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
In order to regenerate electric power from the vibration excited by road unevenness,a novel energy- regenerative active suspension for vehicles was proposed with the description of its structure and its working princi...In order to regenerate electric power from the vibration excited by road unevenness,a novel energy- regenerative active suspension for vehicles was proposed with the description of its structure and its working principle with two modes switched in different operating conditions.Then,the novel active system was modeled and simulated to show the performance improvement in ride comfort in its electrical motor mode.Finally,the performance tests of the actuator prototype were carried out,which proves its capability for damping in its regenerative braking mode.The research results can provide useful guidance for the similar electrical active suspension design and development.展开更多
In this paper,numerical modeling and model testing of a complex-shaped remotely-operated vehicle（ROV） were shown.The paper emphasized the systematic modeling of hydrodynamic damping using the computational fluid dyn...In this paper,numerical modeling and model testing of a complex-shaped remotely-operated vehicle（ROV） were shown.The paper emphasized the systematic modeling of hydrodynamic damping using the computational fluid dynamic software ANSYS-CFXTM on the complex-shaped ROV,a practice that is not commonly applied.For initial design and prototype testing during the developmental stage,small-scale testing using a free-decaying experiment was used to verify the theoretical models obtained from ANSYS-CFXTM.Simulation results are shown to coincide with the experimental tests.The proposed method could determine the hydrodynamic damping coefficients of the ROV.展开更多
Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is ...Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is difficult to control.High pressure automatic variables bang-bang(HABB) was proposed to achieve the desired motor speed.First,the VPDVM nonlinear mathematic model was introduced,then linearized by feedback linearization theory,and the zero-dynamic stability was proved.The HABB control algorithm was proposed for VPDVM,in which the variable motor was controlled by high pressure automatic variables(HA) and the variable pump was controlled by bang-bang.Finally,simulation of VPDVM controlled by HABB was developed.Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed,load and pump speed.展开更多
Existing hydraulic braking systems in the vehicle is composed of the brake pedal, the hydraulic booster and the hydraulic caliper. The driver transmits one＇s breaking intent through the brake pedal stroke and force. ...Existing hydraulic braking systems in the vehicle is composed of the brake pedal, the hydraulic booster and the hydraulic caliper. The driver transmits one＇s breaking intent through the brake pedal stroke and force. The hydraulic booster can amplify the pedal force, only when the engine operates. The hydraulic caliper is composed of cylinders, pistons. There are also hydraulic pipes from the booster to the caliper. Currently, X-By-Wire technology is researched actively due to the exhaustion of fuel and the regulation of CO2. As a chain of this trend, the e-pedal and an electric mechanical brake （EMB） also are highlighted. At the beginning of EMB development, high-torque and high-power motors are required in order to implement the existing hydraulic calipers＇ clamping force. This has some limits as the need of big spaces and high costs. Then the electro wedge brake （EWB） is launching with self-reinforcement features of the wedge structure. EWB can generate big clamping forces with small size and low-torque motors with good braking-efficiency. In recent, the disc＇s circumferential face clamping one has been researched, for better heat-emission ability and better braking-efficiency compared to the existing disc＇s lateral face clamping method. But, this circumferential face clamping method can have worse unbalance-wear features compared to lateral face clamping one. In this study, the authors describe their circumferential EWB concepts, the method for reducing unbalance-wear feature of circumferential EWB, and the cost-effective implementation of circumferential EWB, in particular focused on nonlinear counter-wedge profile which is appropriate to reduce unbalance-wear.展开更多
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.
基金The National Natural Science Foundation of China(No.50575141)
文摘In order to regenerate electric power from the vibration excited by road unevenness,a novel energy- regenerative active suspension for vehicles was proposed with the description of its structure and its working principle with two modes switched in different operating conditions.Then,the novel active system was modeled and simulated to show the performance improvement in ride comfort in its electrical motor mode.Finally,the performance tests of the actuator prototype were carried out,which proves its capability for damping in its regenerative braking mode.The research results can provide useful guidance for the similar electrical active suspension design and development.
文摘In this paper,numerical modeling and model testing of a complex-shaped remotely-operated vehicle（ROV） were shown.The paper emphasized the systematic modeling of hydrodynamic damping using the computational fluid dynamic software ANSYS-CFXTM on the complex-shaped ROV,a practice that is not commonly applied.For initial design and prototype testing during the developmental stage,small-scale testing using a free-decaying experiment was used to verify the theoretical models obtained from ANSYS-CFXTM.Simulation results are shown to coincide with the experimental tests.The proposed method could determine the hydrodynamic damping coefficients of the ROV.
基金Project(51375029)supported by the National Natural Science Foundation of ChinaProject(20091102120038)supported by Specialized Research Fund for Doctoral Program of Higher Education of China
文摘Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is difficult to control.High pressure automatic variables bang-bang(HABB) was proposed to achieve the desired motor speed.First,the VPDVM nonlinear mathematic model was introduced,then linearized by feedback linearization theory,and the zero-dynamic stability was proved.The HABB control algorithm was proposed for VPDVM,in which the variable motor was controlled by high pressure automatic variables(HA) and the variable pump was controlled by bang-bang.Finally,simulation of VPDVM controlled by HABB was developed.Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed,load and pump speed.
文摘Existing hydraulic braking systems in the vehicle is composed of the brake pedal, the hydraulic booster and the hydraulic caliper. The driver transmits one＇s breaking intent through the brake pedal stroke and force. The hydraulic booster can amplify the pedal force, only when the engine operates. The hydraulic caliper is composed of cylinders, pistons. There are also hydraulic pipes from the booster to the caliper. Currently, X-By-Wire technology is researched actively due to the exhaustion of fuel and the regulation of CO2. As a chain of this trend, the e-pedal and an electric mechanical brake （EMB） also are highlighted. At the beginning of EMB development, high-torque and high-power motors are required in order to implement the existing hydraulic calipers＇ clamping force. This has some limits as the need of big spaces and high costs. Then the electro wedge brake （EWB） is launching with self-reinforcement features of the wedge structure. EWB can generate big clamping forces with small size and low-torque motors with good braking-efficiency. In recent, the disc＇s circumferential face clamping one has been researched, for better heat-emission ability and better braking-efficiency compared to the existing disc＇s lateral face clamping method. But, this circumferential face clamping method can have worse unbalance-wear features compared to lateral face clamping one. In this study, the authors describe their circumferential EWB concepts, the method for reducing unbalance-wear feature of circumferential EWB, and the cost-effective implementation of circumferential EWB, in particular focused on nonlinear counter-wedge profile which is appropriate to reduce unbalance-wear.
