RE: Infiniti's variable compression ratio engine

[Krikkit]

RobDickinson said:

BVB said:

Rubbish idea. Far simpler to just deactivate cylinders when efficiency is required.

Its like flicking a switch right if only Nissan had thought of that!

Yeah, idiots! Read a book ffs.

[zeppelin101]

Gixer_fan said:

Doesn't raising the dynamic CR (by raising boost pressure) not give same effect as raising static CR ?

No, because that doesn't give the benefit on the expansion stroke where the higher CR allows for more work to be extracted from gas expansion for the same exhaust events.

[JonnyVTEC]

ads_green said:

Most common way is to simply leave the air in the chamber so you have an air spring. Much of the energy put into compressing the air is returned on the down stroke

Assuming you have the valvetrain tech to allow valve closure.

[Amanitin]

RobDickinson said:

Power generation isnt the big hurdle.

there are 35M cars registered in the UK. 70% = 24.5M.
I googled for EV charger power, first hit: 7 kW.
Let's say on average we have five per cent of those cars on the charger at any given time. That's a bit over one hour charging per day per vehicle.
The above would result a 8-9 GW continuous power draw, at the chargers. Plus conversion and transmission losses.
The current average electric power demand in the UK is 25-30 GW, at the generators.
I am not a grid engineer, but I would be _very_ surprised if those extra 10 could be absorbed without major upgrades.
For context: a typical nuclear plant = 2 GW
A typical CCGT plant = 0.5 GW

[RobDickinson]

They will mostly recharge overnight when there is 10-15gw spare capacity.

But as I said your never going to get an overnight change to BEV"s it will build up over time.

And the UK is chronically under invested in power gen already anyhow, that needs fixing regardless.

[knighty]

I just dont get how they can manipulate the position of the crankshaft up and down and still line the clutch up to the gearbox?......same problem for the SAAB system, or am I missing something?

I always thought the oil pressure controlled variable length con-rods from FEV were a far better route and a lot less aggro, it could be retro fitted to almost any engine configuration with minimal re-work......the Infiniti system looks a right complicated mess to me

Porsche seem on the money with this patent

http://www.extremetech.com/extreme/204531-porsche-...

http://www.enginelabs.com/news/porsche-working-on-...

[MaximumJed]

knighty said:

I just dont get how they can manipulate the position of the crankshaft up and down and still line the clutch up to the gearbox?......same problem for the SAAB system, or am I missing something?

I always thought the oil pressure controlled variable length con-rods from FEV were a far better route and a lot less aggro, it could be retro fitted to almost any engine configuration with minimal re-work......the Infiniti system looks a right complicated mess to me

Porsche seem on the money with this patent

http://www.extremetech.com/extreme/204531-porsche-...

http://www.enginelabs.com/news/porsche-working-on-...

I don't think the crankshaft changes position in either the Infinity or Saab approaches. With the Infinity ones shown here, the multilink which attaches the rod to the crankshaft changes twists down so that the attachment point of the rod is closer or further away from the crank as desired

[PHMatt]

RobDickinson said:

Amanitin said:

PHMatt said:

and say in 10 years time, 60-70% of cars on the road are EV's

I am certain that it would be physically impossible to cover the increase in electric power demand if EVs would really spread at the rate of zero to 60% in ten years. Electricity prices would go through the roof promptly and EVs lose a lot of the sex appeal.
Battery manufacturing capacity is another bottleneck.

Power generation isnt the big hurdle.

60-70% in 10 years is totally unrealistic, it takes 15-20 years to switch a national fleet over, and at the moment there is only battery production for about 1-2% of vehicle production. That is scaling up fast but it'll take a decade plus to be able to even build 60% of the required vehicle volume as EV's

I picked random numbers out of the air to attempt to illustrate a point about road tax.

Neither of you needed to work out the likeliness of this part of the scenario occurring did you? Just whether or not 60-70% of drivers would be getting free road tax or nor.

[Hugh Jarse]

Maybe i should try and sell my website variablecompression.com to them, might get a bit further than my own attempts have. Gotta pay the bills. Pity.

[cptsideways]

There was a patent from the 80's by Williams (iirc) for variable length connecting rods it was really simple. I know this as I found it in the Patent office archives! back when you had to go & rummage reams of files.

Surely a simple spring/oil fed damper arrangement could do the job too, purely mechanical as a spring will always exert the same force subject to speed loadings of course.

[V8 FOU]

Amanitin said:

there are 35M cars registered in the UK. 70% = 24.5M.
I googled for EV charger power, first hit: 7 kW.
Let's say on average we have five per cent of those cars on the charger at any given time. That's a bit over one hour charging per day per vehicle.
The above would result a 8-9 GW continuous power draw, at the chargers. Plus conversion and transmission losses.
The current average electric power demand in the UK is 25-30 GW, at the generators.
I am not a grid engineer, but I would be _very_ surprised if those extra 10 could be absorbed without major upgrades.
For context: a typical nuclear plant = 2 GW
A typical CCGT plant = 0.5 GW

The UK is struggling to keep up with power demands, hence all the panic to get nukes built. Power has to be bought in from France to keep up.
So a huge increase in EV's would possibly tip the balance to power cuts etc.

[otolith]

V8 FOU said:

The UK is struggling to keep up with power demands, hence all the panic to get nukes built. Power has to be bought in from France to keep up.
So a huge increase in EV's would possibly tip the balance to power cuts etc.

