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Designer's Corner

Designer's Corner

Automotive touch switches

With use, arcing, pitting, and oxidation degrade conventional switches. Soon, however, a simple touch will activate a computer chip that starts the desired function--whether it's to turn on a light, change the temperature, or provide a mileage readout.

Integrated into dome lamps, the technology could control lights, dimmers, LED readout bars, delay timers, and other devices. Design benefits:

  • A 1/2-mm-thick actuation depth means touch switches are easily mounted almost anywhere.

  • A sealed surface limits the opportunity for contamination inside the fixture.

  • Touch switches are easily color coded.

  • Legend can change color indicating activation of specific functions.

Cooper Automotive predicts that 'touch-lamp' technology will replace conventional mechanical switches on dome lamps and other lighting and convenience features starting in the year 2000.

Bill Buchman, Cooper Automotive,
1050 Wilshire Dr., Ste. 170, Troy, MI 48084;
Tel: (248) 637-8883.

Easy pressure check

A 10- to 12-psi tire-pressure loss impairs vehicle performance and impacts steering and fuel economy. While most automated techniques for checking tire pressure tend to be complex and costly, General Motors' engineers have developed a technique that mostly uses existing hardware to determine if a tire is losing air.

While the car is moving, speed sensors send signals to the antilock braking system (ABS) module. An algorithm in the module compares the velocities at each wheel. If one wheel loses pressure, and therefore rotates faster than the others, an algorithm in the ABS module senses it and lights a bulb on the dashboard.

The unit takes about five or six minutes to recognize pressure loss, and it doesn't tell the driver which tire is low. But it lets the driver know it's time to pull over and adds virtually no cost to the vehicle.

GM engineers came up with a Tire Inflation Monitoring System for select Buicks and Oldsmobiles. An additional algorithm in the ABS module compares speed-sensor data to determine when tire pressure drops 10 to 12 psi.

Flat-post battery

Heavy-duty starter batteries installed in cars or boats usually use top-mounted terminal posts or side-mounted bolt connections. Split-lead cable connectors for top-post terminals distort if over-tightened and require special pullers to remove. Side battery terminals come off easier, but the 1/4-inch bolt threads strip if over-torqued. Moreover, both connector types require special cleaning brushes to insure good contact.

Bottom-mount flat battery terminals are easily cleaned with sand paper or a wire brush, and existing battery hold-down mechanisms could provide terminal post contact with flat-paddle connectors. Several paddles, crimped or molded on a single cable, would simplify parallel and series battery connection.

Terminal-contact plates on bottom of battery, coupled with special paddle-connector cables, could simplify installation, maintenance, and design, as well as improve safety.

L. Lauder,
698 Bridgeton Pike
Mantua, NJ 08051-1351


Nested transmission

Gear-based speed-conversion devices are relatively bulky and cumbersome because most of the gear's working volume is unused during operation. In contrast, SYNKdrive(R) rotary technology uses nested components to optimize torque density.

The drive cam-gear rotates to displace rollers radially in the reaction disk's slots. As rollers ride the driven cam-gear's flanks, rotary output is produced. Production in metal, specialty plastic,or ceramic construction makes the design suitable for many applications where high-torque density and low backlash are required.

The number of teeth or lobes on the driven cam-gear, compared to the number on the drive cam-gear, determines the speed-conversion ratio.

Jake Maslow, Synkinetics Inc.,
2 Industrial Ave., Lowell, MA 01851;
Tel:(508) 453-4900.

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