Confused about PHEV, Hybrids, etc...

[bdunham7]

If you look closely at the animation in this video from Toyota, you'll notice that the length of the strokes is different:
https://sherbrooketoyota.ca/en/videos/atkinson-cycle-engine So it looks like Toyota is doing more than just having different valve timing.

Length of what strokes compared to what?  Compression vs power on the same engine, like the original Atkinson cycle engine?  That would require an insanely complex mechanism that I can assure you does not exist on any current common product.  Now in general, these types of engines often do use a longer overall piston stroke than similar size/power 'normal' engines, but the movement of the piston is completely set by a rigid connecting rod and crankshaft. 

[edy]

What I saw in that Toyota video is that the cylinder heads move exactly in the same fashion and amplitude in all 4 phases of action (fuel/air intake, compression stroke, power/explosion/expansion, exhaust stroke). However, what I see happening is that in the early part of the compression stroke the intake valves remain open so that the cylinder is not being pressurized from the start... instead as the cylinder head moves up, because the valves are still open, it lets some of the air/fuel mixture push back out into the intake chamber area. Finally when the intake valves do close, the cylinder starts to pressurize, compressing but against a smaller volume of fuel/air. This reduces the effective "size" of the cylinder, as if a smaller cylinder is being compressed.

I assume that part of the fuel savings is simply because it burns less volume on each stroke, you are taking say a 2.8 L engine and effectively only using it as a 2.4 or 2.2 L engine (for example). Perhaps the efficiency is also improved as there is more complete combustion of the contents of the cylinder since there is less fuel trying to completely burn up in the time that the power/expansion stroke occurs. Somewhere there must be a trade-off in power/torque and at what RPM, but perhaps a computer can figure out based on the speed of the car and what is required of it this is a worthwhile trade-off to milk a bit more efficiency out of the engine with nuanced valve timing.

[tom66]

You have to account for the fact that the hybrid system improves the performance allowing for a less than powerful engine tune at the expense of lower performance which is supplemented by the hybrid system.  The hybrid motor adds about 40 hp to the engine output under peak acceleration in the Prius; it adds 100 hp to my Golf GTE. 

Most people don't need the full 100 hp from their vehicle for long periods of time (exceptions apply, yadda yadda, but this is generally true for most driving profiles) and this allows the use of smaller engines and/or less power-optimised tuning for these users.

[gnuarm]

If you look closely at the animation in this video from Toyota, you'll notice that the length of the strokes is different:
https://sherbrooketoyota.ca/en/videos/atkinson-cycle-engine So it looks like Toyota is doing more than just having different valve timing.

Sorry, I don't see that and they don't talk about it. 

[gnuarm]

What I saw in that Toyota video is that the cylinder heads move exactly in the same fashion and amplitude in all 4 phases of action (fuel/air intake, compression stroke, power/explosion/expansion, exhaust stroke). However, what I see happening is that in the early part of the compression stroke the intake valves remain open so that the cylinder is not being pressurized from the start... instead as the cylinder head moves up, because the valves are still open, it lets some of the air/fuel mixture push back out into the intake chamber area. Finally when the intake valves do close, the cylinder starts to pressurize, compressing but against a smaller volume of fuel/air. This reduces the effective "size" of the cylinder, as if a smaller cylinder is being compressed.

Exactly, that's why this is not an accurate representation of where the advantage is. 

In reality, they would design a slightly longer stroke for the Atkinson cycle engine, which would provide a higher compression ratio, if it weren't for the different valve timing.  So now the Atkinson cycle engine has the same compression ratio, but a higher expansion ratio, all with the same stroke length, but not the same stroke length as the corresponding Otto cycle engine.

I assume that part of the fuel savings is simply because it burns less volume on each stroke, you are taking say a 2.8 L engine and effectively only using it as a 2.4 or 2.2 L engine (for example). Perhaps the efficiency is also improved as there is more complete combustion of the contents of the cylinder since there is less fuel trying to completely burn up in the time that the power/expansion stroke occurs. Somewhere there must be a trade-off in power/torque and at what RPM, but perhaps a computer can figure out based on the speed of the car and what is required of it this is a worthwhile trade-off to milk a bit more efficiency out of the engine with nuanced valve timing.

