More starts, better parts
The start-stop concept is hardly new. Toyota is said to have begun testing the technology in the mid-1970s on sedans in Tokyo traffic. In the following decades, Volkswagen, Audi, and Citroen introduced it on their production vehicles.
Adoption in the US, where gas prices are lower and highway driving is more prevalent, has been slower. But the technology is coming. To some degree, it has arrived already in the form of motor-generators on full hybrid vehicles, which inherently incorporate start-stop capabilities. It's also present in so-called mild hybrids, which use a motor-generator for start-stop capabilities and regenerative braking, but not for electric propulsion.
This decade's big change will be the emergence of the "micro hybrid" -- a conventional gasoline-burning vehicle that uses an enhanced 12V, gear-based starter to shut down the engine during short stops.
"It's a big change," says Robert Martin, director of engine electrical engineering for Denso International America. "We're talking about 10 times as many starts. If you start your car two or three times a day now, then you might be doing 25 or 30 activations a day with start-stop."
Suppliers say the new breed of starter motors will have to handle anywhere from 250,000 to 350,000 starts over the lifetime of a vehicle, versus about 30,000 today.
As a result, next-generation starters will be designed and built differently. They will still employ magnet-based DC motors and internal planetary gear sets, but all of the wear components -- such as bushings, commutators, and brushes -- will be upgraded. Brushes will migrate from copper to a harder copper-carbon blend. Bushings will be replaced by needle bearings. Commutators will be reinforced. Mechanical components, such as overrunning clutches and engagement mechanisms for the starter's pinion, will also be upgraded. Stainless steel will replace steel and plastic in some components. Springs will be improved.
"You need to consider all kinds of components," says Frank Frister, product manager for the starters and generators division at Robert Bosch LLC, which makes start-stop systems. "The duration of operation is much longer in all of them."
I think Patton's comments at the end are the message to all engineers working on this next design challenge. While start-stop hybrids may impose real design challenges in terms of wear and tear on parts and some of the other issues Chuck highlighted, the real aim for these systems is that the consumer shouldn't know or shouldn't care that the car they're driving has any kind of stop/start technology. They will care about the value proposition of the technology--i.e., better fuel consumption, less cost, better environmentally--and that the vehicle performs as they expect. Case closed.
I keep Googling to try to find a reference to a TV segment I saw several years ago, where a guy demonstrated his technique to get very high mileage from his Corolla or whatever. It involved turning off the car at all red lights. There's one thing with start-stop that hasn't been mentioned. It's analogous to range anxiety--I'd simply call it "start/stop aniety." Going back to the guy I mentioned above, with a brand new car, you could try that yourself and not feel too worried about the car starting up quickly. (Although you'd be setting yourself up for early starter failure. The starter is not designed to be used for so many cycles. You're liable to get a failure within a year, sted of 5 years.) Anyway, so with an older car, you'd be more worried about the car not starting. My overall point is that all of these new technology require a new way of thinking about what a car is and what one's expectations are of how it works. Notably, those expectations become markedly different as a car ages and we (the owner) tries to keep it on the road at minimum expense.
I agree with your point about setting yourself up for early starter failure, Alex. Suppliers are aiming for a starter that will withstand about 350,000 starts over its lifetime, but that doesn't change the fact that in my mind, I'll always be waiting for the starter to conk out while I'm waiting at a light. My other concern is stopping during deceleration. I have young, rather unsure, drivers in my family who like to go in and out of the accelerator while driving. This already makes me nervous as a passenger, but that nervousness would really grow if the engine turned off every time they pulled their foot off the gas.
You talk about concern over stopping when the foot is off the gas or concern for a starter failing, but isn't the whole point that the technology will evolve to the place where as a passenger/driver you won't notice the stop/start mechinations, or at worst, maybe only slightly so.
I just got back from a visit with my parents who have a Prius. As a passenger, I only slightly noticed the stop/start and that's with what's likely outdated technology. Unless the technology evolves to that degree, there will be few buyers and once it does evolve to that point, it's so in the background, it almost becomes a moot issue.
The Prius has had this on/off technology for a dozen years or so. I have had mine for eight years, with no problems. The "starter" uses the two HV electric motor/generators to kick the engine over. It starts in less than a revolution. Fuel is not fed to the cylinders until sufficient revolution rate is sensed. The car uses electric A/C, so that it will run with the engine off. If the traction battery runs down due to its load, the engine will start to re-charge. BTW, the electric motor in the A/C allows it to be a sealed system, similar to a window A/C, so no service should ever be required. The engine also runs continuously during warmup in order to heat the catalytic converter. The engine shuts off when you let up on the accelerator up to around 42 mph. The only reason for that speed limitation is to limit the rotational speed of one of the motor/generators to its rated maximum of around 10,000 RPM. All of these functions are controlled by the on-board computers.
