Abstract Hybrid drivetrain hardware combines an electric motor and a transmission, gear box, or hydraulic unit. With many hybrid electric vehicle (HEV) hardware designs the transmission fluid is in contact with the electric motor. Some OEMs and tier suppliers have concerns about the electrical properties of automatic transmission fluids (ATFs). Lubrizol has conducted a fundamental research project to better understand the electrical conductivity of ATFs. In this paper, we will present conductivity data as a function of temperature for a range of commercially available ATFs. All fluids had conductivities ranging from 0.9 to 8x10-9 S/cm at 100 °C and can be considered insulators with the ability to dissipate static charge. Next we will deconstruct one ATF to show the relative impact of the various classes of lubricant additives. We find that more polar additives have a larger effect on conductivity on a normalized (per weight %) basis.
Copper-Free NAO Brake Pad Formulation with Improved Electrostatic Paintability Based on Conductive Carbon Powders
Abstract A wide range of different carbon powders is available and currently used in friction materials like coke, graphite and carbon black. The effect of the type of carbon on braking performance has been extensively investigated in the past and it has been demonstrated that graphite can play an important role in copper-free brake pads. However, there are no studies about the influence of carbon powders on the processability of brake pads. Brake pads need to be painted in order to avoid corrosion. Typically electrostatic painting is used on an industrial scale, which requires the brake pads to be conductive. NAO brake pads (and especially Cu-free NAO brake pads) are rather insulating, and therefore difficult to paint. In this presentation we’ll show how special carbon powders can increase the electrical conductivity and therefore allow easy painting of brake pads. Based on these investigations, a new copper-free NAO formulation has been developed.
Surface Conductivity Measurement of Catalyst Materials by EUPS and Its Correlation to Catalyst Performance
Abstract Commercial three way catalysts (TWC) are designed to eliminate HC, CO and NOx pollutants emitted from gasoline powered internal combustion engines. TWC have been optimized over many years to meet ever more stringent emission regulations. It has long been speculated that surface electrical conductivity may be a key parameter in controlling catalytic activity, however until now it has not been possible to reliably measure this physical parameter on a catalytic surface. In this study, the surface electrical conductivity of catalyst powders, such as Rh/ CeO1-x-ZrxO2, Rh/ZrO2 and Rh/Al2O3, were measured by EUPS (Extreme Ultraviolet excited Photoelectron Spectroscopy). Then the measured electrical conductivity was compared with catalyst performance from CO-NO and water gas shift reactions which are important for controlling automobile exhaust emissions from gasoline vehicles.
Influence of Supply Voltage and Fuel Conductivity in the Lifetime of Commutation System by Brushes in Electric Flex Fuel Pumps
Abstract One of the usual measures to increase the energy efficiency in automotive vehicles has been the adoption of generators with variable voltage systems, commanded by the vehicle control unit. Thus, the vehicle system voltage no longer remains constant during operation of the engine, but becomes variable as needed to charge the vehicle electrical system and better use of available engine torque. A study using the Design for Six Sigma (DFSS) methodology was performed in order to understand the influence of the supply voltage and of the fuel conductivity in the lifetime of fuel pump commutation system by brushes. Durability tests were conducted in bench test, where parameters of temperature, current draw, voltage and fuel conductivity were monitored, correlating them with the results of wear in the pump commutation system.
Quantification of Interface Thermal Resistance and Prediction of Thermal Conductivity by Observation of Stereoscopic Filler Dispersion in Polymer Composites
Abstract In electronic products, the recently increasing thermal radiation demands higher thermal conductivity of polymer composites. However, inaccurate observation of the filler dispersion within the polymer does not allow for accurate quantification of Interface Thermal Resistance and subsequently the prediction of thermal conductivity. Therefore, optimum filler design could not be achieved. Firstly in this report, accurate stereoscopic filler dispersion was observed by FIB-SEM. Secondly, quantification of Interface Thermal Resistance could be achieved by thermal conduction analysis using filler dispersion model. Thirdly, this Interface Thermal Resistance enabled the prediction of the thermal bulk conductivity. Lastly, the prediction made above could be validated by comparison of predicted value to measured value. This result may lead to optimum filler design and thereby to the development of higher thermal radiation materials.
