Throttle-less intake

[Tommy Cookers]

I meant to write 3 way, honest ! (it wouldn't make sense with the 2 way)

IMO
IIRC regulation is not a level playing field
my TV said last night diesels produce more Nox (than SI with 3 way) and that's tolerated

I think what you call toggling is just to make the f:a regulation hold the mean value for simultaneous oxidation and reduction
1.02 f:a ..... there's no mystery
all other ratios give either oxidation or reduction
reduction particularly can't happen with any Oxygen preesent
the way the system works is continuous stepping weaker till Oxygen is sensed, then 'instantly' richer by a step
cycling in under 1millisec
then stepping weaker until Oxygen is again detected, and an instant step back richer
the circuit design (steps etc) is what gives that particular mean of 1.02
the catalyst behaviour follows that mean, the toggle is far too small and short duration for the cat to 'see' it
the resulting correct mean ratio is held for ever, without any calibration ever
I could fit it to a 1969 car, it would be fine

a 3 way doesn't have to be operated 3 way all the time
in some modes of operation a lean mixture can be used by more complex engine designs producing minimal NOx in those modes
and now in even the standard engine designs lean mixture can be used for maybe 15-30 sec ??
because the catalyst will allow some 'backlog' that is cleared when the 1.02 mixture is resumed ?

apologies if this is the toggle referred to by my fellow poster
seriously, there seems no proper current information out there, I would like some

the big point is that for 75 years all cars used a lean mixture most of the time
a lean mixture (to the extent that the engine tolerates leaning) controls power by reducing fuel without throttling
1980s engines (in Europe anyway) were designed to tolerate a lot of leaning and were very economical
the 3 way cat killed off leaning

but you wouldn't lean in F1 eg 2014

[olefud]

[quote="langwadt"] modern diesels use throttling together with egr so there is less oxygen in the exhaust limiting the production of NOx[/qu
\
It was my impression that NOx was produced during combustion at high pressure/temperature. Another advantage of throttling diesels is to reduce the volume of air at low fuel injection rates so that the combustion isn’t quenched by the excess air. Of course there needs to be sufficient air to reach threshold combustion conditions.ote]

[thisisatest]

regarding throttle plate position in F1
surely we must fuel at the throttling point ? (for good dispersion/droplet size at the lower velocities/turbulence)
we wouldn't/couldn't have throttling at the duct mouth (behind the drivers head)

according to this, they fuel (or at least did not too long ago) at the intake tract entrance. butterfly must be at least 100mm below.
[youtube]http://www.youtube.com/watch?v=o_QyUD6V5_I[/youtube]

edit: on this one, you can actually see the butterflies as they sweep past WOT. so theyre closer than i thought. the thing's practically spraying onto the back of the butterfly.
[youtube]http://www.youtube.com/watch?v=nX2L-kS7ZL8[/youtube]

[langwadt]

modern diesels use throttling together with egr so there is less oxygen in the exhaust limiting the production of NOx[/qu
\
It was my impression that NOx was produced during combustion at high pressure/temperature. Another advantage of throttling diesels is to reduce the volume of air at low fuel injection rates so that the combustion isn’t quenched by the excess air. Of course there needs to be sufficient air to reach threshold combustion conditions.ote]

NOx is created at high pressure and temperature, but if you use exhaust gas as an inert "filler" instead of air
there is less excess oxygen available to create NOx, while keeping the filling high and pumping losses low

[langwadt]

I meant to write 3 way, honest ! (it wouldn't make sense with the 2 way)

IMO
IIRC regulation is not a level playing field
my TV said last night diesels produce more Nox (than SI with 3 way) and that's tolerated

Diesels does produce more NOx I guess partly because they run at high pressure partly because since they always
run with excess oxygen the reduction of NOx in a 3 way cat won't work

I think what you call toggling is just to make the f:a regulation hold the mean value for simultaneous oxidation and reduction
1.02 f:a ..... there's no mystery
all other ratios give either oxidation or reduction
reduction particularly can't happen with any Oxygen preesent
the way the system works is continuous stepping weaker till Oxygen is sensed, then 'instantly' richer by a step
cycling in under 1millisec
then stepping weaker until Oxygen is again detected, and an instant step back richer
the circuit design (steps etc) is what gives that particular mean of 1.02
the catalyst behaviour follows that mean, the toggle is far too small and short duration for the cat to 'see' it
the resulting correct mean ratio is held for ever, without any calibration ever
I could fit it to a 1969 car, it would be fine

a 3 way doesn't have to be operated 3 way all the time
in some modes of operation a lean mixture can be used by more complex engine designs producing minimal NOx in those modes
and now in even the standard engine designs lean mixture can be used for maybe 15-30 sec ??
because the catalyst will allow some 'backlog' that is cleared when the 1.02 mixture is resumed ?

apologies if this is the toggle referred to by my fellow poster
seriously, there seems no proper current information out there, I would like some

I don't know much about it either, just what I read and was told by a friend of mine that has recently build and
programmed an ECU for a small sportscar manufacturer and made it pass all the test for type approval

Seems the the toggling makes the cat alternate between storing oxygen for the oxidation and storing NOx for
reduction so that both processes happen continuously

combined with all kinds of weird memory effects it is apparently quite tricky to make it work

[bigpat]

Direct injected engines that are throttle-less are well known. They are called diesels......