So please don't wring your hands about how awful it will be to implement start/stop. It has been around and working well for many years, and appears to me to be the best near-term solution to gasoline consumption reduction. My gasoline mileage, averaged over my entire eight years of ownership, is a little over 50 mpg. It does poorer than that in the winter, and better than that in the summer. The difference is mainly due to increased warm-up time in cold weather.
Good grief, a car that goes into sleep mode to save energy. I wonder how long it will take for the mechanisms that control it to fail. I say this as someone whose laptop just started having sudden attacks of narcolepsy. We think we've eliminated hardware problems, but even when we reset the energy controls so it isn't supposed to sleep ever, either display or drive, it occasionally has narcoleptic attacks. So we're looking into possible software issues.
Anyway, I'm with Beth. This has to be completely transparent to the user. And whatever mechanism controls when and how often the engine stops and starts again, I hope it's not software driven.
Bad news, Ann. There are software elements to this technology. There's a lot of anticipation, sensing and timing involved, and it couldn't be done without computers. Worse news: Within 10 years, none of us who buy new cars will have much choice in the matter.
You suggest that the key challenge is to make stop/ start ( S/S) systems seamless. I believe that the 3 million cars now on the road in Europe have proven the technology to be seamless. The American need for automatic transmissions has been a battle but Bosch seems to have resolved the issue.
The engineering struggle has been the battery. It takes 90% of the battery to run the accessories when the car is stopped. It takes only 10% of the battery to start and restart the automobile. The accessory demand keeps the battery in a state of constant discharge. Even the most advances lead acid battery ( AGM) starts to fail in about three months. The S/S system then quits working.
To counteract this a cheap battery had to be found that can accept the Dynamic Charge Acceptance required in a S/S system. Axion Power International has developed such a battery. Here is a link to the BMW white paper that explains the DCA issue and solution.
Interestingly GM is working with the Axion PbC battery for its E-assist program, also. The PbC battery accepts the regenerative braking charge faster and longer than anything else in its class.
Although the American consumer still distrust the idea of a stopped car at a stoplight that idea will wane after positive use. It is my hope that the S/S systems give the positive experience drivers deserve. I can think of no worse waste of fuel than running a vehicle at a stop light.
The figure about the accessories accounting for 90% of battery load at stop confirms my line about modern automobiles: "Today's cars are an electronics platform with an engine and transmission thrown in as an afterthought." Humorous though that may be, there's some truth in it. The start-stop technology about which Chuck writes is clearly positively impacting mileage and many commenters here have spoken of their experiences with the Aspen, Escape Hybrid, etc. The collateral effect that I wonder about is what kind of reliability will we see in these new drivetrains, both predicted (by the manufacturer) and actual, as these vehicles age during their service lives on the road. (I.e.,, will reliability and repairability -- these cars require really well trained technicians -- loom as a big unexpected owner expense as these cars age?
I drive a Ford Escape Hybrid SUV which starts / stops the gasoline engine very frequently. The starter motor is integrated in the flywheel of the engine, so no traditional starter motor is used. This allows the engine to be started without wear on flywheel gear teeth, actuating a high current solenoid, or engaging a starter Bendix. The high low end torque available from the electric hybrid motor allows one to get started moving at stop lights easily, with the gasoline engine starting when the vehicle gets to 40mph.
Its a great design, and a real hoot to drive on mountain roads using the regenerative braking to recover energy which would typically be lost to mechanical brakes.
In my opinion, we will be seeing much more of this type of solution in the future, using electric drive where it makes the most sense, and transitioning to gasoline for highway use.
araasch; I was seriously considering the Ford Escape Hybrid. What I did buy was a 2009 Chrysler Aspen hybrid. The determining factor for me was the 5.7 liter Hemi. I can still tow a trailer. If I pay attention to my driving, and in excellent traffic conditions, I can average 25 mpg (per the computer - and the gas pump has agreed). My mileage does suffer in cold weather as the engine runs until it gets to operating temperature. So the engine runs at the first few red lights in cold weather. All of the accessories seem to be electric - the 'serpentine' belt seems to have only 2 pulleys - it is hard to see buried in the engine compartment. The stop-start is not quite seamless. Passengers do not notice it, but the driver can detect a tiny lag between pressing on the accelerator and the engine kicking in. In a traffic jam or stop-and-go driving I can get about 20 minutes of light acceleration sub-25 mph driving before the engine has to re-charge the battery, vs other cars with the engine constantly idling. That said, I would not have even considered a pure stop-start design.
