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This thesis has been performed at Öhlins Racing AB which is known world-wide for its high quality racing shock absorbers. Öhlins have been developing shock absorbers for more than 30 years and in addition to this they also develop a technology for semi-active suspension. Semi-active suspension technology makes it possible to achieve an intelligent and dynamic vehicle chassis control. Compared to standard passive suspensions, semiactive dampers allow improving vehicle cornering performance while still providing good comfort when cruising. This is achieved by a real time adjustment of the suspensions damping characteristics. Öhlins system for semi-active suspension is called CES (Continuously controlled Electronic Suspension). The systems consist of electronically controlled hydraulic valves for uniflow dampers. These valves are mounted on all four dampers of the vehicle and are controlled individually to provide the desired ride quality. The valves are configurable to suit many types of vehicles by changing internal parts. The first goal of this thesis project was to study the behaviour of the CES valve and uniflow damper. In order to achieve this a simulation model was created using Hopsan which is a 1-dimensional multi-domain modelling tool developed at the division of Fluid and Mechatronic Systems at Linköping University. The model considers mechanical forces from for example springs together with hydraulic forces. It was validated against static and dynamic measurements made in a flow bench and a dynamometer. The second goal was to use the simulation model as part of a tool that configures the CES valve according to a requirements specification. To achieve this goal a method of estimating the characteristics of the internal damper valves was developed. This estimation method, together with the simulation model, was used to choose the best valve configuration by using weighted least-squares. The result is presented in a Matlab-based graphical user interface.

In this study the feasibility of two mathematical models of the dynamics of a hydraulic bypass valve used on semi-active suspension systems for heavy vehicles is investigated. It is envisaged that similar models will eventually be incorporated into a full vehicle, three dimensional simulation study. The valve system contains an electro-hydraulic pilot valve circuit, a logic element, a damper and four check valves in a rectifier configuration. Models were compiled from first principles in the MATLAB environment and with the commercial fluid power simulation software, AMESim. The numerical methods used in the MATLAB model were found to be incapable of solving the stiff, nonlinear and discontinuous governing equations efficiently, while AMESim is very capable of handling detailed and complex fluid power models. Experimental work was conducted to determine certain steady state model parameters and to obtain dynamic performance data with which to validate model integrity. Several external factors influenced the valve behaviour during experiments making data extraction challenging. Simple first order assumptions accounting for the external influences on the valve therefore had to be included in the models. If this is done the basic dynamic behaviour of the valve system is matched well by the models. In general, the number of unknown parameters associated with fluid power systems accounted for the largest portion of the error between the simulated and measured response. The model as developed proved the possibility of creating highly accurate models but also indicated the amount of effort needed for their compilation. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

Hybrid powertrains that use compressed air to help power a vehicle could dramatically improve the fuel economy, particularly in cities and urban areas where the traffic conditions involve a lot of starts and stops. In such conditions, a large amount of fuel is needed to accelerate the vehicle, and much of this is converted to heat in brake friction during decelerations. Capturing, storing and reusing this braking energy to produce additional power can therefore improve fuel efficiency. In this study, three approaches towards air hybrid powertrains are proposed and analyzed. In the first approach, an energy recovery valve or two shut-off valves connected to a convenient access hole on the engine cylinder is proposed to enable the cylinder to operate as a regenerative compressor and/or expander when required. In the second approach, one of the exhaust valves in an engine equipped with a Fully Variable Valve Actuation (FVVA) system is pneumatically or hydraulically operated as a dedicated gas transfer valve connected to an air reservoir. The third approach combines the advantages of the conventional valvetrain’s simplicity with emerging production technologies. In order to achieve this, two well established technologies are used in addition to valve deactivation; Variable Valve Timing (VVT) and/or Cam Profile Switching (CPS). Provided that a conventional, camshaft-operated variable valvetrain is used, the need of adopting fully variable valve actuation is eliminated and thus only minor modifications to the engine architecture are required. The aforementioned concepts are described in details. Some basic principles of their operation are also discussed in order to provide a better understanding on how fuel economy is achieved by means of engine hybridization and regenerative braking. Both experimental and computational results are presented and compared. Finally, a vehicle and driveline model, which simulates the operation of a typical passenger vehicle in urban driving conditions and predicts the efficiency of the energy regeneration, has been set up and used to study the effects of the application of each air hybrid concept on the vehicle’s energy usage throughout the New European Driving Cycle (NEDC) and the 10-15 driving cycle. The results have shown that each concept involves the optimization of valve timing for the best regenerative energy recovery and its subsequent usage. For the modelled vehicle, it has been shown that any of the three concept engines is capable of providing more braking power than needed during every deceleration and braking process, especially throughout the urban driving part of each cycle. The recovered braking energy in the form of compressed air has proved to be always sufficient to start the engine, if stop-and-start engine operation strategy is to be adopted.

