LINCOLN MKS DESIGNED TO BE WHISPER QUIET
The 2009 Lincoln MKS was developed to deliver a luxury driving experience unlike any other vehicle in its class.
“We took a more holistic approach in developing the Lincoln MKS,” said Jim Baumbick, Vehicle Development chief engineer on the MKS. “We knew that to deliver a Lincoln with a ‘business class’ type of feel, that we had to have a total package that worked together in harmony to minimize the trade-offs between noise and comfort.”
The body structure of the Lincoln MKS was optimized for strength and stiffness. Along with noteworthy crash performance the solid structure also delivers the smooth, quiet ride expected of luxury customers.
One key to the luxury ride is the new Independent Rear Suspension (IRS), designed specifically for the MKS. The new suspension features an isolated sub frame and a design that places the shock absorbers out near the wheels, orienting them straight up and down.
“One of the most critical characteristics of suspension design is motion ratio,” said Baumbick. “With this design, the shocks can manage all of the load and keeping the forces from entering the body structure.
“In many cases, stiffer springs and additional damping are used to achieve a more controlled ride,” Baumbick adds. “That will only increase the amount of torsion to the body and result in an increase in structural-borne frequency, or road noise, that you can’t get rid of with sound package.”
The one-to-one motion ratio of the shocks optimizes the efficiency of the damping allowing engineers to make vast changes in the tuning of the suspension for comfort and control with no increase in road noise.
The front suspension was designed to work in harmony with the new IRS. It also is mounted to a fully-isolated sub frame to further reduce road noise and help with the acoustic balance of the vehicle.
Tire and bushing development focused on tuning out low frequency road noise and vibration.
The high-end sound package centers on a new technology that’s a first for Lincoln and the MKS. An injection-molded rubber dash panel runs from the floor, just under the carpet, up to the top of the dash and back over the cowl. The injection-molded part fits snuggly to the steel dash panel to provide a barrier for unwanted wind and powertrain noise. The same technology is used inside the rear wheel wells.
Expandable baffles, inserted into the rear of the front wheel wells, swell under heat (when the painted body is sent through the drying ovens) sealing tightly to the inner fender and under body structure to block unwanted road and wind noise.
Beltline baffles sit at the bottom of the A- and B-pillars. The baffles serve two purposes, blocking noise and vibration from traveling up the pillars and entering the cabin and keeping the noise low and away from the side windows.
A six-millimeter-thick laminated windshield and laminated side glass, sound-absorbing carpeting and acoustic headliner round out the basic sound package.
The shape of the new MKS was massaged in the wind tunnel to help with airflow and reduce wind noise.
No detail was left untouched.
In fact, the team went through more than 50 iterations of the design of the sunroof until they had a unit that is the quietest in its class.
“We made sure that the MKS can cruise at significant speeds with the sunroof open and still allow you to listen to the radio or have a conversation with the person sitting next to you,” said Baumbick.
The Lincoln’s new 3.7-liter V-6 engine also plays an important role in the overall sound of the vehicle.
“It’s important to have harmony between engine sound and performance,” said Baumbick. “When you give the MKS a throttle input, the car responds and there’s a corresponding change in sound. In the Lincoln, those three elements are in harmony and intuitive.”
The Lincoln MKS tuned induction system maximizes air flow to the engine for optimal power and delivers a rich engine sound quality. The exhaust system also has been tuned to deliver the Lincoln’s powerful, low-end growl.
Going With the Flow
The 2009 Lincoln MKS has been fine tuned right down to each individual molecule of air that flows through the cabin. The precise management of air flow is a critical step in assuring exceptional interior quietness and perceived quality.
“We’ve crawled through and accounted for every molecule of air that gets in and out of the car,” said Baumbick. “We’re treating air leakage as an opportunity for noise to get into and out of the car.”
The management of air starts by pressurizing the MKS cabin and then every opening is scrutinized – every nook and cranny in the car, every hole, every weld, every sheet metal attachment – with the specific thought about where to accept leakage and where to reject it.
“You can’t have zero leakage because you have to extract air to defrost and defog the windows,” said Baumbick. “But we know where the leakage is, how it gets into the car and how it contributes to noise.”
Design changes were then made, if necessary, to adjust for sound flow, like fitting the glass front to the door channel, or optimizing or eliminating a pass through in the firewall. For example, a pair of wire bundles can be designed to run through one hole instead of two.
In other cases, a specific strategy was incorporated to make sure the pass through is managed and sealed.
As an example, the MKS uses a new architecture for the steering column boot. The bolt-on attachment has a clean sealed surface with very low leakage compared to the traditional snap-on unit.
“We specifically redesigned the steering column component for low friction and a high degree of noise attenuation to reduce unwanted powertrain noise from leaking into the cabin,” said Baumbick.
Managing airflow also contributes to quality. The sound of a door closing is the result of proper air management.
”The right door closing sound enhances the experience and perception of the quality of the car,” Baumbick said. “The Lincoln MKS feels tight. The cabin has a vault-like feel. That’s quality.”
from ford