I agree that an integrated starter/alternator seems preferable to simply modifying the existing Kettering starter for more durability. Combining two components into one eliminates the weight of a seperate starter assembly, saving between 5 and 10 pounds. In addition, eliminating the belt drive in favor of direct-drive would eliminate the belt slippage and breakage that is still a problem, although less so than in the past with the adoption of "serpintine-belt" systems replacing traditional accessory-drive belts.
This is part of a general trend to replace mechanical accessory drives with electrical substitutes. First, the direct driven engine cooling fan was replaced with an electric motor. Then electric power steering began to replace engine-driven hydraulic power assist. With an integrated starter-alternator, the belt-driven alternator disappears. Eventually, even the internal combustion engine itself may disappear, although it is still not entirely clear what the final replacement for it will be.
The most important point is to look at the problem from a systems point of view, rather than focusing solely on the starting problem. Can we replace water pump and air-conditioning belt drives with electric motors, to allow operation during stopped mode? What demands will this place on the battery (or batteries)? Does a larger battery or additional motors offset the weight savings elsewhere in the system? Should we convert the air-conditioner to a heat pump, to allow for cabin heating before the engine warms up? A systems approach allows us to answer all of these questions and many more, so that we don't create more problems than we solve. It also encourages innovation and "out-of-the-box" approaches, such as sensing which cylinder is on the expansion stroke when the engine turns off, so that you can re-start the engine by injecting fresh fuel and firing the spark plug for re-start, rather than using the starter motor at all (as outlined in a recent Mazda patent).
I had the clutch go out in the K2500 camper while returnin home from a cross country trip. I would turn the engine off when coming to a stop. I had the 5 speed in 1st and would crank when the light turned green. I would use the clutch to shift but it would not through out enough for a stop. 5 speed fully syncromesth manual transmission. Preplaced the clutch and hydraulics but the starter is still going strong. I can shift up pretty good without the clutch but down shifting is a challange to match speeds.
My Dad had a gas - electric golf cart. Push on the go button and off she goes and seamlessly starts the gas motor. No felt changes but you would hear the gas engine start. Pretty quiet too. I see no problems other than realy needing a higher voltage system, 48v or more.
As we prepare (and continue) to evolve to 'higher tech' systems to seemingly fulfil our dreams and needs, concerns of reliability, longevity, etc are very valid.
NASA, a leading technolgy endeavor with huge success, figured these issues out long ago. Carry a spare. Use 2 starters. Most on this forum may have 2
cars. A couple pair of glasses. 2 laptops,..... Check your local car repair shop. The OEMs have plenty of newer models in for warranty, recall, etc.
Sounds like expensive transportation, but job creation at the least. Maybe change starters like oil. Yes sir, 'give me a lube, oil, filter, and starter'.
How many times would a starter re-engage in common commutes where traffic stops, move a few feet, stop, move a few feet?
Will it be hot in the summer when the A/C shuts off? No, just add another battery and stystem to run the A/C, or heater, or wipers, or lights.
How about decreasing the rolling resistance of tires, or no air, this is close! Hats off to tire research!
Use lighter weight materials. Reduce weight; the skin and other body parts aren't 'wear parts'.
What is a 'seamless' restart really worth? How about a 'kill switch' and driver discretion?
Maybe this goes the same way as 42 volts????
We are all in this togehter you know......we are consumers.
I read the part about using a pump to keep coolant flowing to heat the cabin and a secondary evaporator but is the engine allowed to run till it can build up the heat or cooling necessary to be maintained? I think a lot of us stop shortly after we get started in the morning. It takes 5 minutes or so for my car to heat up in the morning during winter. By then I've sat at 3 traffic lights. Same problem when leaving in the afternoon while it's bright and sunny during summer. You go home from the mall and it's 130 deg in your car. The first thing you do after getting started is wait at the light to get out to the main road. I also wonder if a 1 minute reserve will be practical.
In what sense are these vehicles "hybrids" by any stretch of the imagination? The term properly refers to a vehicle that includes two (or more) sources of propulsion. The conventional gas-electric hybrid has some of the characteristics of a gasoline-powered vehicle, and some of an electric car.
Other kinds of hybrids are being developed, for example the gas-compressed air hybrid and the gas-hydraulic hybrid.
Simply shutting off the engine at stoplights doesn't make a gasoline-powered car a "hybrid." Really, we need a better word. This is marketing nonsense at its worst.
These are hybrids in the sense of Toyoto Prius. Gasoline engine/brushless electric generator/motor. They are operating in Mercedes autos in Paris cabs.
Have I missed something? According to the article, the electric motor in a "start-stop hybrid" exists to restart the gasoline engine, not to propel the car.
The Prius, to use your example, is capable of driving for a short distance using only battery power. Not so with these vehicles.
