Variable Compression Ratio V8 engine

[manousos]

Take a look at http://www.pattakon.com .

The patcrank VCR in a V-8:



All it takes is four slim and lightweight secondary connecting rods and one thin and lightweight crankshaft, i.e. 5 lightweight, and cheap to make, moving pieces in total, plus one slow moving control frame.

A modified V-8 patcrank VCR has as vibration-free-operation as the original conventional V-8, no matter what the selected compression ratio is.
The rev limit is as high as the rev limit of the original engine.

The range of available compression ratios of the patcrank VCR is as wide as desirable, for instance from below 7:1 to above 20:1.

A VCR can help the big displacement engines to pass current and future CO2 emission regulations. VCR is an alternative to Hybrid technology.

Thanks
Manousos

 

[XR8tt]

I have seen diagrams where the block deck and cylinder are variable..

 

[sheepers]

Saab? i think already made an engine with a "hinge" in the block and an actuator that moved the top half of the block and head up and down.
ill have search and see what i can find.......

sheepers.

 

[manousos]

Saab? i think already made an engine with a "hinge" in the block and an actuator that moved the top half of the block and head up and down.
ill have search and see what i can find.......

sheepers.

This is the pat-head pattakon VCR.



It is similar to SAAB's SVC, yet quite different.

For more about pat-head VCR : http://www.pattakon.com/pattakonVCR.htm

Thanks
Manousos

 

[XR8tt]

YEP that's it.. Was in our local Zoom mag years ago..
Be good with new direct injection forced fed motors where VERY high compression can be run...
Very hard to get detonation when there's no fuel in combustion chamber !!
Ummm ?? Who owns Saab now ???

 

[V8Datto]

No blowing head gaskets either

 

[Zuffen]

SAab is now owned by Koenigsegg.

The moveable cilinder head must have some fun sealing issues to overcome.

Cam drive would also be interesting.

I hope there's a controller each end of the engine as lifting the top of the negine from just one end isn't logical

Have any of these concepts ever got off the drawing board and into a working engine?

 

[manousos]

The basics of V8 patcrank VCR are shown in this simple gif animation:

The main crankshaft (red) is conventionally supported on the crankcase and drives conventionally the flywheel and the gearbox.
If you do not want to open the "exe" animation for more, you can alternatively open the:

http://www.pattakon.com/patcrank/patcrankVCR.wmv
WMV video animation.
Manousos

 

[Zuffen]

Please bear with me I'm a bit slow!

When you move the crankshaft up to increase the compression the flywheel does what? Does it remain where it is attached via an elastic band or does the engine block move down in relationship to the gearbox so the crank/clutch/first motion shaft remain in alignement.

For that matter what does the harmonic balancer do? Is it also attached with a simillar rubber band? No wait it could be smaller because it isn't transmitting so much power. Hey I think I'm getting this!

Now the question still needs answering, has an engine run with the Pattakon configuration?

A simple yes or no will suffice as I can only read words with a few letters.

 

[manousos]

Please bear with me I'm a bit slow!

When you move the crankshaft up to increase the compression the flywheel does what? Does it remain where it is attached via an elastic band or does the engine block move down in relationship to the gearbox so the crank/clutch/first motion shaft remain in alignement.

For that matter what does the harmonic balancer do? Is it also attached with a simillar rubber band? No wait it could be smaller because it isn't transmitting so much power. Hey I think I'm getting this!

Now the question still needs answering, has an engine run with the Pattakon configuration?

A simple yes or no will suffice as I can only read words with a few letters.

When you move the crankshaft up to increase the compression the flywheel is doing nothing. It does not feel the displacement of the secondary crankshaft (light brown). Only the eccentric rings feel the displacement of the secondary crankshaft (blue) and through the conrods the pistons move a little higher to increase the compression.
The crankshaft (red) is supported on the conventional way on the crankcase. The flywheel is secured in the conventional way onto the crankshaft. The axis of the crankshaft (red) is permanently coaxial with the axis of the primary shaft of the gearbox.

