Animation of the crankless rotors

Crankless

A new efficient mechanical transmission

How does the crankless drive work?

A family of transmissions

The crankless transmission that we are promoting isn't just one drive mechanism, but a family of transmissions with common characteristics that are patent protected.

A simple example

We will illustrate the working of the crankless drive by showing a simple implementation. Please note that these are principle drawings only; many required features have been omitted for clarity (joints, roller bearings, sealing, exact shape of the catches, etc.).

1. Machine axle

2. Rotor rings

3. Assembly

Engineering description

Fig: Rotor 1 in disassembled, assembled and transparent state Fig: Rotor 2 in disassembled, assembled and transparent state

In this implementation, the crankless drive consists of two rotors. Each rotor has a central ring (10), a pair of pistons on the outside of the central ring (17 and 18), and a pair of catches on the inside of the central ring (25).

Fig: Rotors 1 and 2 assembly to toroidal working space

The two rotors can rotate in a fixed housing. This fixed housing together with the inner rings of the rotors limits a toroid (or ring shaped) working space.

Each rotor piston (17 and 18) fills a sector of the toroid working space and the common axes of rotation of the rotors goes through the center of the toroid working space.

Fig: Rotors 1 and 2 in resulting toroidal working space

This creates a total of four chambers (27) in the toroid working space, one in between each two subsequent pistons.

Fig: Machine axle with ball shaped center and transmission grooves

The crankless drive further has a machine axle, on which a ball shaped center (21) is mounted. On this ball there are four grooves (23).

Fig: Crankless drive assembled with machine axle and rotors and fixed housing

The machine axle is mounted through the center of the toroid working space, but at an angle (Y) with the rotor axes. Each rotor catch (25) exactly fits into a groove (23) of the machine axle center. Thus, the catches can slide, or preferably roll, in the grooves (23):

  • when the machine axle rotates, it will induce a rotation of both rings;
  • alternatively, when the rings rotate, they will induce a rotation of the machine axle.

Fig: Angular positions simulation angle indications Fig: Angular positions simulation rotor positions Fig: Angular positions simulation machine axle positions Fig: Angular positions simulation overall drive positions

However, a uniform rotation of ther machine axle transforms into a non-uniform rotation of the rotors. Moreover, both rotors rotate at a different phase.

This is illustrated by the figures to the left, which show the crankless drive at different angular positions of the machine axle (0°, 22.5°, 45°, 67.5° and 90°).

At position 0°, all chambers have equal size. The rotor catches of the rotor with pistons 18 are positioned exactly in the middle of the grooves 23, at the "equator" of the ball 21, whereas the catches of the rotor with pistons 17 are positioned at the extremes of grooves 23 (on the "north" and "south" side). When the machine axle rotates from this position 0° to the position 22.5°, it can easily be seen that the rotor with pistons 18 will rotate faster than the rotor with pistons 17, and this all the way to position 45°. Thus, the volume of two opposite chambers 27 will increase, while the volume of the other two chambers 27 will decrease. In the position 45°, the speed of the two rotors will be the same. Evolving from 45° to 90°, the speed of the rotor with pistons 17 will be relatively higher, so that the volume changes in the chambers 27 will revert. Position 90° is similar to position 0°, however with rotor 17 in the position of rotor 18 and vice versa. Continuing the machine axle rotation will now maximize the volume of the chambers that were previously minimized, and vice versa.

This simple implementation of the crankless drive leads to the following kinematic behavior:

Rotation speeds in function of time for a simple implementation

Fig: Rotation speeds in function of time for simple implementation

Chamber sections in function of time for a simple implementation

Fig: Chamber section in function of time for simple implementation

More sophisticated designs

The crankless drive can be optimized and adapted to a specific application using a broad range of parameters. The same concepts will lead to different implementations, which in turn can lead to a different mechanical design and a different kinematic behavior of the rotors. Or, in other words, the movement of the rotors, the mechanic forces and couples in the drive, and the periodic volume fluctuations of the chambers can be tuned by electing a different mechanic design for the transmission. The figures below show for example the results of a different implementation (not discussed here):

Rotation speeds in function of time for a more sophisticated implementation

Fig: Rotation speeds in function of time for more sophisticated implementation

Chamber sections in function of time for a more sophisticated implementation

Fig: Chamber section in function of time for more sophisticated implementation

We can provide engineering files with details on different implementations and their kinematic and mechanic behavior, as well as the possibilities to fine-tune implementations to a specific application. If you are interested to become an industrial partner and would like to evaluate the implementation of the crankless drive into your product (engine, pump, compressor ...), please contact us at mark.jorissen@crankless.net. We will be happy to discuss other implementations and our engineering files subject to a confidentiality agreement.

Copyright © 2015 Crankless