Maybe these vehicles should be called "zero-RPM idle" to distinguish them from actual hybrids.
GlennA: There are three categoroies. The microhybrid uses a beefed up starter to handle the 10X increase in starts. The mild hybrid (like Buick eAssist) uses an integrated starter-generator for start-stop and for other benefits (such as regenerative braking) but generally does not use it for electric propulsion. The full hybrid, like the Prius, uses its motor-generator for electric propulsion.
I agree with you, Rob. The so-called "microhybrid" doesn't really fall under the definition of the word "hybrid," since it's not being propelled by another power source. I don't know how the microhybrid label originated, but my guess is that the name stuck because it shuts off at traffic lights, like a real hybrid does.
I would assume pure marketing hype. They want the consumer to think they're getting a real hybrid with all the fuel saving advantages at a lower cost point.
I also agree that improvements to regular gas-powered car engines are not hybrids.
My 2012 Honda Civic turns off the engine when coasting (standard 1.8 litre gasoline). The tires spinning on the road surface, going through the drive-train, keeps the engine spinning. The automatic transmission downshifts when decelerating to keep the engine speed above about 1,200 RPM. The engine automatically turns back on when the gas pedal is used, at speeds below about 10 miles per hour, and when stopped. When coasting, the instantaneous fuel economy gage is pegged at 70 miles per gallon. For best fuel economy, I try to coast as much as possible, especially during city driving.
Of course when stopped, the engine is running and using gas...and that's zero miles per gallon. That's the main advantage of "start-stop", not using gas when stopped. For best fuel economy, I avoid driving around looking for a better parking spot, fast food drive-thru's, and even red lights (when possible).
I would love to have a vehicle made for this kind of driving. I can see two major requirements aside from a much different cranking drive, which would be a separate ignition and fuel control switch, and a free-wheeling clutch for efficient coasting. Of course, there is the challenge of the various hgh current draw accessories, air conditioning being the biggest, but power steering being another more important one. It would be trivial to do without AC for a minute or so at a traffic light, although I am certain that some disagree. Headlights would need to stay on while in motion but they could be dimmed while stopped.
What I have found in this "greater Detroit" area is that one can easily cut fuel consumption in half with agressive shutoff-and-coast driving, at least on surface streets. My anticipation is that it would be very hard to duplicate this with a computer program, since a major portion of the decision making is driven by driver observation of the surrounding traffic situation. But if there were available a switch with a "run/coast" function it would be easy for possibly half of the drivers to reach much lower levels of fuel consumption. Of course, some ten percent of the drivers would probably kill themselves, so the idea will probably never be accepted.
I think you've nailed it, William K, when you say that air conditioing and other accessories will be a challenge. For AC, automakers atalking about adding a temperature sensor that could look at ambient air and enable the vehicle to decide if the engine should be turned on again. Regarding steering: If it's electric steering, an extra battery would be needed for coasting.
Electric power steering should not require an additional battery since mostly drivers are not turning the car, and most coasting is done in a fairly straight line. Besides that, there is very little steering done when the car is stopped.
As for the air conditioning, shut it off while coasting! 50% on time should be plenty cool enough, those drivers who can't live without an icey blast 100% of the time are folks that I really don't care at all to accomodate. Really, I don't care. Of course, cars could have better insulation, for example, urethane foam like refrigerated trucks have. That would also make the ride quieter and not add over a pound to the car's weight. It might even make the car stronger.
Another option would be to allow those drivers who must hold 65 degrees to keep the engine running, and let the rest of us save the fuel costs. Then there would be no room to complain for them at all.
Power brakes might be a different story, because although I have seen hydraulic-assisted power brakes, those systems used the power steering pressure, which is gone with electric power steering. Of course, for many years power brakes were an option, they may still be, I am not sure. I do know that my first two cars did not have them, and neither did the race car that I drove for a few minutes once. So dispensing with them altigather is another option.
I agree about the air conditioning. I don't like using it in the car unless I have passengers who want it. My issue with AC is a holdover from the 30 years ago, when I used to have to nervously watch the engine coolant temperature gauge in my '77 Cutlass whenever I turned on the air conditioning.
Non power brakes are not an option with disc brakes - too much pedal force is required, unlike the drum brakes of old. Some manufacturers, Daimler Benz comes to mine, have been experimenting with electric power brakes.
My bus has hydraulic assisted brakes (Hydro-boost), it works off the power steering pump, if the ps hydraulic pressure is low there is an electric pump that provides the boost. It wouldn't be too hard to adapt that to a smaller car.
