Is it a ridiculous idea to invest a little R&D in a new technology that makes cheap electric cars possible? No commitment, step by step assessment.
Article in: Gear Technology (AGMA)
Video presentation: New involute gearing technology/theory & New-CVT transmission
Click this text to see the prototype in action!
Applicable to: cars, bicycles, motorcycles, wind turbines, trucks (electric and fossil fuel), etc...
Small, cheap, efficient, high torque, many ratios - Transmission - Drivetrain
Example of the problem and the solution: The world's best selling electric car, the Wuling Mini EV costs $4200, but it has a top speed of only 100 km/h and its max gradient is not published. With a simplified version of the New-CVT (excellent efficiency due to only three gears plus a reducer) it would have nine gear ratios, ranging from 1:1 to 1:9. This solution would let it go up mountains with ease, as well as let it cruise on the highway at good speed. But also more expensive cars will benefit from this technology as it greatly extends their performance envelope. This is vastly better than a single- or two-speed gearbox (with similar efficiency).
Very cheap highway capable short range electric cars are a huge potential market, either as the primary car for the environmentally minded with long range travel done by train, or as a second car for a quick dash to the shops or to collect the kids. Such a car would be about half the price of a cheap petrol car, it would run on the virtually free solar power from the roof of the house and it would also have very low maintenance costs. Basically like making one of those little cheap electric city cars (NEV) highway capable with a cheap, small and super efficient transmission. But until now such a car has been technically impossible.
The battery is the most expensive part of an electric car, so cost cuttings would logically start with the battery. However, Elon Musk chose Tesla's niche market very carefully, high-end electric cars are in an absolute sweet spot of what is technically possible.
Unlike petrol cars where the size of the tank has no effect on the maximum power output of the engine, with electric cars the size of the battery is directly related to peak power that the battery can deliver to the motor. So the maximum power output of an electric motor is totally dependent on the size of the battery. In fact batteries explode if too much power is taken from them too quickly.
Batteries produce electricity trough a chemical reaction. And the amount of electricity produced is directly related to the amount of chemical reaction, and the amount of chemical reaction in turn is directly related to the amount of heat produced. But while in a big battery the chemical reaction is spread out over a large volume and the battery also has the space to lose the heat, in a small battery that same amount of heat is concentrated in a small volume and it cannot be dissipated fast enough. So the battery heats up to a level where it destroys itself.
So an electric car with a small battery will by definition also have a small motor. However, all cars must both, be capable of going up a mountain at a slow speed while carrying a heavy load, as well as being able to reach a decent speed on the highway. This double requirement simply cannot be met with a small motor paired with the single-speed transmission as is currently the norm in electric cars. (Note: all discussions on single-speed transmissions in electric cars are meaningless if the battery is not taken into account). So the only option is to use a multi-speed transmission instead. But current multi-speed transmissions in petrol cars are very heavy, expensive and not efficient enough (the main reasons why they are not fitted to electric cars). Some electric cars do have two-speed transmissions, but these are a compromise based on current technology.
Fortunately there is now a fundamentally new type of multi-speed transmission. One that beats the old types in almost every way and one that is also cheap to produce. It even matches the efficiency of some single-speed transmissions. Also, single-speed transmissions require the motor to be able to reach very high speeds, which therefore also requires components that are be capable of these very high speeds and these components are very expensive. Multi-speed transmissions do not have this requirement and therefore these components can be a lot cheaper. Furthermore, slower speeds are more efficient.
Lego compatible version of the multi-ratio gear
The game changer technology that makes the new multi-speed transmission possible is the new multi-ratio gear technology (patent pending), combined with new insights gained from the 3D involute shape. Basically gearing technology has taken a huge step forward, and because of this the previously impossible has now become true.
This new type of transmission is called the "New-CVT" (patent pending). The name reflecting the fact that it has many different gear ratios that enable the engine to always run at its most efficient speed. But unlike traditional CVTs, the New-CVT is also very efficient and it can handle huge torque.
But most importantly for cheap electric cars, it is also much smaller, cheaper and lighter than the other types of multi-speed transmissions. This is due to its compact design and the use of much smaller gears. And the reason why these gears can be much smaller is due to the shape of their teeth. These are much stronger and allow for far fewer teeth per gear without the risk of undercutting. Also for electric cars, the New-CVT can be placed before the reducer, resulting in another dramatic reduction in size. The end result is a really small, and therefore also really cheap and lightweight, transmission.
