Recent Patents on Mechanical Engineering - Volume 4, Issue 2, 2011

Continuous research efforts have been devoted to the fundamental understanding of aircraft aerodynamics and the introduction of new concepts and innovations for the improvement of basic and fundamental aircraft aerodynamic performance, and hence economy, which leads to the enhancement of lift and the reduction of drag. It is also well known that the trailing vortices which reflect the lift as well as drag characteristics of the aircraft could be optimized for better aircraft performance characteristics and reduction of environmental impact as well as hazardous interference to other flight vehicles and/or objects. Research in enhanced aerodynamic efficiency has led to geometrical modifications, novel devices and features on the aircraft wings, such as blended-wing-body configuration, airfoil profiles and winglet designs, introduction of and/or invention of sensors for identifying relevant physical phenomena or measuring devices, introduction of novel computational methods to assess the prevailing force system with better accuracy through meticulous modeling, and introduction of control system and procedures for wake vortices alleviation and aerodynamic configuration optimization. Typical winglets configuration can significantly reduce the induced drag (in the order of less than 10%) with a resulting increase in wing lift-drag ratio and near the design lift coefficient. The corresponding improvement in lift-drag ratio is more than twice as great as that achieved with the comparable wing-tip extension. As also observed in many aircrafts produced in the last decades, only winglets have demonstrated sufficient benefits to find application on modern airliners. Further enhanced aircraft aerodynamic performance are suggested by introduction of recent innovative designs and patents of winglets, sharklets, blended winglets, capped winglets, s-shaped winglets and spiroidal winglet. The review identifies stability of various configurations of vortices, vortex decay and means of reducing vortex hazard. Passive wake vortices alleviation systems utilize the natural evolution of the instability modes with the highest growth rates while active systems rely on accelerating selected modes of instability by imposing the vortices individually or as a system. The passive system is essentially a vortex wake, hence an aerodynamic surface design, while an active system is an actuator design effort, respectively.

Linear actuators are widely adopted in a variety of life industries, including hospital beds with automatic lifting mechanism, conveyors, automatic doors and windows, adjustable computer tables, and leisure equipments. The need for more efficient product classification for manufacturers and the demand for product safety for users are two major issues currently that the design of linear actuators encounters. The main purpose of this study is to apply a complete engineering design process to design the overload protection device for mechanical linear actuator. In addition to shortening the timeline for product design, improved design processes can increase the value-added of the products and enhance international competitiveness. By searching domestic and overseas patents and synthesizing them into a summary table of patent analysis, linear actuators and clutches are clearly analyzed to produce a patent map. Then quality function deployment (QFD) is employed for functional decomposition, project specifications decision making, concept examination, and finally product sampling and testing. The most important design point in product development is to understand the existing value of those functions. With this idea, through concept examination, the calculation of mechanics is used to conduct a detailed design.

Quantification of residual stress distribution in materials is useful in the development, applications and quality control of engineering materials. Several residual stress measurement techniques are already well established for characterizing different engineering materials, while others remain largely unexplored. Yet for commercial success, the residual stress measurement methodologies must not only be efficacious but also cost-effective, introducing a potential dichotomy between the need for sophistication and ease of production. As reviewed in this article, there are encouraging results in developing patented methodologies in elasto-plastic (crack-free) instrumented indentation residual stress measurement of materials. Recent developments in instrumented indentation based residual stress measurement are likely to help reconcile the industrial and commercial pressure on improving materials performance and quality control.

