Prius Performance On Hills?

[timberwolf]

I thought e-CVT was a good name, but I'm not sure that Toyota use it any more - I think their marketing department gave up on it?

As an alternative to e-CVT, I would suggest virtual-CVT.

I think there is a conceptual problem, in that far too many people have this expectation that there must be a real physical mechanical piece of machinery that they can call a CVT gearbox. As I understand it, the very essence of the CVT has been moved from the mechanical combination of gears or belts and pulleys into the software/electronic control realm. The Power Split Device, electric motor/generators, and the control circuits are just components that are operated by the software/electronics to produce the effects of a CVT in the physical world.

[Opifex]

I dropped out of this thread after reading Cyker's original post. I didn't have time to respond then but my post would have been similar to a lot of the other responses Cyker has had.

Instead let me give a little real-life example. Yesterday morning I entered a motorway at the foot of a steepish hill with four adults on board, a full Battery and doing about 95kph (59mph). I accelerated fairly quickly to about 135kph (84mph) and still had a full Battery when I reached the top of the hill about two miles further on.

[Cyker]

@johalareewi - The ROFLing at the gear ratio comment suggests you don't know how the HSD works - It is not a 1-ratio box like most of the all-electric cars - It incorporates a continuously variable gearbox! This means the gear ratio of the ICE to the wheels can be varied from a low ratio ('1st gear') to a high gear ('top gear') with a virtually infinite number of steps in between.

Perhaps you are not explaining how the PSD (power split device) works very well.

The ICE, MG1, MG2 and the drive shaft are inter connected via a planetary gear system (the PSD).

All have fixed gear ratios. <-- Note

By mixing the ICE, MG1 and MG2 inputs, the required power output to the wheels is produced.

When going up a hill and more 'grunt' is needed, the HSD will adjust the inputs to get the required output. This may require more grunt from the ICE, or MG1, or MG2. The HSD decides at the time.

There is no downshifting a gear.

The gear ratios are fixed and do not change.

Some reference links.

Enjoy.

http://eahart.com/prius/psd/

http://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

In particular:

"HSD transmission continuously adjusts the effective gear ratio between the engine and the wheels to maintain the engine speed while the wheels increase their rotational speed during acceleration."

You do realize you're just arguing semantics?

You even highlighted the part that says the HSD ADJUSTS the EFFECTIVE GEAR RATIO while arguing that the HSD has no gear ratios!?

I don't understand; Is your problem just that I used the term 'gear ratio' rather than, say, 'magical input-to-output-power-conversion factor'?

You do realize *anything* that uses an ICE to drive something with varying load or speed MUST have some sort of variable gearing to have any kind of efficiency? Just because the HSD does it differently to normal selectable-gear systems (Using MG1 rather than different-sized gear-pairs) doesn't make it a fixed ratio box!

Now, you are TOTALLY RIGHT that the MG1, MG2 and ICE are interconnected to each other and that the gear ratios between them are fixed. No argument from me there.

However, this is totally irrelevant. It would almost be like me saying the intermediate gears between the engine and the gearbox are fixed ratios in a manual transmission; Yeah, they are, but is it a fixed ration transmission? No! (Okay that wasn't as good as the Claudia analogy but it'll have to do!)

The fact of the matter is the ICE in the HSD can, at a given wheel speed, spin faster to give the wheels more torque or slower to reduce fuel consumption. This implicitly means either the ICE is not connected to the wheels (And is thus not part of the drivetrain, but is a generator) or there is variable gearing involved.

MG1 is, in effect, the bit that varies the gearing as it controls the ICE's contribution/balance of torque vs speed going to the drive ring, and MG2 can decide whether to sap energy from that to charge the HV, pass it on to the wheels, or add power to drive the wheels harder. If it wasn't for MG1, the HSD really *would* be a fixed ratio system (and also would also suck horribly because without variable gearing the ICE would only be usable in a very narrow band!)

I will agree the term CVT isn't a perfect fit for describing the HSD as a true CVT only has one power source that it varies whereas the HSD has two which it mixes and varies. Also, when most people hear CVT and imagine variable-width belt-pulleys, sliding cones etc.. *shudder*

Without a better term tho', the term Continuously Variable Transmission is a good enough description of

Personally I just refer to it as a HSD :)

Edit: @Opifex - Yeah it is getting a bit tl;dr in here, sorry, but in my defence I did say the HSD would be totally fine with hills if it had any kind of charge in the Battery. The only scenario where I said it *might* struggle was if the Battery was totally empty and the HSD was tackling a steep hill while heavily loaded.

And when I say 'struggle', I don't mean 'it can't do it', I mean 'struggle' in the same way my Yaris struggled to carry nearly 500kg of concrete slab up a hill on the weekend (It did it just fine but I had to drop gears and rev higher than normal to do so with any kind of noticeable acceleration!)

