Search Results

Passenger air bag mounting (PAB) and packaging have been a concern for the Automotive Industry for the last several years. The newer designs of instrument panels are sleeker, smaller and more like fighter plane cock pits. The tighter package size and convoluted instrument panel surfaces require better dimensional control of the air bag mounting locations. The fit and finish of the air bag door is influenced by the position of the air bag housing. The magnesium die cast housing used for the 1996 Chrysler Minivan is one of the keys to the successful seamless passenger door and sweeping I/P surface.

The need for fuel economy gains is crucial in todays automotive market. There is also growing interest and knowledge of greenhouse gases and their effect on the environment. Paulstra's magnesium powertrain brackets were a solution that was presented not just to reduce the weight of the engine mounting system (which was already under its weight target before magnesium introduction), but in response of the OEM's desire to further reduce the weight of the vehicle for CAFE and weight class impact. This new engine mounting system has three powertrain mount brackets that are high-pressure die cast AZ91D magnesium alloy. This paper will show that these brackets to have a dramatic weight reduction compared to the standard aluminum die-cast material that they replaced. This paper describes the process of approval: concept and material sign-off by the OEM, FEA for strength and modal performance, corrosion, and the final product.

A method for refining magnesium scrap which produces consistent, high quality magnesium metal has been developed. High quality magnesium metal is defined in this paper as metal which has heavy metal contaminants controlled within high-purity ASTM chemical specification, and is relatively free of internal impurities such as non-metallic inclusions (oxides and flux) and dissolved gas. The refining process utilizes a protective gas atmosphere, inert gas sparging and filtration techniques, rather than salt based fluxes, to remove both non-metallic inclusions and dissolved gases. Experimentation results of this refining process indicate magnesium scrap can be remelted and refined to a quality equal to or better than virgin ingot, without the introduction of salt based fluxes or a large capital investment.

The manufacturing of magnesium wheels has created interest since the mid 1930's.1 The potential weight savings and the benefits related to these are pressing engineers to come up with wheel designs and manufacturing processes that can meet the customers quality and cost requirements. The objective of this work is to develop the expertise and knowledge on the design and the fabrication of a sandcast magnesium wheel, 381 mm diameter X 165 mm (6.5 J X 15 in.). Results for the conventional Al-Zn alloy and the Zn-Zr-RE alloy that provides better pressure tightness because of its lower tendancy to microporosity are presented. General design factors are discussed as well as the various quality assurance operations. By better understanding the effects of the design and process parameters, the expertise developed in this program may serve as a first step in the development of a competitive process for high volume production of magnesium wheels.

The production of reinforced plastic/composites is projected at a 21% growth rate, primarily due to better public acceptance, low capital requirements, a wide range of fabricating methods, and technological breakthroughs. The properties obtained in RP/composites are dependent on types of resin, filler, and fiber used, with the type, orientation, length, and percentage of fiber being the key to its usefulness. Examined in detail are the methods used to fabricate fiber reinforced plastics and the effects of the various methods on the types of properties that can be obtained. In analyzing the competitive use of magnesium and reinforced plastics for lawnmower decks, price advantages were apparent in the use of RP, but product performance was unsatisfactory. The author concludes that complementary use of metals and RP will provide means whereby products can be created that will satisfy the market best.

As a common structural metal, magnesium is in its youth, coming into general use only after World War II. On the other hand, its serviceability as an automotive material was first proved in Germany during the 1930’s. This paper traces the history of one of the oldest applications of a relatively new metal by reference to a number of historical events, or mileposts, which clear the way for its large scale use in automobiles.

This paper provides an assessment of many factors which will be important in the successful use of magnesium in automotive components. Included in this comprehensive and extensively documented review are the subjects of magnesium availability, price, energy requirements, properties, manufacturing processes, safety and applications. Potential advantages and problems are highlighted with the hope that this information will aid in the selection and development of components which best utilize the unique characteristics of this lightweight metal.

Many new opportunities are opening up for the use of magnesium alloys in automotive drive train components due to (1) increasing requirements for vehicle weight reduction, (2) better understanding of magnesium's unique physical properties, (3) improvements in magnesiums's corrosion resistance, (4) advancements in magnesium die casting techniques, and (5) magnesium's excellent safety record.

Volvo LCP 2000 is the result of a project study for advanced technology, design and materials development. One of the fundamental ideas of the project has been to take into consideration the energy consumption throughout the entire service life of the car. A light car built out of light materials such as magnesium has contributed to a low total energy consumption. The Volvo LCP 2000 contains a total of about 50 kg magnesium alloys (7% of gross weight). Examples of components made out of magnesium are the transmission and clutch housings, wheels, steering rack housing, rear suspension arms, subframe and the cylinderblock. Surface coating and corrosion of magnesium have been studied in laboratory and by vehicle tests. Corrosion protection of chassis components, creep, relaxation and fatigue strength at elevated temperatures are the most critical properties. This paper highlights some results based on the project studies concerning surface coating, corrosion and strength properties.

Magnesium die casting alloys have the mechanical properties of metals, yet are lightweight like plastics and offer the designer a wide variety of applications. Plastics have previously been considered the most cost effective material for components that have limited mechanical requirements. Also, plastics' past history of being lightweight and easy to manufacture has made them attractive. However, in many instances, using magnesium instead of plastics offers a less expensive part that is much stronger, stiffer, just as lightweight and often easier to manufacture.

For many years cast magnesium alloy components requiring extensive machining have found application in many industries. Unfortunately, those least familiar with magnesium continue to regard its machining as a highly dangerous undertaking. Consequently, magnesium in part because of “safety considerations” has been ruled out of a number of applications where it should have been the material of choice. This paper discusses the machining characteristics of magnesium and the safe handling and disposal of chips.

Die castings made from light weight magnesium alloys have excellent mechanical properties and can be substituted for heavier materials of construction to reduce the weight of functional components. New developments in the areas of fluxless melting and hot chamber die casting have brought significant cost reductions to the processing of magnesium die castings and have made them competitive with die castings of other materials. With their proven record of serviceability in automotive applications, and with an excellent supply of alloy for new applications, magnesium die castings offer the automotive engineer an outstanding means to meet the challenge of vehicle weight reduction.

Vehicle weight reduction accelerated in importance following the 1973 oil crisis. The Ford Motor Company reduced average vehicle weight by approximately 1000 pounds between 1975 and 1980 through downsizing, design efficiencies and material substitutions. This emphasis on vehicle downsizing and weight reduction has provided an opportunity to evaluate magnesium against conventional U.S. automotive materials.. This paper describes magnesium’s advantages and disadvantages for automotive and assesses its future role in weight reducetion. Magnesium’s potential is analyzed from a business standpoint including cost/supply, technical and timing issues.

New global regulations are being implemented, with the intent of reducing pollutants, greenhouse emissions, and continuing improvements in fuel economy. This has caused OEMs to accelerate vehicle electrification in recent years. One of the key components of the electric drive unit is an electric motor (eMotor) constructed with a significant amount of magnet wire (MW). The MW is composed of a copper wire coated with a polymeric insulation material. Other insulation materials found in the eMotor are slot liner, wedge, phase separator, heat shrinkable materials, varnish, etc. However, MW compatibility with electric transmission fluids (ETFs) is the most important performance criteria as poor compatibility can lead to a decrease in performance, electrical short, and even cause catastrophic eMotor failure. This paper discusses new insights gained around MW compatibility with various ETFs.

The new fuel efficiency and emission standards have forced OEMs to put emphasis on different strategies such as engine downsizing, cylinder deactivation… Unfortunately these new technologies may lead to increased powertrain vibrations generated by the engine and transmitted to the chassis and the car cabin, such that their reduction or elimination has become a key topic for the automotive industry. The use of active engine mounts, acting directly on the fluid of an hydromount, or active vibration dampers, acting as an inertial mass-spring system, are very effective solutions, particularly when using electromagnetic based actuators. Nevertheless, all electromagnetic actuators technologies are not equals and the choice of such actuators must be considered carefully by taking into account the full performances and the overall cost of the solutions. This paper presents an electromagnetic actuator technology, that can be considered as the best tradeoff between performances and cost.

The magnetic bearing control system development and integrated system test results are presented for a high speed, high power Switched Reluctance Machine (SRM) Starter/Generator (S/G). The SRM rotor is suspended on magnetic bearings in a single shaft gearless/oilless configuration operating at 42,000 RPM. The SRM sub-system consists of a 6/4-pole machine with dual-power inverters rated at 250 KW (max), 270Vdc with split bus configuration. The magnetic bearing sub-system actively controls the rotor position in five axes (four radials and one axial). The bearing subsystem consists of homo-polar type magnetic bearing actuators with permanent magnet (PM) bias, inductive position sensors, DSP-based embedded controller and PWM current drivers for each control axis. The development and implementation of Single Input Single Output (SISO) and Modal control laws are presented.

Methods of freely, magnetically, suspending rotors in air, in various media, and in a vacuum are described. Rotors weighing from 10−6 lb to over 100 lb have been suspended and spun, but both larger and smaller rotors can be employed. Rotor speeds in excess of 106 rps and centrifugal fields of over 109 g have been obtained. When “coasting” freely in air at a pressure of 10−9 torr, ḟ/f ~ 10−9 sec−1, were ḟ is the loss in rotor speed per second at a speed “f.” A double magnetic suspension also will be described.

This paper assesses the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 % (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems.

This paper describes a dual-track magnetic crankshaft and camshaft position sensor configuration. It uses semiconductor sensors such as magnetoresistors to pick up the magnetic flux modulation created by a toothed wheel rotating across a permanent magnet. This sen-sor's magnetic configuration, with a complementary geometry, enhances the accuracy and repeatability of the position pulses. This is critical in obtaining the engine-velocity measurement precision necessary to detect engine misfires as mandated by the OBD-II legislation. The complementary geometry also makes for a more robust design. Finally, the concept can be used for cam-shaft position sensing, with power-on capability.

Power sources based on magnetic energy derived from superconductivity have been considered for commercial utility power, air and ground mobile power uses, and spacecraft applications [1]. The advent of high temperature superconductors has reduced one of the penalties of superconducting magnetic energy storage in that the refrigeration and cryocontainers become greatly simplified. Still, structural and current density issues that limit the energy density and size of the superconducting inductors do not change. This paper covers basic principles of magnetic energy storage, structure requirements and limitations, configurations of inductors, attributes of high-Tc superconducting materials including thermal instabilities, a relative comparison with the state-of-the-art high energy density power sources, and refrigeration requirements.