Conventional Hydraulic Systems Research Articles

Development of Energy Saving Power Steering

This paper shows the energy saving power steering system, which was named as KEEPS (Kayaba Electronic Controlled Energy Saving Power Steering). In a conventional hydraulic power steering system, the hydraulic pump always supplies enough quantity of oil to the hydraulic circuit. This extra oil flow increases driving torque of the pump, thus the hydraulic power steering system wastes energy. On the other hand, KEEPS can control oil flow electrically in accordance with the condition of a vehicle. In the measurement test for energy consumption of the power steering system with the actual vehicle on test courses, KEEPS got 48% less at city mode, 41% less at highway mode and 39% less at country mode compared with the conventional hydraulic steering system.

Switched reluctance motor based electromechanical brake-by-wire system

This article presents an overview of electronic braking systems using SR (Switched Reluctance) machines. The advantages presented by this structure when compared to the conventional hydraulic systems are discussed. A justification for the choice of the SRM as a valid candidate is provided, with a detailed analysis of its control structure and performance. Experimental results obtained using a digital signal processor are also presented.

The concurrent implementation of high velocity control performance and high energy efficiency for hydraulic injection moulding machines

A high servo control response and a high energy efficiency, which are difficult to achieve simultaneously, are requested in hydraulic servo systems of current hydraulic injection moulding machines. This investigation develops new solutions to concurrently implement energy-saving control and velocity control for simultaneously realising high velocity control response and high energy efficiency for injection moulding machines. Two different hydraulic pump systems, including a variable displacement pump and a variable rotational speed pump, are developed and in each one of them two different energy-saving control concepts, such as load-sensing control and constant supply pressure control, are implemented. Thus, for verifying the feasibility of the integrated control systems and comparing the energy-saving effects, velocity control of the hydraulic cylinder can be integrated with four different energy-saving control systems (ESCSs) and also the conventional hydraulic system without energy-saving control. A fuzzy sliding mode control that can simplify the complex fuzzy rule bases is used for solving the complex two-input two-output systems. The experimental results show the excellent performance of the integrated concurrent control systems.

Parallel Control of Velocity Control and Energy-Saving Control for a Hydraulic Valve-Controlled Cylinder System Using Self-Organizing Fuzzy Sliding Mode Control.

Conventional hydraulic valve-controlled systems that incorporate positive displacement pumps and relief valves have a problem of low energy efficiency. The objective of the research is to implement parallel control of energy-saving control in an electro-hydraulic load-sensing system and velocity control in a hydraulic valve-controlled cylinder system to achieve both high velocity control accuracy and low input power simultaneously. The overall control system is a two-input two-output system. For that, the control strategy of self-organizing fuzzy sliding mode control (SOFSMC) is developed in this study to reduce the fuzzy rule number and to self-organize on-line the fuzzy rules. To compare the energy-saving performance, the velocity control is implemented under three different energy-saving control systems, such as load-sensing control system, constant supply pressure control system and conventional hydraulic system. The parallel control of the velocity control and energy-saving control by the SOFSMC is implemented experimentally.

LINEAR ANALYSIS OF A CONVENTIONAL POWER STEERING SYSTEM FOR PASSENGER CARS

This paper deals with linear analysis of a conventional hydraulic power assisted steering system for passenger cars. The reason for this study is to be able to transfer the steering feel information transmitted to the driver, as well as, the frequency dependency of the assist characteristic of the system to other types of steering systems. Such systems could be electric power assisted steering (EPAS) systems, as they have lately been introduced on smaller passenger cars. In this paper, several relevant transfer functions of the conventional power steering system have been derived and the underlying control structure of conventional hydraulic power steering systems are discussed.

Design of a new high-performance electrohydraulic actuator

This paper describes the design and prototyping of a new high-performance actuation system that combines the benefits of conventional hydraulic systems and direct-drive electrical actuators, namely high torque/mass ratio and modularity. It is referred to as the electrohydraulic actuator (EHA) and results from the fusion of the above-mentioned technologies. The EHA is a unique device with its own characteristics and requires hydraulic components that are specifically tailored to its needs and requirements. Based on a mathematical model of the EHA, the requirements for its components are determined. These requirements are used as a basis for component selection, component modification, and design of a customized new symmetrical linear actuator. The analysis of the EHA presented is supported by experimental data and explains the extremely high level of performance attained by a prototype of the EHA.

