TROY, Mich.—Dayco's Activac vacuum generation system deals with an obstacle to increased fuel efficiency and vehicle lightweighting in the Ford F-150's vacuum pump by skipping it altogether.
The braking system technology replaces the need for vacuum pumps to run auxiliary systems in vehicles, which is a growing issue as engines are being boosted by either superchargers or turbochargers, according to Paul DiLisio, Dayco program and product management.
"As more and more engines are becoming boosted, most auto makers must have some kind of auxiliary vacuum system," DiLisio said. "Typically, in the past, they've been either using mechanical vacuum pumps or an electrical vacuum pump."
Both of those products have disadvantages, DiLisio said. The disadvantage of a mechanical vacuum pump is that it's always running, and that drains power from the engine. An electrical vacuum pump only runs on demand, but is typically expensive.
Instead, the Activac uses the Venturi effect, a natural phenomenon in which a vacuum is created by accelerating air through a chamber of decreasing volume. The two main components of the system are an aspirator and a control valve. As the brake pedal is pressed, the control valve opens and air is pulled through the aspirator by the engine. As air flows through the narrow part of the Venturi tube, it becomes a low pressure region, creating a vacuum that assists with brake application.
"The only moving part in our Activac is the valve, so it's very reliable," DiLisio said. "And it's not parasitic. It doesn't draw power from the engine. When you look at the total system cost versus a vacuum pump, it's a lower system cost and it provides the customer with tremendous value, because it allows them to have the vacuum they need without these auxiliary systems that either drain power or are quite expensive."