Low energy efficiency and high installed cost are the two main problems that prevent water hydrau... more Low energy efficiency and high installed cost are the two main problems that prevent water hydraulics to be popular in application. This research introduces two novel systems: wa-ter hydraulic fluid switching transmission (FST) and pump mo-tor transmission (PMT) that only use cheap ON/OFF valves for lessening the initial cost and reducing the energy consumption; beside, this paper also introduces a conventional servo motor system (SMS) for comparison. Moreover, both FST and PMT systems can recover the kinetic energy of a flywheel in a decel-eration process and store it into an accumulator for using in the next working cycle. The experimental results show that the FST system only need from 33.2 to 47.3 % of total energy consumption of the SMS to complete a full cycle and even much reducing in PMT system with the reduction from 76.0 to 86.0%. A method to
2015 IEEE International Symposium on Systems Engineering (ISSE), 2015
Recently, the application of water hydraulics has been increasing in many fields as shown in [1],... more Recently, the application of water hydraulics has been increasing in many fields as shown in [1], [2], [3]. However, water hydraulic systems using servo/proportional valves have inherent disadvantages such as low energy efficiency and high installation cost, which prevent water hydraulics from applying widely. Water hydraulic variable displacement pump does not exist in the market and therefore supply pressure of water hydraulic systems cannot be adjusted by using load sensing, this is a very important reason for low energy efficiency of water hydraulic systems. This study aims to introduce a novel digital load sensing (DLS) that uses a set of On/Off valves assembled to a servo system for reducing much surplus pressure thanks to the supply pressure track a required pressure. By using of fast On/Off valves, the supply pressure can be tracked the reference pressure quickly, this ensures that the energy consumption of the system is reduced much while the control performance of the load...
Recently, the application of water hydraulics has been paid attention because of its inherent mer... more Recently, the application of water hydraulics has been paid attention because of its inherent merits such as environmental friendliness, clean, high safety against fire hazard and easy availability. However, water hydraulic devices themselves have lower energy efficiency than in oil systems and this prevents from widening its application. The original method for reducing energy consumption and therefore raising the energy efficiency is to make the supply pressure to change depending on the demand. On the other hand, the variable supply pressure affects the control performance besides larger friction force and considerable leakage flow. Thus, the requirement for reducing the effect of the variable parameters in water hydraulic systems becomes very important for highly precise application. In this paper, the simple adaptive control (SAC) algorithm applied to a water hydraulic servo motor system is introduced for compensating the effects of the fast changing of supply pressure that aff...
Beside various fluid power transmissions, a new water hydraulic Fluid Switching Transmission (FST... more Beside various fluid power transmissions, a new water hydraulic Fluid Switching Transmission (FST) has demonstrated outstanding advantages such as environmental friendliness, safety, running cost reduction, and lower energy loss for using only ON/OFF valves. Especially, this system has no servo or proportional valve; thus, lower power transmission loss can be expected. In this paper, two most important aspects of the FST system, velocity control and energy saving performances, will be presented. First, the error of the load rotational velocity is mainly influenced by property of ON/OFF valves, velocity transducer, and control logic. The research solved the problem – how to reduce the percentage error of velocity control. The experimental results showed that the error could be reduced to less than 3% for all given reference speeds equal or above 800 revolutions per minute (min-1). Second, the system regenerated the kinetic energy of the load by storing it into an accumulator during d...
This study aims to determine effective methods for improving the energy efficiency of a water hyd... more This study aims to determine effective methods for improving the energy efficiency of a water hydraulic Fluid Switching Transmission (FST). This paper introduces three methods to reduce energy consumption: lowering the velocity of the electric motor and stopping the motor during the working and deceleration phases, respectively (first method); restricting the working pressure within a certain range by using an unload valve (second method) or using the idling stop method (third method). Next these three methods are analyzed and compared. Experimental results show that by using the proposed methods, the energy and net energy consumption are greatly reduced. The greatest reductions are from 71.5 to 78.3% for energy consumption and from 65.1 to 66.2% for net energy consumption, corresponding to variations in the reference velocity from 600 to 1000 min-1. Additionally, the steady state errors in the proposed methods are slightly decreased in the working phase while the transient response...
