Limitations of various accumulators in hybrid hydraulic excavator are analyzed.A program using capacitor as the accumulator based on constant work-point control is put forward.A simulating experimental system of hybri...Limitations of various accumulators in hybrid hydraulic excavator are analyzed.A program using capacitor as the accumulator based on constant work-point control is put forward.A simulating experimental system of hybrid construction machinery is established,and experimental study on constant work-point control for parallel hybrid system with capacitor accumulator is carried out using the pressure and flow rate derived from boom cylinder of hydraulic excavator in actual work as the simulating loads.A program of double work-point control is proposed and proved by further experiments.展开更多
Procedures of preparation of numerical analysis,consisting in a simulation of cooperation of three different media: steel,liquid and gas undergoes dynamic load were discussed.Modelling of the initial static load of th...Procedures of preparation of numerical analysis,consisting in a simulation of cooperation of three different media: steel,liquid and gas undergoes dynamic load were discussed.Modelling of the initial static load of the mechanical system was presented.By using the MSC.Software products the following exemplary computer simulations were made: dynamic load impact on the hydraulic leg as well as effectiveness of the hydraulic leg protection against overload with help of gas accumulator.展开更多
It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to...It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to induction motor to drive cylinder loads. During upstroke operation, the variable pump/motor （P/M） driven by both electric motor and the second （P/M） works as hydraulic pump and output flow to the cylinders which drive the load. During load deceleration, the cylinders work as pump while the operation of the two secondary units are reversed, the variable （P/M） works as a motor generating a torque with the electric motor to drive the other （P/M） which transforms mechanical energy to hydraulic energy that is saved in the accumulator. When the energy storage capacity of the accumulator is attained as the operation continues, energy storage to the accumulator is thermostatically stopped while the induction motor begins to work as a generator and generates electricity that is stored in the power distribution unit. Simulations were performed using a limited PT2 Block, i.e. 2nd-order transfer function with limitation of slope and signal output to determine suitable velocity of the cylinder which will match high performance and system stability. A mathematical model suited to the simulation of the hydraulic accumulator both in an open-or close-loop system is presented. The quest for improvement of lower energy capacity storage, saving and re-utilization of the conventional accumulator resulting in the short cycle time usage of hydraulic accumulators both in domestic and industrial purposes necessitates this research. The outcome of the research appears to be very efficient for generating fluctuation free electricity, power quality and reliability, energy saving/reutilization and system noise reduction.展开更多
Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and disc...Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.展开更多
According to the composition and the principle of the liquid-electric energy-sensing damper, the corresponding hydraulic regenerative model is designed. In this paper, an advanced type of shock absorber combined with ...According to the composition and the principle of the liquid-electric energy-sensing damper, the corresponding hydraulic regenerative model is designed. In this paper, an advanced type of shock absorber combined with the mechanical and electromagnetic hydraulic structure has been proposed that recycles the energy dissipated by shock absorber in the driving process. In addition, the damping characteristics of the conventional mechanical vehicle and the advanced hydraulic regenerative mechanical vehicle have?been analyzed by using AMESim simulation. The regenerative suspension is reformed from the traditional hydraulic and pneumatic suspension. The suspension absorbs kinetic energy converts it into hydraulic potential and pneumatic power to be stored in the accumulator. The kinetic energy is then converted into electricity instead of heat by using the hydraulic suspension and Power-Generating Shock Absorber (PGSA). The AMESim simulation results have efficiently verified the displacement characteristics curves and flow rate of hydraulic fluid in the body. Finally the conversion of energy produced by advanced hydraulic regenerative mechanical vehicle transferred into electrical energy. The designed hydraulic shock absorber allows a significant fuel saving of 1.5% to 4% depending on the vehicle and driving conditions.展开更多
To improve the energy efficiency of a hydraulic boom, a new energy-saving system adopting a hydraulic accumulator is proposed. First, the principle of the system is presented. Then, the dynamic simulation is intro- du...To improve the energy efficiency of a hydraulic boom, a new energy-saving system adopting a hydraulic accumulator is proposed. First, the principle of the system is presented. Then, the dynamic simulation is intro- duced. Finally, the conclusions are given based on the analysis of simulation data. In Summary, the innovative energy-saving system combines flow regeneration and potential energy recovery, runs steadily and comfortably, saves energy remarkably and has good potential for improving energy utilization of a hydraulic excavator.展开更多
文摘Limitations of various accumulators in hybrid hydraulic excavator are analyzed.A program using capacitor as the accumulator based on constant work-point control is put forward.A simulating experimental system of hybrid construction machinery is established,and experimental study on constant work-point control for parallel hybrid system with capacitor accumulator is carried out using the pressure and flow rate derived from boom cylinder of hydraulic excavator in actual work as the simulating loads.A program of double work-point control is proposed and proved by further experiments.