Dentre os fatores que afetam a uniformidade de aplicação de água, cita-se a variação de pressão no sistema, causada principalmente pela topografia do terreno e pela inexistência ou operação inadequada de reguladores de pressão. Nesse sentido, têm-se empregado válvulas reguladoras de pressão nos projetos de irrigação com variações topográficas. Contudo, a pressão de saída na válvula nem sempre será correspondente a apresentada no catálogo do fabricante. Com o avanço da eletrônica e a modernização da agricultura irrigada, justifica-se a busca para o aperfeiçoamento das técnicas de controle de pressão em sistemas de irrigação, visando à redução das perdas e o atendimento dos preceitos da irrigação sustentável. Portanto, a automação de reguladores de pressão deve torná-lo capaz de manter constante a pressão de saída, independente da pressão de entrada, além de possibilitar estabelecer a pressão de saída de acordo com as necessidades específicas de cada sistema de irrigação. De acordo com o que foi exposto, este trabalho teve como objetivo o desenvolvimento de um regulador de pressão microprocessado. O sistema de regulação desenvolvido foi composto por uma válvula hidráulica, um transdutor de pressão, duas válvulas solenóides, um aspersor e um circuito microprocessado. Baseado na leitura do transdutor de pressão de saída, o controlador eletrônico acionava as válvulas solenóides para pressurizar ou para aliviar o diafragma da válvula hidráulica. O tempo de abertura da válvula solenóide era função da pressão instantânea na tubulação. Avaliou-se o equipamento atuando até uma diferença entre pressão de entrada e de saída de 250 kPa. As pressões de entrada foram alteradas em intervalos de 49,03 kPa a cada 60 segundos, sendo estas avaliadas em um primeiro momento de forma crescente, e posteriormente de forma decrescente. As pressões de ajuste avaliadas foram de 98,06 kPa, 196,13 kPa, 294,19 kPa e 392,26 kPa. A faixa de vazão avaliada foi de 0,75 m3 h-1 a 3,74 m3 h-1, tendo o respectivo intervalo de velocidade de 0,42 m s-1 a 2,12 m s-1. Os resultados mostraram um tempo de ajuste entre 10 s e 20 s nos ensaios com pressão de entrada crescente e de 15 s e 30 s nos ensaios com pressão de entrada decrescente. Ao se avaliar a atuação do regulador eletrônico operando em toda a faixa de vazão estudada, verifica-se que este foi capaz de manter a pressão ajustada dentro dos limites aceitáveis ao valor estabelecido no dispositivo eletrônico, enquadrando-se, em um contexto geral, como controlador com nível de exatidão A (± 10% de desvio). Dessa forma, pode-se concluir que o controlador, operando nas condições definidas acima, apresentou um bom desempenho ao regular à pressão de saída. / The pressure variation is an important factor that affects the uniformity of water application in irrigation systems. This variation is caused by topography, the lack or improper operation of pressure regulators. Pressure regulating valves have been used in irrigation projects where there are problems of uneven topography. However, the output pressure on the valve will not be always corresponding to the manufacturer\'s catalog. Researches on techniques improvement for pressure controlling in irrigation systems are necessary to reduce losses in accordance with sustainable irrigation. The automation of pressure regulators must assure a constant outlet pressure independent of input pressure, and flexibility to set output pressures according to different conditions. Based on the previous content, the aim of this study was to develop a microprocessed pressure regulator. The developed system has a hydraulic valve, a pressure transducer, two solenoid valves, a sprinkler, and a microprocessed circuit. Based on data gathered from pressure transducer, the electronic controller triggered solenoid valves for pressurizing or relieving the hydraulic valve diaphragm. The opening time of the solenoid valve was a function of the instantaneous pressure in the pipe. We evaluated the operating equipment in a difference up to 250 kPa between input and output pressure. The inlet pressures were tested at intervals of 49.03 kPa every 60 seconds. We performed tests increasing and decreasing inlet pressure. The desired and evaluated output pressures were 98.06, 196.13, 294.19, and 392.26 kPa. The flow rate evaluated range was from 0.75 m3 h-1 to 3.74 m3 h-1, which the respective speed range was from 0.42 m s-1 to 2.12 m s-1. The results presented a required adjustment time between 10 to 20 seconds in tests with increasing inlet pressure, and from 15 to 30 seconds in tests with inlet pressure decreasing. The pressure regulator was able to maintain the preset output pressure within desired limits, when evaluating the performance of the electronic regulator operating in the flow range specified. Considering the results, the electronic developed device can be considered a controller that belongs in accuracy level A (± 10% deviation). Thus, we conclude that the controller was successful on controlling the output pressure, when operating under the conditions defined above.