I would have thought that increasing off-peak load would help to make the economic case for an increase in total generating capacity.

[robinessex]

Seen lots of these on drawing boards in the past. End up binned as over weight, and to expensive.

[J4CKO]

V8 FOU said:

Amanitin said:

there are 35M cars registered in the UK. 70% = 24.5M.
I googled for EV charger power, first hit: 7 kW.
Let's say on average we have five per cent of those cars on the charger at any given time. That's a bit over one hour charging per day per vehicle.
The above would result a 8-9 GW continuous power draw, at the chargers. Plus conversion and transmission losses.
The current average electric power demand in the UK is 25-30 GW, at the generators.
I am not a grid engineer, but I would be _very_ surprised if those extra 10 could be absorbed without major upgrades.
For context: a typical nuclear plant = 2 GW
A typical CCGT plant = 0.5 GW

The UK is struggling to keep up with power demands, hence all the panic to get nukes built. Power has to be bought in from France to keep up.
So a huge increase in EV's would possibly tip the balance to power cuts etc.

The EV thing wont happen overnight, it will be very gradual, so capacity can be expanded to suit, like as the IC engined car came in and the infrastructure grew to service it, garages and petrol stations didnt appear one day in 1911.


Also, other things are getting more efficient, appliances, LED bulbs etc, demand will go up but perhaps not as agressively as we might expect.

[hufggfg]

otolith said:

V8 FOU said:

The UK is struggling to keep up with power demands, hence all the panic to get nukes built. Power has to be bought in from France to keep up.
So a huge increase in EV's would possibly tip the balance to power cuts etc.

I would have thought that increasing off-peak load would help to make the economic case for an increase in total generating capacity.

This.

The reality of power generation and electricity markets is more complicated than people consider most of the time, hence lots of conversations that go round in circles about nuclear, renewables etc. You have to consider both peak and base load, both in terms of generation capacity, requirements, locations, etc etc.

[JaguarsportXJR]

otolith said:

I would have thought that increasing off-peak load would help to make the economic case for an increase in total generating capacity.

The only problem I can see with this is that the load wouldn't necessarily be off peak. For EVs to replace the IC powered cars the charge time of the batteries will need to be drastically reduced. The moment this happens people will not need to charge them over night, instead charging at work or service stations (as many do already). This would mean the load would be throughout the day, not just when there is spare generating capacity.

[otolith]

JaguarsportXJR said:

The only problem I can see with this is that the load wouldn't necessarily be off peak. For EVs to replace the IC powered cars the charge time of the batteries will need to be drastically reduced. The moment this happens people will not need to charge them over night, instead charging at work or service stations (as many do already). This would mean the load would be throughout the day, not just when there is spare generating capacity.

That's where the use of smart meters for demand side management comes in. Keep in mind that most people have their car parked most of the time, and that average weekly mileage for the UK is about 150 miles. If you used something like an i3, with a range of 125 miles and charging from 0% to 80% (100 miles) in ten hours on a standard domestic outlet, if you stuck it on to charge every time the range dropped to 25 miles you'd only need to charge it twice a week for 15 hours in total. You could choose to top it up whenever you parked it, but if it was appreciably cheaper to charge it off peak, you would probably try to do it then.

[T-Rev]

I don't consider the additional components and their weight to be worth the while? The ICE is not dead yet and there will no doubt be some serious developments to improve design and efficiency in order to compete with the increase in EV's. An example would be the recent Axial engine from Duke in New Zealand which is very impressive, but not sure if its still ongoing? See http://www.dukeengines.com/technology/overview/

[robinessex]

T-Rev said:

I don't consider the additional components and their weight to be worth the while? The ICE is not dead yet and there will no doubt be some serious developments to improve design and efficiency in order to compete with the increase in EV's. An example would be the recent Axial engine from Duke in New Zealand which is very impressive, but not sure if its still ongoing? See http://www.dukeengines.com/technology/overview/

There has been a succession of axial design internal combustion engines, but for some reason, they never 'take' off'. Maybe it's the colossal investment in conventional engines that keeps potential users from using it. Never understood why it's not been tried in a race car, unless an equivalence criteria is the problem, like the wankel.

https://www.google.co.uk/search?q=axial+engines&am...

[annodomini2]

otolith said:

JaguarsportXJR said:

The only problem I can see with this is that the load wouldn't necessarily be off peak. For EVs to replace the IC powered cars the charge time of the batteries will need to be drastically reduced. The moment this happens people will not need to charge them over night, instead charging at work or service stations (as many do already). This would mean the load would be throughout the day, not just when there is spare generating capacity.

That's where the use of smart meters for demand side management comes in. Keep in mind that most people have their car parked most of the time, and that average weekly mileage for the UK is about 150 miles. If you used something like an i3, with a range of 125 miles and charging from 0% to 80% (100 miles) in ten hours on a standard domestic outlet, if you stuck it on to charge every time the range dropped to 25 miles you'd only need to charge it twice a week for 15 hours in total. You could choose to top it up whenever you parked it, but if it was appreciably cheaper to charge it off peak, you would probably try to do it then.

The problem is the car becomes like night storage heaters, you need to plan everything in advance. But the need for Journeys varies like the weather, if you have an 'emergency' and need to be somewhere. It's no good having to take 2 days to get there.