Research of the feasibility of using hybrid hydraulic transmissions in utility vehicles
Students Name: Pecherytsia Roman Yuriiovych
Qualification Level: magister
Speciality: Motor Vehicle Transport
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: In the master’s qualification work, the design features of hydraulic hybrid systems in utility vehicles are considered, namely: serial and parallel. Each design scheme of the drive offers its own set of advantages. A sequential system provides simplicity by eliminating most elements of a traditional transmission. The engine drives a hydraulic pump/motor that mechanically transfers power to and from the vehicle’s wheels. This solution allows the engine to run at the most efficient speed instead of constantly accelerating and decelerating. The problem is that all the power is transferred through the hydraulic components, so they have to be very efficient. In a parallel system, the hydraulic system serves as an auxiliary transmission and complements the traditional one. This design typically uses hydraulic drive when frequent stop-and-start operations occur, but can be switched to conventional drive for highway driving. This design allows only partial control of the engine, which can limit potential fuel savings. One of the main advantages of a hydraulic vehicle is the ability to capture a large percentage of the energy that is normally lost during vehicle braking. During city driving with frequent stops, about half of all energy delivered to the vehicle’s wheels is lost during braking, and the hydraulic design can capture and reuse a significant portion of this energy. In the second chapter, the features of modeling the power drive elements of a hydraulic hybrid vehicle are considered, namely: hydraulic accumulator, power pump/motor. Modeling is performed on the basis of mathematical equations that describe the parameters of the drive element and their influence on their performance. In addition, this section describes hydraulic losses in the system during energy transmission under different operating modes. To prevent overloading of the system, the parameters of the overpressure relief valve were determined. The third final section describes the results of modeling the movement of public transport under different driving cycles with the determination of the efficiency of energy use and storage. On the basis of the conducted research, it formulated conclusions and recommendations regarding the further use of hydraulic hybrid power plants with the appropriate structural scheme of construction, depending on the selected operating conditions of public transport. The purpose of the work is to investigate the feasibility of using hybrid hydraulic transmissions in utility vehicles. Object of research: technical and operational parameters of utility vehicles. Research subject: energy efficiency of a hydraulic hybrid power plant. Keywords: utility vehicle, hybrid power plant, driving cycles; operational parameters. 1. Karl-Erik Rydberg. Energy Efficient Hydraulics – System solutions for loss minimization. National Conference on Fluid Power, Linkoping University, Linkoping, Sweden, 16 - 17 March, 2015 2. Jean Van Rensselar. Power to spare: Hydraulic Hybrids. Tribology & lubrication technology. February 2012.