May 2004

Table of Contents

Randy Frank
Randy Frank & Associates, Ltd.

The Next American Idle

Hybrid cars, such as Toyota’s Prius and Honda’s Insight and Civic Hybrid, have been sold in the U.S. for several years. A hybrid, which runs off a rechargeable battery in addition to gasoline, was traditionally designed to achieve higher fuel efficiency without great concern for performance. That’s why hybrid volumes have remained low.

But the newest hybrids are addressing performance and still managing to improve fuel economy. And that’s why the next “American Idle” will be 0 rpm (move over Clay and Ruben!). In more and more future vehicles, hybrid technology will let the internal combustion engine rest when the vehicle does. An electric motor will propel the vehicle under a variety of driving conditions (such as acceleration from
hybrid vehicle
By 2006, 350,000 hybrids will be sold in the U.S.
hybrid web site
Toyota’s recently redesigned Prius II hybrid adds 17% more horsepower and increases motor drive voltage—while also boosting fuel efficiency.
New vision sensors will let cars “see” what the driver may not.
hybrid vehicle
stop), and also drive the front end in some models so the belt-driven loads (such as power steering and air conditioning) can be used even when the engine isn’t running.

The performance issue is important to the American market, so Toyota’s recently redesigned Prius II delivers by raising the engine’s horsepower by 17% and increasing the motor drive voltage from 288 to 500 V, maximum, for improved acceleration (0–60 mph in 10 s). And yet, it gets combined highway/city mileage of 55 mpg, compared to 48 mpg for its precursor. The Prius II has already won accolades such as Motor Trend’s Car of the Year award for 2004 and Automotive Engineering International’s (the magazine of the Society of Automotive Engineers) Best Engineered Vehicle award for 2004.

Awareness of the transition will be even more apparent when hybrids such as the Chevrolet Silverado, GM Sierra, Lexus RX400h, Honda Accord, and Ford Escape go on sale later this year. By 2006, J.D. Powers & Associates expects 350,000 hybrids to be sold annually in the U.S.

Impact on Sensor Development
What impact will this have on sensor development? Surely, new sensor applications will be created, and don’t forget that because of the auto industry’s horsepower, this will affect you regardless of whether your business has anything to do with Motown.

Sensing accuracy for maintaining a stable 600 or 700 rpm idle may be relaxed a little. But because the battery will provide the energy to run components when the vehicle is stopped and energy drain will naturally follow, the battery’s state of charge will have to be sensed to avoid excessive discharge under prolonged idle conditions. New state-of-health sensors will eventually be able to predict when the battery is near the end of its life so drivers can avoid the unpleasant surprise of a dead battery. (This will be especially appreciated, as consumers are keeping their vehicles longer than they did a decade ago.) Also, while electric motors require position sensing that’s typically provided by Hall effect sensors, cost-effective “sensorless” approaches are being pursued.

Knowing the system level changes that will occur lets sensor suppliers ask the right questions to determine the impact to their business and set their development priorities.

When the driving public casts favorable votes for these heroes of performance, fuel economy, and conservation, we will benefit as engineers and consumers. Now that’s beautiful music—and not just some idle notion. n

Randy Frank will explore related sensor developments during the Automotive Sensors Symposium at Sensors Expo in Detroit on June 7. Click here for details.

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