Applied Mechanics and Materials Vols. 278-280

Abstract: Environmental pollution and energy crisis urge people to explore new power devices without burning fossil fuels and pollutant emission. Air powered engine (APE) is among these power devices. The medium and power source of APE is compressed air whose expansion makes it possible for APE to output work. Based on the principal and working process of APE, the mathematic model is established and afterwards made dimensionless. On the basis of the simulation of the non-dimensional mathematic model, the influences of the non-dimensional cylinder stroke and Kagawa coefficient on APE’s performances are analyzed

Abstract: The node position of amplitude transformer was determined by the finite element method, and the flange was designed at the nod position for conveniently installation. By the finite element software, the amplitude transformer with flange was optimized and dressed, and its structural parameters were determined. During the actual manufacturing process, it was used impedance analyzer to test its vibration performance, the testing results show that this system vibration performance is good, its resonant frequency is 34.771kHz, anti-resonant frequency is 35.008kHz. The above-mentioned results are very much coincided with the system natural frequency of 34.893kHz which is drew by finite element method. Compared to the traditional dressing this method has many advantages such as convenience, green, environmental protection, low cost and others.

Abstract: The distribution of temperature and NOX concentration field under different crank angle of a CNG direct-injection engine converted from a four-valve gasoline vehicle engine are calculated by the computation model of the CNG direct-injection engine work process using CFD software. The results show that the temperature field spreads around the center of the spark plug in initial combustion period. The position of maximum temperature in combustion chamber moves from the spark plug to the wall and temperature tends to uniform distribution as the piston goes down along with the spread of flame front and the completion reaction after the flame. Temperature distribution is vital to the generation of NOX which changes along with high-temperature zone. The change principle of quantity of NOX in the cylinder is that at first, the quantity continues increasing, then declines, and finally remains stable. Besides this, the generation amount of NOX increase along with the speed.

Abstract: The heat storage capacity of the drum boiler plays an important role in the Coordination Control System (CCS) of units. The theoretical calculating method of the heat storage capacity is achieved through the mechanism analysis of the risers, drum and over-heater, which solves the problem of the traditional method effectively. The calculating results based on the units design data and the real running data shows that the heat storage capacity of saturation water and metal increases with the pressure decreasing, and the heat storage capacity of steam is same with pressure changes. The heat storage of every medium has different proportion under different load, the heat storage of drum boiler shows different characteristics when the working conditions changes.

Abstract: The calculation method for transmission system parameters matching of an electric forklift powered by zinc-air fuel battery was raised according to the electric forklift dynamic requirements. And the method was introduced by determining parameters of driving motor, battery and gear ratio. A certain domestic electric forklift was used as an example to match its designing transmission system parameters. The power performance is simulated using the simulation software at the same time. The results show that the electric forklift dynamic performance meets the design requirements, and the application of zinc-air fuel cell to electric forklift truck is feasible.

Abstract: The principle and structure of ferrite orthogonal core controllable reactor(FOC-CR) were discussed. The analysis of FOC-CR's magnetic equivalent circuit and basic equations was presented. Based on these, this paper establishes the relationship of FOC-CR's input voltage and flux through a odd polynomial assumption of MMF-Flux and gives a simulation model of FOC-CR in Matlab by using S-function.The modeling method is accessed from the result of both current wave and control characteristics of simulation model and experimental prototype.

Abstract: A new-type frictionless pneumatic cylinder with an aerostatic bearing as its piston can decrease the friction significantly. The stability and the leakage of this cylinder mostly depend on the radial load carrying capacity(RLCC) and the air consuming of the bearing. In order to make a better use of this cylinder in pneumatic servo systems, a simulation study on the influence of the structural parameters and time-varying surrounding parameters to this cylinder was carried out on the basis of a numerical solution method based on finite element method(FEM) which was constructed to solve Reynolds equations in this paper. Simulation shows that introducing a recess chamber at the end of the orifice hole can increase the RLCC significantly and smooth the sharp distribution of the pressure around the orifices in the air film, which makes the bearing working more stable; the time-varying parameters have a combined effects on the performance characteristics of the bearing.

Abstract: For a highly clean vacuum environment, magnetic levitation is plausible technology because of its noncontact nature. Especially, due to the potential occurrence of an electric spark in spite of low voltage in a vacuum a passive tray without any circuits is required. In consideration of spatial limitation and cost reduction, the electromagnets of the passive tray levitation should be located discontinuously. This paper presents the characteristic analysis of the passive tray levitation system according to an interval of discontinuously arranged electromagnets. For doing this, the 3D dynamic model, which consists of the mechanical components, joints, and force elements, is proposed to predict the levitation stability.

Abstract: An error mapping modeling and identification technology for the circular path test of NC machine tools is proposed. First, geometric error modeling of the NC machine tool was established and the theory of the laser measurement method was introduced. Then through further analyzing the influence of the geometric errors to circular path deviations, the error items were identified, such as the displacement errors, backlashes and squareness errors. Finally measurement and compensation experiment of circular path was conducted. The experimental results show that the geometric error modeling is feasible, and the measurement method can be set up easily and rapidly, even can be used to measure smaller radius circular path under a high feed rate condition. After compensation, the accuracy of the circular path of the machine tool is improved by 50.88%.

Abstract: This paper mainly analyzes the hydraulic system principle during the monorail braking, and come to a conclusion that the spring stiffness and the throttle valve flow area are main factors affect the brake system. Then we use the MSC.EASY5 to modeling the hydraulic system, and simulate the unloading time of hydraulic cylinder under the spring force, the result shows that, the response time of a braking system can meet the requirement of the coal mine safety regulation, and change the flow area of throttle valve will affect the brake system.