Denso

About: Denso is a company organization based out in Southfield, Michigan, United States. It is known for research contribution in the topics: Signal & Internal combustion engine. The organization has 20832 authors who have published 29150 publications receiving 253556 citations. The organization is also known as: Denso Corporation & Nippon Denso Co. Ltd..

Lead-free piezoceramics

Abstract: Lead has recently been expelled from many commercial applications and materials (for example, from solder, glass and pottery glaze) owing to concerns regarding its toxicity. Lead zirconium titanate (PZT) ceramics are high-performance piezoelectric materials, which are widely used in sensors, actuators and other electronic devices; they contain more than 60 weight per cent lead. Although there has been a concerted effort to develop lead-free piezoelectric ceramics, no effective alternative to PZT has yet been found. Here we report a lead-free piezoelectric ceramic with an electric-field-induced strain comparable to typical actuator-grade PZT. We achieved this through the combination of the discovery of a morphotropic phase boundary in an alkaline niobate-based perovskite solid solution, and the development of a processing route leading to highly textured polycrystals. The ceramic exhibits a piezoelectric constant d33 (the induced charge per unit force applied in the same direction) of above 300 picocoulombs per newton (pC N(-1)), and texturing the material leads to a peak d33 of 416 pC N(-1). The textured material also exhibits temperature-independent field-induced strain characteristics.

Enhancement of Piezoelectric Response in Scandium Aluminum Nitride Alloy Thin Films Prepared by Dual Reactive Cosputtering

Abstract: Adv. Mater. 2009, 21, 593–596 2009 WILEY-VCH Verlag Gm The industrial demand for higher-temperature piezoelectric sensors is drastically increasing, for the control of automobile, aircraft, and turbine engines and the monitoring of furnace and reactor systems, because environmental problems, such as carbon dioxide (CO2) and nitrogen oxide (NOx) reduction, are becoming more globally serious. The sensors are also desirable for health monitoring coal-fired electric-generation plants and nuclear plants. It is generally known that piezoelectric materials with a higher Curie temperature possess a lower piezoelectric coefficient. Furthermore, the results of a study (Fig. 1) of the relationship between maximum use temperature and piezoelectric coefficient d33 shows that the piezoelectric materials with a higher maximum use temperature possess a lower piezoelectric coefficient d33. [3–9] For example, the Curie temperature and piezoelectric coefficient d33 of lead zirconium titanate (PZT), which is widely used in many electronic devices, are 250 8C and 410 pCN , respectively. The maximum use temperature and d33 of aluminum nitride (AlN), which is a typical hightemperature piezoelectric material, are 1150 8C and 5.5 pCN . It is difficult to achieve a good balance between high maximum use temperature and large piezoelectricity in a material, and no effective piezoelectric materials with these characteristics have yet been found. In this communication, we report a hightemperature piezoelectric material that exhibits a good balance between high maximum use temperature and large piezoelectricity. This was achieved by the combination of the discovery of a phase transition in scandium aluminum nitride (ScxAl1 xN) alloy thin films and the use of dual co-sputtering, which leads to nonequilibrium alloy thin films. Sc0.43Al0.57N alloys exhibit a large piezoelectric coefficient d33 of 27.6 pCN , which is at least 500% larger than AlN. The large piezoelectric coefficient d33 is the highest piezoelectric response among the tetrahedrally bonded semiconductors, despite the fact that the crystal structure of scandium nitride (ScN) is rock-salt (nonpolar). Moreover, the large piezoelectricity is not changed by annealing at 500 8C for 56 h under vacuum. This work demonstrates the new route to design of this high-temperature piezoelectric material. ScN has a rock-salt structure (nonpolar). However, Takeuchi reported the existence of a (meta)stable wurtzite structure in ScN, and the possible fabrication of Sc-IIIA-N nitrides by firstprinciples calculations. Farrer et al. predicted that the wurtzite structure is unstable in ScN, and that the hexagonal structure is (meta)stable in ScN, unlike the wurtzite structure. The piezoelectric responses of hexagonal ScxGa1 xN and ScxIn1 xN alloys can be enhanced by an isostructural phase transition (from wurtzite to layered hexagonal). However, the piezoelectric responses and Curie temperatures of the nitride alloys have not yet been confirmed by experiments. AlN, GaN, and InN are IIIA nitrides and have a wurtzite structure (polar). In particular, the thermal stability and piezoelectricity of AlN are the highest among the IIIA nitrides. AlN is a piezoelectric material compatible with the Complementary metal–oxide– semiconductor (CMOS) manufacturing process, and is a promising material for integrated sensors/actuators on silicon substrates. Wurtzite and rocksalt structures have rather different lattice forms and unit sizes. The formation of