You are comparing two engines based on the power stroke.  Compare them based on equivalent (effective) compression strokes and compression ratio, and you get a different picture.  Now they can have the same compression ratio, but the Atkinson with a longer expansion stroke to make it more efficient. 

[emece67]

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[tom66]

The energy needed to move a car depends primarily on:

• front area
• Cx
• speed
• mass

Yes.  And a lot of this is down to the relatively new obsession with SUVs.  They have a place for people with large families, but the majority of people would be absolutely fine with a small to medium hatchback car, or an estate, which all have better aerodynamic profiles due to the small frontal profile and lower road position, and usually they weigh less.

[nctnico]

If you look closely at the animation in this video from Toyota, you'll notice that the length of the strokes is different:
https://sherbrooketoyota.ca/en/videos/atkinson-cycle-engine So it looks like Toyota is doing more than just having different valve timing.

Sorry, I don't see that and they don't talk about it.

I put the mouse pointer at the lowest point and at some point the piston doesn't reach it. But this could be an animation effect / artefact. Bottom line is that I have not been able to find whether Toyota Atkinson engines do or do not have different stroke lengths. I don't want to get into the mechnanical details; if Toyota uses it they probably found a clever way of doing this.

[NiHaoMike]

Yes.  And a lot of this is down to the relatively new obsession with SUVs.  They have a place for people with large families, but the majority of people would be absolutely fine with a small to medium hatchback car, or an estate, which all have better aerodynamic profiles due to the small frontal profile and lower road position, and usually they weigh less.

Big cars don't have to be inefficient. The new Sienna gets 36 MPG - better than some sedans!
https://www.toyota.com/sienna/

The EPA really should tighten up efficiency requirements. Toyota showed what's possible, no excuse for automakers to keep cutting corners.

[gnuarm]

The energy needed to move a car depends primarily on:

• front area
• Cx
• speed
• mass

I see car manufacturers selling progressively bigger, faster and heavier vehicles, but trying to convince us that they are doing all technically possible to enhance fuel economy by 1 % putting into it more and more technology, but not touching, in fact worsening, any of the main factors.

There have always been plenty of small cars to buy, and this will always continue.  If you can't find a small car, that's on you.

The previous Toyota video is interesting. One of the cars appearing on it has a front area well above 2 m2, a Cx ~ 0.4, a mass above 2 ton and a top speed ~170 kph, but they are showing us the benefits of its Atkinson capable engine to get a fuel economy of 8.8 l/100 km. It is plainly obscene, the last car I owned with such a poor fuel economy was build/bought in the early 80's.

Car makers have to sell the vehicles people want to buy.  Otherwise they become another Hudson or Studebaker.

Car manufacturers deserve heavy regulations limiting the amount of energy their cars can use, or banish.

How about we simply put the responsibility on the people buying the cars.  How about a tax on gross vehicle weight and/or frontal area, or even just increase the fuel taxes?  A fuel tax gets right to the heart of the matter.  To make it less regressive, we can offer a income tax credit for the first 280 gal (14,000 miles at 50 mpg).  So buying a car with worse mileage than 50 mpg or driving more than 14,000 miles, incurs the tax.  It also equates to a credit to drive less than 14,000 miles or getting better than 50 mpg.

[emece67]

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[nctnico]

@gnuarm:
The EU already has limits for the average CO2 emissions for all cars sold per manufacturer. Toyota is the only manufacturer meeting the requirement without needing to sell BEVs to compensate because they are the only manufacturer that actually foresaw the future right (and develop hybrid cars). The rest of the manufacturers just screems 'jobs get lost if you add more regulations!' and hope the politicians will swing their way. In the end that isn't going to hold up.

And no, you can't leave it to consumers! People say they like to take action but the reality is that they would like to see other people take action. The government needs to be the driving force behind making cars more efficient and more clean while keeping mobility affordable.

