Automotive

New Bosch system shuts off coasting cars' engines

Bosch's new system is intended to reduce fuel consumption and CO2 emissions
Bosch's new system is intended to reduce fuel consumption and CO2 emissions
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Bosch's new system is intended to reduce fuel consumption and CO2 emissions
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Bosch's new system is intended to reduce fuel consumption and CO2 emissions

Cars don't need to have their engines running when they're stopped at red lights. That's why a number of automakers have developed start-stop systems, which stop a car's engine when the vehicle comes to a halt, and start it again as soon as the gas pedal is pressed. Bosch, however, is taking things farther. Its new start-stop system shuts the engine off not only at stops, but also whenever the car is coasting.

Putting it simply, the "start-stop system with coasting mode" turns off the engine whenever the vehicle can maintain its present speed by rolling. In other words, if the driver's foot isn't on the gas or brake pedals, the engine is off. A simple touch of either pedal causes the engine to instantly start back up.

According to Bosch, tests carried out by the company indicate that most vehicles could coast for about one third of every trip. If the engine was shut off for those periods, it would result in fuel savings of about 10 percent. Additionally, Bosch claims that if every new car sold in Germany were equipped with the system, "the theoretical annual reduction in CO2 would amount to over 30,000 metric tons" (33,069 tons).

What's more, with the engine off, the decreased mechanical resistance should allow cars to coast for longer distances than would otherwise be possible.

The system can reportedly be added to almost any type of existing combustion engine (including hybrids), and requires the installation of relatively few additional parts. It can even be added to cars with manual transmissions, if Bosch's eClutch is also used – this disengages the clutch whenever the vehicle is in coasting mode.

There's no word on availability or pricing of the system, although it is described as "affordable."

Source: Bosch

19 comments
xenocog
Saving fuel is great, but if the engine is off while coasting, so is power steering. If you've tried to steer a vehicle when the power steering is inoperative, you know how difficult it can be. Also, imagine a string of start/stop cars at a red light. The light turns green and the accumulating delays between touching the gas and the engine resuming operation seems like it could cause a few lost tempers...
James Harold McNeil
I do not understand how this is different from Deceleration Fuel Cut-Off, which became standard on all cars in 1996, requiring the engine control unit to cut fuel after the accelerator is released. Some require certain RPMs or have other conditions, but it marginally improves fuel, while cutting emissions while at part throttle. The engine continues turning without fuel, as long as the car is in-gear, the wheels turn the engine and alternator, so you still have power steering and brakes, electricity, everything, and the ECU starts sending fuel as soon as you touch the accelerator.
Adrien
no more engine braking I guess then! Don't think I'd like that.
MD
For those who haven't driven newer cars recently. In many newer cars many of the ancillaries (including power steering) are electric. Therefore turning of the engine whilst driving doesn't affect these. One thing which needs to be in place will be an electric brake booster (instead of vacuum powered boosters), though I assume (not familiar with the specifics) that in hybrid cars, and indeed other late model vehicles this already exists. (Or the brake circuit may be a high pressure, servo actuated system.)
slarmas
I already have this feature on my car, it is called a clutch and a diesel. Diesels are astoeometric compression so use very little fuel under 0 load and the clutch provides engine / transmission disconnect for efficient coasting. And when I need power I just lift my foot off the clutch and I have instant power. I also maintain engine temperature on longer coasts (down mountain hills etc) so I don't have to waste more diesel warming the engine back up or worry about wearing out a starter, or freezing to death because my primary heat source is gone, or cooking while the ac compressor is off when it is hot.
Alex Haws
In the UK, coasting (with the clutch in) is frowned upon during driving tests because it's considered 'potentially dangerous' for many of the reasons mentioned above: http://www.drivingtesttips.biz/what-is-coasting.html Plus, as James said, ECUs have been using fuel-cut on overrun for years so this is redundant. It's just a gimmick to sell even more starter motors!
Mel Tisdale
There are many consequences of installing this technology, as the above comments indicate. However, I doubt that the engineers at Bosch will be surprised by any of them. Cars kill and any death that can be attributed to design error will result in criminal proceedings against all the engineers deemed to be responsible. Such a prospect tends to focus the attention somewhat. There will be no chance that any vehicle equipped with this system will have its braking and steering functions degraded as a result of its installation. As for de-clutching on the overrun, free-wheel systems have been around for ages. They have never really caught on, but who knows, perhaps they are due for a re-think, especially if only fitted to the top one or two ratios so that engine braking was still available if the brakes failed. That, of course, assumes that the driver would be capable of letting go of the steering wheel with one of his white knuckled hands in order to change to a lower gear as the car rolled ever faster down the hill it was on!
Billysgrandad
Sounds like a great idea but maybe the feeling of coasting without the engine running will seem a little weird at first. A small point re the calculated saving of 30,000 metric tonnes of CO2, surely this equates to approx. 29,500 tons not 33,000 as quoted.
fenshwey
As others have said, in Europe coasting will fail you on the driving test. You are expected to work down the gears, engine brake or use the brakes and only push the clutch in at the last moment where the engine begins to struggle before coming to a stop. There are a number of reasons for this, where coasting is seen as a big no no. I also remember hearing topgear saying that you use no fuel at at all or next to nothing when you drive to a stop in gear, the cars wheels basically keeping the engine turning over as fuel is cut. This technology would mean you could save fuel while coasting, but wouldn't save you any fuel compared to driving to a stop. Currently when you coast the engine has to keep itself ticking over instead of the wheels keeping it ticking over, so the engine could cut off. But instead, just learn to drive properly, and drive to a stop, "coasting" in gear. Although it would be interesting to see how much people actually coast and how much could be saved.
Mac McDougal
Phew! What a bunch of negativity! I bought a Honda Insight in 2000. It has stop/start, obviously, and the only bad moment I had with it in 13+ years was during the initial test drive; we came to a stop light and I heard the engine "die" (or so I thought). The sales guy said "Oops, I forgot to tell you . . . " Regarding power steering, the engineers at Honda made sure that "stop" mode did not interfere with it. Real world performance over the past 130,000 miles: 53.4 mpg. If Bosch's 10 percent estimate is correct, that would have been 58.7 mpg--a home run, in any ballpark.