We know the HSD can still go up said hill in said scenario just fine, just the engine will be revving higher than normal and won't have the acceleration it would otherwise have as it won't have the torque from the leccy motor to help out.

[timberwolf]

Cyker, at one time it was believed that the Earth was the centre of the solar system, they came up with very complicated explanations to explain how the planets apparently moved across the sky - it was junk science. Your explanation of how the Hybrid works on the motorway, doesn't fit with observation or current knowledge published elsewhere on how the Toyota Hybrid works, and I don't know understand your motivation in posting long-winded, and flawed misinformation.

If you hate the Hybrid fine?, there are enough genuine reasons to dislike a Prius and not buy one, you don't need to make stuff up.

[Cyker]

Why do you think I hate the HSD?! It's like, the only major innovation we've had in automotive gear trains since I've been alive!

Anyway, the original discussion was what it was like fully loaded on hills (Answer: Fine, but will rev more than usual if Battery charge is critical.), I don't think motorways was a major point of this thread (I think I mentioned it, like, once, and every generalization I made was swiftly corrected )

I think most of what I've written is right or at least ballpark; The rest is there to be corrected because that is what discussion forums are for - The spread of information! (Case in point: I didn't know the car could run on the Battery alone above 40mph!). I'm not attacking the HSD!

Now I'm just swapping flamebait with johalareewi over whether the HSD counts as a variable gearbox or not. :(

I should probably just stop posting at this point before I get hunted down by angry HSD drivers! :)

[Mkuk0]

Sheesh this place is full of pedants!

To the OP, I've had 2 now, drive all over the country, on all types of roads, with all types of loads, its great.

what else do you need to know?

[Opifex]

Anyway, the original discussion was what it was like fully loaded on hills (Answer: Fine, but will rev more than usual if battery charge is critical.),

I think most of what I've written is right or at least ballpark; The rest is there to be corrected because that is what discussion forums are for - The spread of information! (Case in point: I didn't know the car could run on the battery alone above 40mph!). I'm not attacking the HSD!

I'm afraid you're still bit off the mark about the ICE revs "if the Battery charge is critical". It will in fact rev whenever maximum power is required, regardless of the state of the Battery. In practice I find this is only noticeable when fully laden and accelerating either up a steep hill or if I'm already at motorway speeds. Most of the time, including when cruising at constant speed up hill or on a motorway, the car is using much less than maximum power so the ICE noise is usually very low or silent. I think it is this variability which makes the loud bits more noticeable than they would be in a conventional car. If it's normally noisy you don't notice if it gets a bit louder. If it's normally quiet you are more likely to notice when it's not.

I seem to remember that when I read the original post (just before WW3 broke out), as you say, most of what you had written was in the right ballpark. The problem was that the rest would give the wrong impression to any potential owner who happened to drop in and only read that bit without coming back to see the corrections.

[Cyker]

That is a good point, plus I can't imagine many people would bother reading further once 'WW3 broke out' as you put it! It also doesn't help that most people seem to ignore most of the qualifiers I use (e.g. I say it will do x in situation y and people only read the 'it will do x' part and then flame on how that's rubbish because it only does that in situation y)

Alas that is just one of those things on forums; I'm sure there have been some equally heated arguments on e.g. diesel engines!

[Opifex]

That is a good point, plus I can't imagine many people would bother reading further once 'WW3 broke out' as you put it! It also doesn't help that most people seem to ignore most of the qualifiers I use (e.g. I say it will do x in situation y and people only read the 'it will do x' part and then flame on how that's rubbish because it only does that in situation y)

Alas that is just one of those things on forums; I'm sure there have been some equally heated arguments on e.g. diesel engines!

Don't mention fog lights, when to use B setting, using parking brake at traffic lights.........

[timberwolf]

Why do you think I hate the HSD?! It's like, the only major innovation we've had in automotive gear trains since I've been alive!

<snip>

Just a hunch, and I note you did not answer

What about the Direct-Shift gearbox? The advancement of electronics in Automatic gearboxes? Engine braking with an Automatic gearbox was pretty revolutionary for the sort of Automatics that I could afford - before that driving automatics involved a lot more going back and forth between accelerator and brake pdeals, and leaving much bigger gaps when merging with traffic.

[Mickfb]

Not wishing to up set anyone but why don't they just drive and enjoy their car. I know I asked questions. I listened to the answers, made a decision on the information given. If people have to ask so many questions maybe a hybrid is not the car for them.

Rung the dealer today, my Auris S/T is on the production line. So not long now.

Mick

[Cyker]

@Optifex -

@timberwolf - You forgot to mention locking torque converters!