Low energy efficiency and high installed cost are the two main problems that prevent water hydrau... more Low energy efficiency and high installed cost are the two main problems that prevent water hydraulics to be popular in application. This research introduces two novel systems: wa-ter hydraulic fluid switching transmission (FST) and pump mo-tor transmission (PMT) that only use cheap ON/OFF valves for lessening the initial cost and reducing the energy consumption; beside, this paper also introduces a conventional servo motor system (SMS) for comparison. Moreover, both FST and PMT systems can recover the kinetic energy of a flywheel in a decel-eration process and store it into an accumulator for using in the next working cycle. The experimental results show that the FST system only need from 33.2 to 47.3 % of total energy consumption of the SMS to complete a full cycle and even much reducing in PMT system with the reduction from 76.0 to 86.0%. A method to
2015 IEEE International Symposium on Systems Engineering (ISSE), 2015
Recently, the application of water hydraulics has been increasing in many fields as shown in [1],... more Recently, the application of water hydraulics has been increasing in many fields as shown in [1], [2], [3]. However, water hydraulic systems using servo/proportional valves have inherent disadvantages such as low energy efficiency and high installation cost, which prevent water hydraulics from applying widely. Water hydraulic variable displacement pump does not exist in the market and therefore supply pressure of water hydraulic systems cannot be adjusted by using load sensing, this is a very important reason for low energy efficiency of water hydraulic systems. This study aims to introduce a novel digital load sensing (DLS) that uses a set of On/Off valves assembled to a servo system for reducing much surplus pressure thanks to the supply pressure track a required pressure. By using of fast On/Off valves, the supply pressure can be tracked the reference pressure quickly, this ensures that the energy consumption of the system is reduced much while the control performance of the load...
Recently, the application of water hydraulics has been paid attention because of its inherent mer... more Recently, the application of water hydraulics has been paid attention because of its inherent merits such as environmental friendliness, clean, high safety against fire hazard and easy availability. However, water hydraulic devices themselves have lower energy efficiency than in oil systems and this prevents from widening its application. The original method for reducing energy consumption and therefore raising the energy efficiency is to make the supply pressure to change depending on the demand. On the other hand, the variable supply pressure affects the control performance besides larger friction force and considerable leakage flow. Thus, the requirement for reducing the effect of the variable parameters in water hydraulic systems becomes very important for highly precise application. In this paper, the simple adaptive control (SAC) algorithm applied to a water hydraulic servo motor system is introduced for compensating the effects of the fast changing of supply pressure that aff...
Beside various fluid power transmissions, a new water hydraulic Fluid Switching Transmission (FST... more Beside various fluid power transmissions, a new water hydraulic Fluid Switching Transmission (FST) has demonstrated outstanding advantages such as environmental friendliness, safety, running cost reduction, and lower energy loss for using only ON/OFF valves. Especially, this system has no servo or proportional valve; thus, lower power transmission loss can be expected. In this paper, two most important aspects of the FST system, velocity control and energy saving performances, will be presented. First, the error of the load rotational velocity is mainly influenced by property of ON/OFF valves, velocity transducer, and control logic. The research solved the problem – how to reduce the percentage error of velocity control. The experimental results showed that the error could be reduced to less than 3% for all given reference speeds equal or above 800 revolutions per minute (min-1). Second, the system regenerated the kinetic energy of the load by storing it into an accumulator during d...
This study aims to determine effective methods for improving the energy efficiency of a water hyd... more This study aims to determine effective methods for improving the energy efficiency of a water hydraulic Fluid Switching Transmission (FST). This paper introduces three methods to reduce energy consumption: lowering the velocity of the electric motor and stopping the motor during the working and deceleration phases, respectively (first method); restricting the working pressure within a certain range by using an unload valve (second method) or using the idling stop method (third method). Next these three methods are analyzed and compared. Experimental results show that by using the proposed methods, the energy and net energy consumption are greatly reduced. The greatest reductions are from 71.5 to 78.3% for energy consumption and from 65.1 to 66.2% for net energy consumption, corresponding to variations in the reference velocity from 600 to 1000 min-1. Additionally, the steady state errors in the proposed methods are slightly decreased in the working phase while the transient response...
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