The proof of concept is in the prototype. A 3D printed (PLA 0.4 mm nozzle) prototype built with Lego motors, a piece of string and controlled by an Arduino computer. So it is so ridiculously cheap and so low-tech that even a kid could have produced it in his or her bedroom. But also with a real world output wheel speed that would make a truck do 112 km/h on the highway (1 m wheel diameter, main gear 372 rpm, Lego motor 198 rpm, gear shift in 0.08 sec, gear ratios from 1:1 to 1:9 and 59 unique gear ratios). So not only does the prototype prove the concept, it also proves that this new technology is inherently cheap, efficient and very forgiving. Science has done its job and the rest is up to the engineers. A game changer technology has been born.
Once cheap electric cars become popular, people will soon realize that with an electrified highway system (like elonroad) the limited range of these cars would no longer be an issue. Next this electrified highway system would then in turn also make long range electric trucks possible (also equipped with the New-CVT transmission).
For creating a sustainable world this new technology is hugely important. Current electric cars are only a niche solution, but with the new technology of the New-CVT there is now a cheap mainstream pathway to the world going carbon neutral. Cheap electric cars, electric trucks and an electrified highway system, are the road to the future!
So while the initial R&D investment is likely to be very small indeed, the potential returns, both financially and environmentally, of this investment are very large.
The multi-ratio gear (patent pending) is a new type of involute gear. As it rotates it continuously cycles between two different gear ratios, due to its two halves having different amounts of teeth per unit of rotation. So in essence this gear is already a multi-speed transmission by itself, and without the normally big problem of having to get the gears in phase and sync with each other. This greatly simplifies transmission design and also makes the previously impossible, become possible. For example:
The New-CVT transmission (patent pending) is (almost) as efficient as a single-speed transmission, functionally alike a CVT (meaning it has many gear ratios), suitable for high torque, compact, light and cheap. Its only defects are that it needs to be computer controlled and that drive must be disengaged while changing gear. So while a geared CVT has always been regarded as a unicorn, as well as the holy grail in mechanics, it has now become a reality thanks to the multi-ratio gear.
For electric cars the New-CVT results in longer range, longer battery life, higher battery efficiency, cost reduction and much better performance in demanding conditions.
While for cars with combustion engines it offers both the engine efficiency advantages of a CVT as well as itself being much more efficient than even a manual gearbox. The New-CVT transmission demonstrates the immense potential of the multi-ratio gear.
The multi-ratio gear consists of two gear halves with different amounts of teeth per unit of rotation, and with both halves intermeshing with another gear at the same distance between the axes. In the New-CVT the multi-ratio gears function as intermediate gears in-between single-ratio gears, thereby allowing the intermeshing gears to change gear by simply sliding from one gear to the next. In the New-CVT conical involute, also know as beveloid or tapered, versions of the multi-ratio gear are used to enable sliding at an angle along the gear's axis.
Many versions of the New-CVT are possible, but the most interesting ones use the New-CVT to phase and sync the transmission's main input and output gears that
intermesh with a stack of helical bevel gears that are on the same shaft as the main gear in the New-CVT. During gear changes these input and output gears are
disengaged. For electric cars not all the single-ratio gears in the New-CVT have counterparts in the stack of helical bevel gears. So for example,
a 1:1 to 1:9 New-CVT starting with 8 teeth (all teeth numbers of the counterpart gears are multiplied by a constant to prevent undercutting) has a main
gear with 9 gears resulting in 59 unique gear ratios. But if only 3 of these 9 have counterparts for the electric version, then it goes from 1:1
to 1:9 with 7 unique gear ratios. This set-up results in a very compact transmission. So the New-CVT ensures that all the gears are always in phase and
sync with each other as to enable gear change, while the efficient and low noise helical bevel gears are the ones actually driving the car and determining the
efficiency of the transmission as a whole. So efficiency is mostly due to only three gears intermeshing at any one time, and this can even be reduced to just two
gears at the cost of fewer gear ratios. These values are equivalent to the efficiencies of the single-speed transmissions commonly used in electric cars.
Cars need to be able to go up a steep slope at slow speed and under heavy load, so designers of single-speed transmissions are forced to choose battery types that are optimised for sustained peak power rather than range, battery life and battery efficiency. Simply using a very big electric motor to solve the problem also requires all the other parts to be a lot bigger. A compact transmission design is meaningless when the actual transmission plus motor is four times the size (weight and cost) it could otherwise be. It is often stated that electric motors have an enormous amount of torque. This is true, but it is also true that the power requirements to make this possible are a major design headache that leads to horrible compromises. That super fast acceleration time is a gimmick that hides a real problem.
So for electric cars the New-CVT is a major game changer.