"On-off control of hydraulic circuits enables significant improvements in efficiency compared with throttling valve control. A key enabling technology to on-off control is an efficient high speed on-off valve. This project aims to design an on-off hydraulic valve that minimizes input power requirements and increases operating frequency over existing technology by utilizing a continuously rotating valve design. This is accomplished through use of spinning port discs which chop the flow into pulses, with the relative phase between these discs determining the pulse duration. A mathematical model for determining system efficiency is developed with a focus on the throttling, leakage, compressibility, and viscous friction power losses of the valve. Parameters affecting these losses were optimized to produce the most efficient design under the chosen disc-style architecture. Using these optimum parameter values, a first generation prototype valve was developed and experimental data collected. The experimental valve matched predicted output pressure and flows well, but suffered from larger than expected torque requirements and leakage, resulting in a maximum efficiency of 38% at 1.0 duty ratio. Also, due to motor limitations, the valve was only able to achieve a 64Hz switching frequency versus the designed 100Hz frequency. Future design iterations will need to focus on controlling leakage, hydrodynamically balancing the spinning port disc axially to reduce torque requirements, developing a computational fluid dynamics model to gain further insight into the workings of the valve, and creating a control methodology for single and multiple high speed valves."

Dentre os fatores que afetam a uniformidade de aplicação de água, cita-se a variação de pressão no sistema, causada principalmente pela topografia do terreno e pela inexistência ou operação inadequada de reguladores de pressão. Nesse sentido, têm-se empregado válvulas reguladoras de pressão nos projetos de irrigação com variações topográficas. Contudo, a pressão de saída na válvula nem sempre será correspondente a apresentada no catálogo do fabricante. Com o avanço da eletrônica e a modernização da agricultura irrigada, justifica-se a busca para o aperfeiçoamento das técnicas de controle de pressão em sistemas de irrigação, visando à redução das perdas e o atendimento dos preceitos da irrigação sustentável. Portanto, a automação de reguladores de pressão deve torná-lo capaz de manter constante a pressão de saída, independente da pressão de entrada, além de possibilitar estabelecer a pressão de saída de acordo com as necessidades específicas de cada sistema de irrigação. De acordo com o que foi exposto, este trabalho teve como objetivo o desenvolvimento de um regulador de pressão microprocessado. O sistema de regulação desenvolvido foi composto por uma válvula hidráulica, um transdutor de pressão, duas válvulas solenóides, um aspersor e um circuito microprocessado. Baseado na leitura do transdutor de pressão de saída, o controlador eletrônico acionava as válvulas solenóides para pressurizar ou para aliviar o diafragma da válvula hidráulica. O tempo de abertura da válvula solenóide era função da pressão instantânea na tubulação. Avaliou-se o equipamento atuando até uma diferença entre pressão de entrada e de saída de 250 kPa. As pressões de entrada foram alteradas em intervalos de 49,03 kPa a cada 60 segundos, sendo estas avaliadas em um primeiro momento de forma crescente, e posteriormente de forma decrescente. As pressões de ajuste avaliadas foram de 98,06 kPa, 196,13 kPa, 294,19 kPa e 392,26 kPa. A faixa de vazão avaliada foi de 0,75 m3 h-1 a 3,74 m3 h-1, tendo o respectivo intervalo de velocidade de 0,42 m s-1 a 2,12 m s-1. Os resultados mostraram um tempo de ajuste entre 10 s e 20 s nos ensaios com pressão de entrada crescente e de 15 s e 30 s nos ensaios com pressão de entrada decrescente. Ao se avaliar a atuação do regulador eletrônico operando em toda a faixa de vazão estudada, verifica-se que este foi capaz de manter a pressão ajustada dentro dos limites aceitáveis ao valor estabelecido no dispositivo eletrônico, enquadrando-se, em um contexto geral, como controlador com nível de exatidão A (± 10% de desvio). Dessa forma, pode-se concluir que o controlador, operando nas condições definidas acima, apresentou um bom desempenho ao regular à pressão de saída. / The pressure variation is an important factor that