GM has filed a patent application for so-called “Multilink Cranktrains with Combined Eccentric Shaft and Camshaft Drive System for Internal Combustion Engines.” The system is designed to provide variable compression ratios, thus providing high power output when needed, and high efficiency when it’s not.
The GM patent filing has been assigned application number US 11,092,090 B1 with the United States Patent and Trademark Office (USPTO) and was published August 17th, 2021. The patent was originally filed September 30th, 2020. The patent lists Andrew G. Balding from Wixom, Michigan as the inventor.
The patent describes a system that incorporates a multipoint linkage that engages the piston to the crankshaft, rotating on a secondary axis offset from the first axis between the crankshaft and engine block. A control shaft is incorporated into a third axis and can be used to rotate the multipoint linkage, thus adjusting the compression ratio inside the cylinder as needed.
Critically, the system could be applied to GM’s overhead valve (pushrod) engines, possibly for inclusion with the automaker’s pickups and SUVs. This patent is also noteworthy as it indicates GM is continuing to develop its internal-combustion vehicle technology, even though the automaker is poised to phase out tailpipe emissions from its light-duty vehicle lineup by 2035.
General Motors isn’t the only automaker exploring the possibilities of variable compression combustion engine technology. Nissan (as well as Nissan’s luxury brand, Infiniti) is already offering variable compression with the Infiniti QX50 SUV, making the QX50 the first production vehicle to incorporate a variable compression ratio engine.
Indeed, as fuel economy standards grow ever stricter, technologies like variable compression ratio engines will enable automakers to continue to offer internal combustion platforms to consumers. Essentially, the technology enables a variable volume above the piston head when it is at top dead center in the stroke, adapting to needs on the fly to either produce more power under heavy load, or greater efficiency while cruising.
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Comments
Let’s see.
How can we make an unreliable V8 engine even worse?
Let’s introduce variable compression ratio engines!!!
The lifter issues were just a walk in the park.
If I had to guess, the new pushrod V8’s will use a supercharged miller cycle with a 16:1 compression ratio, per a 2019 detailed patent. Basically an LT4 if it was optimized for efficiency and its power being a bonus. Way simpler, with proven technology.
Sadly it is not GM that wants to make these vehicles worse, turn and look at the AOC crowd that is attempting to legislate that we all walk everywhere or ride a bus as if the NYC bubble of perceived efficiency works nationwide, which it does not.
First, what unreliable GM V-8 engine are you quoting? Last I looked the original small block chevy( used across all GM lines) is STILL in production after 6+ DECADES of successful production. 2nd, what lifter problems since we are talking GM here and not Fords…
Yeah the traditional “small block Chevy” is an insanely reliable workhorse. The newer 5.3s have been plagued with head gasket and cracked head issues, excessive oil consumption, lifter failure… A few additional ansillary issues that are unrelated to the engine itself. Sometimes they’re great, other times they will push an owner to never buy gm again.
But but I thought ICE was dead and had nowhere else to go. I guess GM is still investing in this tech a while longer after all. So much for the naysayers that claim otherwise.
This is nothing new. I worked on one of the first true variable stroke engines way back in the 70’s. It was designed by Harvy Pouliot a brilliant man while working at Sadia National Lab. Converting a slant six engine to a five cylinder verbal stroke. It worked perfectly and cut emissions to less than 20% of today’s standards. Because of politics and other issues it never made it.
Sat on a shelf till 2014 then thrown in the trash one week before asked to get it.
Yes I still have the t-shirt. Different stroks for different folks.
Nissan is already doing this
And Nissan is not known for the reliability of their vehicles.
Again when this starts breaking and costing thousands to repair as Scotty Kilmer said then come back and preach about it.
Oh I wasn’t preaching about it. I was just saying they’re already doing it.
Evan is simply too poor to any car less than 20 years old be it import or domestic.
What you dont realise is the variable compression mechanism in the Nissan engine does not increase the number of moving parts because variable compression engines dont need double balancer shafts so its likely to be more reliable that their fixed compression engines.
Nissans are and always have been reliable as far as engines go, the only Achilles heel in the entire lineup is the FWD CVT transmissions. The ka24, qr25, vg30, vg33, vq35, vq37, vr38,vq40, vq38, vk56… All reliable, all in production for years and years with nary an internal known common failure. And news flash, Nissan has been producing it’s variable compression engine for over 2 years now with no issues. By the way it was in the Altima as the qr25dd before it was in the infiniti qx50. So the author is incorrect as well.
Unless gm wants to buy engines (or license) from nissan, gm has to come up with a different way to do it. You can’t patent variable compression engines, only the method to create one.
This is different from Nissan.
Note that the headline says “GM files to patent variable compression combustion engine TECHNOLOGY” (emphasis added). The words ahead of “technology” are used to describe the specific technology for which a patent application has been filed. No claim of patenting the concept of variable compression combustion engines was made.
You can’t patent a concept without “proof of concept” I.E. a design. Not sure what you’re implying or what you think is inferred, but my previous statement stands. They can patent their particular design for that technology, but not the concept of variable compression, otherwise innovation would be stagnant.
Nissan…the Chrysler of Japan.
I want no part of this technology in a mass produced car / truck. Not yet, anyways.
It’s even worse…. The VC turbo was a French startup, bought by Renault, and sent over to Nissan for “refinement”. It was supposed to provide 30% better efficiency, but downsizing and turbocharging means that like the 2.7 LB3, it doesn’t perform any better because it can never run in its efficiency band when you replace a 3.5 v6 with a 2.0 L I4.
