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In this paper, the operating states of a wheel loader were studied for diagnostics purposes using a real time simulation model of an articulated-frame-steered wheel loader. Test drives were carried out to obtain measurement data, which were then analyzed. The measured time series data were analyzed to find the sequences of operating states using two different data sets, namely the variables of hydrostatic transmission and working hydraulics. A time series is defined as a collection of observations made sequentially in time. In our proposed method, the time series data were first segmented to find operating states. One or more segments build up an operating state. A state is defined as a combination of the patterns of the selected variables. The segments were then clustered and classified. The operating states were further analyzed using the quantization error method to detect anomalies.

Hydraulic systems are widely used in working actions of mobile machines. They offer good power to weight ratio, robustness and relatively good controllability. However, there has been growing interest on the energy efficiency of such machines during recent years. Load sensing proportional valve control is a typical solution for multi-actuator systems leaving a significant margin for improvement of energy efficiency. Digital hydraulic valve system enables independent metering and reduces losses significantly without a need of complete redesign of the hydraulic system of such machine. Digital hydraulic valve system consists of parallel connected on/off-valves and offers deterministic operation which is crucial for successful implementation of independent metering. Four different digital hydraulic valve control approaches are analyzed in the paper: four-edge-control, four-edge control with pressurized tank line, five-edge-control and six-edge-controlled three-chamber-cylinder.

The level of automation, including operator assisting functions, is becoming more sophisticated in heavy machinery. This involves using new types of sensors and embedded computers. However, considering the long life cycles of heavy machinery, the electronic control systems should be modular and flexible. A modular control system of an automated machine is often distributed over CAN and Ethernet. However, many interesting sensor and actuator types do not have these interfaces. In this paper, a generic microcontroller board with analogous and digital communication is presented. With this board, CAN communications can be added to many sensors. The board can also perform sensor-related data processing. The microcontroller board is tested in several applications. In an automated wheel loader, the board is used in control of the work hydraulics circuit that is based on digital hydraulics.

The Electro-Hydraulic Valve Actuation (EHVA) gives fully programmable variable lift and event duration of the gas exchange valves. Thus the controllability and performance of the gas exchange process in diesel engines can be improved within a range of various load conditions. The dynamic and steady state behavior of the electrohydraulic system can be tuned by selecting the suitable controller. The aim of this study is to compare different control strategies of an electro hydraulic valve actuation system of a middle speed diesel engine. The studied controllers are P- and State Feedback controller. The State Feedback controller is used with or without the velocity and acceleration feedforward loops. The research results are represented through simulations and experimental tests. The operation time range, lifts, and seating velocities etc are shown in the paper.

This paper presents an experimental study of the correlation between rail-to-injector connection pipe geometry (3 lengths and 3 diameters) and pressure oscillation characteristics (amplitudes, mean pressure drop, frequency, damping of the oscillation) and injected volume, respectively. The injection input parameters are based on a single injection with 5 pressure levels and 4 injection durations. Pressure recordings are available for the injector inlet, an adjacent injector port, and the rail. The study shows that the connection pipe geometry may have a considerable impact on the analyzed variables. Particularly interesting appears the unexpected bond between pipe diameter and oscillation frequency.

Electro-Hydraulic Valve Actuation (EHVA) is one of the most promising ways to improve the performance and reduce the emissions of the diesel engines. The EHVA gives fully variable lift and event duration of the gas exchange valves and thus the combustion process can be better controlled in different operation points such as idle and partial load situation. Also totally new kind of gas exchange processes are possible to achieve. This paper consists of alternative solutions of EHVA systems, the comparison of them by means of simulation and measurements, the empirical tests of EHVA system in a laboratory and finally conclusion and future research activities. The developed EHVA system fulfills the requirements very well. The lift of the gas exchange valve is fast enough, and the seating velocity is under control. The system is able to run with open and closed loop control.

Electronically controlled automatic hydraulic bucket stabilizer system is considered as an example case while researching how suitable a typical proportional mobile valve is for fast control applications. A verified simulation model, including hydraulics, mechanics, and electronics is used for developing the stabilizer system. The most suitable type and size for the spool of the valve is found out with help of the simulation model. The simulation model is also used for discovering system characteristics, and thereby improving control algorithms. Simulated results for different type of spools are introduced. Also, effects of the most critical characteristics of the valve are enclosed.

The goal of the paper is to study the properties of a teleoperated mobile machine by means of simulation model of the system and measurements. In this paper some parts of the prototype of the teleoperated machine and the verification results of simulation model of the mobile machine are introduced. The challenge in teleoperation is to have a smooth and accurate control of the machine, because the operator can not feel any force feedback. The machine is valve controlled and the influence of different types of valves is significant for the control of the machine. In this paper is studied via simulation model different kind of valve solutions such as different spool types and effect of pressure compensator among others. The goal in future is to have a totally autonomous mobile machine and it needs more research and development work. With simulation model of the machine it is possible to test new components and hydraulic solutions for power transmission of the mobile machine.

This paper investigates the source of pressure fluctuations in a common rail (CR) system for high speed diesel engines as a function of injection parameters and system design (pipe between rail and injector). The pressure values are recorded experimentally at the inlet of the injector. In addition, a simulation model has been developed. The parameters include: injection pressure (800 to 1500 bar) and duration (0.4 to 1 ms), and connection pipe length (180 to 500 mm) and diameter (2.2 to 3 mm). The model shows good agreement with the measurements. The study shows that all parameters have an effect on the pressure oscillation at the injector inlet.

One way to improve diesel engine performance and to reduce emissions is improving power density and combustion cycle efficiency. It can be done by increasing combustion pressure and engine speed drastically and also by improving the controllability of the engine. Besides of the fuel injection system the key element in improving controllability is the valvetrain. Extreme combustion pressure and engine speed set special requirements for valvetrain design. As the pressure and engine speed are increased the load on the valve actuation mechanism becomes higher because of the higher pressure acting on the valve plate and also the need for higher acceleration. High instantaneous power required due to high load makes electrohydraulic system a natural choice for actuation mechanism. An electrohydraulic camless valvetrain (IHAflex) for extreme value engine (EVE), developed by Institute of Hydraulics and Automation of Tampere University of Technology, uses neither cams, nor retainer springs.

This research work deals with common rail fuel injection system of a diesel engine. Fuel injection system tuning is important to provide similar conditions to each injections. This means that the timing of the fuel injection and control of the amount of the fuel during the injection have to be done accurately. The pressure oscillations might disturb the behaviour of the fuel injection event if the system is not properly designed or tuned. In this work the pressure oscillations and how to prevent them were studied. The study started with the modelling of the components of the Common Rail fuel injection system. The simulation results were verified to measured ones. After the fluid properties were also taken into account the correspondense were acceptable. The simulation model were used for studying the performance a Common Rail fuel injection system. This study deals also with the fluid properties in high pressure.