affects the uniformity of water application in irrigation systems. This variation is caused by topography, the lack or improper operation of pressure regulators. Pressure regulating valves have been used in irrigation projects where there are problems of uneven topography. However, the output pressure on the valve will not be always corresponding to the manufacturer\'s catalog. Researches on techniques improvement for pressure controlling in irrigation systems are necessary to reduce losses in accordance with sustainable irrigation. The automation of pressure regulators must assure a constant outlet pressure independent of input pressure, and flexibility to set output pressures according to different conditions. Based on the previous content, the aim of this study was to develop a microprocessed pressure regulator. The developed system has a hydraulic valve, a pressure transducer, two solenoid valves, a sprinkler, and a microprocessed circuit. Based on data gathered from pressure transducer, the electronic controller triggered solenoid valves for pressurizing or relieving the hydraulic valve diaphragm. The opening time of the solenoid valve was a function of the instantaneous pressure in the pipe. We evaluated the operating equipment in a difference up to 250 kPa between input and output pressure. The inlet pressures were tested at intervals of 49.03 kPa every 60 seconds. We performed tests increasing and decreasing inlet pressure. The desired and evaluated output pressures were 98.06, 196.13, 294.19, and 392.26 kPa. The flow rate evaluated range was from 0.75 m3 h-1 to 3.74 m3 h-1, which the respective speed range was from 0.42 m s-1 to 2.12 m s-1. The results presented a required adjustment time between 10 to 20 seconds in tests with increasing inlet pressure, and from 15 to 30 seconds in tests with inlet pressure decreasing. The pressure regulator was able to maintain the preset output pressure within desired limits, when evaluating the performance of the electronic regulator operating in the flow range specified. Considering the results, the electronic developed device can be considered a controller that belongs in accuracy level A (± 10% deviation). Thus, we conclude that the controller was successful on controlling the output pressure, when operating under the conditions defined above.

The aim of the paper was to proposed new manufacturing technology. In the beginning, the diploma thesis deals with the technological aspects of manufacturing hydraulic valve. Subsequently is described the usage of manufacturing technology. The existing production process is analysed in detail. Better efficiency was achieved by using hard turning instead grinding technology. Economic evaluation is described in the end of thesis, where is efficiency of hard turning technology supported by calculations.

This thesis is solving issues concerning deburring of hydraulic valve blocks with industrial robot. Thesis is focused on deburring of inside space of hydraulic valve blocks, although deburring of outer edges is marginally mentioned due to determining of approximate deburring time of all edges on the valve block. Search of deburring methods and tools suitable for deburring of inside and outside edges is made on the basis of valve blocks´ analysis. Paths of tools chosen for deburring of valve block B1 are programmed in CAM program. CAD program ProEngineer is used to create simplified model of robotic workplace and its layout. According to customer´s requirements, deburring method, which allows creating universal robotic workplace for deburring of hydraulic valve blocks, was chosen. Approximate deburring time of all edges on B1 block was set on the basis of tools´ paths and these were checked in the simplified model of robotic workplace in PowerMill Robot Interface. Deburring procedure, estimating of approximate deburring time of B1 block and layout of robotic workplace are main results of this thesis.

The thesis deals with design and implementation of proportional hydraulic valve, which will be integrated to hydraulic system of small hydro in Rájec - Jestřebí. This valve will be used to control one of the wicket gates of double Francis turbine. The thesis is processed for the company Mavel a.s., which is the owner of SH. The goal of this thesis is to create control of the valve according to the client's requirements, its implementation to the control system and commissioning.