One other concern, which is probably the one that will kill the versions with the very greatest efficiency, is what the NTSA people will conclude about how safe the start stop system will be. My guess is that engine shutoff at traffic lights is all that they will allow. After all, these are the same poorly advised folks who allowed cars to be sold that did not have a positive means to switch off the engine. That piece of stupidity has cost a few lives and a fair amount of property damage so far, and I am not aware of any changes to the functionality of that system that would make it any less dangerous.
Good story about eAssist, Rick. One of the beauties of this system is the relative small size of the luthium-ion battery (0.5 kWh). Compare that to the Volt (16 kWh) and the Prius PHV (5.2 kWh), then compare the cost savings. Assuming these batteries cost $1,000/kWh, as the National Academy of Engineering has said, that's a savings of multiple thousands of dollars. True, it's not a full hybrid system like the kind you'd get in a Prius, but it's an inexpensive way to get SOME of the hybrid features.
Maybe I missed it, but it seems like there should be a clutch on the flywheel and a way to keep the flywheel spinning for restart energy (this energy would be almost free.). Seem like a lot of energy is lost stopping and starting the flywheel.
I agree with the basic idea of starting and stopping the IC engine when it is not needed in a hybrid but there are is another opportunities right now with conventional vehicles that is being overlooked. In the quest for fewer losses in the automatic tansmission the designer monkeys have tightened up the torque converters so that there is significant "engine braking" everytime one lets up on the foot feed regardless of what 'gear' it is in. Why doesn't the sense all and do all computer controlled engine and transmission controls have the smarts to monitor the foot feed and simply let the car coast? Manually slipping into neutral lets the engine run at idle, with less gasoline consumption, while the car just keeps rolling along. I can always use the brake when I want to slow down or stop and put it back in gear to accelerate. Slipping the car in and out of neutral during my daily commute through stop and go city traffic with gentle rolling hills increases my mileage by several mpg.
There is a reason for the torque converter dragging when decelerating as opposed to disengaging and letting the engine idle. Not all Auto companies have adopted it i.e. if you drive certain Chrysler products they coast freewheel style when you take your foot off the gas. If you drive a Honda (and other brands) when you let off the gas you feel the engine braking. Since the 90's Honda has shut off the fuel injectors during deceleration to save fuel, when you hit the gas again the fuel injectors turn back on. The torque converter stays connected to the engine to keep the engine turning--while it's just pumping air.
S/S .... I have every confidence any remaining issues will be resolved. Will it matter (be enought?) is another subject.
However, I have not seen any discussion/mention of the legal issues of implimenting it.
It is eligal in many states (mine included) to allow a car to "coast" on public roads (unless it is unavoidable - as in engine failure).Enforceablity of such a law is questionable (as is many laws).
Basically, a well meaning attempt at improving public safety, because it was viewed as a "un-safe" practice by people that were more concerned with the cost of fuel when cars / trucks had become widespread (1910-1930).. but costs were critical (during depression).
think :
ma and pa kettle.... coming to town, with some quaint ideas on being frugle and causing some "disruption" to the town folk's traffic. Because the law (in this state) was inacted before power steering/power brakes was common place, this was the only explaination given to me that made any sense. (told to me during traffic safety class when asked on the subject - coasting via clutch disengagement)
Every state has some laws on the books - from another era - that should be removed.
A few years ago... a vendor of mine (I am in the electronics industry) told me of the engineers he was working with at one of big American car test tracks he visits regularly (in our area).
Their focus : reduce size of battery required in cars.. saving costs on battery
The engineers told him they had worked out the details on "instant" start on their engines. These engines had most of the engine management requirements being described for Start/Stop.. but had NO starter required. Because the ECU "knew" the crank position, it could fire up the engine by directly injecting fuel into appropriate cyclinder and fire it - starting the engine from a stop. They demonstrated working units, everything was going fine .. then...
The idea was dropped.
Reason: some of the battery companies got wind of the project and threaten to charge as much for the much smaller batteries as the larger batteries... killing most of the incentive for the change.
Apparently the viewed risks of eliminating the starter (public perception) and the additional costs required of the ECU/additional sensors and valve controls at that time.. were not enough to offset the elimination of the starter.
Maybe this idea is finally seeing it' time "come"?
