Recent Patents on Mechanical Engineering - Volume 11, Issue 3, 2018

Background: The pneumatic conveying system has some advantages such as simple structure, easy loading and unloading, and low environmental pollution, but there are also problems such as pipe wear, blockage and limitation of the transmission distance. Objective: To relieve pipe blockage, reduce in-pipe dust and remove in-pipe blockage, this paper introduces three recent patents of pneumatic conveying systems and methods. Methods: The precision supercharging system and method can produce a more reasonable supercharged flow field; the in-pipe dedusting system and method can offer a satisfying spray effect; the reverse impacting system and method can rapidly form a reverse impact flow field to breakup blockage. Results: The precision supercharging system and method can not only satisfy the demand of local or whole supercharging but also prevent the material breakage and energy loss caused by excessive supercharging; the in-pipe dedusting system and method can not only satisfy the demands of local or whole dedusting but also avoid problems such as clogged pipes and dust explosion; the reverse impacting system and method can not only satisfy the demand of local or whole supercharging but also eliminate the blockage in pipeline. Conclusion: These three recent patents of pneumatic conveying devices have important guiding significance for the development of the pneumatic conveying industry.

A qualitative observation has been undergone to review the various geometries of a microchannel that has been reported for the last two decades in literature majorly for the application of high power devices. Recent research on microchannel is more focused on numerical and experimental work with various configurations of the heat sink. In this paper, a comparative work on different flow geometries used in the microchannel and their influence on heat transfer and pressure drop is investigated with the brief representation of different working fluids used in microchannel heat sink for the purpose of electronic cooling and their associated performance characteristics with various examined parameters. Background: The microchannel cooling is an established cooling technique for high power electronic components which effectively enhances the performance of the high power devices. Objective: This article presents a general overview of microchannels with novel constructional bifurcations structures with related patents. Further, the influential parameter on thermal and flow characteristics with greater depth is also reviewed by authors. Methods: This review directs by presenting standard and benchmark investigation in the microchannel and different working parameters continued with recent studies. Further, it is addressed with the application of electronic cooling with latest patents using bifurcations and fractal microchannels. Result: The current situation of 3D cooling requires a robust cooling system to accommodate increased heat flux without compromising the packaging. Moreover, the recently developed patents also evolved with improved thermal load handling under constrained packaging. Conclusion: The advanced microchannel cooling with an optimized fluid handling system with effective packaging results in a highly effective heat dissipation system.

Background: A novel micro wedge-platform thrust slider bearing with a small wedge angle registered in the patent is introduced. This bearing depends on the physical adsorption and is applied in special cases with a pronounced load-carrying capacity. Objective: To show the newly developed micro wedge-platform thrust slider bearing with a small wedge angle by the physical adsorption technology. Methods: The fundamental lubrication analysis is presented for the load-carrying capacity of the mentioned bearing. The bearing depends on the use of hydrophilic and hydrophobic coatings on the stationary surfaces respectively in the bearing inlet and outlet zones. Results: The calculation results show that the load-carrying capacity of the invented bearing is greatly higher than that calculated from conventional hydrodynamic lubrication theory, and it is also considerably higher than that of the bearing by using homogenous surface properties when the wedge angle of the bearing is less than 10-4°. Conclusion: The micro wedge-platform thrust slider bearing with a significant load-carrying capacity can be developed by using the physical adsorption when the wedge angle ; of the bearing is 10-5° ≤ < 0.01°.

Background: An abnormal micro/nano step bearing with the film thickness in the inlet zone lower than that in the outlet zone registered in the patent is introduced based on the physical adsorption technology. This bearing does not follow conventional hydrodynamic lubrication principles. Objective: To introduce an abnormal-geometry micro step bearing for application in special cases. Methods: The operation of the mentioned bearing is based on the physical adsorption of the lubricating film to the bearing surface. The modified Reynolds equation for the analysis of this bearing is presented, based on the flow equation for a nanoscale fluid flow. Results: The calculation results showed that the mentioned bearing has a load-carrying capacity when the lubricating film thickness and the size of the step of the bearing both are on the 1nm scale. The physical adsorption of the lubricating film to the bearing surface has a significant effect on the bearing performance. Conclusion: The abnormal bearing in which the inlet film thickness is lower than the outlet film thickness, can be developed based on the physical adsorption of the lubricating film. It requires the physical adsorption of the film to the contacts in the inlet zone stronger than that in the outlet zone. The exemplary calculation results for the load-carrying capacity of this bearing are presented. This bearing does not follow conventional hydrodynamic lubrication principles, which rely on the convergent surface separation or the surface squeezing. The surface separation in this bearing is indeed divergent.

Background: Various relevant papers and patents which have reported non-circular gears are widely used in many types of mechanical instruments. The Pascal limacon gear is one new type of noncircular gear. Many researchers have only focused on the design of Pascal limacon gears and their applications. Little attention has been paid to the machining aspects. Shaping is a better method for fabricating non-circular gears. The Equal Rotary-Angle of Workpiece Method (ERAWM), the Equal Arc- Length of Workpiece Method (EALWM), and the Equal Polar-Angle of Workpiece Method (EPAWM) are the three linkage-methods for shaping Pascal limacon gears. However, which linkage-method should be chosen in practical has not been studied. Objective: In order to choose the excellent linkage-methods for shaping Pascal limacon gears, the three linkage-methods were compared from three aspects: density of shaping cutter trace, uniformity of arc length of program blocks and control of motion axes of machine tools. Methods: Firstly, the shaping models of Pascal limacon gears was deduced. Secondly, based on the mathematical model, shaping linkage-methods of Pascal limacon gears were obtained. Thirdly, under different shaping linkage-methods, developing regularity of shaping cutter trace, arc length of program blocks and motion axes of machine tools, were compared. Results: Finally, the excellent shaping linkage-method EALWM is obtained with the characteristics of a high density of shaping cutter trace, high uniformity of arc length of program blocks and ease of control. Conclusion: It has been proven that EALWM is the best linkage-method to shape Pascal limacon gears.