Abstract As the world is going through an evolutionary development in most of the science fields, there is an essential and exceptional demand for higher efficiency power generators to recover the thermal losses. Recently thermoelectric materials have attracted extensive attention for this purpose. The recent advancement in nanotechnology has a remarkable impact on thermoelectric materials development. This resulted in nano structured materials whose thermoelectric properties exhibit a great challenge to its bulk form, such as Silicon nanowires (SiNWs). Silicon nanowires are promising thermoelectric materials as they offer large reductions in thermal conductivity over bulk Si without significant decrease in the electrical conductivity. In the present work silicon nanowires have been implemented in fabricating a thermoelectric device which can be employed in different applications, such as engines, to recover part of the energy lost in these applications.
Abstract Effectiveness of current electromagnetic shielding techniques in composite aircraft has been called into question several times before and is a subject of interest and research in the aerospace industry. We present an analytical approach to understand the issues in detail. It was found using first order approximations that a panel with Aluminum expanded metallic foil (ExMF) along with carbon fiber plies used on composite aircraft provides fair albeit lower electromagnetic shielding from source frequencies of a few KHz until well into MHz range when compared to an aluminum panel used on metallic aircraft. This was primarily attributed to relatively large skin depth value at low frequencies which was due to: a) low electrical conductivity of aluminum ExMF when compared to bulk aluminum; b) low electrical conductivity of resin impregnated carbon fiber layers and; c) very thin layer of aluminum ExMF used.
Development of High Strength, High Thermal Conductivity Cold Sprayed Coatings to Improve Thermal Management in Hybrid Motorcycles
Abstract The deposition of thick, pore-free, high-performance copper alloy matrix composite coatings is a topic of interest for several industrial applications, including friction materials, high-strength electrical contacts, and welding electrodes, among others. This study investigates the use of cold spray to deposit CuCrZr/Al2O3 cermet coatings on aluminum alloy 6060. The objective is to integrate copper-based materials with aluminum-based materials, ensuring a high degree of mechanical and thermal contact, using a low temperature process that does not adversely affect the properties of the base materials. This technique can be used to produce integral coolers and aluminum-based bearings for automotive and motorcycle applications. Fused and crushed alumina and gas-atomized CuCrZr powder blends have been used as initial feedstocks, with compositional weight ratios of 65/35 and 80/20 (ceramic/metal).
Abstract Nanofluid is a new class of heat transfer fluids containing nano-sized particles, fibers, or tubes that are stably suspended in a carrier liquid. They possess very high potential technological significance which is yet to be realized. This paper intends to provide a brief overview of area of effectual applicability of nanofluids in automotive application. Investigation and research studies pointing out the significance of nanofluids, emphasizing their improved heat transfer properties that are controllable and their specific characteristics that make them suitable for such application have been reviewed and presented. The synergy within an integrated experimental and analytical approach is being used to guide the development of nanofluids with improved effectiveness and applicability in automotive application.
Multi-Layer Insulation (MLI) is the thermal insulation typically used in spacecraft or any other devices that are exposed to both extreme heat and cold. MLI blankets work to protect delicate internal and external applications from UV radiation, atomic oxygen, and mechanical stresses by using Teflon coated fiberglass cloth. The layers are usually made of a film made out of polyester or polyimide with vapor deposited layers of aluminum on one or both sides of the film to form reflector layers. These reflectors are separated by materials with low thermal conductivity. All the layers simply protect the system by preventing excessive heat loss from inner components and excessive heating from outer sources. Typically, MLI blankets are divided into a cover or outer layer, a reflector, a separator layer, an inner layer, and it has hardware installed to pass electrical charge from the surface of the blanket.