Small cars get more rare as well (at least in the EU). Manufacturers are pulling out of this market because the margins are too thin. 10 years ago you could buy a car for 8000 euro. Nowadays the same car costs twice as much due to stricter safety regulations and emission requirements. For example: Citroen and Renault used to have a tiny car but they don't sell it any longer.

Fuel taxes aren't the answer either. This has been tried in the NL and it doesn't work. Only drives up inflation. So the NL government is taxing purchase prices of cars based on fuel consumption. For some cars that tax is several times the price of the car (a Lada Niva with a list price of 12k euro ends up costing 47k euro including taxes).

[tom66]

The EU regs seem pretty effective if the goal is electrification of vehicle fleets.  We wouldn't have the ID.3 without dieselgate fines and EU regulations.  So I think it's still a good thing that they're there.

And hybrids are a technology that is going to rapidly die out as larger capacity EV batteries become more common.  58kWh is standard in the ID.3, prior to the chip shortage that was a 26,000 GBP car, not much more than a standard Golf of similar trim.  That battery will do over 200 miles.  I doubt that most people will pay a lot extra to avoid one charging stop, but we'll see. 

[nctnico]

Again, you are not counting in public charging costs which make BEVs an uneconomic choice for many. Hybrids will be here to stay for the next several decades in larger numbers compared to BEVs simply because hybrids are more economic to drive in.

Rest assured that public charging prices will go up when the investors in charging infrastructure (none of them is making a profit at this moment!) start wanting to see return on their investment. After that governments will step in to regulate prices. Just look at how mobile phone operators used to charge an arm & leg for certain services and now got clamped down by governments to charge fair amounts for their services.

[gnuarm]

There have always been plenty of small cars to buy, and this will always continue.  If you can't find a small car, that's on you.

It is not on me at all. Even Smarts and Fiat 500 do weight a ton. Smaller cars like Microcar or Ligier are not even legal here to be driven thru a freeway. Maybe you know of any machine allowing one to commute using, say, one fourth of the energy needed by a Prius. Or maybe our concepts of a small car are different. Or maybe I must use a different expression to "car" to noun a machine allowing one to commute.

I see car manufacturers selling progressively bigger, faster and heavier vehicles

This is what I responded to.  You seem to be saying there are no smaller car, but that they keep making larger cars.  Now you seem to think a car should weight less than 2,000 lbs (or maybe thats 1,000 kg, a metric ton).  Not sure what you are expecting.

Car makers have to sell the vehicles people want to buy.  Otherwise they become another Hudson or Studebaker.

We no longer can afford to buy anything we want.

Sounds great.  So build the cars you want to force on people.  I'll wait while you try that.

A fuel tax gets right to the heart of the matter.  To make it less regressive, we can offer a income tax credit for the first 280 gal (14,000 miles at 50 mpg).  So buying a car with worse mileage than 50 mpg or driving more than 14,000 miles, incurs the tax.  It also equates to a credit to drive less than 14,000 miles or getting better than 50 mpg.

Fuel taxes exist now and are useless, as they tax equally small and big cars, if I can afford a Hummer, I can afford its petrol. A tax on cars, taxing energy consumed, will be more appropriate, supposed that the tax on monster cars is so high that manufacturers need to think twice.

You don't seem to understand fuel taxes.  Or maybe they are different where you are.  Here, in the US, they are based on the gallons you burn.  If you drive more or drive a less efficient vehicle, you pay more tax.  My understanding is fuel taxes are much, much higher in the EU and it very much impacts the choice of cars.

[gnuarm]

@gnuarm:
The EU already has limits for the average CO2 emissions for all cars sold per manufacturer. Toyota is the only manufacturer meeting the requirement without needing to sell BEVs to compensate because they are the only manufacturer that actually foresaw the future right (and develop hybrid cars). The rest of the manufacturers just screems 'jobs get lost if you add more regulations!' and hope the politicians will swing their way. In the end that isn't going to hold up.

And no, you can't leave it to consumers! People say they like to take action but the reality is that they would like to see other people take action. The government needs to be the driving force behind making cars more efficient and more clean while keeping mobility affordable.

