West/Otto/Atkinson/Miller cycle multimode hybrid engine.

By request...

An ideal ICE would adjust the compression ratio as a function of cylinder charge. DFI, Direct Fuel Injection, engines are now running with a 12:1 CR with a FULL cylinder charge. Wouldn't it be highly desireable to keep that compression ratio even at part throttle, especially just cruising allong at a relatively constant speed..?

But until the technology is available, readily and inexpensively available, then how about...?

"EFFECTIVE" CR change..?

A West/Otto/Atkinson/Miller cycle multimode "variable" compression ratio engine using current "off-the-shelf" mechanical technology/capability.

The new RX450h V6 uses multimode capability, switching between Otto mode and Atkinson cycle mode as engine power output requirements change.

The RX450h doesn't yet make use of DFI so the native/static CR, purely mechanical CR, is 13:1. As long as the cylinder charge due to throttle opening doesn't rise above ~70% then the net "effective" CR is only 10:1.

But once the cylinder charge reaches or exceeds 70% the RX450h's e/VVT-i, Extended VVT-i, system enters Atkinson cycle mode. e/VVT-i is used to change, delay, the intake valve closing time in order to keep the effective CR at 10:1.

Once the RX450h adopts DFI the native/static CR can become 15-16:1.

But then that results in a relatively small combustion chamber area and with only the possibility of further reduction, effective reduction. How do we reach 100-150HP from the hybrid ICE alone as the US public demands.

So, how about changing the actual engine displacement volume, EFFECTIVELY, via TurboCharging...?

Turbocharging....NO...!

Atkinson engines typically use up more/most of the power derived from air/fuel combustion within the cylinder, resulting in only enough power left in the exhaust to keep the catalyst up to operating temperature.

SuperCharging.....?

Yes, YES, but not in the traditional way/method.

But in the mid-fifties Studebaker used a positive displacement VARIABLE SPEED SuperCharger in the Golden Hawk product series. Studebaker used a conventional, V-belt, CVT to vary the level of intake air compression independent of engine RPM.

SuperCharging....CVT....hmmmmmmmm.....PSD....

A small, lightweight, carbon fiber composition positive displacement SuperCharger driven by a Toyota HSD type CVT/(PSD). The ICE as one input and a small permanent magnet rotor electric motor as the "opposite", opposition or aiding/addition, input. Say like, and maybe even closely equal to, the low HP motor/inverter current driving the "electric" A/C compressor.

No SuperCharging at all unless the driver "calls" for it. No intake airflow for even ICE idling, none at all, actually, unless the engine control ECU "calls" for it.

No throttle plate....???

Intercooling is a given, so why not "store up" A/C refrigerant and then use it selectively to cool the SC charge when the ICE is running under boost...?

Sub-1L I4(***) engine doing the work of the current Prius ICE...?

75MPG...?

And why not throw in an Oxygen generator/separator (500W) to effectively increase the ICE's displacement at/with WOT..?

Compress and store the Oxygen for use only during serious, WOT acceleration events. And when the low duty cycle generator/separator is running port the separated nitrogen to the intake to lower pumping losses in the same why EGR works.

Every little thing helps.

Maybe even use a LOX tank.

*** Only 4 cylinder engines, or multiples of 4, are "natural" Atkinson engines. One cylinder "exhausting" (compression stroke/cycle) airflow back into the intake manifold just as its opposite cylinder is drawing air in (intake stroke/cycle). The two pistons are operating in perfect angular, crankshaft angular, synchronization.

That's why the RX450h's V6 doesn't normally run in Atkinson mode, otherwise it would have too much intake noise from "non-synchronous" reverse airflow pulses within the intake manifold.

Clever, those Toyotians.

 

Not if you use DFI and only partially, 70%, fill the cylinder with A/F mixture. Actually only AIR initially and then adding, injecting, fuel near TDC.

At 1/2 throttle and above the e/VVT-i system would begin moving the intake camshift such that the intake valve closing is delayed. So at WOT 30% of the intake charge is now ejected back into the manifold.

 

The bad news, really BAD news, about TurboChargers is the fact that the base, static, compression ratio must be substantially below what would be standard for a NA Otto engine. Take Ford's gas-guzzling EcoBoost TurboCharged DFI engine's for instance. Porsche and Lexus DFI engines have a CR in the range of 12:1 while the Ford, and other TurboCharged DFI engines have a CR in the range of 10:1.

The base/static CR of a DFI TurboCharged engine must be keep low, INEFFICIENT, in cruising mode, low to moderate throttle openings, in order to all for boost pressure. TurboCharging BOOST pressure, assuming intercooling, might easily raise the EFFECTIVE CR above 12:1.

So the engine is highly efficient "on-boost", but of relatively poor effeciency for simply cruising along, probably 98% of the time for most of us.

Poor compromise, REALLY poor compromise, unless you have the mentality of a "boy-racer".

 

The 2010 Prius, when running in Atkinson cycle mode, has an effective CR of 10:1. Base/static CR is 13:1 so part throttle Otto mode is/remains highly efficient.

 

Sorry, now not so sure, but I thought that I saw in the Prius factory repair/shop manual that the latest model did use e/VVT-i to change modes.

I remember for certain that the RX450h does.

 

You're missing the point.

If the throttle is only open less than 30%(***) then it is NOT possible to full fill the cylinder on a single intake stroke. Absent a fully filled cylinder the base/static CR could be 20:1 (***) and still run on 87 octane.

Octane only becomes important when the cylinder gets a "FULL FILL" on each intake stroke.

*** Random, meaningless, numbers selected, except for relativity..

 

I can tell you quite factually that E85 is detrimental to gasoline system seals, sealing. It even appears me that the wintertime addition of ethanol might also be detrimental but over multiple years of use...

 

Yes, ALL Atkinson engines can be run WOT, ACTUAL WOT, since the intake valve closing delay is used downstream to effectively limit the "throttle" opening.