert opinion) -1 A, voltage 600 V, scale division -1 V); Sensor scanning must be made with a frequency of at least 2 Hz.
As pressure sensors there were selected MIDA-DI-02P [5].The spaced design of sensors MIDA-DI-02P (primary converter is cable-connected with the processing unit) allows to use them in a wide range of measurement environment temperatures (50-150°C) while maintaining high performance.As the temperature sensors there were selected resistance temperature transducers TSM-364-01.Working range of measured temperatures from 0 to + 150°C.Permissible deviations of indicators constitute ± |0.3 + 0.005t|°C.Switching-on is per-formed by bridge circuit with the supply voltage (24 … 36) V.
To register the characteristics deviations from the nominal sensor values the pressure and temperature sensors were calibrated in conjunction with converters.
As signal converters of temperature, pressure, voltage and current sensors the indicators of technological parameters «MicRA I3» and «MicRA I4» were used.These indicators convert the re- ceived analogue signals into the digital ones and transmit them to the data collection system.According to the documentation [12,11] for measuring range the above mentioned devices fully satisfy the technical requirements for testing, because their built ADC bit capacity is 21 bit.Current and voltage are measured through the shunt, where the maximum voltage is 75 mV.Sensor scanning is performed at a speed of 2.5 Hz, which also satisfies the given conditions.
To implement this task all indicators are RS-485 standard networked, and using the specially designed by university IRL converter of RS-485 interface into USB 2.0 the data are transferred directly to the data collection system.The data exchange is performed using link layer protocol Modbus RTU [18], which gives additional protection against high electromagnetic fields produced during the tests at industrial enterprises.Modbus RTU protocol can detect logical errors, as well as errors in data transfer that when used as a communication line of shielded twisted pair and complete galvanic isolation in RS-485 to USB 2.0 interface converter provides the necessary protection of the above negative impacts.
Given the considerable electromagnetic interference during testing, one should use both hardware obstacles (shielded twisted pair, RS-485) and program digital filters, such as Kalman filter [17].
A separate development is the rotation velocity sensor data processing subsystem.In terms of plant testing the data on rotary speed of drive motor, generator, turbine shaft are measured using obsolete (to save money) tachometric sensors D-2MMU-2, which transmit pre-processed analogue signal to the special ATMEL microcontroller for further processing and transmission through USB 2.0 interface to the computer.However, D-2MMU-2 sensor characteristics do not allow to perform measurements in the low speed range of electric motors (due to the fact that the speed-voltage generator transfers imperfect sinusoidal signal as shown in Fig. 5, and the amplitude increases in proportion to rotary speed and therefore at the speed of up to 125 min -1 it is not possible to get reliable indicators at all).Herewith the measurement range made 125-1500 min -1 , and the accuracy is quite low (significant nonlinearity of indications when reducing scale division below 125 min -1 ).However, work is underway on the use of modern optical encoder to expand the measurement range, and to greatly improve the measurement accuracy.
At this stage of development it became possible to implement the check of temperature, turbine shaft acceleration, hydro device filling time, time measuring for switching transients of hydro devices (Fig. 6).All data received from the sensors are recorded in an electronic test report with print option.When developing the information-measuring system the technical requirements for testing hydraulic transmission are met (except for the requirements for range and accuracy of rotary speed measurement), but for further research survey the suggested 2 Hz sensor scanning speed and the resulted after the system implementation 2.5 Hz speed is unsatisfactory and cannot follow the fast dynamic processes such as, for example, change in voltage and current values.Fig. 7 shows current and voltage graphs where it can be observed that transients are not clearly traced because of the low sampling frequency.
Therefore it is necessary to implement as rotary speed sensors the modern optical encoders, and in order to measure current and voltage to implement digital ammeters and voltmeters on microcontrollers to obtain the necessary and sufficient speed scanning.

Findings
Based on the conducted analysis there was grounded the necessity of improvement the plant hydraulic transmission stand testing by creating a microprocessor testing system, supported by the experience of developing such systems abroad.

Originality and practical value
The paper proposed the alternate design of microprocessor test system of diesel locomotive hydraulic transmission, which has no analogues in Ukraine.The data collection was automated during the test in order to capture the transient processes to determine the hydraulic transmission technical condition.The designed information-measuring system improves the hydraulic transmission test process by automating and increasing the accuracy of measurements of control parameters.The measurement results are initial data for carrying out further studies to determine the technical condition of the hydraulic transmission UGP750-1200 during the plant post-repair tests.

Conclusions
The existing hydraulic transmission test systems are reviewed.Based on the review the prototype of future microprocessor test system of locomotive hydraulic transmission was created according to test program of the plant «Promteplovoz».There was developed the information-measuring system enabling to raise and improve efficiency of

Fig. 1 .
Fig. 1.-Block diagram of the computer stand for testing and running-in the hydromechanical transmission (HMT)[6]

Fig. 2 .
Fig. 2. Block diagram of the stand for testing and running-in the hydraulic transmission HMT-1000 Analysis of existing hydraulic transmission test systems in order to improve the technology of plant post-repair testing of hydraulic transmission by creating an information system of testing and diagnostics based on test stand of the locomotive repair plant.

Fig. 3 .
Fig. 3. Pressure sensor installation in the circulation circle of hydro apparatus