Although compression ignited, they alter their power by the amount if fuel injected only. Newer turbo diesels run throttles, but they are not essential to their operation.

[olefud]

[modern diesels use throttling together with egr so there is less oxygen in the exhaust limiting the production of NOx

Diesel throttling also improves efficiency by limiting air intake to that necessary to gain ignition. At lower power production settings, excess air quenches the combustion gases and lowers the combustion temperature and available energy.

[riff_raff]

Direct injected engines that are throttle-less are well known. They are called diesels......

Although compression ignited, they alter their power by the amount if fuel injected only. Newer turbo diesels run throttles, but they are not essential to their operation.

There are no current auto/truck CI engines that "throttle" their intake airflow. However, there are some auto CI auto engines using multistage turbocharging systems that use valving to divert airflow around one compressor stage to improve performance under certain conditions. CI engines all use control of injected fuel mass to meet load demand. CI engines use EGR and intercooling to control NOx emissions.

There are a few SI gasoline auto engines that are "throttleless". There are engines from BMW and Infiniti that use IVC systems on the intake valves that require no conventional form of intake throttle.

[Desertrunner]

interesting post

[BBolze]

Those Infinity and BMW motors still have a throttle though. Those cars still use vacuum assisted power brakes, and likely other vacuum dependent systems as well. It's a shame the full potential of a throttle-less system couldn't be realized

[Holm86]

Those Infinity and BMW motors still have a throttle though. Those cars still use vacuum assisted power brakes, and likely other vacuum dependent systems as well. It's a shame the full potential of a throttle-less system couldn't be realized

You dont need a throttle to create vacuum. Electric or belt driven pumps can take car of that.

[OdinYggd]

Plenty of 'throttleless' engines out there, especially direct injected diesels that always compress a full charge and then only inject enough fuel to maintain the set RPM.

Also worth noting- variable displacement is an idea well over 100 years old and was most commonly seen without any kind of throttle. A lot of surviving examples exist of the hit & miss style engine, which was governed entirely by allowing the engine to freewheel with the exhaust valve held open. Modern variable displacements are nothing more than copycats of this century-old technology, implemented in modern mechanisms instead of the governor lever simply latching the exhaust valve of the single cylinder open.

WWI vintage 'rotary' engines- where the cylinder block rotated around a stationary crankshaft were also universally without a throttle. These engines used blipmags, where in each rotation only certain cylinder numbers would get ignition.

In a modern fuel-injected engine you can get a similar result by combining stratified charge with ignition timing changes- when the engine is at speed, inject as little fuel as possible and run the timing late- allowing the fuel to burn cleanly but not produce quite as much shaft power. Of course this will make things get hot, so it isn't an ideal solution.

[Tommy Cookers]

....WWI vintage 'rotary' engines- where the cylinder block rotated around a stationary crankshaft were also universally without a throttle. These engines used blipmags, where in each rotation only certain cylinder numbers would get ignition.
In a modern fuel-injected engine you can get a similar result by combining stratified charge with ignition timing changes- when the engine is at speed, inject as little fuel as possible and run the timing late- allowing the fuel to burn cleanly but not produce quite as much shaft power. Of course this will make things get hot, so it isn't an ideal solution.

more Gnome Monosoupape rotary engines and illegal copies thereof were made than all other rotary engines combined
these others were founded on avoiding the Mono's bizarre features, and came closer to proper carburation and control by throttling ?
eg Bentley and Clerget ?

retarded sparking (by manual manipulation) is an effective but poor means of control, useable at partial power
used in cars till the 1940s and much later in some 4 stroke motorcycles
again it worked by being more inefficient than throttling
so consuming at partial powers more mixture, it avoided the difficulties of carburation over a great range of flows

no-one would do that today, except for special purposes such as hot blowing or maybe some brief anti-pollution measure ?

recent N/A F1 had reduced need for throttling, having poor cylinder fill at lower rpm due to the valves extreme timing and size ?

[majicmeow]

Those Infinity and BMW motors still have a throttle though. Those cars still use vacuum assisted power brakes, and likely other vacuum dependent systems as well. It's a shame the full potential of a throttle-less system couldn't be realized

The BMW Valvetronic system uses the variable lift of the intake valves to control engine throttling. The throttle valve remains completely open during normal running and as a physical backup in case of valvetronic failure. It also serves the function of reducing engine output for traction control purposes.
In this way power is more smoothly and quickly adjusted without having to turn back the valve lift. As soon as traction is regained, the electronic throttle opens and the engine is immediately at full power again.
Vacuum is created using the gear or camshaft driven vacuum pump. Again, in case of a failure of the vacuum pump, the throttle valve can close and create the necessary vacuum in the mean time.
Just FYI

[pp51]

Guys,

I am working on an electronic control system for a throttle-less petrol engine and I'd like your input on the control strategy. Sensors available are WB02, coolant temperature, TPS and, possibly, mass-airflow. The idea is that the TPS is simply an RPM-request that maps to a desired RPM. Because of lack of throttle plate, the only way to control RPM is by varying the quantity of fuel injected.

The first idea was to simply increase the injector opening time to increase RPM and to decrease it in order to reduce RPM, but, after reading more about throttle-less engines, it simply doesn't look like such a bright idea anymore. Now I am thinking of maybe targeting a specific AFR using the WBO2 and just miss some injection events in order to keep the RPM in check.

What do you think?