Atkins Cycle

[Cyker]

Summary:

1.5 1NZ-FXE - Atkinson ONLY

1.8 2ZR-FXE - Atkinson ONLY

1.5 M15A-FXE - Atkinson AND Otto

2.0 M20A-FXS - Atkinson AND Otto

[TonyHSD]

13 hours ago, Cyker said:

Summary:

1.5 1NZ-FXE - Atkinson ONLY

1.8 2ZR-FXE - Atkinson ONLY

1.5 M15A-FXE - Atkinson AND Otto

2.0 M20A-FXS - Atkinson AND Otto

So the 1.8  are electric cars with petrol range extender 🪫⚠️😅

the 1.5 and 2.0 are petrol cars with electric motors ⚡️🏎

 

Just kidding 😅

[rado77]

I think that for 1.5 and 2.0 it's because of combination of direct/indirect injection...maybe

[APS]

14 hours ago, Cyker said:

Atkinson ONLY

Possible marketing monikers Toyota could have considered:

Quasi Atkinson Cycle Kinetics - QACK! 🦆 

Generator with Atkinson Imposter - GenAI 

Really Reduced Squeeze with Pathetic Bang - RRSPBerry

[Cyker]

7 hours ago, rado77 said:

I think that for 1.5 and 2.0 it's because of combination of direct/indirect injection...maybe

Alas while the 2.0 M20A-FXS does have D4S (i.e. port and direct injection), the 1.5 M15A-FXE is port-injection only!

Whether they support Atkinson-only or Atkinson/Otto is all down to the VVTi system installed on the car - The ones that can do both are VVT-iW, with the W meaning it has wideband cam phasors, so it can advance or retard the timing a lot more than the normal VVTi

 

[rado77]

Good to know Cyker ;-) Thx! I didn't know about VVT-iW. But the fact is that I don't study new engine techs...stucked on classic athmosferic engines (age 46) :-)

[Cyker]

I do get a bit obsessive with them  

Partly the fault of this website https://toyota-club.net which has more about Toyota engines than you'd ever want to know   

but I've always been a function-over-form person, so while others are looking at rim size and colour choices I'm looking at the engines and how many degrees of advance and valve lift it has  

Edit: These sorts of videos are fun too  

 

 

[Roker]

On 8/3/2024 at 7:23 PM, AndrueC said:

No, I think you're the one who is confused. I'm well aware of how the HSD power split device works. Toyota's HSD has nothing to do with Otto or Atkinson cycle.

The HSD just blends power from the electrical motors and the ICE. How the ICE is operating internally is irrelevant to that part of the transmission.

It's possible that the ICE is also switching between those two modes but I have never experienced any evidence of it. I suspect it would overcomplicate the ECU logic or as another person suggested is just pointless because the electrical motors can make up the difference.

Do you have any actual documentary proof that it can do that? The reason I mentioned the Jazz was to show that I have experience of how the two modes perform.

That tells me that the 1.8 litre engine in my Corolla never operates in Otto mode because it does not have the same raw power that the 1.3 litre in my Jazz had.

 

For extra boost when overtaking it uses ottoman cycle and power boost to the motor for a limited time because of the Battery capacity

[AndrueC]

45 minutes ago, Roker said:

For extra boost when overtaking it uses ottoman cycle and power boost to the motor for a limited time because of the battery capacity

Where is your evidence for that?

Firstly it's not the 'ottoman' cycle. That alone would lead any knowledgeable person to question you. It's 'Otto' cycle named after Nikolaus Otto (1832–1891). 🙄

The Ottomans were an empire based in and around Turkey and whilst they might have invented a useful type of furniture they are not noted for their engineering acumen.

The YouTube video I posted showed that the cam profile only supports Atkinson cycle. If the ICE was already capable of Otto cycle he wouldn't have needed to take it apart. He could just have had the ECU reprogrammed.

Toyota do produce some ICE that can operate in  both cycles. They do not install them in any of their hybrid vehicles. If you drive a Toyota hybrid the ICE operates solely in Atkinson cycle.

[Cyker]

*aside from the newer DynamicForce-branded engines...   

[trashman1965]

1 hour ago, AndrueC said:

The Ottomans were an empire based in and around Turkey and whilst they might have invented a useful type of furniture they are not noted for their engineering acumen

According to our local Turkish takeaway,  they also invented a rather nice kebab

[Red_Corolla]

On 8/7/2024 at 7:35 PM, Cyker said:

Alas while the 2.0 M20A-FXS does have D4S (i.e. port and direct injection), the 1.5 M15A-FXE is port-injection only!