Small cars get more rare as well (at least in the EU). Manufacturers are pulling out of this market because the margins are too thin. 10 years ago you could buy a car for 8000 euro. Nowadays the same car costs twice as much due to stricter safety regulations and emission requirements. For example: Citroen and Renault used to have a tiny car but they don't sell it any longer.

Fuel taxes aren't the answer either. This has been tried in the NL and it doesn't work. Only drives up inflation. So the NL government is taxing purchase prices of cars based on fuel consumption. For some cars that tax is several times the price of the car (a Lada Niva with a list price of 12k euro ends up costing 47k euro including taxes).

Ok, I guess we are all doomed!

[gnuarm]

The EU regs seem pretty effective if the goal is electrification of vehicle fleets.  We wouldn't have the ID.3 without dieselgate fines and EU regulations.  So I think it's still a good thing that they're there.

And hybrids are a technology that is going to rapidly die out as larger capacity EV batteries become more common.  58kWh is standard in the ID.3, prior to the chip shortage that was a 26,000 GBP car, not much more than a standard Golf of similar trim.  That battery will do over 200 miles.  I doubt that most people will pay a lot extra to avoid one charging stop, but we'll see.

Hybrids and BEVs are completely different animals.  Hybrids reduce fuel consumption, but do little for carbon emissions, because "reducing" emissions are pointless when we need to get to zero!  Hybrids have never been about anything other than saving money spent on fuel. 

[tom66]

Again, you are not counting in public charging costs which make BEVs an uneconomic choice for many. Hybrids will be here to stay for the next several decades in larger numbers compared to BEVs simply because hybrids are more economic to drive in.

Not really my experience.  Even the most expensive public charging has been cheaper than petrol here.   And of course if you can charge at home on your drive or similar you can take advantage of very cheap domestic rates in the off peak.  Even with the current energy hikes I'm still paying about 2 pence per mile for my PHEV when on electric - that's around 8x cheaper than petrol is per mile.

What we need is more 'slow charging' infrastructure for people parking on streets, it's just as vital as rapid chargers to enable mass EV adoption.  And these chargers would incentivise overnight charging for those who don't need priority charging.

Rest assured that public charging prices will go up when the investors in charging infrastructure (none of them is making a profit at this moment!) start wanting to see return on their investment. After that governments will step in to regulate prices.  [...]

Like all markets, there will be an inflection point at which competition and demand keeps prices low.  Your argument makes no sense, as otherwise petrol stations could charge as much as they like.

For Ionity for instance you can already get a membership with e.g. Bonnet EV which gets rates at under 40p/kWh, not much more than a domestic daytime electric tariff right now costs.  I think these membership schemes will end up being part of your domestic energy tariff eventually, you will pay for home and away electricity from the same provider.

[gnuarm]

Again, you are not counting in public charging costs which make BEVs an uneconomic choice for many. Hybrids will be here to stay for the next several decades in larger numbers compared to BEVs simply because hybrids are more economic to drive in.

Even when charging a pay chargers, BEVs save a lot of money compared to gas.  In reality, BEVs are not about saving money.  That's just a nice side effect.  What is important is eliminating carbon emissions.  It is essential, in fact.  That's why we also need to invest heavily in renewable energy sources to complete the process.  Hybrids will NEVER do anything but slightly reduce carbon emissions, which is ENTIRELY pointless.

Rest assured that public charging prices will go up when the investors in charging infrastructure (none of them is making a profit at this moment!) start wanting to see return on their investment. After that governments will step in to regulate prices. Just look at how mobile phone operators used to charge an arm & leg for certain services and now got clamped down by governments to charge fair amounts for their services.

Cell phone providers are regulated???  I think you need to check again.  Well, maybe you are someplace other than the US.  I only know about the US. 

BEV charging is not very expensive.  Mostly it is done at home.  With time, every apartment, condo and detached home will provide charging at nominal rates, or even include it as part of the overall cost, just like parking.  Average miles driven is 40 or 10 kWh.  In the US, that mostly ranges between less than a dollar, to $2.50 per day.  It's not going to break anyone.  They can raise the rent $50 a month and you'll save $150 a month on gas. 