While your history of it is accurate, I’m not sure you understand the concept of it. The idea behind it is that whether you want performance or economy, it’s always in it’s efficiency band. Your statement sounds dangerously close to the old “there’s no replacement for displacement”. Which is exactly what forced induction is, a replacement.
Return of the Cadillac V8-6-4?…
Maybe it’s a better replacement then the current DoD system, who knows..
The 8-6-4 was still a big block motor, and was highly reliable. It failed to meet emissions standard so was rapidly replaced by the 4200 grenade V8. Its only problem was harmonic issues in V6 mode.
I much prefer Chevys new skip fire. Skip fire works off a gun trigger style mechanism, which is much more reliable and frankly simpler.
How about GM puts the current DFM V8 in a smaller vehicle so we can see how efficient it can be outside a truck? Specifically, a retuned 5.3L in the CT5.
Il me semble que le premier moteur a combustion interne à compression variable était le saab de la 9-3. Qui avait conduit Gm à nommer le département Saab au développement des poteurs essence 4 cylindres.
To improve CAFE simply stop developing large 6.2 and 8.1 liter engines. Zero-to-sixty and full-to-empty times travel the same direction.
Set the example, GM.
6.6 L and up aren’t going into CAFE vehicles.
Also displacement doesn’t directly correlate with efficiency, it’s a myth spread by obsolete European tax laws. First, turbocharging increases the “effective” displacement, or more accurately, mass of air that goes in a cylinder. The boost pressure at operating points needs to be known for a comparison.
Second, larger displacement means slower operation meaning lower viscous drag. Larger displacement is necessary for lean-burn (e.g. diesel, advanced GDI) and other tricks. Take Ford, their 2.5 L Atkinson is more efficient than their 1.5 and 2.0 L turbos.
Turbo engines are efficient because a small 4 cylinder can run at 2500 rpm and WOT while cruising. Thus heat lost to the head is minimal, pumping losses are almost non existent. That was preferred to a large V8 like gen II small blocks.
However, modern GenV small blocks have cylinder deactivation so they have the same pumping losses. They also don’t have much more friction with modern oils. Further, because they are not running WOT, the retard the cam and run a mild Atkinson cycle upon cruising.
The result, the 5.3 with skip fire tech matches a modern turbo in MPG like the 2.7 Lb3. An 8.1 with the same tech wouldn’t guzzle too much more gas.
Mary Barra says: “GM is the EV leader…”
She didn’t say GM was the ICE leader, but pay her another $20 Million and she’ll say that too.
… wait … why they need this, they are going all EV …
It’s probably the same as everyone else’s. It looks clunky on paper.
Didn’t SAAB do this 20 years ago?
Yes it was the SVC, Saab Variable Compression. It was a 5 cylinders 1,5v liter of displacement with a turbo delivering 2,8 bars.
Excuse my language, i’m french.
They did come up with a different way. This design is incredibly more complicated than Nissan’s design. And just from looking at it, it screams planned obsolescence with that linkage that goes from the crank to the cam.
30 years ago…
I AM TECHNICALLY ILLITERATE. FOR HOT ROD APPLICATION & TO SAVE MONEY I ALWAYS THOUGHT YOU COULD MANUALLY SCREW THE TOP OF THE CYLINDER HEAD UP OR DOWN. LIKE A NINE TO 13 LB. SPREAD. I WOULD THINK ABOUT 5/16THS SHOULD ALLOW THIS BUT I AM UNSCHOOLED. THIS DOES SEEM LIKE INTERESTING TECHNOLOGY. EVENTUALLY SOMEONE WILL COME UP WITH A STRAIGHT FORWARD WAY. CAN YOU SQUEEZE CONNECTING RODS TO MAKE THEM LONGER? CHANGE THE ROD TO TWO FLEXIBLE ARMS SANDWICHED BETWEEN AN ADJUSTABLE RACE? THERE IS AN ABUNDANCE OF EMPTY SPACE UNDER THE CYLINDER HEAD RIGHT? SO BASICALLY A VICE UNDER EACH HEAD. THE CONNECTING RODS ARE REPLACED WITH TWO BOWED OPPOSING HORIZONTAL LEAF SPRINGS. YOU SQUEEZE AND THE ARM LENGTH GROWS A SMALL AMOUNT. LIKE I SAID. I AM TECHNICALLY ILLITERATE. BUT THE THINGS I SEE YOU GUYS MAKE AMAZE ME. STEADY STRONG SAFE. BEEP-BEEP! 600 HP 3 CYLINDERS? DO WE ‘NEED’ MORE? IT SEEMS OUR FOCUS SHOULD BE TRANSMISSIONS. AGAIN. TECHNICALLY ILLITERATE.
Whats the difference between this and honda VTEC?
The Vtec Honda is a variable timing opening valve. It’s not change the compression ratio. This engine can run like a confortable car or like a sports car and make down the engines emissions and consumption. Did i answer (with my french accent,lol) to your question ?
The short of it is that vtec controls valve lift and not piston stroke. The compression doesn’t change with vtec, just valve timing and lift duration. That being said, based on your question I highly suspect this answer will go not understood. You have a LOT of research to do to learn about engines.
GM needs to purchase my iVCR/true-Atkinson patent. “Simple yet Revolutionary”. GM showed lots of interest at the WCX-2022. See sowda007.com for details.
Too many moving parts…
How silly is this response? If “too many moving parts” was a deterrent, the we would still be using a two-speed torque-flight transmission and 4-valve and 5-valve heads would not be even considered.
Mazda is way ahead,
GM, way behind.