Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine ca...Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied.The quantity and forms of its sealing surfaces are reduced and simplified,and what's more,the advantages of twin-rotor piston engine are inherited,such as high power density and no valve mechanism.Given the motion law of two rotors,its kinematic model is established,and the general expression for some parameters related to engine performance,such as the trajectory,displacement,velocity and acceleration of the piston and centroid trajectory,angular displacement,velocity and acceleration of the rod are presented.By selecting different variation patterns of relative angle of two rotors,the relevant variables are compared.It can be concluded that by designing the relative angle function of two rotors,the volume variation of working chamber can be changed.However,a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions,the swing magnitude of rod is proportional to link ratio λ,and the position of rod swing center is controlled by eccentricity e.In order to reduce the lateral force,a smaller value of λ should be selected in the case of the structure,and the value of e should be near 0.95.There is no relationship between the piston stroke and the variation process of relative angle of two rotors,the former is only proportional to the amplitude of relative angle of two rotors.展开更多
Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First,...Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First, a vertical swing detection model for the cutting boom is established. Then, a kinematic analysis of the vertical swing mechanism is made and formulae describing the geometrical relationship between the vertical swing of the cutting boom and the telescopic length of vertical hydraulic lift cylinders and vertical swing angle of the boom are presented. Various factors such as complexity of the calculation model, the difficulty of installing the sensor and the cost are compared for two methods. Finally, directly measuring the vertical swing angle of the cutting boom with a tilt sensor is decided to be the more simple and effective method. The detection sensitivity and the vertical cutting error of a tilt sensor are studied. Vibration tests on an EBZ160 roadheader were performed in a coal mine. The characteristic vibration frequencies are analyzed. A design of a vibration isolation mount for the tilt sensor is presented. It makes the detection device work more reliably under conditions where vibration is present and lays a foundation for the implementation of an automatic roadhead cutter. A tilt sensor is installed on an EBZ160 and an EBZ200, and experiments have been done in a coal mine. The re- suits show that the experimental result is favorable and achieves the goal of automatic control of the vertical swing of the cutting boom.展开更多
In the age of global warming, energy saving features and overall reduction of environmental impact are critical components that must be addressed when developing new HVAC （heating ventilation and air conditioning） u...In the age of global warming, energy saving features and overall reduction of environmental impact are critical components that must be addressed when developing new HVAC （heating ventilation and air conditioning） units. We chose R32 refrigerant, with its lower LCCP （life cycle climate performance） as a more sustainable choice than R410A. However, R32 has its drawbacks. Due to its smaller molecular weight, internal leakage loss is higher for R32. Moreover, high discharge gas temperature decreases the reliability of the compressor, and makes a large overheating loss increase. In this study, we will describe the technologies （reducing the piston pressurizing force, heat-insulating structure, optimizing the port diameter） that were developed to overcome these drawbacks. We will also oresent the performance and reliability of the newly develoned high efficiency swing, comnressor series for R32 refrigerant.展开更多
文摘Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied.The quantity and forms of its sealing surfaces are reduced and simplified,and what's more,the advantages of twin-rotor piston engine are inherited,such as high power density and no valve mechanism.Given the motion law of two rotors,its kinematic model is established,and the general expression for some parameters related to engine performance,such as the trajectory,displacement,velocity and acceleration of the piston and centroid trajectory,angular displacement,velocity and acceleration of the rod are presented.By selecting different variation patterns of relative angle of two rotors,the relevant variables are compared.It can be concluded that by designing the relative angle function of two rotors,the volume variation of working chamber can be changed.However,a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions,the swing magnitude of rod is proportional to link ratio λ,and the position of rod swing center is controlled by eccentricity e.In order to reduce the lateral force,a smaller value of λ should be selected in the case of the structure,and the value of e should be near 0.95.There is no relationship between the piston stroke and the variation process of relative angle of two rotors,the former is only proportional to the amplitude of relative angle of two rotors.
基金support from China University of Mining and Technology (Beijing)Financial supports for this work provided by the National Hi-tech Research and Development Program of China (No.2008AA062201)
文摘Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First, a vertical swing detection model for the cutting boom is established. Then, a kinematic analysis of the vertical swing mechanism is made and formulae describing the geometrical relationship between the vertical swing of the cutting boom and the telescopic length of vertical hydraulic lift cylinders and vertical swing angle of the boom are presented. Various factors such as complexity of the calculation model, the difficulty of installing the sensor and the cost are compared for two methods. Finally, directly measuring the vertical swing angle of the cutting boom with a tilt sensor is decided to be the more simple and effective method. The detection sensitivity and the vertical cutting error of a tilt sensor are studied. Vibration tests on an EBZ160 roadheader were performed in a coal mine. The characteristic vibration frequencies are analyzed. A design of a vibration isolation mount for the tilt sensor is presented. It makes the detection device work more reliably under conditions where vibration is present and lays a foundation for the implementation of an automatic roadhead cutter. A tilt sensor is installed on an EBZ160 and an EBZ200, and experiments have been done in a coal mine. The re- suits show that the experimental result is favorable and achieves the goal of automatic control of the vertical swing of the cutting boom.
文摘In the age of global warming, energy saving features and overall reduction of environmental impact are critical components that must be addressed when developing new HVAC （heating ventilation and air conditioning） units. We chose R32 refrigerant, with its lower LCCP （life cycle climate performance） as a more sustainable choice than R410A. However, R32 has its drawbacks. Due to its smaller molecular weight, internal leakage loss is higher for R32. Moreover, high discharge gas temperature decreases the reliability of the compressor, and makes a large overheating loss increase. In this study, we will describe the technologies （reducing the piston pressurizing force, heat-insulating structure, optimizing the port diameter） that were developed to overcome these drawbacks. We will also oresent the performance and reliability of the newly develoned high efficiency swing, comnressor series for R32 refrigerant.