Reducing Temperature Gradients in High-Power, Large-Capacity Lithium-Ion Cells through Ultra-High Thermal Conductivity Heat Spreaders Embedded in Cooling Plates for Battery Systems with Indirect Liquid Cooling
For lithium-ion battery systems assembled with high-capacity, high-power pouch cells, the cells are commonly cooled with thin aluminum cooling plates in contact with the cells. The cooling plates extract the cell heat and dissipate it to a cooling medium (air or liquid). During the pack utilizations with high-pulse currents, large temperature gradients along the cell surfaces can be encountered as a result of non-uniform distributions of the ohmic heat generated in the cells. The non-uniform cell temperature distributions can be significant for large-size cells. Maximum cell temperatures typically occur near the cell terminal tabs as a result of the ohmic heat of the terminal tabs and connecting busbars and the high local current densities. In this study, a new cooling plate is proposed for improving the uniformity in temperature distributions for the cells with large capacities.
Polyamide 6(PA6)/hexagonal boron nitride(h-BN) and polyphenylene sulfide(PPS)/graphite composites have been prepared to investigate the possible usage as battery housing materials. The addition of the highly conductive filler improved thermal conductivity of polymer matrix more than 2 times. On the basis of the experimental results and intrinsic material parameters, thermal behavior in a battery pack has been monitored by computational simulation. The heat generated within a cell was readily dissipated as a highly thermal conductive aluminum(Al) was used and thus the temperature was evenly distributed over a whole package. In the case of a battery pack made of polymer or polymer composites, on the other hand, the temperature inside cell is much higher due to the accumulation of heat. The predicted heat flow behavior may be useful in selecting proper housing materials.
It may be possible to simplify the structure and control systems of a lithium-ion battery by replacing the conventional liquid electrolyte with a solid electrolyte, resulting in higher energy density. However, power performance is a development issue of batteries using a solid electrolyte. To increase battery power performance, in addition to lithium ionic conductivity within the bulk of the electrolyte, it is also necessary to boost the lithium ionic conductivity at the interface between the electrode active material and the electrolyte, and to boost electron and lithium ionic conductivity within the cathode and anode active material. This research studied the mechanism of resistance reduction by electrode surface modification. Subsequently, this research attempted to improve electron conductivity by simultaneously introducing oxygen vacancies and carrying out nitrogen substitution in the crystalline structure of the Li4Ti5O12 anode active material.
In order to make the wireless power transfer system, the fabrication process of coils and the design of electric insulation and high thermal conductive materials are proposed by taking high current inductor system as an analogy. The fabrication process of the coil is developed for high current inductors. The copper plate is pressed and folded double at two fulcrum points to produce coils. The developed process restrains the cracks in the coil, compared with the conventional process involving the bend of rectangular wire in the lateral direction. The electric insulation coatings on the coil are developed. The electrical breakdown strength of the developed coatings is slightly higher than that containing polyamideimides. The developed material has a higher thermal conductivity of 0.83 W/m K. The high thermal conductive potting materials are developed to use between the coil unit and the aluminum case.
Multiwall carbon nanotubes are an extremely small conductive additive for plastics. They are about 10 nanometers in diameter and 10 or more microns long. Their high aspect ratio (1000:1) allows equivalent conductivity at lower loading compared to carbon black, chopped carbon fiber or stainless steel fiber. The advantage of a lower additive loading is a greater retention of the inherent ductility of the resin. Additionally, the small size of the nanotubes, coupled with the low loading, results in a much smoother molded part surfaces than when larger additives are used. In this paper, we will present comparative data of physical properties, surface smoothness, moldability and electrical conductivity for compounds containing different conductive additives. Finally, existing and evolving commercial applications will be reviewed.
Proper lubrication of moving parts is a critical factor in internal combustion engine performance and longevity. Determination of ideal lubricant change intervals is a prerequisite to ensuring maximum engine efficiency and useful life. When oil change intervals are pushed too far, increased engine wear and even engine damage can result. On the other hand, premature oil changes are inconvenient, add to vehicle maintenance cost, and result in wasted natural resources. In order to determine the appropriate oil change interval, we have developed an oil condition sensor that measures the electrical properties of engine oil, and correlates these electrical properties to the physical and chemical properties of oil. This paper provides a brief background discussion of the oil degradation process, followed by a description of the sensor operational principles and the correlation of the sensor output with physical and chemical engine oil properties.