I think you mean FEV's VCR and the likes, wherein the main crankshaft is displaceable relative to the crankcase to control the compression ratio. Yes, the FEV VCR has aligment issues because the crankshaft cannot transfer efficiently its power to the gearbox. But no, patcrank VCR has nothing to do with this. It is different.
On the other hand, FEV's VCR - with all its problems - have been installed on a VW engine/car and proved reliable and fuel efficient.
patcrank VCR resembles to FEV's VCR. Is it clear now the simplicity of patcrank VCR?

What do you mean by "For that matter what does the harmonic balancer ... ". There is no such thing in patcrank VCR. Where?

No.

Manousos

 

[V8Datto]

Please bear with me I'm a bit slow!

When you move the crankshaft up

Zuffen the crankshaft doesn't move at all (red)

The big end of the conrods have an offset which changes the distance from the center of the crankshaft to the top of the pistons.

 

[manousos]

The hybrid cars are way better in CO2 emissions (i.e. in fuel economy) in downtown traffic compared to conventional cars of same weight.

In the hybrid car the thermal engine operates only from time to time (at optimum – as regards economy and emissions – conditions, like 3500 rpm and 80% "open throttle") to charge the battery.

Despite the energy lost in order to change the mechanical energy into electrical energy by the electric generator, the energy lost in order to store the electrical energy into the battery, the energy lost into battery until discharge, the energy lost to change the electrical energy of the battery back into mechanical energy on the electric motor to finally move the car, the total efficiency (Kg of fuel per Km of distance covered) is way better than in the case of the conventional engine running at light load.

Most people admire the low consumption of the hybrid cars and forget that the energy that finally moves the car is generated by the thermal engine.

In other words: the efficiency of the conventional reciprocating engine at heavy load is way better than the efficiency of the same engine at light load.
This "defect" of the thermal engines leaves room for the hybrid cars.

The operation of a big V8 of a SUV in urban cycle resembles more to a CO2 generator than to a mechanical energy generator.

Having a thermal engine that achieves to run at light loads at similar efficiency with the good efficiency it has at heavy load, the hybrid technology becomes, more or less, meaningless (the recovery of a part of the bracking energy cannot justify the cost, weight and complication added by a high-tech hybrid).

Alternative to the hybrid technology is the Variable Compression Ratio (VCR) for both naturally aspirating and turbocharged engines, under the reasonable assumption that the VCR system offers continuously variable compression ratio in a wide range (to keep the engine continuously at optimum compression ratio) without introducing "side effects".
At partial loads the VCR system increases the compression ratio as much as possible (just before knocking) making the engine as efficient as if it were working in heavy load (if necessary combined with a VVA in the cylinder head).
The HCCI combustion is an easy option.


Manousos

 

[spf_lexus]

very interesting stuff. what kind of power could you get out of a 4cyl 2.0L naturally aspirated VS a 2.0L with this new tech?

 

[stevechumo]

very interesting stuff. what kind of power could you get out of a 4cyl 2.0L naturally aspirated VS a 2.0L with this new tech?

Sorry to change the subject. Hey Sean, how's your 4.7 project? Curious to know.

 

[manousos]

very interesting stuff. what kind of power could you get out of a 4cyl 2.0L naturally aspirated VS a 2.0L with this new tech?

A 2.0L naturally aspirated with this new tech will increase the peak power of the conventional same engine, but not too much. The increase is expected by the optimization of the compression ratio at and above peak power revs where the aspiration of the engine worsens.
On the other hand, a good VCR improves a lot the partial load operation.
Companies like Gomecsys and MCE-5 claim a more than 30% CO2 reduction in urban cycle by their VCR prototype engines.

A good variable valve actuation, or VVA, system (take a look at http://www.pattakon.com , even a fully variable desmodromic VVA is presented there) can increase the power of the naturally aspirated engine a lot.

The combination of both system seems the best: the VVA reduces the valve lift at high compression ratios (used in medium - low revs and partial-light load operation) and keeps the good shape of the combustion chamber by avoiding deep pockets on the piston crown.

Manousos

 

[spf_lexus]

To be honest I sorta forgot about it. It's still sitting at Tims shop begging for a computer-literate tuner lol. David said he'd give Tim some help with it once the 5.2 gets fixed. My hands are tied right now, car in CA and im stuck in CO for school. I just hope its finshed in time for my thanksgiving break. hows your new system holding up?