With the advent of gasoline direct injection soon most cars will have the means to start without a starter motor. The only additional requirement will be some type of absolute encoder for crank position. You would need a direct injection device capable of operating at electric fuel pump pressures, but that should be possible using electronics. Most EFI cars are already computerized so I am not as worried about that. The system that injects fuel and starts the car would be much lighter than any electric motor/starter/alternator system. you couldn't do regenerative braking though. You could do regenerative braking using a compounding alternator. Turbo-compounding is another way to increase mileage that is already in use by some diesel trucks. That could be used along with the start stop technology. The energy to restart the engine would need to come from somewhere and the battery is the likely victim, but could be designed to handle it. The direct fuel injection method would also be easier on the battery using the energy in the fuel to do the job. coasting also works, but everyone here needs to remember that the highest selling car in america is usually a TRUCK. this makes the need for continuous power steering and brakes a non-removeable item. I don't want to be too antagonistic here but the guy who "doesn't care if people can run their AC all the time" is being silly. the reason that modern cars DEFROST so fast is because the compressor runs and the reciever /dryer of the AC system is used to augment the simple air blown through the ducts. Before putting on your hair shirt you should think about 80 year olds stuck in traffic in Arizona. The system should be seamless or people SHOULDN'T accept it period. We already have way to much government involvement in the car business and don't need more. Soon the only people to have new cars will be government employees driving fleet vehicles because no one else will be able to afford them.
I think the theory on start stop has potential but some recent road tests I have seen have raised questions about the current state of the art.
The Malibu ECO (start/stop: eAssist)has been in two comparison tests against other mid-size sedans (Motor Trend and Edmunds IIRC) and has not demonstrated any mileage advantage in either case. The testers also found the system rather intrusive as I recall. The EPA estimated advantage isn't there apparently.
Over the years I have found that EPA milage ratings provide a rather poor basis for real world comparisons. Features that will do well on the govt treadmill don't always translate to an advantage on the road.
Interesting story about battery manufacturer pressue, but I'm guessing that today the auto mfgr's will go smaller if possible to save on weight.
I have a 10 year old, first generation Honda Insight, one of the rare manual transmissions, & will address some of the design issues they put in place two generations ago.
The IC engine does not auto-stop until it warms up, and on colder days it stays running more frequently on the in-town portion of my commute. The car does have a 12 v Kettering starter, but it only engages if I run the NiMh battery pack down too low. I think it has engaged twice in 6 years. The motor/generator in the flywheel/clutch pack does the starting: I turn the key and the engine is running.
This first gen design still has traditional HVAC so when the engine stops the HVAC fan stays running but there is no water through the heat exchanger or no AC compressor run. Sometimes I will start the IC engine if it is a long wait, no big deal. I can restart whenever I want, or swtich off the auto-stop if I want.
Electric steering boost doesn't seem to put much load on the storage, and the commonly used vacuum assist brakes are good for about 3-4 stops with the IC engine off. It restarts if the vacuum goes too high. (How many times do you need to start, then stop without the engine?) This first gen does not move on electric motor alone: Honda designed an assist approach, not a parallel one.
Lots more, but in summary: the sytem is pretty flawless, no excessive wear on the Bendix, instant restarts because the egnine is up to speed right away, electric HVAC would be a big plus, as would some power in this case: a 3 cylinder 1 liter engine is not the best choice for SanFran area traffic, although the 5 speed manual helps.
My other car is getting replaced this year, probably will be a diesel or something with a stop/start, even if not a hybrid. In my daily commute I would save idling about 7 to 10 minutes, twice a day.
electricplugincars.com reports insignificant sales making economical justification for tooling up for their manufacture to likely end their availability
Start-stop can be even more efficient and more convenient without the stupid programmed engine controller to make all the wrong decisions. The big challenge is the means to disengage the engine so that the vehicle can coast. The alternator that doubles as a cranking motor is the part that will need some work, mostly to assure a quickly sequenced crand-spark-fuel on sequence at each startup. The regular flywheel engaging starter would wear out way to soon, so it is not a good choice, I don't think.
I have driven a regular car with auto trans in the start-stop mode, manually, and the improvement in economy can be close to 30% with some practice. Just add a hydraulic booster for the brakes, and an accumulator for steering and brakes, and that solves that problem. Auto restart for the engine when the accumulator runs low, and no loss problems. The big deal items are the quick clutch and the direct drive starter. Add a simple sequencer for restarts and manual control is the very best choice ever.
This is nothing but marketing hyperbole, and Engineer's shouldn't help such attempts to confuse the market place. This is nothing but a beefier starter circuit, a circuit that exists already in non-hybrid vehicles. Better to call it "Golf Cart" starting (yes, it's the same as gas powered golf carts which start the engine when you press the accelerator).
It's certainly easier to implement in true hybrids, since while the engine is starting, your initial propulsion is by electric (hiding what's really going on from the driver).
As far as shutting the engine down while coasting, most modern computer controlled engines already do this, the trick is knowing how to implement it. Basically, you want to press down on the throttle just enough to keep the car from using the engine drag to slow down, but not enough for the computer to give it any gas. You don't want to shift into neutral, because the engine needs gas to idle. I did this with a friends gas guzzler on a long trip and was able to get 20% better mileage than the best they could do.