Did you mean the VW DSG when you said Direct Shift? I must admit I tend to look down on these 'automatic manuals', but the DSG is definitely best of breed if you don't mind the astronomical repair costs! (And much better than the hated MMT! )

Personally, until the HSD came along, I'd considered the best autoboxes were torque converter based ones - Even now I think they are the only autobox that you can tow things with without lots of ECU limiting to avoid damaging the drive train by overtorquing. The only major downside being the high loss, but with advances in locking torque converters I'm hoping we see a resurgence! (LFA! GT86!! :D)

Most innovation in the gear train department has been refinement; The HSD has been the first real new development. It's also the first non-experimental system I know of that uses electric motors to control the gear ratio rather than physical different-sized gear pairs/pulleys etc.

As automatics go, it's hard to beat. It's easily the best autobox Toyota fit to their car cars! :)

[Parts-King]

That Don't mention fog lights, when to use B setting, using parking brake at traffic lights.........

Or dog forbid.................what oil do I use?

[timberwolf]

Yes, I meant the VW DSG, I was writing that off the top of head, so I wouldn't be surprised if I got the name wrong.

I've never thought of MMT to be anything other than a horrible kludge, it sounded rubbish on paper, I can't believe the motor industry dreamt it up in the first place and then to actually make it and sell it to customers - what had they been smoking?

[timberwolf]

That is a good point, plus I can't imagine many people would bother reading further once 'WW3 broke out' as you put it! It also doesn't help that most people seem to ignore most of the qualifiers I use (e.g. I say it will do x in situation y and people only read the 'it will do x' part and then flame on how that's rubbish because it only does that in situation y)

Alas that is just one of those things on forums; I'm sure there have been some equally heated arguments on e.g. diesel engines!

Don't mention fog lights, when to use B setting, using parking brake at traffic lights.........

I thought we were reasonably well behaved when the traffic light question came up again recently? I reckon the pent up energy must have rebounded into this topic though!?

[Chris Fisher]

I got some helpful replies to my traffic light question :-).

[Chris Fisher]

I got some helpful replies to my traffic light question :-).

[barrycoll]

just for the record, my new 2013 T Spirit, fully loaded with windsurf kit and 50 kgs of bikes on the Thule tow bar rack, sailed up and over the middle of the Pyrenees and down into Spain....no problems when in Power mode, and more economical than my Golf TDI DSG which was chipped to 170bhp, and over 300lb/ft of torque....

the mileage dropped to the low 40s on the climb, and then resumed the high 60's down the other side.....the Gold never managed to crack 50mpg, even when molly-coddled

[Surv1v0r]

Someone commented that "I do know that people come to this forum to hear from owners and drivers of hybrids to get real world answers to their questions". That was certainly the case with me, I had no intention of stirring up a hornet's nest and I am genuinely grateful for the many helpful observations that Prius owners and drivers have posted. I am also grateful for Cyker's input, there can be good reasons why someone isn't a Prius owner and disciples aren't always the most reliable source of objective advice.

Incidentally, what is it about fog lights, when to use B setting, using parking brake at traffic lights and what oil to use? PSD, ICE, MG1, MG2 - I guess I need to do more research into TLAs ;)

Don't buy a Prius if you think it's going to be the most economical car in the world.

I hadn't planned to do so. I have a 15 year old Toyota Picnic and it has been a great car for me so I would certainly look first at another Toyota. The Prius ticks many boxes other than just economy, I am however somewhat concerned about its qualities on long (motorway) runs, up hills and in very cold weather.

... you also have to live with all the usual negatives of diesel driving and ownership which may or may not bother you.

I am not really that familiar with the weaknesses of diesels, would you care to elaborate?

The driving characteristics of the HSD are uniquely tuned to relaxing and de-stressing modern, traffic-choked driving.

Sounds good to me, I just don't want to be rocking back and forth in my seat trying to urge a comfy sofa up a hill or past an HGV.

Someone, I can't recall who, pointed out that I should fit winter tyres when driving in the Alps and this raises an interesting question. I seem to have read somewhere that the Prius uses special low rolling resistance tyres. Is this going to make if that much expensive to find suitable winter tyres? Likewise the mandatory snow chains.

Yesterday morning I entered a motorway at the foot of a steepish hill with four adults on board, a full battery and doing about 95kph (59mph). I accelerated fairly quickly to about 135kph (84mph) and still had a full battery when I reached the top of the hill about two miles further on.

My new 2013 T Spirit, fully loaded with windsurf kit and 50 kgs of bikes on the Thule tow bar rack, sailed up and over the middle of the Pyrenees and down into Spain....no problems when in Power mode

Now those are what I call useful, real-world experiences - many thanks.

