Want Cool Air? Take a Seat

Seen in time’s rearview mirror, the heated and chilled car seat seems a no-brainer.

The basic technology has been available for a century, and the auto industry had been heating things like seats and side-view mirrors for years before Lincoln debuted the hot ‘n’ cold seat in its 2000 Navigator sport-utility vehicle.

And long before Lincoln’s variable temperature bucket seats came out, outdoor-recreation stores sold dual-purpose food and beverage “coolers” that also would heat up things with the flick of a switch.

So why did it take so long to add air conditioning to a heated car seat?

Well, it was an idea that took a long time to perfect--and once perfected it was for several years an idea whose time had not come, said Rick Weisbart, president and chief executive of Irwindale-based Amerigon Inc., which patented the climate-control seat system.

Weisbart said the immediate future is in the luxury vehicle market, but he sees a day when Amerigon seats--or competitors’ models in development--”could be a poor man’s air conditioning” in economy vehicles where regular air conditioning would add too much cost.

A pair of the seats, which heat and cool by induction--direct contact--is a $595 option in the Navigator. A full but basic air-conditioning system that must change the climate in the entire passenger cabin is easily four times that.

The system is based on the Peltier effect, the 1834 discovery that passing an electrical current through a sandwich of two dissimilar metals will make it hot on one side and cold on the other.

Cold, by the way, is what is left when the heat is removed from an object. In a Peltier device, all the negative electrical contacts are in a metal-infused ceramic disc on one side and the positives contacts are in the disc on the other--the positive ones generate heat and the negative ones absorb it.

The devices--also known as thermoelectric devices, or TEDs--have made possible those office coolers that chill and heat water, the insulated heater-cooler devices for food and beverages, and, by using just the chilled side, coolers for microprocessors.

Amerigon, started in 1991 to develop electric vehicle components, stumbled on the hot-cold technology when Lon Bell, founder and chief technology engineer, put his mind to the task of devising a climate-control system for a small electric vehicle that wouldn’t take up much room or consume much power.

“He wanted comfort without having to cool or heat the entire vehicle and hit on the idea of a climate-controlled seat to do it,” Weisbart said. “That’s when he found a patent for a Peltier device for a seat and bought it.”

Amerigon spent the next few years making it work.

The biggest problem: “Figuring out how to get the heating and cooling from a little Peltier device to [spread over] a large portion of the seat surface.”

The answer was a patented system of air channels in the seat just beneath the upholstery, which is perforated to let the warmed or cooled air flow through. A fan in the base of the seat pushes the air, and the channels conform to the area of the seat occupied by the average human.

The company’s first working seat was completed in 1995, “and then we started talking to people in the auto industry,” said Dan Coker, Amerigon’s marketing and sales chief. “We exposed the concept to the industry for several years, but Lincoln was the first to show an interest. They had customers looking for comfort and willing to pay to get it.”

Lincoln said its buyers seem to love the system--the company had anticipated that about half of all Navigator buyers would select the option, but the number is closer to 70%.

Weisbart said Amerigon, which has about 80 employees, has dropped most other pursuits, including its electric car development, to concentrate on development and refinement of the climate-controlled seat system.

The 2000 Navigator was the first vehicle with Amerigon’s seat--but other luxury car makers saw the potential.

Lexus bought the seat system from Amerigon for its 2001 LS 430 sedan, Lincoln is using it in the 2002 Blackwood luxury sport-utility truck as well as continuing its use in the Navigator, and, Weisbart said, “we have commitments for more than 20 applications with other auto makers through the 2005 model year.”

Amerigon will announce four of those contracts during the next 18 months, he said.

It is a potentially huge market, especially if volume results in reduced cost to the consumer. The company has sold more than 150,000 climate-controlled seats, or about 1% of the annual volume of the solely heated seats it hopes to replace.

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Climate-Controlled Seat

It might sound easy, but a car seat that can heat or cool its occupant took years to develop. The key is a thermoelectric device, or TED, which is based on a principal discovered more than 150 years ago. The solid-state device uses a positive electrical charge to heat one side of a metal-infused ceramic wafer and a negative charge to drain the heat from the other side to create a chilled surface.

Perforated leather

Allows warm or cool air to pass from the seat interior through the upholstery to the occupant.

TED

The heart of the system, a 1.5-inch square by .15 inch thick metal-infused wafer that gets hot on one side, cold on the other.

Distribution layer

Special porous foam allows air to flow to the seating surface.

Supply duct

Brings air from the blower fan to the TED, where it is heated or cooled.

Waste duct

Channels unwanted heat or cold to an outlet under the seat, where it dissipates. Volume is so small that it doesn’t affect ambient cabin temperature.

Blower assembly.

Fan sends air to the TED and through the distribution layer to the seat surfaces.

Control module.

Switch-activated microprocessor lets seat occupants select heating, cooling or “off” functions.

Source: Amerigon Inc.