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The Cummins 5.0L V8 Turbo Diesel which makes its debut in the upcoming 2016 Nissan Titan XD full-size pickup truck (earlier post) features a unique Cummins M² Two-Stage Turbocharger and is configured to work well at both low and high engine speeds.
The series sequential turbocharging system, involving two differently sized turbochargers, effectively provides a small turbocharger for low air flow requirements and a large turbo for high air flow. The small turbo delivers good transient response due to its low inertia, while the large turbo maintains power at higher engine speeds. This helps eliminates turbo lag, providing a continuous delivery of peak torque through the RPM range.
In order to control the air flow between the two turbochargers, the new M² system from Cummins Turbo Technologies uses a patented rotary valve to open ports that perform the bypass or waste-gate functionality and provide exhaust after-treatment thermal management.
In a study investigating switched reluctance motors (SRMs) for in-wheel motor applications, researchers at Chongqing University in China have found that the vertical component of the residual unbalanced radial force of the motor deteriorates the lateral and anti-rollover stabilities of the vehicle in addition to having a considerable impact on vehicle comfort. (The unbalanced radial force is the radial force difference between a pair of opposite stator poles.)
In their paper, published in the Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, they suggest that a control method addressing these issues will be needed if SRMs are to see use in in-wheel applications. In an earlier paper, members of the team had proposed the use of an FxLMS (filtered-X least mean square) controller based on active suspension system to generate controllable force to suppress the vibration caused by SRM vertical force. In that paper, they found that utilizing active suspensions could reduce the effect of SRM vertical force on suspension performance.
In a switched reluctance motor (SRM), torque is produced by the magnetic attraction of a steel rotor to stator electromagnets; there are no permanent magnets, and the rotor carries no windings. A controller energizes each stator winding only when it can produce useful torque. With suitable timing of the stator excitation, the machine can operate as a motor or generator. Switched reluctance motors are simple, inexpensive, robust and can offer very good efficiency over a wide load range.
SRMs also offer a high torque density, high operating efficiency, and excellent power-speed characteristics. Accordingly, there is some interest in exploring their use as vehicle traction motors. As one example, Cobham Technical Services is collaborating with Jaguar Land-Rover (JLR) and engineering consultancy Ricardo UK to develop a switched reluctance traction motor. (Earlier post.)
However, one of known challenges with SRM devices is delivering a torque-dense motor that is quiet enough for vehicle use. While SRMs can have very high power density at low cost, they have had issues with high torque ripple when operated at low speed, and the acoustic noise caused by torque ripple and vibrations.
Unbalanced radial force caused by rotor eccentricity may degrade the performance of SRM, increasing vibration and acoustic noise. In practice, some degree of rotor eccentricity is always present due to the tolerances introduced during the manufacturing process, wear of bearings, and static friction especially when the rotor is sitting idle, as well as other reasons. The air gap of the SRM is generally between 0.2 and 1 mm which is much smaller than any other type of motor and is more sensitive to rotor eccentricity. A relative eccentricity between the stator and rotor of 10% is common. On the other hand, SRM unbalanced radial force will be magnified by the vehicle continuously idling, road excitation, and unbalanced load. This phenomenon is particularly serious to IWM-EV [in-wheel motor electric vehicles], because the vertical component of SRM unbalanced radial force, namely, SRM vertical force, applies directly on vehicle wheels and will change the tire load. Although SRM unbalanced radial force is inevitable and serious, the contributions of SRM unbalanced radial force to IWM-EV stability and comfort have not been studied thoroughly yet.—Wang et al. (2014)
The eccentric positioning of the SRM creates unbalanced electromechanical radial forces due to asymmetrical magnetic pull. In a 6/4 outside-rotor SRM: Left: The eccentric rotor overlap stators 2 and 5. Right: The eccentric rotor overlap stators 1 and 4. Wang et al. (2014). Click to enlarge.
In the new study, Wang et al. specifically examined the role of the vertical force of the switched reluctance motor in the stability and comfort analysis for in-wheel-motor-driven electric vehicles.
The results in this paper indicate that the vertical force of the switched reluctance motor has a great effect on the lateral and anti-rollover stabilities of the vehicle. The direct cause of this phenomenon is that the vertical force of the switched reluctance motor is directly applied on the wheels, which will result in a significant variation in the tire load, and the tire can easily jump off the ground.
Furthermore, the frequency of the vertical force of the switched reluctance motor covers a wide bandwidth which involves the resonance frequencies of the vehicle body’s vibrations and the wheel bounce. As a result, the comfort of the vehicle is greatly harmed. Therefore, the effect of the vertical force of the switched reluctance motor on the the comfort of the vehicle is also considerable in some resonance situations. The conclusion is that the vertical force of the switched reluctance motor not only causes the stability of the vehicle to deteriorate but also has a considerable effect on the the comfort of the vehicle.—Wang et al.