CHARACTERISTICS OF WATER HYDRAULIC SERVO SYSTEM

Recently, the demand for using pure tap water as a pressure medium in hydraulic applications has increased due to its availability, Its low cost and its high safety levels against pollution and fire hazard. This is a report on the result examining the Influence that was exerted by the characteristics of the water on the performance of the water hydraulic servo system by experiments and simulations also comparing with the conventional oil hydraulic servo system. The comparison is based on the position control of a cylinder using PI controller by changing the temperature of the pressure medium.

Micro‐actuators: not so small any more

Increasing demand is being voiced for actuators whose range of movement lies somewhere between the many centimetres of conventional pneumatic and hydraulic systems and the nano‐metre ranges of micromovers. Two recent international conferences held this June, in Germany, have demonstrated a convergence of interests in this direction; the research and development‐orientated “Actuator”, held traditionally every two years in Bremen, and Berlin’s annual industrially‐based “Coil Winding International”. The first deals mainly with new innovations, the latter tends to be more concerned with present‐day applications.

Interaction of Clethodim with Pyrithiobac and Bromoxynil Applied in Low Volume

Greenhouse and field studies were conducted to determine the interaction of clethodim sprayed in low volume with pyrithiobac or bromoxynil and to determine the influence of these mixtures on large crabgrass control. A low-volume, air-assisted spraying system was calibrated to deliver 26 L/ha and was compared to a conventional hydraulic fan spraying system calibrated to deliver 140 L/ha. Greenhouse data indicated that carrier volume had no effect on large crabgrass control with clethodim. The addition of pyrithiobac to clethodim in mixture was antagonistic compared to control with clethodim applied alone. The addition of bromoxynil to clethodim in mixture was synergistic. Field studies showed similar results.

Efficacy of Pyrithiobac and Bromoxynil Applied with Low-Volume Spray Systems

Field experiments were conducted in 1994 and 1995 to determine if the sodium salt of pyrithiobac or bromoxynil applied in a low-volume, air-assist spray system controlled entireleaf morningglory, pitted morningglory, and smallflower morningglory as well as treatments applied with a conventional hydraulic fan spraying system, and to determine if herbicide rates could be reduced when using the low-volume spraying system. Pyrithiobac at 0.035 and 0.071 kg ai/ha and bromoxynil at 0.56 and 1.12 kg ai/ha were applied alone and in combination with DSMA at 1.7 kg ai/ha or MSMA at 1.7 kg ai/ha. Spraying systems were calibrated to deliver 26 L/ha and 140 L/ha for the low-volume and conventional systems, respectively. No significant differences in control were noted between low-volume and conventional spray systems when herbicides were applied at the suggested use rates of 0.071 and 1.12 kg ai/ha for pyrithiobac and bromoxynil, respectively. Morningglory control was reduced when pyrithiobac and bromoxynil were applied at one-half the suggested use rate regardless of the spraying systems. Bromoxynil alone generally controlled pitted and entireleaf morningglory better than pyrithiobac alone regardless of rate and application method. However, pyrithiobac generally provided better control of smallflower morningglory than bromoxynil. Adding MSMA or DSMA to bromoxynil and pyrithiobac increased control of both weed species.

Development of Water Hydraulic Servo Control System Considering Water Characteristics.

The oil hydraulic servo control system has a long history of application to various machines. However, a cleaner hydraulic fluid is necessary as we are faced with problems of fire or contamination due to oil leakage. We succeeded in improving the performance of a water hydraulic servo control syrstem over that of the oil hydraulic servo control system. Our water hydraulic servo control system is based on the analysis of the advantages of the physical properties of water for servo control. Furthermore, we can fabricate a simple water servo control system consisting of least components which can cover a wide dynamic performance range and can guarantee the same applications fields as the oil hydraulic servo control systems. Important components are the wide-dynamic-range water hydraulic pump system and the high-response, wide-dynamic-range water servo valve. The performance and durability of the system and components were tested and verified. As a result, the water hydraulic servo control systems are found to be the same as or superior to the oil hydraulic servo control system. Applying the advantages of the properties of water to a design, we can achieve better performance and lower cost with the water hydraulic servo control system than the conventional oil hydraulic servro control systems.

Effects of Ultra-low Volume Application on Herbicide Efficacy Using Oil Diluents as Carriers

The efficacy of postemergence herbicide applications was evaluated in the greenhouse and the field in 1993 and 1994, using variables of carrier volume and diluent type. Ultra-low volume (ULV) applications of herbicides using an air-assisted sprayer calibrated at a volume of 9.4 L/ha were compared to 94 and 187 L/ha applications with a conventional hydraulic system. In greenhouse studies, reduced rates of sethoxydim, clethodim, fluazifop-P, and quizalofop were used to compare the effects of carrier types and volumes on their efficacy to yellow foxtail. All herbicides applied in oil diluents at 9.4 L/ha, with the exception of fluazifop-P and quizalofop applied in soybean oil, provided better yellow foxtail control than when applied in water at 94 and 187 L/ha. Sethoxydim and clethodim applied at 25 and 16% of the recommended rate, respectively, provided over 90% control in both petroleum oil and methylated seed oil. Reduced rates of glyphosate in petroleum oil or soybean oil were more effective at reducing bermudagrass growth than in water or methylated seed oil. Activity of glyphosate in methylated seed oil was no more effective than in water. Field experiments were conducted to study the efficacy of ULV applications of sethoxydim, clethodim, fluazifop-P, imazethapyr, and bentazon. Rates of the postemergence grass herbicides could be reduced by applying them at ULV in oil diluents while maintaining annual grass control equal to that achieved with higher herbicide rates in larger volumes of water. Control of annual grasses and annual broadleaf weeds with bentazon and imazethapyr applied at ULV were inconsistent and did not provide acceptable weed control. This may be partially due to the poor suspension of these herbicides in oil carriers.

A Suboptimal Controller Design Method for the Energy Efficiency of a Load-Sensing Hydraulic Servo System

The dynamic characteristics of a load-sensing hydraulic servo system are complex and highly nonlinear and, furthermore, the stability is critically deteriorated compared with that of the conventional hydraulic servo systems. Another property of the systems is that the setting value of the pump pressure-compensator considerably affects energy efficiency as well as control performance of the system. These features significantly add complexity to the controller design of the load-sensing systems. To guarantee satisfactory control performance and energy efficiency of the system an effective controller design method, therefore, needs to be developed. This paper considers a suboptimal PID control for the velocity control problem of a loadsensing hydraulic servo system. To show the effectiveness of the controller a series of simulations and experiments were performed. Both results show that the proposed suboptimal controller can produce satisfactory response characteristics and yield an effective trade-off between control performance and energy efficiency of the system.

Electromechanical Actuation Technology for the All-Electric Aircraft

Electromechanical actuation is a critical element that must be developed and verified to make the all-electric aircraft a viable concept. For several years the Flight Control Division of the Air Force Wright Aeronautical Laboratories has sponsored activities to demonstrate the credibility of electromechanical actuation systems (EMAS) for primary flight control actuation functions. The foundation for these EMAS activities and several electromechanical actuation development programs are described here. One involves the design, fabrication, and laboratory test of a rotary, hingeline electromechanical actuator. Another involves the development and flight test demonstration of a linear electromechanical actuator for controlling an aileron of a C-141 aircraft. A third involves the design and development of a linear electromechanical actuator for missiles having severe performance, temperature, and volumetric requirements. In addition, a brief summary of the results from two aircraft actuation trade studies compare the baseline (conventional) hydraulic flight control system with an all-electric airplane concept including quantitative comparisons of weight, reliability and maintainability, and life cycle costs.

Evaluation of an Electrostatic Spray Application System for Control of Insect Pests in Cotton

The efficacy of an electrostatic spray system was compared to a conventional hydraulic boom system for the control of insect pests in cotton. Two years of trials indicated that comparable levels of insect control and resulting cotton yields could be obtained using 1/2 rate of AI through the electrostatic system, compared to a full rate through the conventional system. The 3rd year’s results indicated that efficacy of electrostatic application may be reduced when malfunctions of machinery prevent the induction nozzles from delivering the optimum charge level to the spray cloud. Even when not properly calibrated, full rates applied electro statically performed as well as conventional application of full rates of pesticide.

Comparison of a controlled droplet application and hydraulic nozzle spray systems for application of fungicide to controlPithomyces chartarumand reduce facial eczema in livestock

Abstract A conventional hydraulic nozzle spray system and a controlled droplet application spray boom were used to apply benomyl to pasture for the control of Pithomyces chartarum, the causative organism of facial eczema. The controlled droplet application system reduced Pithomyces chartarum spore levels to those obtained by conventional means. Both application systems reduced to an equivalent level the liver damage typical of facial eczema in lambs.

A High-Performance ac Position Servo Using a dc Motor

This paper describes the construction of an electromechanical servo system designed to compete at high power levels and in industrial environments, with conventional hydraulic systems.