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That's a commonly proposed design.

​@@brianb-p6586 do you know where generic requirements for these generators are discussed? for example reactive vs active energy which would suggest a mechanical vs electromagnetic interaction of the two pistons? An a priori discussion of the principles rather than actual design

That's it's main draw back but with the right kind of mounting like some elastic mounting idk I'm no engineer but that's what I heard is the main problem is the vibration. But it doesn't need any linkage to a generator. It is the generator

Place a pair side by side running in anti-phase as they shown in the presentation.. then there's little difference to the magnitude of the issue in a conventional engine.

That (Karno) is the most recent highly promoted linear engine, although it is very different from this internal combustion engine.

An electric vehicle powered fossil fuel generated electricity.

No, it makes them hybrid vehicles.

It’ll be here right after the blue sky and unicorns start producing cheap, clean, zero emission fairy dust as an alternative to what the world was built on, Fossil Fuels!

Wow, great engine, great DURHAM ENERGY UNIVERSITY, I am going to contact you..... Tq

Hyliion / Karno generator

@@stevetk8174 Inventions like this need to be made. I guess it's not a very well known company right now. Thanks.

The problem is not the technology. The technology is good. If adopted, free piston linear generators like shown in this video really would increase fuel efficiency, especially in portable electric generators, by a meaningful and net beneficial amount. The problem is not technological. The problem is a lack of motivation and interest by the corporations that manufacture internal combustion engine products, most importantly, the established automakers and the portable generator manufacturers. The output of free piston linear generator engine designs is electricity, rather than mechanical motion. If you start from a non-hybrid gasoline engine automobile, swapping out the gas engine with a free piston linear generator engine like shown in this video, means that you would also need to add a large electric motor, a large amount of power electronics, and a small battery or capacitor bank, in order to achieve mechanical propulsion at the wheels. Adding the electric motor, power electronics, and the battery bank makes the vehicle's initial purchase price substantially more expensive, compared to the basic unmodified conventional gasoline engine design. Additionally, developing such a powertrain requires substantial additional research and development expenses, which legacy automakers do not like doing. The primary benefit to implementing a free piston linear generator, is to increase fuel efficiency, but automakers do not pay their customer's annual fuel bills. Consequently, the automaker is not incentivized to make more fuel efficient designs, unless they are being forced to do so by market forces and/or government regulations. If a pioneering automaker decided to build a more fuel efficient car, and it sold really well, this would create market forces indicating that people like more fuel efficient vehicles, and are willing to pay more for them. However, most people in US society currently do not appear to care very much about fuel efficiency, and it does not appear to be their primary deciding factor, when picking a model of vehicle to purchase. Consequently, there are little in the way of market forces that encourage investing research and development money in making more fuel efficient vehicles, especially when the changes are quite substantially different (and relatively expensive), like in the case of designing and deploying a free piston linear generator engine with associated electric powertrain. The free piston linear generator concept is however solid, and it really does enable engine designs that can produce meaningfully higher fuel efficiency. The thermodynamic efficiency of an internal combustion engine is strongly related to the expansion ratio during the combustion stroke. Conventional crankshaft based internal combustion engines are restricted by the crankshaft, both in the expansion ratio that is readily implemented, and in applying down force on the crankshaft at the wrong time during the combustion cycle. To achieve highest thermodynamic efficiency, one would want to burn all of the fuel instantaneously at "top dead center", and then allow the hot combustion gases to expand a very large amount, until the gas pressure inside the cylinder is no longer higher than the surrounding atmospheric pressure. This is however not realizable with conventional internal combustion engine designs with a crankshaft, as burning all the fuel at top dead center would create an excessively strong downforce on the crankshaft that would squish the oil out between the bearing surfaces and produce engine knock (with associated bearing damage), rather than a smooth conversion of combustion chamber pressure into mechanical rotational energy. To avoid this problem, conventional internal combustion engines are instead designed to burn the fuel somewhat later and slower, at lower peak temperatures, which lowers the theoretical "Carnot" efficiency of the engine (which favors high peak combustion temperatures and substantially low exhaust temperatures, associated with high expansion ratios following combustion). Free piston linear generators are different, in that they do not have a crankshaft and bearings to worry about. One can make designs with much higher expansion ratios and much high peak combustion chamber temperatures. This directly improves the "Carnot" efficiency of the engine. However, the output of the free piston linear generator is electricity, which is a disadvantage if interested in simply replacing a gasoline automobile engine with a drop in engine of higher efficiency. However, the electricity output is actually quite advantageous, if you are trying to augment an electric vehicle, with a range extending engine, or, if you are making a portable or stationary electric generator. Currently available portable generators are notoriously inefficient, and are far below the potential efficiency achievable and what is commonly implemented by commercial electric utilities operating thermal power plants. However, free piston linear generators have the potential of being highly scalable, whereby they can offer an individual at their own residence, with a generator with similar thermodynamic efficiency as what commercial electric utility operators can achieve. If you wanted to live "off grid", where your residence is primarily powered by solar panels, but is backed up with a fuel based combustion generator for use on foul weather days, then a free piston linear generator has the potential to be an excellent choice. Unfortunately, no portable generator manufacturers currently care, in part because there are no standards for even comparing portable generator fuel efficiency between models. Consequently, consumers are almost totally in the dark as to the efficiency of the available generator models, which makes it impossible to preferentially select a model with high fuel efficiency. To fix this, consumers must have access to uniform generator efficiency data, like as what is supplied for automobiles, in the form of "Monroney fuel efficiency labels" for vehicles sold in the US.

@@Fritz_Schlunder thanks for sharing your vast knowledge. Free piston linear generators are probably 2 stroke. Ceramic coated piston rings would be required to keep oil premix at a bare minimum and help with emissions. Fixed RPM will minimise the short circuit release of un-burnt fuel air mix. It's construction without a flywheel, crankshaft or valve-train means it is inexpensive. Then why on earth are generator manufacturers staying away? I understand using free piston linear generators in a car involves considerable electrical components but should be viable for generators? I'm from India. We have a generator manufacturer called Kirloskar. Wonderful organisation. They actually partner with Toyota here ( only for automobiles) . But even they don't have a free piston linear generator. Only flywheel based ones. There have been diesel free piston linear generators in the past. I think Rolls Royce made them once. Even series hybrid cars like the Nissan note don't use free piston linear generator. They employ the conventional ICE. I don't know if it avoids a flywheel though.

​@@Fritz_SchlunderThank you Fritz for that very comprehensive explanation of the principles and problems/challenges involved with this motor design; LOL, I think I understood most of it...... It seems to me that this motor, being a direct generator of electric power, should be well placed to power small, private, ICE-electric, commuter or emergency VTOL aircraft.

Six years is nothing for an engine design. This design is actually much older than that, and many people and companies have tried it.

If you add another one operating in opposition to the other one however...

That's a good point, but those 2 cylinders should not be made as a single part. The automobile bends and twists, so that may break part that long.

You don't need to invent a new term. You're discussing the operating frequency, in cycles per unit time like any other frequency. This can be per minute or per second or any other time unit, but per second makes the most sense -that's "hertz", the base frequency unit of the SI system. For an example, the Karno linear engine designed by GE and now being developed and promoted by Hyliion runs at 20 hertz (20 Hz, 20 cycles per second).