Recent Patents on Mechanical Engineering - Volume 10, Issue 4, 2017

Background: In this study, an energy conserved wedge-platform thrust slider bearing is introduced. The realization of this bearing depends on the occurrence of the boundary slippage on the stationary surface in the bearing inlet zone. Objective: The aim was to show the improvement of the performance of the wedge-platform thrust slider bearing by applying the boundary slippage technology. Methods: The modified Reynolds equation incorporating the corresponding boundary slippage was used for analyzing the performance of the mentioned bearing. The coupled Reynolds equations in the bearing inlet and outlet zones were solved for finding the pressure distribution in the bearing. Results: It is shown that the load-carrying capacity of the present bearing can be increased by 90% compared to the conventional type of the bearing in the same operating condition. While the friction coefficient of the present bearing can be reduced by 60% compared to the conventional type of the bearing for the same case. Conclusion: The overall performance of a wedge-platform thrust slider bearing can be significantly improved by applying the boundary slippage technology.

Background: In recent years, the influence of tire noise on vehicle noise, vibration, and harshness (NVH) has increased because of the reduction of other types of noise such as engine noise and aerodynamic noise. Studies have focused on the influence of the tire structure on vibration noise, but not specifically on the belt structure. Objective: The aim of this study was to analyze the influence of the belt structure on tire vibration and noise and as well as the relevant physical laws. Methods: The modal acoustic transfer vector technique and acoustic boundary element simulation analysis were performed to study the vibration noise in a belt layer scheme designed using an orthogonal test. A combination of belt structure parameters yielding low noise was obtained using the range method. Results: The results indicate that when the belt structure was optimized, vibration noise declined by 7.55dB, the vibration noise sound pressure peak shifted to a higher frequency, and the acceleration peaks of the tread and sidewall decreased. The influence of the belt structure on the acceleration of the tread was mainly reflected in the middle-frequency band; however, for the sidewalls in the highfrequency band, the fluctuation and peak of the optimized excitation force spectrum, especially 440-Hz power spectrum, decreased considerably. Conclusion: The tire belt structure has considerable effect on vibration noise. This finding provides a theoretical basis for the development of low-noise tires in the future.

Background: A freezer drawer in a French door refrigerator subjected to repetitive food loading was found to have fractured in the field. Inspection of the field failures was carried out to determine the root causes in the design failures of the drawer. The primary failures came from a faulty design of the drawer that was not strong enough to withstand the loads caused by repetitive open and closing of the drawer. Objective: Based on the analysis of field data and a tailored set of parametric Accelerated Life Tests (ALT), the freezer drawer system for food storage in the French refrigerator was redesigned to improve its reliability. Methods: To carry out parametric Accelerated Life Tests (ALTs) using a force balance analysis, the simple mechanical loads of the drawer system were evaluated and an accelerated factor was found. Sample size equations with accelerated factors also were derived and used. Results: For the first ALT, the handle of the freezer drawer was fractured. The failed shapes found in the tests were similar to those of the failed samples from the field. The drawer was redesigned by increasing the width of the reinforced handle. During the second ALT, the slide rails were fractured. Conclusion: After the parameter ALTs, a corrective action plan was developed. The reliability of the newly designed freezer drawer system was assured to have a B1 life of 10 years with a failure rate of 0.1%/year. Recent patents on French refrigerators were also addressed.

Background: Hydraulic excavator as important engineering machinery plays an extremely significant role in engineering construction. Multi-way valve is the core element of hydraulic system of excavator, which is used for controlling the flow of oil and the flow distribution of actuators, its performance has important implications for the whole machine. Objective: In order to guide the design and optimization of spools of main valve of a medium hydraulic excavator quickly, a numerical simulation model of hydraulic system of working device was built based on AMESim. But it is impossible to simulate the ever-changing load accurately just with numerical simulation method. Methods: To make up the shortage, a real-time testing system for excavator based on CompactRIO was built. Then the simulation model was embedded into the testing system through interface modules to establish a semi-physical simulation platform for hydraulic system. The platform was used to test and simulate the hydraulic system of the excavator’s working device. Results: It shows that the simulation results are in good agreement with the measured data, which means the platform performs well. Conclusion: The platform has great significance to accelerate the design and development of main valves, and it also can provide strong support for analysis and research of hydraulic system of excavator. It could be of great significance both in designing multi-way valve and reducing the debugging cost.

