How much fuel is wasted at red lights? Or while you're trapped in gridlock during your daily commute?
The National Highway Traffic Safety Administration (NHTSA) estimates Americans waste about 3 billion gallons of fuel each year stuck in traffic, which amounts to billions upon billions of consumer dollars.
How can we stop wasting gas and start saving money? Start/stop technology is one way to do just that.
As automakers race to meet increased fuel economy requirements, many are looking at start/stop systems to meet their needs. Right now, the technology can help improve fuel efficiency by approximately 3 to 5 percent. And, DENSO has future start/stop system technology that will bump that up to over 7 percent. When it comes to saving fuel, every percent counts.
Start/stop systems stop the engine when the vehicle is idling at a stop light or in other traffic situations. This helps reduce fuel consumption and CO2 emissions.
In North America, these systems are expected to proliferate the market as fuel economy regulations become more stringent. You'll see these vehicles on U.S. roads in the 2012-2013 timeframe.
Denso has been developing start/stop components since the 1980s. This experience, paired with the company's in-depth knowledge of powertrain and thermal management systems, gives it a unique advantage to provide automakers with an overall systems approach, the company says.
Denso has a three-level system approach to start/stop technology:
Level 1: Basic Start/Stop Technology: The Engine Stops After the Vehicle Stops
In this level, which the company has already implemented in Europe, the focus is the starter technology. The Advanced Engagement (AE) Starter helps automakers achieve approximately 3-5 percent in fuel savings. Also, it uses existing, proven technology and also allows for easy packaging for the customer.
Level 2: The Engine Stops Before the Vehicle Stops
When the engine is cut prior to the vehicle fully stopping, this "coasting time without fuel usage" bumps the overall fuel-savings potential to over 4 percent, but it requires a unique starting system that is able to restart the engine before it reaches zero rpm. That means it doesn't need to wait for the engine to completely drop from idle speed to zero rpm, like the AE starter.
With a traditional starter or even longer life starter like AE, the engine rpm must be at zero in order for the starter motor to engage to restart the engine. If not, the starter and ring gear could be damaged if the engagement took place while the engine was moving.
Why is it important to have a starter that can restart the engine before reaching zero rpm? Well, most engines shut off in about a half second. But if a light changes green fast or another situation demands the immediate ability to move and accelerate the car, then waiting a half second could be a consumer annoyance.
Denso has developed two different starters that have the capability of restarting before zero rpm. The Tandem Solenoid Starter (TS) and Permanently Engaged Starter (PE) provide customers with two unique solutions for this problem.
The starters represent two different packaging options for automakers, as well. The PE starter has been in production since 2008, and the TS starter is scheduled to go into production later this year.
Level 3: Premium System: Electrical Regeneration
Above and beyond Denso's Level 2 system, additional gains need to come from changing the electrical system to one that is more tailored to the repeated on/off cycling of a start/stop system. To have a more efficient system a more efficient power source is needed.
By supplementing the standard lead-acid battery and switching to a more efficient power source to handle the lead-acid battery's inefficient modes, we estimate this start/stop system to achieve an additional 3 percent in fuel savings, with a total potential of over 7 percent.
Denso is now offering this system to customers as a way to effectively double the fuel savings of the basic start/stop system.
An integrated start/stop system approach is more than just starter technology. There are many other products and components that can be added at any level to improve comfort and convenience (air conditioning) and powertrain performance.
Many of these products better manage energy in a vehicle, which translates into fuel efficiency.
