Applied Mechanics and Materials Vol. 610

Abstract: This investigation was carried out to study the characteristics of boiling heat transfer for hydrocarbon refrigerant R600a (isobutane)/oil mixtures flowing in a circular pipe within dispersed-copper porous inserts. The oil was the EMKARATE RL 32H with a viscosity 150 SUS. The test was conducted at a saturation temperature of 10 , vapor qualities from 0.076 to 0.87, inlet oil concentration from 0 to 3 mass% oil, mass flux of 120 1100 and heat flux of 12-65 . The effects of the concentration of the refrigerant/oil mixtures, and the sizes of inserts on the heat transfer of R-600a for present study were presented.

Abstract: Human sitting posture and dynamic behavior at work are analyzed systematically by using the principle and method of ergonomics. And from the scales and functionality limited by both aspects, put forward new design ideas of office chair which are fit to modern office work so as to provide reference to design practice.

Abstract: Electric mining haul trucks are one of the most challenging applications of power electronics in automotive systems. This paper presents some advances of AC drive system with multiphase induction motor in high power mining haul trucks used in the special operation and environment. It is established that the use of inverter-fed dual three-phase (DTP) induction motors with vector control is the preferred solution to reach the required high starting torque, widely variable-speed range and good dynamic performance required by these vehicles. Key technologies and design features for the drive systems under extreme operating conditions are discussed.

Abstract: Nowadays, the equipment for processing special-shaped stone products is developing towards high efficiency, intelligent and multifunction. Based on the features of stone processing technology, a sawing-milling compound machining center with eight axes and double five-axis simultaneous control for special-shaped stone products was designed. The dynamic performance and processing capacity were tested. Research shows that the sawing and milling compound machining in the same horizontal slide saddle is practicable. This machine can realize both vertical and horizontal machining under five-axis simultaneous control, and its machining accuracy is better than the normal industrial standard.

Abstract: In order to study heat generation and dissipation of water-cooled permanent magnet synchronous motor in electric vehicle, the major energy loss was calculated and the finite element model for interior heat transfer simulation was established based on appropriate simplification and equivalent processing. The fluid-solid-thermal coupling simulation was accomplished by CFD method and the steady state temperature field of the motor under rated condition was obtained. The simulation is verified by experiment and gives an effective support in motor’s cooling system design.

Abstract: According to the characteristics and demand of the armored vehicle cabin environment evaluation, the cabin environment parameters are processed the method of dimensionless normalized processing, the weight coefficients of each parameters are evaluated by using analytic hierarchy process (AHP), the result vector of fuzzy comprehensive evaluation is analyzed by using weighted average principle, the result is ideal. At the same time, considering the problems of the fuzzy comprehensive evaluation and the particularity of military vehicle evaluation, the ultra limit additional evaluation is proposed.

Abstract: This paper proposes a novel high power factor LED driver based on SY5800A for interior-lighting applications. High power factor is achieved by using the transformer with back winding coil and the transformer with “sandwich” winding coil. In addition, the proposed driver features cost-effectiveness, high circuit efficiency, low input current ripples and a reduced components count. A sample driver is developed to supply a 15W LED interior-lighting module with a 0.99 power factor. Experimental results demonstrate the functionalities of the proposed circuit.

Abstract: This article proposed a Double Extended Kalman Filters (Double EKFs) observer to estimate states of 4WD in-wheel motor electric vehicle. One EKF observer was used to estimate vehicle longitudinal velocity. The other EKF observer was employed to estimate vehicle sideslip angle. The structure has two benefits: Firstly, two EKFs reduce the order of the wholly state observer, so that calculation load could be lower. Secondly, the two EKFs could be adjusted easier and more independently. The paper investigates the feasibility of this observer in two vehicle test conditions. The test results indicate the effectiveness of the Double EKFs State estimation.

Abstract: The electromagnetic brake has already been acknowledged by users as one kind of contactless brake. In this paper, the basic principle and application of electromagnetic braking technology were briefly introduced first. Then the structure of the innovative hybrid brake with double disc was put forward. It employed an electromagnetic braking to reduce brake pad wear and braking system thermal recession. Based on the design requirements, the friction brake and the electromagnetic brake were designed respectively. Finally, in order to verify that whether the designed hybrid brake meets the design requirements, a bench test was carried out. The electromagnetic braking torque characteristic was tested. The results showed that the electromagnetic braking torque could approach 198N·m.Thus the design method is feasible..

Abstract: Electric hydraulic power steering system (EHPS) is an on-demand power steering system that uses a small displacement and high speed electric pump. By optimizing the assist characteristic curve, EHPS can save energy more significantly than traditional hydraulic power steering system. After overview of the energy saving principle for EHPS system, the energy consumption of the EHPS system is elaborated, and the energy loss of the mechanical, electrical, hydraulic subsystems is analyzed. Finally, targeted measures are proposed for energy conservation.