Background: When an unbalanced flexible rotor passes through its critical speed, it is very easy to result in great vibration amplitude, even the destruction of rotor and bearings. Therefore, it is significant for high-speed rotating machines to reduce the vibration amplitude of flexible rotor. Various patents have been discussed in this article. Objective: The purpose of this study is to find out the amplitude reduction method and simulate the feasibility of flexible rotor passing through critical speed. Methods: On the basis of the model of single disk rotor system with eccentric mass, a novel method is presented to reduce the vibration amplitude passing through critical speed by modulating the acceleration and stiffness simultaneously. Firstly, the amplitude characteristic of a flexible rotor with different acceleration and supporting stiffness was investigated. Then, the method of changing the stiffness during variable acceleration was carried out by numerical simulation based on Newmark algorithm. Furthermore, the strain energy of rotor and input power were also analyzed by using the method of simultaneous modulation of acceleration and stiffness. Results: The simulation results revealed that the simultaneous modulation of acceleration and stiffness could reduce the vibration amplitude of rotor effectively, which was reduced by 44% and 13%, comparing with the single variable acceleration and the single variation of stiffness, respectively. Moreover, the variation tendency of total energy was similar to that of the rotor amplitude, which could be controlled at a very small level. The input power was mainly dependent on the acceleration, but had very little to do with the stiffness. Conclusion: The method was suitable for the model of single disk rotor system, and it could also be applied to complex rotor systems, which was very useful for the security of high speed rotating machine.

Background: Large centrifugal fans with high efficiency are being developed fast recently, reflecting the trends that saving energy is becoming more and more important. Objective: The purpose of this study is to explore the design method of efficient impeller, and to form the design ideas and concepts, this can provide reference for the enterprises to design efficient impeller in the future, and improve enterprises' production efficiency. Methods: In order to improve the comprehensive quality of centrifugal fan, an integrated optimization strategy based on Kriging surrogate model and Genetic algorithm combined with Particle Swarm Algorithm (GA-PSO) was proposed. The optimization strategy was used to optimize the impeller parameters of centrifugal fan. Coupled with Computational Fluid Dynamics (CFD) analysis, the Orthogonal test method was used to arrange the experimental points. In the paper, inlet blade angle, outlet blade angle, inlet width, outlet width, inlet radius, outlet radius and blade number were considered as impeller significant structure parameters, Then Kriging surrogate model was introduced to establish predictive model between centrifugal fan comprehensive aerodynamic quality and the impeller structure parameters. Besides, GA-PSO was used to seek the best result of the predictive model in the feasible solution space. Results: After optimization, the efficiency is increased by about 2%, and the efficiency increased significantly. The optimal impeller parameters were inlet blade angle of 36.35 degree, outlet blade angle of 58.87 degree, inlet width of 189.2mm, outlet width of 91.9mm, inlet radius of 239.45mm, outlet radius of 515.65, and blade number of 16. Conclusion: CFD analysis and actual experiment achieved good agreement, showing that the integrated optimization strategy was feasible and reasonable in centrifugal fan impeller quality optimization.

Background: According to the characteristics of engine cooling system, a BLDC (Brushless direct current motor) modeling method based on the electronic water pump is proposed. In the MATLAB/ Simulink environment, according to the different functions of the motor body module, the driver module, and the control module, we can build each independent module, and then let them make an organic integration, so we can build the brushless direct current motor system simulation model based on the electronic water pump. We adopt the BLDC double closed-loop control system which is made up of the classic speed loop PI control and the current hysteresis control to ensure the rapid and effective response of the electronic water pump. Through the qualitative analysis of simulation analysis, this control method has better control effect for BLDC of electronic water pump, at the same time, the model can be applied to verify the rationality of other algorithms for BLDC control of electronic water pump, and provides a new idea for the research and debugging of BLDC motor for electronic water pump in the later period. Objective: This paper mainly focuses on the qualitative analysis of simulation, the model can be applied to verify the rationality of other algorithms for BLDC control of electronic water pump, and provides a new idea for the research and debugging of BLDC motor for electronic water pump in the later period. Methods: Firstly, according to the characteristics of engine cooling system, a BLDC modeling method based on the electronic water pump is proposed. Secondly, in the MATLAB/Simulink environment, according to the different functions of the motor body module, the driver module, and the control module, we can build each independent module, and then let them make an organic integration, so we can build the brushless direct current motor system simulation model based on the electronic water pump. Thirdly, we adopt the BLDC double closed-loop control system which is made up of the classic speed loop PI control and the current hysteresis control. Results: In the MATLAB/Simulink environment, according to the different functions of the motor body module, the driver module, and the control module, we can build each independent module, and then let them make an organic integration, so we can build the brushless direct current motor system simulation model based on the electronic water pump. Through the classical speed loop PI control and the current loop hysteresis control, the double closed loop control of the BLDC control system is formed. Conclusion: On the basis of analyzing the performance characteristics of the automobile electronic water pump, this paper puts forward the method of selecting the BLDC motor for the electric water pump, and designs the BLDC speed regulation system based on this, through the design of classical speed and current hysteresis control method, the model is simulated. The simulation results show that the waveform conforms to the theoretical analysis, and the system has better dynamic and static characteristics. Furthermore, on this basis, theoretical verification of various control algorithms for BLDC motors for electronic water pumps can be achieved, it can better realize the qualitative analysis of the BLDC working state of the electronic water pump. In this article, some patents have been discussed.