Recent Patents on Mechanical Engineering - Volume 5, Issue 3, 2012

In recent years, significant patents have been devoted to developing control methods and apparatuses of permanent magnet synchronous motor (PMSM). PMSM, as an energy converter, has been popular in a wide range of industry for its tremendous advantages. The focus of this paper is to survey recent patents related to PMSM. Firstly, a general overview of PMSM is provided. Then the structure and advantages of PMSM are introduced. Twelve patents since 2008 are collected, in which four deal with control method, four refer to apparatus design, and the rest involve the subjects of both control method and apparatus design. Analysis and comparison are made to the evaluation of development of PMSM. Lastly, the prospect of PMSM is presented.

In recent years, many patents have been devoted to developing methods and means of producing driving force in different types of underwater vehicles. This paper considers fish-like designs of underwater vehicles with oscillating tails and fins. On the base of dynamic analysis of a robotic fish motion, two original methods to produce driving force have been recently patented. The first method is based on the cyclic variation of the effective working area of the fin during the operation of a propulsive device. The optimal control law for variation of an additional area of a vibrating fin has been found. It is shown that the realization of this law ensures maximal positive impulse of driving forces and minimizes energy losses. New designs of one-tail and two-tail propulsive devices with varying working area of vibrating fin have been patented. In accordance with another developed method, driving force is produced by an internal two-stage gyroscopic device. In this case, vibrations of the tail of the fish are generated due to the action on it of reaction torque from a swinging internal high speed rotor with two degrees of freedom. The proposed device has no external moving parts; therefore, its operation in various surroundings becomes more reliable and effective. The results of theoretical study are confirmed by experiments with robot fish models.

In recent years, significant patents have been devoted to developing nanotechnology in industry since materials with sizes of nanometers possess unique physical and chemical properties. Due to recent advances in nanotechnology, a new class of heat transfer fluids called nanofluids was discovered. A nanofluid is a mixture produced by dispersing metallic nanoparticles in low thermal conductivity liquids such as water, oils, lubricants and others to enhance the heat transfer performance. Many patents have been devoted to the methods of preparation of new nanofluids heat transfer. Nanofluids are now being developed for medical applications, including cancer therapy and safer surgery by cooling. In this paper, a study of a boundary layer flow and heat transfer characteristics of an incompressible nanofluid flowing over a permeable uniform heat flux surface moving continuously in the presence of radiation is reported. The Rosseland diffusion approximation is used to describe the radiative heat flux in the energy equation. The resulting system of non-linear ordinary differential equations are solved numerically using a finite difference method. Numerical results are obtained for the velocity, temperature and nanoparticles volume fraction profiles, as well as the friction factor, local Nusselt number and local Sherwood number for several values of the parameters, namely the velocity ratio parameter, suction/injection parameter, Brownian motion parameter, thermophoresis parameter and radiation parameter. It is found that an increase in either of the Brownian motion parameter or the thermophoresis parameter leads to reductions in the local Nusselt number and the local Sherwood number. In addition, increasing either of the suction/injection parameter or the radiation parameter causes enhancements in both the local Nusselt number and the local Sherwood number.

Transient boundary layer flow and heat transfer of a viscoelastic fluid due to non-linearly stretching surface subject to a power-law surface temperature are investigated numerically. The dimensionless unsteady, coupled and nonlinear partial governing differential equations are solved by an implicit finite difference scheme of Crank-Nicolson type. The effects of various parameters entering into the problem on the flow and heat transfer transient characteristics are studied. It was found that, the velocity inside the boundary layer increases as the viscoelastic parameter increases, and accordingly the skin friction coefficient increases. Meanwhile, an opposite behavior is observed for the temperature profiles. The power-law index has significant influences on the temperature profiles and the Nusselt. The computed numerically results are compared with previously reported work and were found to be in excellent agreement. This paper is the first attempt in introducing the heat transfer of a viscoelastic fluid due to non-linearly stretching surface subject to a power-law surface temperature and this model is essential in many patents based on drawing devices for viscoelastic fluid over a non-linearly stretching surface subject to a power-law surface temperature.

In recent years, a number of patents have been devoted to the development of flat-panel speakers. Among them, one patent is about the use of interior elastic restraints to help stabilize the motion and smooth the sound pressure level (SPL) curves of flat-panel speakers. It is important that the sound radiation behavior of a flat-panel speaker can be accurately predicted when the optimal system parameters of the speaker are to be determined. In this paper, a simple yet effective method constructed on the basis of the Rayleigh-Ritz method and the first Rayleigh integral is presented for the vibroacoustic analysis of flat-panel speakers with masses attached to the interior elastic restraints of the speaker. In the proposed method, the interior elastic supports are modeled as discrete springs and the masses at the interior restraints are treated as lumped masses attached to the back surface of the plate. The displacement field of the sound radiation plate of the speaker is formulated on the basis of the first-order shear deformation theory. The accuracy of the proposed method has been validated by the experimental SPL curves of an orthotropic flat-panel speaker with interior elastic restraints at different locations and having various attached masses. The effects of the locations of the interior elastic restraints and the magnitudes of the attached masses on the sound radiation characteristics of the orthotropic speaker are studied using the proposed method. It has been shown that the proper use of attached masses in the design of flat-panel speakers can help improve the SPL curves of the speakers.

In recent years, large numbers of patents have been devoted to evaluating the dynamic characteristics of coupled double-rotor spindle system of high speed grinder for significant improvement in both the removal rate and quality of grinding. This study was focused on the theoretical modeling and numerical simulation about the dynamic characteristics of coupled double-rotor spindle system of high speed grinder. The influences of the grinder spindle's major structural parameters on its critical speed and vibration mode were investigated. The results showed that the critical speeds of coupled double-rotor system were arranged in a similar increasing order as to those of each single rotor. It was thus indicated that the critical speeds of each order for coupled double-rotor system corresponded to those of single rotor. Furthermore, we analyzed the effect of preload of bearing, overhang length, span of bearing, rotor structure and mass of spindle system on critical speeds of various orders for the coupled spindle system. The results showed that increased bearing rigidity could increase critical speeds of each order and the effect of overhang length of coupled rotors was the superimposition of effect of single rotor on critical speeds of each order of the coupled double order system. The critical speeds of spindle system of coupled double-rotor system could be decreased by increasing the mass of its spindle system.

Patents record the continuous development of the disk brake. The disk brake is widely used as a brake device in the car and other vehicles. To enhance the braking stability of the disk brake, and acquire optimal structure parameters, we built the finite element (FE) models of the disk brake to conduct the constrained modal analysis; the first six order natural frequencies and vibration mode of each part were obtained, which indicated the third-order frequency of the friction disk and the second-order frequency of the caliper to be very close, easily leading to resonance of the system. The collaborative optimization was then carried out by using optimization algorithm; the optimal results showed the probability of the resonance to be reduced, where the braking stability of the system is enhanced.

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......