文摘Procedures of preparation of numerical analysis,consisting in a simulation of cooperation of three different media: steel,liquid and gas undergoes dynamic load were discussed.Modelling of the initial static load of the mechanical system was presented.By using the MSC.Software products the following exemplary computer simulations were made: dynamic load impact on the hydraulic leg as well as effectiveness of the hydraulic leg protection against overload with help of gas accumulator.
文摘It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to induction motor to drive cylinder loads. During upstroke operation, the variable pump/motor （P/M） driven by both electric motor and the second （P/M） works as hydraulic pump and output flow to the cylinders which drive the load. During load deceleration, the cylinders work as pump while the operation of the two secondary units are reversed, the variable （P/M） works as a motor generating a torque with the electric motor to drive the other （P/M） which transforms mechanical energy to hydraulic energy that is saved in the accumulator. When the energy storage capacity of the accumulator is attained as the operation continues, energy storage to the accumulator is thermostatically stopped while the induction motor begins to work as a generator and generates electricity that is stored in the power distribution unit. Simulations were performed using a limited PT2 Block, i.e. 2nd-order transfer function with limitation of slope and signal output to determine suitable velocity of the cylinder which will match high performance and system stability. A mathematical model suited to the simulation of the hydraulic accumulator both in an open-or close-loop system is presented. The quest for improvement of lower energy capacity storage, saving and re-utilization of the conventional accumulator resulting in the short cycle time usage of hydraulic accumulators both in domestic and industrial purposes necessitates this research. The outcome of the research appears to be very efficient for generating fluctuation free electricity, power quality and reliability, energy saving/reutilization and system noise reduction.
文摘Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.
文摘According to the composition and the principle of the liquid-electric energy-sensing damper, the corresponding hydraulic regenerative model is designed. In this paper, an advanced type of shock absorber combined with the mechanical and electromagnetic hydraulic structure has been proposed that recycles the energy dissipated by shock absorber in the driving process. In addition, the damping characteristics of the conventional mechanical vehicle and the advanced hydraulic regenerative mechanical vehicle have?been analyzed by using AMESim simulation. The regenerative suspension is reformed from the traditional hydraulic and pneumatic suspension. The suspension absorbs kinetic energy converts it into hydraulic potential and pneumatic power to be stored in the accumulator. The kinetic energy is then converted into electricity instead of heat by using the hydraulic suspension and Power-Generating Shock Absorber (PGSA). The AMESim simulation results have efficiently verified the displacement characteristics curves and flow rate of hydraulic fluid in the body. Finally the conversion of energy produced by advanced hydraulic regenerative mechanical vehicle transferred into electrical energy. The designed hydraulic shock absorber allows a significant fuel saving of 1.5% to 4% depending on the vehicle and driving conditions.
文摘To improve the energy efficiency of a hydraulic boom, a new energy-saving system adopting a hydraulic accumulator is proposed. First, the principle of the system is presented. Then, the dynamic simulation is intro- duced. Finally, the conclusions are given based on the analysis of simulation data. In Summary, the innovative energy-saving system combines flow regeneration and potential energy recovery, runs steadily and comfortably, saves energy remarkably and has good potential for improving energy utilization of a hydraulic excavator.
