Company quietly positions itself in diesel NVH marketplace - Eagle-Pitcher Industries Hillsdale Division; noise, vibration and harshness

Diesel Progress North American Edition, June, 1999 by Mike Brezonick

While noise generation by engine-powered vehicles and equipment has become an increasingly important issue over the last decade, in truth noise, vibration and harshness (NVH) have been key design considerations for almost as long as engines have been coupled to driven machines. An excess of engine-generated vibration not only means more noise, but it ultimately impacts the durability and reliability of the engine and powertrain. In short, both the equipment and in some cases the operator, wears out faster.

A number of companies have engineered components and systems designed to alleviate NVH problems. One at the forefront of such developments is the Hillsdale Division of Eagle-Pitcher Industries, Hillsdale, Mich., which manufactures torsional and linear vibration damping systems, powertrain pump systems, driveline and precision machined components. Long active in automotive markets, Hillsdale has become increasingly involved in diesel engine applications, both on- and off-highway. And its capabilities were recently enhanced by its acquisition of Traverse City, Mich.based Carpenter Enterprises for an estimated $71.5 million.

Carpenter, established in 1974, is a precision machining operation that manufactures engine products, including front engine covers, connecting rods. intake/exhaust manifolds and engine bracketry and conducts machining and assembly of chassis and suspension system products, including front and rear knuckles, wheel spindle housings and damper forks.

"They offer chassis and engine related products, such as front engine covers and connecting rod assemblies, which Hillsdale previously did not offer," said Jeffrey W. Nichols, manager, sales engineering at Hillsdale. "What this acquisition enables us to do is offer our customers more of the system solutions approach.

"We have vibration control products and pump systems that integrate to the front end accessory drive (FEAD) of the engine. Carpenter would offer the front covers, the bracketry, etc., supporting the total front engine cover subsystem. So looking at the whole system, we can design not only the vibration products, but additionally offer our NVH expertise and development to refine the system response characteristics with integrated solutions to the engine and powertrain."

A prime example of the kind of NVH engineering the Hillsdale Division specializes in is the crankshaft damper-isolator it developed for Land Rover's Discovery SUV. Essentially two assemblies in one, the unit con-sists of an elastomeric crankshaft damper combined with an isolator assembly. The damper is designed to attenuate the traditional crankshaft torsional vibration caused by the firing forces from the engine. The isolator assembly effectively de-couples the crankshaft pulley from the crankshaft itself. The isolator is tuned and designed to control the FEAD vibration created from the ancillary system on the engine.

"This is a complex assembly that has proven itself in testing conducted by our customer as well as by the Hillsdale technical center," said Nichols. "The damper-isolator is unique because most dual-mass flywheel engines - like the one used for the Land Rover Discovery - do not have the damper-isolator combination in one component. With the damper-isolator assembly, the engine's NVH performance is optimized throughout the camshaft drive and FEAD systems.

"It's very different from the simple absorbers you see out there," Nichols emphasized. "Our isolator assembly attenuates a frequency span and prevents vibration anomalies from propagating throughout the engine system."

"What we've done is actually design our assembly for two separate purposes, with two elastomeric elements precisely tuned to attenuate the resonant frequency problems - considering the engine as a system, not just the individual componentry. We can accomplish this because we're one of the few companies in our industry that has its own in-house rubber compounding capability and expertise in NVH modeling and design."

The benefits of the Hillsdale damper-isolator include improved belt durability, belt tensioner durability and camshaft chain durability. "The assembly provides a tremendous benefit to any diesel engine with a dual mass flywheel and direct injection design," Nichols said. "We're already seeking similar product applications in the U.S. and abroad."

The crankshaft damper-isolator is being manufactured at a division facility in Hillsdale, Mich., and is shipped to Hillsdale's facility in Tarnworth, England, for assembly and just-in-time delivery to Rover.

While most of Hillsdale's activities have been aimed toward the automotive side, Nichols said the company has a long history with some heavy-duty suppliers - notably Caterpillar, Detroit Diesel, Isuzu and Mitsubishi Heavy Industries - and anticipated significant growth in nonautomotive applications.

"Some of the technology that we've developed with the automotive customers is even having somewhat of a recirculatory effect coming back into the heavy-duty applications," noted Nichols. "The Land Rover application helped us learn more about direct injection diesel technology and how the isolators can help with the overall system performance of the engine.