In the era of miniature, laser microjoining has been evolving as a prospective smaller scale manufacturing process. The latest development in the field of laser technology brought new opportunities for laser to join wide variety of materials used in microsystems. In the growing technological field like micro-electro-mechanical systems (MEMS) and biomedical applications, the laser microjoining has the potential for application as encapsulation of miniature. However, the feasibility of microjoining depends on pulse modulation strategy and wavelength for selective range of laser power and laser irradiation intensity. Development and adaptation of new methodology also brings the flexibility in micro scale joining process with reduced defects and sound quality. A number of patents on the design of apparatus and methodology in this area show the signature of the development of the field. The current review article is focused on various aspects of micro scale joining process in the perspective of practical application. First, experimental investigation on the type of laser, process conditions, materials and feasibility of microjoining processes is reviewed. Secondly, on-line monitoring and control of the microjoining process is analyzed. An extensive part of the article is devoted to the review of numerical process model. It is anticipated that at ultrashot pulsed laser, the non-Fourier heat conduction analysis is more appropriate to signify rapid propagation of heat wave. Except from current prospective application, the future research direction and potential applications are also discussed. In a nutshell, the review article provides an overview of microjoining process which is extracted from literature and is required for promising development in microsystem technology.

Advanced nonconventional renewable & clean energy technologies which are used for generation of electricity have shown real promise and received renewed interest in recent years due to an increasing concern of environmental issues of greenhouse gas (GHG) emissions responsible for global warming effects, environmental pollution, and the limitations and conservation of natural energy resources. One of these innovative emerging technologies includes renewable low-enthalpy geothermal energy sources for clean electrical power generation. This promising technology offers potential applications in generation of electric power which can be produced using renewable low-enthalpy geothermal energy resources available in many parts of the world. In this paper, the basic concept of Organic Rankine Cycle (ORC) binary power technology using low-enthalpy geothermal heat sources is introduced and its potential applications and limitations for small-scale geothermal power generation and its relevant environmental and economic considerations are presented and discussed. Also, some recent developments and patents related to the energy conversion of low-enthalpy geothermal energy into electrical power with their important and relevant applications are reviewed. The list of patents reviewed here is by no means supposed to be thorough or complete but demonstrates, however, evolution trends related to low-enthalpy power generation.

This paper presents a compliant actuator based on Dielectric Electroactive Polymer (DEAP) technology. The presented advanced robotics concept requires smart materials, mostly in the form of actuators, for the development of biomimetic and flexible robotic systems. Smart materials such as Shape Memory Alloys (SMAs) and Electroactive Polymers (EAPs) are promising candidates for developing Bio-inspired smart robots without using conventional rigid links and joints. However, a major issue with SMAs is their slow response and limited bandwidth. The actuator made of DEAP is composed of a pre-stretched silicon film sputtered with very thin silver electrodes on both sides so as to form a smart capacitor as explained in patent [1, 20]. When an electric field is applied across the capacitor, the silicon film, which is of highly deformable dielectric medium, strains in the direction of application of voltage due to electrostatic pressure. Hence, thickness of the capacitor reduces that leads to corresponding enlargement of area in the other two directions. Different varieties of DEAP actuator models have been studied by various researchers for large displacement, precision motion and for associated control difficulties. Some of the applications are given in patent [23-28]. The experimental results obtained show that a suitable nonlinear control algorithm is required for obtaining accurate results. The suitability of DEAP actuator towards development of a spatial compliant mechanism is discussed and presented here.

Thermophotovoltaic (TPV) energy conversion devices which are used for direct generation of electricity as a clean energy source technology have shown innovative aspects and received renewed interest in recent years due to an increasing concern of environmental issues of emissions and the limitations of energy resources. TPV technology potentially offers several distinct advantages over other technologies. TPV power generation offers a potential application in direct generation of electricity in portable electric generators, stand-alone domestic gas-furnaces, silent electrical power supplies on recreational vehicles, hybrid electric vehicles, cogeneration of electricity and heat, large-scale recovery of high-temperature waste heat from industrial processes such as glass-manufacture, and many others. In this paper, a background on the basic concept and performance aspects of TPV energy conversion are presented and some recent patents of TPV power generators with their important and relevant applications to direct generation of electricity are reviewed. The list of patents reviewed here is by no means supposed to be thorough or complete but demonstrates, however, evolution trends related to TPV power generation technology.

The patents annotated in this section have been selected from various patent databases. These recent patents are relevant to the articles published in this journal issue, categorized by different analytical methods, designs, manufacturing and analysis of automobiles, aircrafts, manufacturing plants, industrial instruments, machines, heating and cooling systems and processes involved and related to mechanical engineering.