Designer's Corner 23311

Molded-in harness wiring

Wiring harnesses used on automotive intake manifolds often experience fraying, which can result in shorts. Also, the harnesses add weight to the vehicle and are relatively costly to manufacture, install, and repair.

Instead of using a separate harness, conductors can be molded into the plastic or fiberglass manifold. This approach promises to reduce vehicle weight, reduce assembly cost and time, and provide a more reliable electrical system. Fuel injector installation requires only a half-turn twist. The main harness to the intake manifold can be designed as an umbilical cord.

Larry Lueder, 698 Bridgeton Pike, Mantua, NJ 08051, (609) 464-6864.

Global broadcasting

Having secured international rights to a portion of the L-band, WorldSpace Inc. recently announced plans to begin Direct Audio and Video Broadcasting (DAVB) to the developing world with satellite launches starting in 1998. Built by Alcatel Espace of France, the satellites will accept as many as 288 uplink channels from which they can create up to 96 broadcast channels (near-cd quality stereo sound requires four uplink channels to create). The broadcast is to be at a single frequency, with individual channels encoded simultaneously via time-domain multiplexing. Hand-held receivers on the ground will incorporate proprietary chipsets to decode the signals. The company estimates that operating costs will be one-quarter to one-half those of conventional wide-area radio broadcasting.

Eugene S. Reich, WorldSpace, Inc., 1730 Rhode Island Ave. NW, Suite 1200, Washington, DC 20036, 201-408-8071.

Efficient ion thrusters

The recently introduced SPT-100 stationary plasma thrusters from International Space Technology, Inc. combine Russian design with American and European electronics and materials. Said to be five times more efficient than chemical thrusters, they are completely throttleable and have been tested through thousands of on/off cycles.

In operation, electrons spawned from hollow cathodes become trapped in a radially symmetric magnetic field created by inner and outer electromagnets. Pressurized Xenon gas discharged between the magnets collides with the electrons forming ions that are accelerated by the field, producing thrust. The design would reduce the propellant mass needed for station-keeping a one-ton satellite over a 15-year period by more than half compared to a hydrazine thruster.

Atlantic Research Corp., Aerospace Group, 5945 Wellington Rd., Gainesville, VA 22065, 703-754-5192.

Light touch

Control engineers needed a low-cost way for pipeline workers to access data from a gas-flow computer. Unfortunately, the computer had to be sealed in a gas-tight enclosure which prevented the use of conventional switches. The answer? A pair of Omron EE-SPZ401-A photomicrosensors within the enclosure angled toward a porthole in its face. Operators press their fingertips against the porthole in the appropriate spots to scroll through data on the computer's LCD. The sensors detect the fingertips by the change in light reflected off the porthole surface. Requiring only minimal programming, the technique retains the integrity of the enclosure without the expense of a dedicated touch-screen control.

Nazario Biala, Omron Electronics, Inc., One East Commerce Dr., Schaumburg, IL 60173, 800-55-OMRON.

Versatile rolls

Made from a compressed stack of annular, non-woven discs on a balanced steel core, Atlanta Mill Rolls solve several problems found with rubber or elastomeric rollers. The rolls can be made in any hardness from 30 to 95 shore A by varying the axial compression of the discs during manufacturing. With eight different non-woven materials currently available, users can specify a desired hardness, chemical resistance, and operating-temperature range.

The design makes the Mill Rolls self-healing. Minor nicks and cuts disappear as adjacent compressed disc material flows into the space. Debris caught in the roller during material-handling or lubrication operations will be pressed between discs away from the outer surface.

Don Stephens, Atlanta Brush Co., 3289 McCall Dr., Atlanta, GA 30340, 770-457-9494.