Recent Patents on Mechanical Engineering - Volume 12, Issue 2, 2019

Background: Parallel plate structures are widely used in micro-electromechanical systems, and the measuring technology of parallelism of parallel plates becomes more and more inevitable. More and more attention has been paid on the development of measuring technology of parallelism of parallel plates. Objective: To meet the increasing requirement of measuring precision and measuring efficiency of parallelism measurement of parallel plates, the measuring devices and measuring methods of the parallelism measurement are constantly being enhanced. Methods: This paper retraces varieties of representative patents relevant to the measuring devices and measuring methods of the parallelism measurement of parallel plates. Results: Through retracing the characteristics of different types of measuring devices and measuring methods of parallelism measurement of parallel plates, the main problems existing in the current development such as low measuring precision and low measuring efficiency are concluded and analyzed. Development of patents on the measuring devices and measuring methods of the parallelism measurement is discussed in the future. Conclusion: The optimization and development of parallelism measurement are beneficial to improve measuring precision and measuring efficiency of parallelism measurement of parallel plates. More related patents on parallelism measurement of parallel plates will be invented.

Background: Ankle is an important bearing joint in the human body. Unreasonable exercise patterns and exercise intensity can cause ankle injuries. This will seriously affect patients’ daily life. With the increase in the number of patients, the labor intensity of doctors is increasing. Ankle rehabilitation robot can help doctors free themselves from repetitive tasks, which is, of more practical value. Objective: To give a general summary of recent ankle rehabilitation robot and introduce the respective characteristics and development including structure type, drive type and rehabilitation training mode. Methods: This paper investigates various representative studies related to the ankle rehabilitation robot. The structure type, drive type, rehabilitation training mode and applications situation of these ankle rehabilitation robot are discussed. Results: The characteristics of different types of ankle rehabilitation robots are analyzed. This paper analyzes the main problems in its development. The solutions to the issues and the current and future research on ankle rehabilitation robot are discussed. Conclusion: The ankle rehabilitation robots are classified into motor drive type, pneumatic artificial muscle and pneumatic cylinder drive type and others. Further improvements are needed in the aspects of mechanical design, safety, virtual reality, brain-computer interface, control strategies and algorithm of bio-syncretic mechanism system of ankle rehabilitation robot. More related patents about ankle rehabilitation robot need to be developed.

Background: As one of the core components of high-speed CNC machine tool, high-speed motorized spindle is the core functional component of high precision CNC machine tool, which has become the key research and development object of the world. Objective: By comparing and discussing the patents of high-speed motorized spindle, some valuable conclusions have been drawn to predict the future research and development of high-speed motorized spindle. Methods: By analyzing the characteristics of high-speed motorized spindle structure, the influence of high-speed motorized spindle on high-speed machining technology was explicated. Combining with the key technology of high-speed motorized spindle, the patents related to high-speed motorized spindle structure were used for investigation. Results: With the rapid development of high-speed cutting and numerical control technology and the need of practical application, the requirement for high-speed spindle performance has increased. Motorized spindle technology has the characteristics of high speed, high strength, high power, high torque and low speed, high precision, high reliability and long life, offering diversified bearing and lubrication cooling methods and serving as an intelligent system. Conclusion: The different levels of improvement and renovation of the structure with high-speed motorized spindle, by adding lubrication and cooling device to the spindle have improve the performance of spindle, addressing the loopholes in the technology and making it more practical.

Background: More and more noncircular gears are reported in various relevant patents and papers. The Pascal limacon gear is one kind of noncircular gears and widely used in many mechanisms. The pitch curve is a key accuracy index for the noncircular gears and influenced by many errors, included worktable errors. Objective: The goal of this paper is to analyze the influence of worktable errors on the Pascal limacon gear’s pitch curve. Methods: Firstly, according to the mathematical model for hobbing Pascal limacon gear, a vector expression for the Pascal limacon gear pitch curve errors caused by the worktable rotary angle error and the center distance error was derived. Then, with consideration of the above errors, a comprehensive method was proposed, and the Pascal limacon gear pitch curve errors were calculated. The concept of the sensitivity degree of the errors of the Pascal limacon gear pitch curve to the center distance was proposed. Thirdly, the influence of the center distance errors on the pitch curve could be assessed. Results: Using one Pascal limacon gear as an example, the results show that the worktable rotary angle error has a slight effect on the Pascal limacon gear pitch curve, and the center distance error has a great effect on the Pascal limacon gear pitch curve. Conclusion: The Pascal limacon gear pitch curve error is highly sensitive to the center distance error near the polar angles of π/ 2 and 3π / 2.