[nctnico]

@gnuarm: the situation in the EU is different compared to the US. Prices are very much regulated. With today's high oil prices, governments across Europe are cutting taxes on fuel in order to maintain low price levels so people can afford to go to their work and keep their homes warm.

And please don't move the goal posts by bringing in 'charging at home' when I explicity state 'public charging'. Just do the math for people that have to rely on public charging exclusively and you'll see a hybrid wins hands down on 'fuel' costs.

Fuel from oil isn't going away overnight so franticly going after electric cars and trying to shoehorn BEVs as a universal solution isn't going to work. There is a market segment for which BEVs work well at this point in time. For the remaining market, hybrids are currently the best solution. Looking at the trends, hydrogen looks to become the new oil so who knows what the future will bring. It might as well be that BEVs go away and cars will move towards FCEVs (fuel cell -typically hydrogen powered- electric vehicle). Even today a FCEV would be more economic to drive compared to a BEV when needing to rely on public charging.

[emece67]

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[bdunham7]

Even today a FCEV would be more economic to drive compared to a BEV when needing to rely on public charging.

If your 'public' EV charging is actually a privately owned for-profit enterprise while the H₂ stations are highly subsidized, then that is probably true.  But the problem is easily solved by making the public charging universal and free, or else subsidizing at least the delivery systems so that the end user pays roughly the cost of the electricity.  Gas-hybrids wouldn't work very well either if there weren't fuel stations.

b/t/w, how many H₂ stations are there in the EU?

[tom66]

FCEV is not cheaper - that's bollox.

Hydrogen at a filling station is £14 per kilogram[1], about the same in EU, if you can find somewhere to refuel.

And you can't refuel at home, so you had better live somewhere near a refuelling station - but let's pretend you do and you don't mind the inconvenience of this - unlike at least with petrol where the infrastructure is common.

A Mirai is rated around 60 miles per kg, so one mile will cost 23p.   In euros, roughly 28 cents.  Average UK petrol price is £1.75/L right now and a typical car might get 50 mpg or about 4.7L/100km so the same distance on petrol is about £8.20 - 75% the cost of hydrogen even considering the inflated cost.  A diesel car might push 60 mpg, 3.9L/100km (~£1.90/L around here right now) = £7.41 for the same journey.    If it's an EV, getting 3.5 miles per kWh, the cost-parity with hydrogen is only reached at a fast charger costing 80p/kWh, and with diesel around 43p/kWh.  Ionity charges up to 69p/kWh for non-members, but as mentioned before which you so conveniently ignore, most people do not pay this.  The average rate is closer to 40p/kWh.   That's *still cheaper* than diesel for an entirely unusual scenario of no AC charging and no home charging.

So even relying purely on fast-dc charging, the BEV is half the price of the FCEV.  If it can be charged at home (which roughly 50% of people can do with just a home charger install) then the BEV is around 1/10 to 1/20th the cost and with no inconvenience of having to find fuel all the time, petrol or hydrogen.

[1] https://cafcp.org/content/cost-refill (US price, but it should be cheaper than the UK)

[bdunham7]

If it can be charged at home

I think that is one of the two real questions for most people, the other being the cost of a car.  Even in todays inflated market, you can find (here at least) a decent used car for $10-12K that will go 500 miles between trips to Costco for gas.  A BEV with home charging eliminates those trips, which is really nice, but a reasonable range BEV (it doesn't have to be 500 miles, 150-200 is good enough) will be at least 3-4X that new and there aren't many used.  Without home charging, its hard to see the point.

[Cerebus]

What we need is more 'slow charging' infrastructure for people parking on streets, it's just as vital as rapid chargers to enable mass EV adoption.  And these chargers would incentivise overnight charging at times of low demand or of cheap production for those who don't need priority charging.

FTFY.

In some cases it's the same thing, but with the amount of PV on the grid nowadays it's not the case that overnight now always represents the cheapest or 'greenest' electricity.