Background: The 6-DOF super-length journey parallel robot is one of the most important equipments in the spacecraft docking motion simulation platform, and the simulation precision of the spacecraft docking motion simulation platform is determined by the 6-DOF super-length journey parallel robot’s pose accuracy. The pose error exits unavoidably because of the effect of kinematic parameter errors on the pose. Objective: In order to improve the 6-DOF super-length journey parallel robot’s pose accuracy, a kinematic calibration method considering all kinematic parts that have an influence on pose accuracy is presented in this paper. Methods: A kinematic calibration model is established through the inverse kinematics and vector differential theory. The correctness and rationality of the kinematic calibration model are verified by number simulation. The kinematic parameter errors are measured and estimated by 3-D coordinate measuring machine and least square algorithm. A measurement method is developed to measure the pose of the 6-DOF super-length journey parallel robot, which mainly measures the nine lengths from three reference points on the end-effector to three reference points on the base by 3-D coordinate measuring machine, after that calculates the 6-DOF super-length journey parallel robot’s pose by the lengths. Results: The simulation and experimental results are presented to demonstrate that the kinematic calibration and pose accuracy compensation method can decrease the pose error of the 6-DOF super-length journey parallel robot. Conclusion: The kinematic calibration technology has improved pose accuracy of the 6-DOF superlength journey parallel robot built in Aerospace System Engineering Shanghai. In this article, we have discussed some recent patent on error modeling and kinematic calibration of parallel robots.

Background: In several practical contexts, the core-shell interface of a soft particle may exhibit hydrodynamic slip. A significant enhancement in fluid transport over a hydrodynamically slipping surface is expected. However, in the present context, the hydrophobic surface is covered by a permeable shell. The impact of the hydrophobic core on the hydrodynamics of a soft particle has not been addressed before. Objective: We investigate the hydrodynamics of a soft particle in which the surface of the rigid core is hydrophobic. The impact of the shell thickness and permeability on the hydrodynamics of this type of soft particle is analyzed. The fluid inertia effect is also assessed for O(1) Reynolds number. Methods: A single-domain approach, in which two sets of equations for the fluid and the porous regions are combined into one set by introducing a binary parameter, is adopted. The Finite volume method is used to discretize the governing equation and a pressure correction based iterative method SIMPLE (Semi-Implicit Method for Pressure Linked Equation) is used to solve the resulting algebraic equations. The numerical solutions for the soft particle with no-slip core are in good agreement with the analytic solutions based on the linear Stokes-Brinkman model for a lower range of the Reynolds number. Results: The effect of the slip length of the inner core as well as the thickness and permeability of the soft layer on the hydrodynamics and settling velocity of the soft particle in the creeping flow regime is studied extensively. The validity of the linear analysis in describing the hydrodynamics of a soft particle with hydrophobic core has been illustrated. We have also addressed the situation when the fluid inertia has a non-negligible effect. In addition, the effect of volume fraction on the drag force experienced by the concentrated suspension of soft particles is addressed. Recent patents on the design of soft particles with a hydrophobic core are also discussed. Conclusion: Our results show that the impact of the core hydrophobicity is strongly influenced by the shell permeability. The core hydrophobicity creates a significant reduction in the drag of the soft particle with highly permeable shell. For a low permeable shell, the hydrophobicity of the core has a negligible impact when the shell thickness exceeds the core radius.

Background: With the rapid development of global economy, the utilization of water resources has become a prominent issue. Water shortage is a serious challenge, thus, water conservation is an important measure to help alleviate a water resources shortage and promote economic and social sustainable development. Currently, the inefficient use of water resource is very common in metropolitan and rural areas. Therefore, the efficient use of water in sustainable development has become an important issue in recent years. Previous research documents that the water tap switch speed affects water-saving efforts in the civil and industrial industries. Objective: The purpose of this study is to develop a new type of water-saving control device for a water tap switch that provides an effective and efficient method of water-saving. Methods: In this study, the patent is based on the Archimedes principle, lever principle and liquid pressure relating to water-saving and environmental protection machinery. Results: A control device is utilized for water-saving application in an unmanned operation maintaining an established water level without utilizing any resources. Conclusion: The control device of a water tap switch improves the efficiency of water use. Advantages include a simple structure, convenient use, ease of maintenance, and reliable performance. Recent patents of water-saving control devices promote water-saving technology that leads to additional watersaving control devices for water tap switch.