Background: It is always difficult to fabricate micro parts in complicated machines. As one of the most promising micro machining methods, micro electrochemical milling based on the principle of anode electrochemical dissolution is useful for the fabrication of micro structures in hard metal material with advantages irrespective of the material hardness and strength along with no residual stress or heat treatment being observed on the surface of the workpiece. Objective: The purpose of this paper is to propose a method of micro pattern structures machining by using high-speed helix electrode in micro electrochemical milling, and reveal the relationship of rotating speed of helix electrode and machining efficiency. Methods: This paper presents a micro electrochemical milling technique for fabricating micro pattern structures with high efficiency. Firstly, a mathematical model of gap electric field under the condition of ultra short pulse power supply is established, and the surface profile change of workpiece in micro electrochemical milling is simulated by COMSOL Multiphysics. Secondly, the gap flow field of the machining under the conditions of different rotating speed of helix electrode is analyzed by simulation. Finally, a set of experiments are carried out to discuss the influence of the rotating speed on maximum feed rate. Results: The surface profile change of workpiece in micro electrochemical milling is predicted by simulation. The graphs of gas-liquid distribution and velocity vector of the flow field in the machining are obtained. A series of micro pattern structures with a groove width of 150μm are machined successfully. Conclusion: By using high-speed helix electrode, the electrolyte circulation can be promoted and machining efficiency of micro electrochemical milling can be improved obviously. The experiment results demonstrate that the micro electrochemical milling with high-speed helix electrode is an efficient method to fabricate micro pattern structures. In this article, various patents have been discussed.

Background: This patent is based on the wind industry technology called Diffuser Augmented Wind Turbines (DAWTs). This technology consists of a horizontal axis wind turbine, which is housed inside a duct with diverging section in the direction of the free air stream. In this paper, a review of preceding patents related to this technology is carried out. Objective: This paper presents an innovative patent to improve the performance of horizontal axis wind turbines. In particular, this system is aimed at improving the performance of those turbines that otherwise might not be installed due to the low wind resource existing at certain locations. Methods: The most innovative elements of this patent are: (1) the semi-spherical grooves, which are mechanized on the surface of the two diffusers in order to guarantee a more energetic boundary layer; (2) the coaxial diffuser, which is located downwind following the first diffuser in order to increase the suction effect on the air mass close to the inlet; (3) the coaxial rings located around the first diffuser outlet, which are used to deflect the external airflow toward the turbine wake; and (4), the selforientating system to orientate the system by the prevailing wind direction. Results: An application of the patent for increasing the power generated by a horizontal axis wind turbine with three blades is presented. The patent is designed and its performance is evaluated by using a Computational Fluid Dynamics code. The numerical results show that this system rises the airflow going through the rotor of the turbine. Conclusion: The patented device is an original contribution aimed at enabling a more profitable installation of wind turbines in places where the wind resource is insufficient because of the wind shear caused both by the proximity of the earth and the obstacles on the earth surface.

Background: Transitional twin air-intake is a vital component of the air-induction system of single-engine combat aircraft. Combat aircraft do not always fly at steady, uniform flow conditions. But in some cases, it operates at different asymmetric flow conditions, which cause a change in aerodynamic performance of aircraft components like compressor and combustor. Objective: In order to improve the air quality at the outlet of air-intake- called Aerodynamic Inlet Plane (AIP) of this twin air-intake and to improve its aerodynamic performance for wide ranges of inflow conditions, slotted synthetic jets are used. Methods: Computational studies are carried out using Computational Fluid Dynamics (CFD) software for various types of skewed turbulent velocity profiles at inlet-2 with skewness number (ξ = 0, 0.3, 0.5, 0.7), while an average uniform velocity of 20m/s at inlet-1. Based on this analysis, worst case is selected and a pair of slotted synthetic jets is used just before the inflexion plane of the twin air-intake using transition SST turbulence model. Results: The flow behaviour of transitional twin air-intake becomes more complex with the increase in skewness number, thereby decreasing the aerodynamic performance of the air-intakes. With the use of slotted synthetic jets, an improvement in static pressure recovery and decrement in total pressure loss coefficient, distortion in coeffient swirl coefficient and secondary flow non-uniformity are observed which is a great sign of improved aerodynamic performance for the twin air-intakes. Conclusion: It is proved in this study that synthetic jet can be used effectively in twin air-intake to control the flow features leading to better flow uniformity and increased overall performance at the AIP without increasing the net-mass flow rate, thereby reducing the chance of stall/surge in the aeroengines. Hybrid flow control technique (synthetic jet coupled with vortex generator array) or newer flow control technique (plasma jet) are being explored for its possible use in engine air-intakes as revealed from recent patents filed/published in this area.