[Cyker]

re. the "Incidentally what is it about...", that was just a reference to the fact that all those topics have generated equally heated flamewars and/or angry long thread postings

re. Diesel problems, basically the era around when the Corolla 2.0 D4D and Yaris Mk1 D4D came out was when the last really reliable diesel cars were made by Toyota and other mfgs - After that, Euro emissions legislation have forced all car manufacturers to put stupid devices on their cars, the EGR and DPF being two of the biggest causes of problems, which have made diesels go from being far more reliable than petrol engines to actually slightly worse.

(EGR - Exhaust gas recirculation, designed to reduce NOx pollutants, but raises SO, CO2, CO, soot and lowers mpg. Causes performance and mpg loss when it inevitably blocks up; DPF - diesel particulate filter, filters out soot from the exhaust but also creates a huge obstruction in the exhaust which increases back-pressure, drops mpg by 5-10 and clogs up quickly when during urban driving, sapping more power and making emissions worse).

The last big diesel annoyance (Also coming to petrols near you! :D) is the dual-mass flywheel - Because diesel engines produce so much torque but run at lower RPM, they used to have big heavy flywheels, but this made the acceleration bad, so some bright spark thought to stick two-much-lighter flywheels in, connected by springs. This makes acceleration much more responsive and smoother, but introduces a fragile wearing part into the drive-train which has a tendency to randomly break (Less so in smaller diesels (e.g. 1.6 and less) but is a common issue in 2.0+ where it's under a much higher stress)

Older diesels that didn't have these things were pretty filthy emissions wise but are rock solid and indestructible; Alas this is not so much the case with modern diesels and makes them much worse for urban driving where they never get a chance to clean themselves out.

Diesel still has many advantages - For one thing few things can beat them for carrying heavy loads long distances and towing stuff - but they are being killed off by emissions regs which is why Toyota have ceased diesel development (Hence the use of horrible BMW diesel engines in the future!) and ploughed everything into the HSD.

re. Tyres, although the HSDs often come with LRR tyres, you don't HAVE to use low rolling resistance tyres - Lots of people fit tyres rated for better longevity or grip. I don't think there is such thing as an LRR Winter tyres anyway (Thank goodness as they're enough of a gouge as it is!!) so you should be okay to buy any Winter tyre that fits :)

(I had my eye on the Conti Winter Contacts but TBH I drive a Yaris D4D in a city - Can't really justify the outlay!)

17"s are pretty pricey anyway tho', esp. Winter tyres - Last time I looked I could get 1 17" winter tyre for the cost of a full set of summer tyres for my Yaris , so you're kinda stuck there... (I do love having 14"'s on my Yaris as I pay about £20-30 less per tyre than Yaris owners with 15" rims! And the ride is more comfy! And it gives better mpg having smaller rims! )

[Parts-King]

although the HSDs often come with LRR tyres, you don't HAVE to use low rolling resistance tyres - Lots of people fit tyres rated for better longevity or grip.

You could put mud grabbers on it but why would you? You could also stick any old oil in it, but you don't because to get the best MPG you use LRR tyres and 0w 20 oils

I don't think there is such thing as an LRR Winter tyres anyway

Oh yes there is ;)

Once again there is another misconception, that winter tyres are big and chunky, thats not the case, its the rubber compound that works at its best below 7 degrees that makes a winter tyre, not chunky grips

Kingo

[Cyker]

Again you blow my mind!

I know it's more the compound than the tread pattern, which was why I didn't think there was such a thing (I've not come across them anyway!)

Reasoning: We know LRRs are made of a harder compound so they are stiffer and don't soak up as much of the car's momentum, but the whole point of winter tyres is that the compound is softer and more pliant so it doesn't harden in winter!?!?

How is this contradictory magic achieved!?!?

[timberwolf]

Cyker, Clarke's 3rd law? :hokus-pokus: http://en.wikipedia.org/wiki/Clarke's_three_laws

[Cyker]

Yes!

[johalareewi]

I have been using LRR winter tyres on the gen3 prius for the last 3 winters. Easy to find in the 15 inch flavour (but not so in the 17 inch). Similar price to the summer tyres so not expensive. I even did a write up in this very forum.

For some more real life info about long journeys and hill climbing. I have just returned from a break in Dartmoor (Devon). The gen3 prius with 4 adults and a boot full of luggage managed the trip to Dartmoor, motorways, dual carriageways, and the a35 across Dorset (lovely hills) with no problems. I was able to accelerate up the hills, fly along the faster bits of road and still get 60mpg.

While on Dartmoor, the prius was able to haul itself up the hills - even when the road was wet and muddy (we are talking those little roads with not much tarmac used by farmers, 4x4s and satnavs). The mpgs suffered a bit, but still a respectable 50mpg for the week.

For help with the TLAs, I did start a Toyota Hybrid TLA thread. Should be findable with the forum search.