Alternator for vehicle

Abstract: It is an object of this invention to provide an alternator for a vehicle in which all electric conductors forming bridge portions are sufficiently exposed to cooling winds so that the cooling performance is remarkably improved. It is another object of this invention to provide an alternator for a vehicle which is excellent in cooling performance, insulating characteristic, and heat resisting property. An alternator for a vehicle includes a stator. The stator includes an iron core 22, an electric conductor 21, and an insulator 23. The electric conductor 21 forms a winding on the iron core 22. The insulator 23 provides electric insulation between the electric conductor 21 and the iron core 22. The stator is supported by a housing. The dimension of openings of slots in the iron core 22 is smaller than the distance between inner side surfaces of the slots. The electric conductor 21 has accommodated portions accommodated in the slots, and bridge portions connecting the accommodated portions. Pieces of the electric conductor which extend out of the slots are approximately separated into a conductor groups 21f located on outer radial sides of the slots and a conductor group 21g located on inner radial sides of the slots, and form the bridge portions. Predetermined gaps are provided between pieces of the electric conductor in the bridge portions. The bridge portions have ridge portions inclined in a same circumferential direction in each of the outer radial side and the inner radial side, and top portions connecting the ridge portions along an axial and radial direction.

Vehicle control algorithms for cooperative driving with automated vehicles and intervehicle communications

Abstract: Describes the technologies of cooperative driving with automated vehicles and intervehicle communications in the Demo 2000 cooperative driving. Cooperative driving, aiming at the compatibility of safety and efficiency of road traffic, means that automated vehicles drive by forming a flexible platoon over a couple of lanes with a short intervehicle distance while performing lane changing, merging, and leaving the platoon. The vehicles for the demonstration are equipped with automated lateral and longitudinal control functions with localization data by the differential global positioning system (DGPS) and the intervehicle communication function with 5.8-GHz dedicated short range communication (DSRC) designed for the dedicated use in the demonstration. In order to show the feasibility and potential of the technologies, the demonstration was held in November 2000, on a test track with five automated vehicles. The scenario included stop and go, platooning, merging, and obstacle avoidance.

Ultrahigh-quality silicon carbide single crystals

Abstract: Silicon carbide (SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for next-generation electronic devices. Careful consideration of the thermal conditions in which SiC [0001] is grown has resulted in improvements in crystal diameter and quality: the quantity of macroscopic defects such as hollow core dislocations (micropipes), inclusions, small-angle boundaries and long-range lattice warp has been reduced. But some macroscopic defects (about 1-10 cm(-2)) and a large density of elementary dislocations (approximately 10(4) cm(-2)), such as edge, basal plane and screw dislocations, remain within the crystal, and have so far prevented the realization of high-efficiency, reliable electronic devices in SiC (refs 12-16). Here we report a method, inspired by the dislocation structure of SiC grown perpendicular to the c-axis (a-face growth), to reduce the number of dislocations in SiC single crystals by two to three orders of magnitude, rendering them virtually dislocation-free. These substrates will promote the development of high-power SiC devices and reduce energy losses of the resulting electrical systems.