BTW - Europeans have been living this technology manually for decades. Traffic lights there go "yellow-red" just prior to turning green. It gives everyone a chance to start their engines and be ready to go (eliminating the need to predict when to start your engines).
I love technology....so this isn't a condemnation by any means.
Listen to the discussions. I have a great idea (in my simple mind). I think you should buy it. So I market/lobby my idea to safety and regulatory bodies. Basically I am legislating myself a profit.
Lots of good automotive ideas: nitrogen filled tires, E85+, start/stop systems, drowsiness detection, back up cameras, lane change warning systems, on-board navigation systems, anti-lock brakes, autonomous vehicles, intelligent headlights....on and on.
Each is technologically wonderful.
At what point have we made autos prohibitively expensive to purchase and maintain after the warranty has expired?
When my gun safe was delivered (yes, I am clinging, bitterly, as BHO quipped), the truck driver was complaining that his company, a large national firm, had installed Stop-Start technology on all their diesel trucks, and that they were suffering a high frequency of starter failures as a result. His disdain for the "improvement" was palpable. This is real world feedback.
I'm glad some of you choose to reap the benefits of this technology, more power to you, but I will gladly pay for the extra fuel needed to keep my engine idling at red light, etc. The extra complexity and cost that all these lovely and oh-so-helpful systems inherently bring to the table, from ABS brakes to tire pressure monitoring to air bags to catalytic converters, is always minimized, until it is time for repairs, as someone mentioned. And usually out of warranty. Can we please let the market decide whom wants this stuff, and let others buy the more basic alternative? That would be a true example of "diversity" and "tolerance" that I could get behind.
I can understand why you might want the reliable, easy to fix catalytic converter free gas guzzler. But you don't get to choose because that car drives up gas prices and pollutes the air for all of us. I am old enough to remember LA summers in the years before emission controls. On some days you could hardly breathe. And if you think $4 a gallon is bad, try $6. Or $20.
An equally serious problem is that prior to the "54.5 mpg by 2025" agreement, our 35MPG standard put us at risk of losing all auto sales to China, whose standards will be 42.2 MPG (18km/L) as iof 2014. It's the same for low emissions in Europe. Meet the rules or don't sell. 50 years ago US automakers could do whatever they wanted. No more. If we can't sell internationaly our automakers will fail. Depending on who you believe, the US auto industry is responsible for 5-14 million jobs, or 4-10% of total US employment. You think unemployment is bad now? Try it at 15% and watch the pundits fly.
Emissions controls, hybrids, start-stop, and plug-in electrics are all here to stay. But they don't need to be half-baked like your friend's truck, that was using the starter motor in ways it was not designed to be used. Soon they will get it right: someting like a brushless motor with the magnets built into flywheel. No brushes, no solenoids or mechanics to fail. Either way, like it or not, it's coming.
I will never buy a car with an electric starter - the convenience does not outweigh the cost and the inconvenience of having to repair it when it breaks. And, one crank handle can be used to start many different cars - no need for awkward jumper cables.
Any hybrid that can't keep the engine and therefore A/C running at a light won't sell in the southwest. Prius (and I assume Honda) keep the engine running so the A/C works. My Prius starts up on battery, the shift to engine is imperceptable and reliable. If the start-stop is properly integrated into the engine and controls, it should be reliable. And on the subject of an all battery electric, it is totally illogical and a waste of ink (or bandwidth) to discuss.
A study was done years ago that said about 80% of engine wear happens in the first few seconds after starting because of lack of oil pressure. What is being done about this? Haven't heard. Maybe yet another motor running the oil pump?
I keep cars for years & now they are getting even more complex, I don't want disposable cars like all other current day appliances.
I will never buy a S/S car. The percentage of fuel savings doesn't come close to what the cost of fixing it, or the wear it will see.
Just give me that 50 mpg diesel power as in Europe.
Providing oil pressure to assure adequate lubrication is in place at startup would indeed require additional hardware, but the devices that would do the job are old technology, fully mature and already used for other applications for many years. Besides that, most of the time the restart would be soon enough that the oil would not have much time to drain away.
For the very largest improvements there will need to be driver control rather than computer control, and those savings will be more in the 40% to 60% range, at least for city-type driving. But only at the hands of the more skilled and attentive drivers. On the other side, running the air conditioner would not only kill the mileage improvement, it would also probably increase the needed battery size by a factor of at least ten.
Federal-Mogul has released a new line of engine bearings that function well under frequent stop-start cycles. It is called Irox and comes in versions for both diesel and gas engines. I see it is used in the new (2014) Corvette v8 engine, and most likely is being used more widely. Other technologies exist for cylinder walls, valve guides, piston rings, etc., which allow long engine durability under start-stop conditions.