Whether they support Atkinson-only or Atkinson/Otto is all down to the VVTi system installed on the car - The ones that can do both are VVT-iW, with the W meaning it has wideband cam phasors, so it can advance or !Removed! the timing a lot more than the normal VVTi

 

I get this, but I thought dynamic force engines only had the electrical system on the intake cam. Exhaust cam (which is what Atkinson cycle is all about) is phased using traditional hydraulic solenoids, is it not?

https://www.motorreviewer.com/engine.php?engine_id=156

The other thing I'm wondering about is how you can truly switch cycles without altering the dwell rather than just the timing. I imagined it would take a system similar to the one in my bike engine, where there's two sets of cams on the same shaft and the solenoid shifts it lengthways to swap between. Interesting debate. 🙂

[Cyker]

It's actually very simple - The cam phaser just opens the intake valve *really* late, much later than you normally would in the Otto-cycle - If you look carefully at the video I posted above, you can see in the Otto-cycle the intake valve is *already open* when the Atkinson/Miller-cycle is only starting to open.

It stays open the same length of time, but because it opened so late it also closes late by the same amount - In the Otto-cycle the valve is closed before the cylinder starts coming back up for the compression stroke, but with the A/M-cycle it's still open so some of the air-fuel mix actually gets pushed back out before the valve closes.

That's why it's so gutless - Even though it's e.g. a 1.5L engine, it's only compressing maybe 1.0-1.3L worth of air-fuel mix! But it gets the full 1.5L of expansion which is where the extra efficiency comes from.

Like the whole Toyota hybrid system, it's simple but complicated  

 

[Roker]

On 9/30/2024 at 6:46 PM, AndrueC said:

Where is your evidence for that?

Firstly it's not the 'ottoman' cycle. That alone would lead any knowledgeable person to question you. It's 'Otto' cycle named after Nikolaus Otto (1832–1891). 🙄

The Ottomans were an empire based in and around Turkey and whilst they might have invented a useful type of furniture they are not noted for their engineering acumen.

The YouTube video I posted showed that the cam profile only supports Atkinson cycle. If the ICE was already capable of Otto cycle he wouldn't have needed to take it apart. He could just have had the ECU reprogrammed.

Toyota do produce some ICE that can operate in  both cycles. They do not install them in any of their hybrid vehicles. If you drive a Toyota hybrid the ICE operates solely in Atkinson cycle.

A slight mistake on my part of course you're correct Otterman is an empire.

If the engine is running in Atkins Cycle only, what is the point of having Variable Valve timing

[rado77]

VVT is needed to pass emissions limit and it also gives some "afditional power". If I compare atmosheric 1.6 16V engine withot VVT , and with VVT, that with VVT is more "powerful"...let's say 10% 

[Roker]

On 10/5/2024 at 6:11 AM, rado77 said:

VVT is needed to pass emissions limit and it also gives some "afditional power". If I compare atmosheric 1.6 16V engine withot VVT , and with VVT, that with VVT is more "powerful"...let's say 10% 

That's a contradiction 

To get some additional power it's got to go out of the Atkins Cycle and how does it do it, it goes into Otto cycle, it is always inside the emission limits 

[rado77]

I just shared my experience from Renault Megane 2 - when I unplugged cable from VVT solenoid and drove, engine was weaker (10 - 20%). If Toyota wanted "pure" engine to run only in Attkinson cycle, they could get rid of VVT and use intake camshaft with specific shapes. That's why I said that VVT is useful - higher rpm = more advance on intake valves timing

[Saxmaniac]

The gas can only flow into the cylinder at a certain rate and this becomes relatively slower at high rpm so advancing inlet valve allows more time for the gas charge to get into the cylinder 

[Cyker]

Variable Valve timing is on pretty much all cars simply because it's impossible to optimise fixed valve timing for low-rpm torque and high-rpm power, but being able to change the valve-timing on the fly lets you have your cake and eat it, so to speak, and the benefits are generally considered to outweigh the added complexity.

If you've driven a car without variable valve timing, you'll find they tend to either be really easy to stall at low rpm and only drive well maybe over 3000rpm, or feel really nice and torque-y at lower rpms, but as the rpms pick up it seems weirdly gutless compared to what you'd experienced from the performance at the lower-end.

It's less important with forced induction, but with naturally aspirated engines it makes them much nicer to use and gives a wider band of actually usable rpm.

Some engines have valve lift at higher RPMs too, which lets more air in at higher rpm, but I'm not sure that's a thing in Toyota land any more; I've only seen it on the old Corolla T-Sport 1.8 and some Valvematic engines.

 

[Red_Corolla]

1 hour ago, Cyker said:

Some engines have valve lift at higher RPMs too, which lets more air in at higher rpm, but I'm not sure that's a thing in Toyota land any more; I've only seen it on the old Corolla T-Sport 1.8 and some Valvematic engines.

 

My wife's car has this technology, but it's not just for high rpms, it actually replaces the throttle plate. The valves alone regulate the intake.

[Cyker]

The Valve lift is separate to Valvematic, I just mentioned it because Valvematic engines also do valve lift   The Corolla engine only has the valve lift, but is otherwise a normal engine - It was made to be a rival to the Honda Civic Type-R and its VTEC.

Valvematic engines do a whole load of other clever things and I'm surprised it isn't used in more engines as it makes a lot of sense to me to use the valve lift and duration to meter the intake charge instead of a butterfly valve.

It's something the fabled Freevalve cam-less valve actuation system could have done too, although it looks like the chances of that getting to market before ICE is killed off is very low...