Background: One of the labor-consuming and dangerous operations in technological process of processing reactors is the one on transportation of firm wastes, as it is necessary to take into account the danger of materials to an environment and their harmful influence on health of the attendants and population. Objective: The recent paper is devoted to theoretical and experimental study of two phase (particle/air) media propagation inside a pipeline (part of pulsed pneumatic transport devices where materials are delivered to containers) with attention on possible harm influence of the flow on the tube walls, especially at the pipelines bends. Methods: Physical model corresponds to experimental study described in the patents. Numerical modeling was performed within the framework of model of non-stationary two-dimensional motion of ideal compressible media on the basis of laws of conservation of mass, momentum and energy. The thermodynamic flow field has been computed both in gas and solid phases. Results: Processes of particles mutual interactions, coalescence, fragmentation, interaction with a tube surface and motion have been investigated in detail. Interface borders have been considered as contact discontinuity surfaces. Modeling was performed numerically on the basis of the method of individual particles. The comparison of the computational and experimental data stated in patents was executed as well. Conclusion: It was found that the greater the radius of the pipeline bend R, the smaller value of gas pressure we have in the bend, but this effect becomes insignificant for R > 2.2m. The values of gas velocity at the bend have little variations depending on R. For small values of R (close to right angle of the bend) inverse motion of the particles is possible that may result in blocking of the flow. The formation of jet (consisting of particles) may take place at changing of radius R value (up to R = 1m). This may lead to sufficient damage to pipeline walls. At R > 4m volumetric concentration of particles starts to grow at the outer wall of the bend and effect of fragments dragging takes place that is also harmful for device operation. So if the value of radius R belongs to the interval (1.5; 3.5)m, we have minimal damage for the system operation.

Background: In the face of heavy production pressure, harsh processing environments and the increasing shortage of energy, spindles, the core part of CNC machine tools, must be modified from the traditional model and developed into a new form featured by intelligence and energy-saving. Objective: This paper reviewed recent papers and patents related to the electric spindle and aimed to design a multifunctional spindle which can reach high speed and high torque so as to meet the requirements of the modern production environment. Methods: By reviewing some patents related to electric spindle technique a dual-driving electric spindle was designed including rotating shaft design, bearing selection, link parts design and cooling system design. The author used the finite element method to conduct modal analysis and simulation verification, respectively. Results: Current and future developments of the patents on Dual-Driving Electric Spindles are finally provided to improve the current design technology and electric spindle system. Conclusion: The result showed electric spindle satisfying the design requirements for vibration and thermal properties. The dual-driving electric spindle was designed to meet the increasingly harsh demands of the machining environment.

Background: The load characteristics of pick cutting coal seam with coal-rock interface were studied by Time-frequency method in this paper. The common signal processing schemes were compared, and the suitable test load EMD (Empirical Mode Decomposition) empirical mode decomposition scheme for signal decomposition and denoising was selected. Objective: The cutting load power spectra were obtained and the cutting load 3D (three dimensional) combined amplitude, time frequency, spectrum and marginal spectrum were obtained by Hilbert Huang transform. Methods: The analysis by 3D combined amplitude, time frequency, spectrum and marginal spectrum shows that it becomes one of the main cutting bands of coal rock interface in 15Hz frequency band, which corresponds to the theoretical analysis of the load fluctuations in drum bands. Because the parameters related to the single cutting rotation frequency are affected by the interface change. The more obvious frequency components are near 45Hz and 75Hz which are due to the frequency doubling of the frequency variation with the interface load, which should be related to the frequency of the included angle with the pick speed. Results: It can be seen from the power spectrum analysis of roller cutting test that the main frequency distribution is generated by the crossover motion parameters and the caving effect of the picking and the role of coal and rock, and the material parameters of the cutting object are related. Conclusion: The coal load amplitude transition will appear with coal seams cut into the rock formation in the coal seam, which is consistent with the previous theoretical analysis and load characteristics analysis. The blasting of coal and rock has a great relationship with the homogeneity of coal and rock material itself, the material with the uniformity index is more stable, while the material load with smaller uniformity index fluctuates violently.