Automotive supplier Visteon Corp. wants to move the sound system out of the trunk and closer to the passengers.
"Many times, the subwoofer chamber is in the rear of the vehicle or buried in the trunk system," said Doug Parks, business director of Dearborn, Mich.-based Visteon. "When you pay $600-$1,000 for a prime sound system, you don't want to put it in a place that's detrimental to overall sound performance."
Visteon is making plans to move the sound system front and center. The company has developed an integrated door-trim module that replaces the lower half of the door with a subwoofer chamber and a high-end audio system.
The 5- to 8-inch subwoofer, on the driver's side, also will act as a carrier to hold hardware on the door panel, including the window regulator and latch.
The move should in-crease acoustic performance and open up the rear of the vehicle, where space is at a premium, said Visteon advanced application engineer Jitesh Desai. Extra side intrusion beams for air bags also are needed in the rear of many cars, he said.
"Large speakers take more space requirements," Desai said. "It comes up against a customer's need for more interior space. And it became an engineering challenge for us."
The company expects the integrated module to appear on an undisclosed luxury model for the 2004 model year.
Visteon is considering where to mold and assemble the piece, Parks said. The project team, working for the past three years, faced some design and engineering challenges.
Those included evaluating the use of blow molding for manufacturing. The group eventually decided against it because of concerns about surface finish, said Mike Keil, Visteon new business development manager. Instead, the door module will be injection molded in a two-piece, sealed design. Graining or carpeting can be added to the module, using polypropylene and other structural materials for the substrate.
Another concern was transporting the parts to a carmaker's assembly plant without damaging the delicate subwoofer chamber, Keil said. The company decided to assemble the entire module itself, using adhesives as a bonding agent, before shipping the module as one piece.
Visteon spent considerable engineering time testing the module for crash-worthiness, moisture penetration and noise resistance.
"On the test fixture in an environmental chamber, the door had to be slammed, vibrated, washed with water and subjected to temperature extremes," Parks said. "There were some unknowns as we created the chambers and started carrying the heavy speakers. Plastics became the structure."
And plastics has seemed to hold up under those tests, he said.
Visteon's quest to mix a door system with an audio system has deeper roots in the auto industry, said consultant Robert Eller of Akron, Ohio-based Robert Eller & Associates. Several companies have molded metal and plastic hardware pieces into a one-piece door panel, especially during the past five years, he said. Other auto suppliers are using the molded door space for unconventional parts. That includes door-release handles, armrests, wire harnesses and switches, said Steve Hollingsworth, door system engineering manager for Plymouth, Mich.-based Johnson Controls Inc.
But adding speaker chambers to a door panel brings some structural issues, he said. If you move a heavy object such as a subwoofer from a sheet-metal structure to a piece of plastic trim, you need to consider how to attach it correctly to absorb impact, he said.
Plus, audio experts sometimes prefer to have speakers securely mounted to sheet metal, he said.
"We haven't been able to explain it," Hollingsworth said. "But some experts think the sound quality is better."
At the same time, suppliers are challenging old guidelines on attaching hardware to door trim, added Dave Phillips, JCI director of material and process development for interiors.
"We are putting partnerships together with others to do that," Phillips said. "It's probably the area we've focused on the most in the past few years."
Visteon's focus currently is sound quality, especially for those paying a pretty penny for a vehicle sound system.
"Something is not right in many packages," Parks said. "You lose half the sound in the trunk cavity or hear it come off the glass surface. What we don't want is the consumer driving out of the dealership straight to a local radio shop for help."