Dayco product helps fuel efficiency, lightweighting

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."

When compared to a mechanical pump, it also reduces weight between 500 grams and 2.8 kilograms, depending on whether the pump is cam-driven or belt-driven, according to a company statement. The system also improves fuel economy by about 0.3 percent over the mechanical vacuum pump. When compared to an electrical pump, it reduces weight by about 2.3 kilograms.

The system was developed as customers, particularly Ford, became interested in the technology, and thought it could be useful for braking systems and eliminating the need for a vacuum pump, DiLisio said.

"So we partnered with Ford and developed this system for its application. We continued working on it until we launched it last year on the Ford F-150," DiLisio said. "It was a good partnership that allowed us to satisfy a customer need and allowed us to introduce an innovative product."

The Activac is currently planned to be produced for seven platforms total with various vehicles, including passenger cars and SUVs, DiLisio said.

"We're also looking at other applications besides brakes. We've been working on other applications that could potentially be used in the emissions control airspace that we're working on with some customers right now. So the applications are actually quite exciting," he said.

News about developments for that space could come by this time next year, he said.

Earlier this year, Dayco won a 2017 Automotive News Premier Automotive Suppliers' Contribution to Excellence Award for its Activac. Winning the PACE award marked a big achievement for the team at Dayco, said DiLisio. The award was presented in April at the Max M. and Marjorie S. Fisher Music Center in Detroit.

"It's the first PACE Award application that Dayco has done, and we won the first time," he said. "For the team, it's quite satisfying for all this work and effort they've put into this product, to have won such a prestigious award."

The awards are sponsored by EY, Automotive News—a sister publication to Rubber & Plastics News—and the Original Equipment Suppliers Association. SAE International provides further support.

Other products

At the end of 2017, Dayco will launch a new electric power steering belt for a major domestic platform, DiLisio said.

Its electric power steering belt line debuted in 2015, designed for belt-drive systems used in electrically powered steering.

"Power systems are going away from the traditional hydraulic systems and moving toward electric-assist," DiLisio said. "And there are certain applications, typically in larger vehicles or sport-utility or pickup trucks, because of the size of the motor, there is a belt that's required."

In EPS systems with paraxial servo units, an electric motor mounted to the side of the rack housing drives a ball-screw mechanism by a toothed rubber belt to provide steering assistance. The Dayco belt transfers torque from the motor to the steering gear to provide assistance while driving, according to a company statement.

"We've developed this electric power steering belt to satisfy that need, and it's been received very well with customers. It's a special construction, and a special HNBR (hydrogenated nitrile butadiene rubber) material," DiLisio said. "Customers have been very happy with this in terms of performance, in terms of both tooth jump preventions and durability."

The new electric power steering belt will be produced from Dayco's Manoppello, Italy, facility, but the company is looking at expanding into other regions. No new jobs will be added, "but if there is a need for expansion, it's standard manufacturing capabilities that we have, so expansion is fairly straightforward," DiLisio said.

Another product debuted in 2017 is Dayco's crankshaft decoupler developed to improve fuel economy, reduce emissions and decrease noise.

The damper and decoupler with compression spring system improves noise, vibration and harshness performance of the accessory drive within the engine, DiLisio said. As hybrid systems become more prolific, more stress is put on typical accessory drive systems.

"It's an enabler for the belt starter generator," he said. "In some cases, because of the loads in the system the decoupler is a critical component of the belt starter generator system."

Higher vibrations generated by newer engines are related to the increase of peak cylinder pressure, optimization of the crankshaft for weight, cylinder deactivation and general reduction in the number of cylinders, which can be transferred into the accessory drive. The DDCS isolates the belt drive from the vibrations produced by the crankshaft to minimize negative effects. The measured isolation rate of the DDCS is up to 90 percent, meaning 10 percent of the vibrations produced by the engine are transmitted to the belt, according to a company release.

The DDCS will be produced out of manufacturing facilities in Tychy, Poland, and Italy, and the company is looking into expanding capacity in the future.