Since this was first posted, I have learned that at least one Canadian city is making it illegal to idle for more than 60 seconds! Stated concern: polution at stop lights during the winter months (inversion layer during winter?)
Ouch!..
If this comes even close to being enforced (70%+), a lot of older cars are going to see a lot of their local mechanics! Older cars are simply not designed for this level of abuse.
time and tide wait for no one......
I was kinda hoping to keep my older sports car for alot longer.. .(sigh)
"A study was done years ago that said about 80% of engine wear happens in the first few seconds after starting because of lack of oil pressure."
It is my understanding that the 80% wear referred more to cylinder wall wear as opposed to engine bearing wear. Most wear occurs before cylinders come up to normal operating temperatures and properly mate with pistons and piston rings. It was quite common to see air cooled Volkswagen cylinders with over 100,000 miles that have no wear ridge at the top because they warmed up so fast.
With start-stop technology, certainly oil would not drain off bearings completely. As mentioned, pre-oil systems are already available to combat cold start bearing wear should that prove to be a problem. Study the maintenance history of the U.S. Postal System vehicles if you desire more data, as they are mandated to shut down between stops. Starters and associated systems will definitely be a problem, but one that can be mitigated with a more robust design.
For start-stop driving, it would be very easy to have a small hydraulic accumulator to apply full oil pressure before cranking begins. It would take less than a second to bring up the oil presure and about another second to flood all of th bearings. So there would not need to be a lack of oil pressure concern.
One other thing is that with manual control it is easy to get much better than the ten percent reduction in fuel consumption while driving in rush-hour type traffic. Adding the coasting to the stopping does a great job of reducing fuel consumption. At least, that was my experience.
This is fascinating but I certainly can see engineering hardware and software challenges with this technology. I am definitely going to follow up with GOOGLE searches to learn more about those automotive companies with systems already in place and being testing. Charles, do you feel this technique would be adaptable to 400 Hp diesel engines--in other words, 18 wheelers? Great post and very informative.
I don't understand the discussion about the need to synchronize the starter to restart when a car is at substantial speed. A starter motor is not needed when the momentum of the car can be used (as almost anyone who has driven a standard shift car before steering wheel locks knows). Restaring an engine at speed effiicently is only a matter of reconnecting the engine to the wheels and then knowing the right time to put in fuel and spark. With electronically actually valves it is even easier because rengaging the engine is even more seamless if the valves are held open. Engine managment computers make all of this relatively easy.
I have always believed that the hybrid was the most innovative and effective improvement on the ICE-based motor vehicle, and past short personal experiences with the Prius (as a rental) were nothing but positive; actually spectacular, iin my view.
The outcome of a recent negative vehicular experience, has me now driving a Ford Escape Hybrid. Just the evolution from 15-16 mpg to 29-31 mpg has been a god-send, and the performance experience has been very admirable. Clearly, there is a start-stop component to the vehicle propulsion system, and I must say it is quite seamless. Watching the tach go from 1000 rpm to zero, either on coast, or stop is quite gratifying. Quite frankly, there is nothing negative I have yet encountered about the vehicle itself or the technology. Clealry , Ford has gotten it right.
First, auto and battery makers are actively researching using higher voltage batteries. Current draw on a 12V system is severely taxing the electrical systems of current cars; 24, 32 and 48V systems are being evaluated. Second, Mercedes seems (based on observation during a loaner day) to be using start-stop by injecting fuel into a cylinder past top-dead-center, then igniting the spark. No audible starter engagement was evident even with the hood open and the only noticable side-effect was a very slight shudder. Time delay was less than half a second from brake release to power-available. The system did not engage until the engine was fully warmed-up and if frequent starts/stops were necessary in traffic such that the engine cooled-down, the system would disengage. They may have another method but it was inaudible. As far as A/C goes, there shoudl be enough liquid left to evaporate to provide sufficient cooling for up to 5 minutes. I'd guess there must have been an auxilliary electric coolant pump because shutting off an engine after extended highway driving without coolant movement would be destructive. I was unable to notice a change in the cabin air outlet temp in traffic. There was sufficient vacuum available to hold the brakes indefinitely after the car was stopped, though there could have been a hydsraulic motor to assist. Because most new cars have multipoint fuel injection and computer controlled spark, a similar system for start/stop could be used without necessitating a separate starter.
As energy efficiency becomes more and more a concern for makers of electronics devices, researchers are coming up with new ways to harvest energy from sound vibration, footsteps, and even electromagnetic fields in the air.
The government wants to study your brain, and DARPA wants to use similar information to give robots true autonomy beyond any artificial intelligence developed to date. Sound like science fiction? It's not.
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