Yan-yang Wang, Yi-nong Li, Wei Sun, Ling Zheng (2015) “Effect of the unbalanced vertical force of a switched reluctance motor on the stability and the comfort of an in-wheel motor electric vehicle” Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering doi: 10.1177/0954407014566438
Yan-yang Wang, Yi-nong Li, Wei Sun, Chao Yang, and Guang-hui Xu (2014) “FxLMS Method for Suppressing In-Wheel Switched Reluctance Motor Vertical Force Based on Vehicle Active Suspension System” Journal of Control Science and Engineering doi: 10.1155/2014/486140
Chemical company BASF has decided to exit the current R&D collaboration with Novozymes and Cargill to develop a bio-based process for producing 3-hydroxypropionic (3-HP) and acrylic acid from renewable raw materials. BASF joined the collaboration with Novozymes and Cargill in 2012. Novozymes and Cargill have collaborated on the project since 2008 and will continue their work to commercialize bio-based 3-HP and derivatives. The two companies have initiated efforts to find a new commercialization partner.
The partners said that the R&D cooperation on bio-based acrylic acid has achieved the technical and business targets. In 2013, the project accomplished the production of 3-HP in pilot scale, and in September 2014 announced the successful conversion of 3-HP to glacial acrylic acid and super-absorbent polymers.
Acrylic acid is a high-volume chemical that feeds into a broad range of products. One of the main applications is in the manufacture of super-absorbent polymers that can soak up large amounts of liquid and are used mainly in baby diapers and other hygiene products. Acrylic acid is also used in adhesive raw materials and coatings. Presently, acrylic acid is produced by the oxidation of propylene derived from the refining of crude oil.
Researchers at the University of Michigan, with colleagues at Ford and the Harbin Institute of Technology in China, have developed a dendrite-suppressing membrane exhibiting high modulus, ionic conductivity, flexibility, ion flux rates and thermal stability for Li-ion batteries by using a composite made from Kevlar-derived aramid nanofibres assembled in a layer-by-layer manner with poly(ethylene oxide).
In a paper published in Nature Communications, they report that the porosity of the ion-conducting membrane (ICM) is smaller than the growth area of the dendrites; the aramid nanofibers thus eliminate “weak links” where dendrites can pierce a membrane. The aramid nanofiber network also suppresses poly(ethylene oxide) crystallization detrimental for ion transport.
A U-M team of researchers also founded Ann Arbor-based Elegus Technologies to bring this research from the lab to market. Mass production is expected to begin in the fourth quarter 2016.
Dendrite growth threatens the safety of batteries by piercing the ion-transporting separators between the cathode and anode. Finding a dendrite-suppressing material that combines high modulus and high ionic conductance has been a major technological and materials science challenge.
Unlike other ultra strong materials such as carbon nanotubes, Kevlar is an insulator. This property is perfect for separators that need to prevent shorting between two electrodes.—Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering and corresponding author of the paper
While the widths of pores in other membranes are a few hundred nanometers, the pores in the membrane developed at U-M are 15-to-20 nanometers across. They are large enough to let individual lithium ions pass, but small enough to block the 20-to-50-nanometer tips of fern-like dendrite structures.
The special feature of this material is we can make it very thin, so we can get more energy into the same battery cell size, or we can shrink the cell size. We’ve seen a lot of interest from people looking to make thinner products.—Dan VanderLey, an engineer who helped found Elegus through U-M’s Master of Entrepreneurship program
Thirty companies have requested samples of the material.
Kevlar’s heat resistance could also lead to safer batteries as the membrane stands a better chance of surviving a fire than most membranes currently in use.
While the team is satisfied with the membrane's ability to block the lithium dendrites, they are currently looking for ways to improve the flow of loose lithium ions so that batteries can charge and release their energy more quickly.
The research was funded primarily by the National Science Foundation under its Chemical, Bioengineering, Environmental and Transport Systems and its Innovation Corp. Partial funding also came from Office of Naval Research and Air Force Office Scientific Research. Kotov is a professor of chemical engineering, biomedical engineering, materials science and engineering and macromolecular science and engineering.
Siu-On Tung, Szushen Ho, Ming Yang, Ruilin Zhang & Nicholas A. Kotov (2015) “A dendrite-suppressing composite ion conductor from aramid nanofibres” Nature Communications 6, Article number: 6152 doi: 10.1038/ncomms7152
Mitsubishi Motors Corporation (MMC) said it will unveil a world premiere compact SUV plug-in hybrid concept car on 3 March at the 85th Geneva International Motor Show.
Mitsubishi said that the compact SUV concept was designed to achieve top-of-class reduced CO2 emissions and features MMC’s @earth TECHNOLOGY stable of environmental technologies.
Mitsubishi’s Outlander SUV PHEV was the best selling plug-in hybrid electric vehicle in Europe in 2014, posting 19,980 units, or 52% of all 38,617 Outlander models sold into that market. Top selling national markets for the Outlander PHEV in 2014 were: