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The automotive pressure sensor is one of the most widespread applications of a micromachined device, and has evolved into a relatively mature technology, expanding beyond its original use as an engine control sensor into other vehicle control and diagnostic systems. The need for flexibility in various applications, low cost, high volume manufacturing capability, and survivability in harsh environments has strongly influenced sensor signal conditioning, calibration, element design, and packaging. Many of the issues affecting the development and commercialization of micromachined automotive pressure sensors are also relevant to other emerging microfabricated devices. This paper shows how the commercial success of a product using microfabricated technology is highly dependent upon other core competencies, beyond just the capability to perform the micromachining operations necessary to create the sensing device.

Using Loop Heat Pipes (LHPs) for controlling the temperature of the source of heat has been considered for many applications. However, traditional LHPs can require significant amounts of power for source temperature control. A number of techniques have been identified and implemented to reduce control power requirements. One of the very first design approaches was to thermally couple the liquid line bringing subcooled liquid from the condenser to the vapor line entering the condenser with a number of “coupling blocks”. In another application, a variable conductance heat pipe (VCHP) was used to couple the liquid line to the LHP evaporator. A third generation approach has been developed that offers even further reductions in control power. The paper discusses earlier generations of control power reduction approaches with their advantages and disadvantages. It also describes the third generation of the approach, which is currently in manufacturing.

This paper is going to discuss typical requirements for micromachined sensors. The most common examples today are pressure and acceleration sensors. We will discuss the function and applications of pressure and acceleration sensors. There are two differences between accelerometers and pressure sensors: sensor technology and signal conditioning. Pressure sensors employ bulk micromachining techniques where accelerometers use surface micromachining. Pressure sensors are typically signal conditioned with bipolar circuitry. Acceleration sensors use CMOS signal conditioning. We will also explain the electrical characteristics of both pressure and acceleration sensors along with mechanical package styles. We will be focusing our effort on automotive based applications. Some typical applications for pressure sensors in the automotive environment are MAP, BAP, lumbar seat, air bag and tire pressure. The requirements of the MAP/BAP application will also be discussed in detail.

This paper introduces the concepts utilized for the integration of a cryogenic capillary pumped loop into a flight experiment. The Cryogenic Capillary Pumped Loop (CCPL) version V, which was recently manufactured (9/97), is to be integrated into the Cryogenic Thermal Storage Unit (CRYOTSU) flight experiment as a secondary experiment. CRYOTSU, a Get-Away-Special (GAS) Can experiment, is currently manifested on STS-95 with an anticipated launch date of October 1998. The CCPL uses nitrogen as the working fluid with a 70-120 K operating temperature. The primary benefit of the CCPL is as a heat transport device in cryogenic bus systems. The primary issue of structurally supporting the CCPL while reducing parasitic heat loads will be detailed.

The ADRAD deployable radiator is in development at Swales Aerospace to provide additional heat rejection area for spacecraft without envelope impact. The ADRAD design incorporates ALPHA loop heat pipes, an aluminum honeycomb radiator with embedded condenser, OSR optical coating, spherical bearing hinges, pyrotechnic release devices and snubbers. This paper describes the design of ADRAD to a set of “generic” GEO requirements, including a nominal heat rejection capacity of 1250 W. Thermal, structural and mechanism considerations are described along with the comprehensive systems approach necessary to produce an integrated subsystem.

As features in vehicles and their associated loading on the vehicle's power supply increase, the existing 14V power supply system is being pushed to its limits. At some point it will be necessary to provide a complementary higher supply voltage for higher power loads to ensure reliable operation. Industry efforts have been underway to define the next step(s) toward a common architecture. These efforts are currently focused on a dual voltage 14V/42V system with specified voltage limits. A change in the vehicle's power supply voltage and over-voltage specifications have a direct impact on semiconductors. Cost, reliability, available process technology, and packaging are among the areas that are affected. Reducing or eliminating the load dump transient can provide cost reduction, especially for power switching devices. Smart semiconductor switches with integrated diagnostic and protection features provide the potential to replace fuses in the new architecture.

As the new generation of RISC powertrain MCUs propagate through the automotive development cycle, there will likely be more difficulty in debugging the ECU reliably and efficiently. Simply stated, there is less support for the development process in the new high-performance single-chip RISC MCUs, which could create critical and costly delays in the development cycle. Additionally, as powertrain MCUs continue to evolve, superscalar or multiple-issue RISC implementations may be used as the central processor. With the capability to issue multiple instructions in one clock cycle, this will only magnify the development support problem. Thus it is essential to address this impending problem with a strategy that both automotive and tools developers can agree. A strategy for development standards is presented in this paper, and a new powertrain MCU development interface standard is proposed.

The Earth Observing-1 spacecraft, built by Swales Aerospace for NASA's Goddard Space Flight Center (GSFC), was successfully launched on a Boeing Delta-II ELV on November 21, 2000. The EO-1 spacecraft thermal design is a cold bias design using passive radiators, regulated conductive paths, thermal coatings, louvers, thermostatically controlled heaters and multi-layer insulating (MLI) blankets. Five of the six passive radiators were aluminum honeycomb panels. The sixth panel was a technology demonstration referred to as the Carbon Carbon Radiator (CCR) panel. Carbon-Carbon (C-C) is a special class of composite materials in which both the reinforcing fibers and matrix materials are made of pure carbon. The use of high conductivity fibers in C-C fabrication yields composite materials that have high stiffness and high thermal conductivity.

A small SINDA/FLUINT logic routine was developed to improve upon standard spacecraft-to-instrument thermal model interface methodology for steady state analysis. Rather than the standard approach of providing backloads and/or conductive limits with uniform spacecraft temperatures, this methodology enables the instrument thermal engineer to make more informed design decisions by providing more information regarding the source and magnitude of the sink temperatures and backloads. The instrument thermal engineer can use the model information provided from the spacecraft thermal engineer to make more informed design decisions in subsequent analysis, and can be less dependent on the spacecraft thermal engineer.

The Spacecraft Radiative Thermal Model Exchange System is a technology developed for the bi-directional exchange of spacecraft radiative thermal models via the TMG thermal software package. It provides a means for quickly and accurately transferring models between TMG and theree of the major thermal radiation codes used in the spacecraft industry, particularly the ESARAD and Thermica packages, which are widely used by contractors to the European Space Agency, and the TSS code which is prevalent in the United States space industry. In order to reconcile element-based and primitives-based modeling approaches, this system includes an interactive primitives-based modeling system, enabling users to construct, import, and manipulate primitives-based radiation models in TMG.

A Small Loop Heat Pipe (SLHP) featuring a wick of only 1.27 cm (0.5 inches) in diameter has been designed for use in spacecraft thermal control. It has several features to accommodate a wide range of environmental conditions in both operating and non-operating states. These include flexible transport lines to facilitate hardware integration, a radiator capable of sustaining over 100 freeze-thaw cycles using ammonia as a working fluid and a structural integrity to sustain acceleration loads up to 30 g. The small LHP has a maximum heat transport capacity of 120 Watts with thermal conductance ranging from 17 to 21 W/°C. The design incorporates heaters on the compensation chamber to modulate the heat transport from full-on to full-stop conditions. A set of start up heaters are attached to the evaporator body using a specially designed fin to assist the LHP in starting up when it is connected to a large thermal mass.

This paper describes the development and testing status of several novel components and integration tools for space-based cryogenic applications. These advanced devices offer functionality in the areas of cryogenic thermal switching, cryogenic thermal transport, cryogenic thermal storage, and cryogenic integration. As such, they help solve problems associated with cryocooler redundancy, across-gimbal thermal transport, large focal plane array cooling, fluid-based cryogenic transport, and low vibration thermal links. The devices discussed in the paper include a differential thermal expansion cryogenic thermal switch, an across-gimbal thermal transport system, a cryogenic loop heat pipe, a cryogenic capillary pumped loop, a beryllium cryogenic thermal storage unit, a high performance flexible conductive link, a kevlar cable structural support system, and a high conductance make-break cryogenic thermal interface.

Like a Loop Heat Pipe (LHP), a Cryogenic Loop Heat Pipe (CLHP) is a passive two-phase heat transport system that utilizes the capillary pressure developed in a fine pore evaporator wick to circulate the system's working fluid. To demonstrate startup from a supercritical temperature and an operation below ambient temperature for passive bench cooling applications, a CLHP was developed and tested in a thermal vacuum chamber. The system requires startup from a maximum outgassing temperature of 335K over an operating temperature range of 215 to 218K, and an orbital average heat transport capability of 39W. Ethane was selected as the working fluid because it has heat transport properties that are suitable for the operating temperature of 218K. This paper provides a description of the CLHP concept, the development of the design including proof of concept development and testing of a CLHP designed to provide passive cooling of optical instruments.

Sophisticated electronic control unit (ECU) systems are required to achieve optimal performance in electric vehicles, especially in the areas of charge management and climate control. Some of the important control parameters for these systems include charge control and state of charge determination (SOC). Motorola's Automotive Group recently developed an electronic control unit (ECU) that controls and manages the heart of electric vehicles, the battery.

Now that the SAE J1850 recommended practice has essentially been completed, attention has turned to the message schemes which the network will be using. SAE J2178 has been developed to define the message strategy for SAE J1850 networks. This paper will describe the message strategy incorporated in SAE J2178 and possible transaction classes to drive SAE J1850 networks.

NASA's current vision for exploration dictates that radiators for a Crew Exploration Vehicle (CEV), a Lunar Surface Access Module (LSAM), and a lunar base will need to be developed. These applications present new challenges when compared to previous radiators on the Space Shuttle and International Space Station (ISS). In addition, many technological advances have been made that could positively impact future radiator design. This paper outlines new requirements for future radiators and documents a trade study performed to select some promising technologies for further evaluation. These technologies include carbon composites substrates as well as Optical Solar Reflectors (OSRs), a lithium based white paint, and electrochromic thin films for optical coatings.

Battery cell operating characteristics were determined for a unique load profile planned for the Motorola Iridium™ spacecraft. The Iridium™ mission requires that the battery be on line at all times and operated for extended periods with a short duration, high rate, charge/discharge duty cycle. The effort reported here reflects a repetitive duty cycle of 1.3 milliseconds discharge and 2.9 milliseconds charge, with discharge rates in the range 2.0 C to 3.0 C and charge rates in the range 0.9 C to 1.4 C. Cell transient characteristics were determined for candidate cell types including nickel-hydrogen individual pressure vessel (IPV), nickel-hydrogen common pressure vessel (CPV), Super nickel-cadmium, and fiber nickel-cadmium (FNC). Experimental approach, cell performance data, derived transient characteristics, and cell electrical models are presented.

As more automobile designs utilizing serial multiplex network protocols such as SAE J1850 and CAN go into production, automotive system designers must now seek ways to lower the cost of the multiplex communication devices used in order to allow the number of components communicating across the multiplex bus to expand. The first generation of J1850 multiplex devices were designed as the different versions of the protocol were being developed and as a result seem better suited for use as development tools rather than for use in cost-sensitive production applications. As the next generation of multiplex devices is being defined, a hard look needs to be taken at the actual system requirements for communication on a multiplex bus.

This paper describes a series of power ICs designed specifically for powertrain control applications. The series includes low-side drivers and high-side drivers. The drivers are capable of fault detection and reporting to the Micro-Control Unit (MCU). Reported faults include short circuit detection, thermal limit, over-voltage protection, “on” open load detection, and “off” open load detection.

A monolithic sensing solution for manifold absolute pressure (MAP) is presented. This work includes examination of design, fabrication, temperature compensation, packaging and electromagnetic compatibility (EMC) testing of the fully integrated monolithic sensor. The circuit uses integrated bipolar electronics and conventional IC processing. The amplification circuit consists of three op-amps, seven laser trimmable resistors, and other active and passive components. Also discussed is a summary of an automotive application MAP sensor general specification, test methods, assembly, packaging, reliability and media testing for a single chip solution.