Oppertus is an independant European research and development team, working since 2001 in number of fields, and now concentrated on six main projects.

Latest: the HOMOKINETIK infinitely variable transmission

We agree it does not look conventional... but it might be the very best transmission you have ever seen!
Just read this:

This new mechanical transmission is frictionless and slip-free. It transfers the movement using only perfectly conjugated gears, which allows the transfer of a very strong torque with a very high efficiency.

The speed of the output shaft is permanently proportional to the one of the primary shaft. There is no possible acyclism.

The transmission ratio may be changed step by step or continuously, according to the wishes of the user. In all cases, the ratio change is made instantly and without any loss of energy.

The ratio may vary from any value to zero, which means there is no need for any additional clutch.

Other advantages are the simplicity of conception, the very small weight and footprint, and of course the very low manufacturing cost.

The movement is transmitted alternately by two similar transmissions turning the rotary motion into a back and forth motion before turning it back into rotary motion. This is what enables the transmission ratio to be changed continuously from any value to zero.

The cycle of one of these transmissions is shifted so that each of them acts only in the parts of its cycle where the movement is transmitted linearly. The other parts of the cycle are used to slow down the racks at the end of the race and gradually re-accelerate them, in order to avoid vibrations.

The absolute regularity of the movement allows running the device at a very slow speed, using gears to slow down the primary shaft and to accelerate the output one.

How it works

This is one half of the transmission, explaining the functioning of each of the very few components.

The primary shaft (yellow) cooperates with the crown (green) whose shape is left to the discretion of the designer. This crown may be similar to the above design to get a constant speed of the output.

A wheel (pink) rotates on the periphery of the fixed guide (orange), so that the gear of the primary shaft remains at all times in contact with the teeth of the crown.

The reciprocating movement of the crown causes the lever (brown) to oscillate and to transfer its movement to the reciprocating racks (blue-green).

The connection point of the racks with this lever is variable. The user can slide it from one end where it is in the axis of rotation of the lever to the upper end, which has the effect of changing the transmission ratio (continuously or step by step) from zero to the maximum value chosen by the designer.

Each of the two racks is connected to a gear through a one-way clutch which rotates the output shaft (red) in only one direction. Each of them enters into action alternately so that the output shaft always turns in the same direction.

One rack moves in four steps:

  1. sliding at constant speed from left to right,
  2. slowing down, reversing its movement and accelerating up to the same constant speed to the left
  3. sliding at constant speed from right to left,
  4. and slowing down, reversing its movement and accelerating up to the same constant speed to the right.

The designer designs the crown so that steps 1 and 3 are equal or longer than steps 2 and 4.

The movement of one of the transmissions is shifted by one quarter of a cycle, and due to the presence of the free wheels, the movement is transferred only by the steps 1 and 3 of each rack.

That is why the speed of the output shaft remains permanently proportional to the one of the primary shaft.

A specific patent protecting this transmission has been filed on June 21. 2018 (FR1870734) and will be extended worldwide.

The "LiToR"

What is well conceived is clearly stated, and the design to explain it arrives easily...

Applications are numerous : gearboxes and clutches for cars, scooters, bicycles and ships of all sizes, electricity generation, no-crank piston engines, absorbers and suspension generating electricity, braking systems, etc.

A major scooter manufacturer has started working on the subject, and one of the leading European bicycle manufacturers is already building a prototype.

The Variable Diameter Gears
This invention is a CVT (continuous variable transmission) which, for the first time, uses gears. It also brings a very efficient feature which is that the transmission ratio varies as a function of the resistive torque.

The model of the new version is nearly finalized:

How it works

The engine rotates the planet carrier (dark blue), which makes the three "secondary planets" rotate when they are in contact with the crown sector (bright pink). These secondary planets in turn make the primary planets and the sun rotate. The movement is sent out through the aluminum shaft.

A freewheel inside the "secondary planets", combined with synchronization teeth at the begining of the crown sector, guarantees that there cannot be any teeth conflict between them and the crown sector.

Modifying the angle between the secondary crown sector (light blue and the crown sector carrier (yellow) changes the radius of the crown sector, which changes the transmission ratio continously from positive to negative, going through a "zero" position where the secondary shaft would have to stop if the crown sector carrier (yellow) itself could not be rotating. When the crown sector rotates, it drives an electric generator or any type of KERS. The crown sector may also be driven by an electric enging adding its power to the one of the main engine.

Main advantages

Althought it is pretty small and light, with a quite low cost, it has the following characteristics:
it is a continuously variable transmission;
it is compatible with high powers, because it uses teeth and not friction;
there is a whole set of continuously variable forward and reverse transmission ratios;
it also natively works as a clutch;
it also natively works as a braking system, which can be used as a very powerful kinetic energy recovery system;
the energy efficiency is very high because there is practically no friction;
it allows to combine two engines, for example a thermic engine and an electric one.

This concept also allows a very large number of other combinations.


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