Justification of the technical requirements for diagnosing a robotic gearbox
Students Name: Kobrynets Nazarii Yuriiovych
Qualification Level: magister
Speciality: Motor Vehicle Transport
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: full
Academic Year: 2023-2024 н.р.
Language of Defence: ukrainian
Abstract: The modern development of automatic gearboxes makes it impossible to carry out their repair using defecting. Therefore, the development of new diagnostic methods is a necessary process for carrying out a high-quality and effective restoration of the performance of this unit. The main reasons for the rapid failure of the automatic transmission are its improper operation. Every driver who drives a car with an automatic transmission should remember that this gearbox does not like abruptness, and a smooth driving style and timely maintenance increase the resource of this unit several times. In this work, a technological process of diagnosing automatic transmissions is proposed, which makes it possible to deepen the level of diagnostics based on the analysis of cause-and-effect relationships and the multiplicity of defects. In the first chapter, an overview of the available methods of diagnosing automatic transmissions is performed and suggestions are made regarding their improvement. The design features of the automatic gearbox are analyzed. It is much easier to defect clutches than brake belts. This is due to the fact that they wear evenly over the entire pressing surface and it is enough only to measure their thickness. In turn, the brake tape wears out unevenly, therefore, after measuring the thickness, it is much more difficult to draw a conclusion about its replacement. In the second section, a theoretical analysis of the diagnosis process is performed from the standpoint of cause-and-effect relationships and statistics of the occurrence of malfunctions. A structural model of the automatic gearbox was built in accordance with the conditions for the occurrence of structural signs of malfunctions. In this section, statistical information on detected failures of the ZF 4HP20 gearbox is also collected and processed. Recommendations are provided to improve their reliability. A diagnostic model is being developed for maximum optimization of this process. On the basis of the structural model and statistical data on the occurrence of failures of automatic transmissions, an improved diagnostic algorithm has been developed, which is characterized by a higher failure recognition coefficient. In the third section, the methodology is developed and the test results are described. The content of the tests was that actual causes of automatic box failures were practically established. A Stall Test was also conducted. It is recorded that it is very important to have a conversation with the car driver about the level of operation, which gives a lot of starting information to the diagnostician. In the fourth section, the means of diagnosing the hydraulic unit were improved. A stand for implementation of the developed diagnostic algorithm is also proposed. The stand is based on well-known designs, but has a targeted set of functions. At the same time, a stand for testing the electronic control unit has been developed. The goal is to increase the accuracy of diagnosis and reduce the time it takes by developing a model and new diagnostic tools. The object of the study is the ZF 4HP20 automatic transmission. The subject of the study is cause-and-effect relationships of possible malfunctions of the gearbox. Research methods – collection of statistical data on detected malfunctions, detailed analysis of the received malfunction, determination of the cause of its occurrence. Scientific novelty. The method of submitting test signals from sensors to the electronic control unit in order to check its serviceability has been improved. The method of checking the hydraulic control unit and torque converter by installing them on special stands has been improved. The practical significance of the obtained results is that the obtained diagnostic methods should be used when detecting such malfunctions of the electronic control unit, hydraulic control unit, and torque converter, which cannot be found using defect detection and other methods. The results of the research in this work make it possible to increase the reliability of the repaired automatic transmission due to the detection of defects that were not previously detected by known methods. Keywords: automatic transmission, diagnostics, structural model.