Gage design improves liquid-level monitoring

Mequon, WI--Few things annoy a driver more than a flickering display light on an oil gage. Flickering can mean that the vehicle's oil level has dipped too low, or it might simply indicate a faulty gage. To settle the matter, drivers must manually check the oil level, which defeats the purpose of having a display light.

By using a new design, however, engineers from Kelch Assemblies say they eliminate the primary cause of flickering oil lights. Employed on snowmobiles and various types of agricultural and construction equipment, the new gage is not affected by the splashing and movement of oil or other liquid. As a result, it provides a steady, reliable signal to the dashboard display.

Key to the new gage's performance is a design that provides a built-in hydraulic damping effect. Unlike conventional liquid level gages, the new model allows liquid to enter only through a single port at the bottom of the unit. That represents a departure from the designs used in competing liquid level sensors, which allow liquid to splash over multiple openings. Because the new unit, known as the E-Gauge, only allows liquid ingress through a single hole, changes in terrain do not affect it. As a result, it doesn't flicker on and off every time the vehicle traverses a rolling hill.

The E-Gauge consists of a 1-inch-diameter plastic tube containing a float, a magnet, and electronics. During operation, liquid enters or exits through the bottom port, lifting or dropping the float. A thin plastic stem atop the float holds the magnet. When the liquid level drops, the magnet moves down. When it approaches a reed switch, the magnet closes a circuit, turning on a warning light or buzzer. When fuel or oil are added to the tank being monitored, the float moves back up, breaking the circuit.

Reliability represents another inherent advantage of the new design, say Kelch engineers. Separated from the active area by a plastic wall, the E-Gauge's reed switch and electronics are potted in epoxy. "All of the electronics are isolated from the liquid by the nature of this design," notes Michael J. Holz, applications engineer for Kelch Assemblies.

Kelch engineers accomplish that isolation by placing the magnet high in the float stem. In contrast, conventional designs typically incorporate the magnet in the float and, consequently, engineers must also position the unit's sensing electronics there. As a result, conventional designs expose the electronics and conductors to the liquid in the tank.

By employing high-pressure injection-molding techniques, Kelch engineers also endowed the unit with a smoother exterior finish, resulting in less leakage of fluid. In the past, rougher, "orange peel" surfaces sometimes permitted fluid to seep around the tank seal, they say.

For users, however, the E-Gauge's most important feature remains its ability to provide a steady and reliable monitoring signal. "By restricting the way fluid flows into the tube, we've isolated it from the sloshing that normally occurs in a tank," Holz says. "So you don't have the constant on-off flickering of the oil or fuel light."

Additional details...Contact Doreen Lettau, Kelch Assemblies, 11035 No. Industrial Dr., Mequon, WI 53092, (414) 238-6080.