of a helicopter is the only known widely used mechanism which achieves the transmission of rotation from a driving shaft onto a stationary frame to a driven shaft onto an endlessly rotating carrier, independently of the rotation of the carrier.
However, there are two features which render this mechanism suitable only for the transmission of a mechanical signal and not for power transmission:
- it uses delicate rods which can not transmit torque of a significant magnitude and
- the stroke of its output, linear or rotary, is finite.
On the other hand, when the need of a variable orientation of the horizontal axis of a windmill appeared, in order to follow the wind front for better exploitation of the wind energy, several centuries ago, the solution was a complicated configuration, where all the necessary work -wheat milling, for example- was taking place "up there", in a whole building which was supported on a rotatable base.
The continuous designing and redesigning of similar windmills established a specific practice for the construction of the windmills.
At the same time, it established a perception, a "dogma"
that this is the only way to have a variable orientation of the axis of the windmill and to use this wind energy on-site only, without the capability to transmit it onto a stationary frame ...
So the windmills of other types, either used only reciprocating motion to transmit power to the ground -the water-pumping windmills for instance- or produced electric power "up there"; and they are still producing electric power "up there" until today.
The present Invention has to fight this "dogma", especially trying to be applied on a wind turbine; however, fortunately, has many other applications.
For the moment, it is necessary to take the things from the beginning.
Technical Problem to be solved:
In many applications, specific or not, there is the need to transmit endless rotation from a driving shaft on a stationary frame to a driven shaft on a rotating carrier, or vice versa, without the endless rotation of the carrier affecting this transmission.
Such an example is the horizontal axis wind turbine, the horizontal propeller shaft of which rests on a carrier, named "nacelle", which rotates about a vertical axis, and therefore any conventional way of transmission from the horizontal axis to a vertical axis on a frame which is stationary with respect to the ground, results in the prohibitive presence -to some extent- of the angular velocity of the nacelle in the finally produced angular velocity of the last element of this power-train.
This, of course, at the same time results in the presence of a torque on the nacelle, which is directly related to the transmitted torque of the propeller shaft; it is necessary to impose a torque on the nacelle in order to be always oriented at its optimal operating position for work production, but this orientation torque must have nothing to do with the transmitted torque from the propeller shaft to the stationary frame.
Other examples are the transmission of rotation between the chassis of a large excavator or a battle tank and their endlessly rotating turret, or between the chassis of a vehicle and its drive wheel which is supported on a -possibly endlessly- rotating steering bracket.
Another such example is the propeller pitch adjustment mechanism for a propeller-driven aircraft, a helicopter, a propeller-driven craft or a wind turbine, as well, although the existing mechanisms for these applications have satisfactory performance, as the required motion is finite and not endless.
There are, however, many other examples that require an independent endless rotational transmission to a shaft on an endlessly rotating carrier.
The aim, therefore, is to design a purely mechanical mechanism that performs a transmission of endless rotation from a driving shaft on a stationary frame to a driven shaft on an endlessly rotating carrier, or vice versa, independently of the rotation of the carrier, with the least possible number of moving parts and the highest possible degree of efficiency.
Relevant Prior Art:
The most known -and the most explanatory, at the same time- way of transmitting motion, in general, using purely mechanical means, to an element on an endlessly rotating carrier, independently of the rotation of the carrier, is the way to adjust the propeller pitch in a helicopter:
on the frame of the helicopter, the one end of a first rod moves linearly in a direction, resulting in moving, also linearly, the other end of this rod in a direction perpendicular to the previous one, while this direction coincides with the axis of rotation of the rotating propeller hub, and from this point, through axial thrust bearings, this motion is transmitted -independently of the endless rotation of the propeller hub with respect to the frame of the helicopter- at the one end of a second rod, the operation plane of which rigidly lays on the propeller hub, and in this way the other end of this rod finally performs the adjustment of the propeller pitch, independently of the endless rotation of the propeller hub with respect to the frame of the helicopter.
Therefore, if the first end of the first rod, of a similar mechanism, is driven by a crankshaft which rotates endlessly on the stationary frame of this mechanism, and the second end of the second rod drives another crankshaft which rotates endlessly on the also endlessly rotating carrier of this mechanism, a transmission of endless rotation from a driving shaft on a stationary frame to a driven shaft on an endlessly rotating carrier is achieved, independently of the rotation of the carrier.
However, the two conversions of endless rotary motion into reciprocating linear motion and vice versa, as well as the axial thrust, through the axial thrust bearings, are processes that require many moving parts in an inflexible and rather bulky arrangement and, of course, the overall degree of efficiency appears significantly low, while, in addition, there are problematic points -usually named "dead centers"- of instant indeterminacy of the direction of motion during the conversion of reciprocating linear motion into endless rotary motion.
Such a technique is described -in fact it is applied to a wind turbine- in the patent application
In the patent applications
there are attempts to transmit rotation from the nacelle to the base of the tower, through bevel gears and two coaxial vertical shafts or one, respectively.
In the patent application
a proposal for a nacelle rigidly connected to a rotating tower is shown.
As for other applications except the wind turbine ones, perhaps there is no any relative proposal, and patent applications such as
stand far from the concept of the present invention and do not solve directly and effectively the problem of independent transmission with the aforementioned requirements.
So, except the above described way, it seems that there is no other similar proposal, in the prior state of the art, of achieving, via purely mechanical means only, the required transmission independently of the rotation of the carrier.
Disclosure of the Invention:
In order to directly solve the aforementioned problems, using purely mechanical means, it is necessary to somehow remove the effects, kinematic and dynamic, of the endless rotation of the carrier on the transmitted rotation.
So, a Compound Planetary Mechanism is proposed, the planets of which belong to another Planetary Mechanism, which therefore may be named "Eccentric Planetary Mechanism", and this Compound Planetary Mechanism may be named "Epi-Planetary Mechanism", in a sense that this configuration is a Mechanism onto a Mechanism.
The Eccentric Planetary Mechanism can be any mechanical assembly with three ports, inputs or outputs, such as the classic differential mechanism of a vehicle, where the one input of this mechanism is the main rotation, which must be transferred, but mixed with the -in some way- undesired endless rotation of the carrier, with a positive sign, the other input is this undesired endless rotation of the carrier, with a negative sign, while its output is the filtered final endless rotation, directly related to the initial main rotation only.
The Compound Planetary Mechanism generally has a frame and a first carrier, which is the already existing one and rotates with the undesired endless rotation with respect to the frame, a first gear which is coaxial with the first carrier and rigidly connected to the frame, a second gear which is coaxial also with the first carrier and freely and endlessly rotates, constituting either the input or the output of the Compound Planetary Mechanism, and on the first carrier, eccentrically and preferably parallel to its axis, has also one -or more- Eccentric Planetary Mechanism.
Each Eccentric Planetary Mechanism, generally, has a second carrier, on which eccentrically and preferably parallel to its axis there is one -or more- axis, about which a first shaft rotates, with a third gear and a fourth gear rigidly connected to both ends of it, while on the one side of the second carrier, coaxially with it, freely and endlessly rotates a second shaft, with a fifth gear and a sixth gear rigidly connected to both ends of it, cooperating with the first gear and the third gear, respectively, and on the other side, also, of the second carrier, coaxially with it, freely and endlessly rotates a third shaft, with a seventh gear and an eighth gear rigidly connected to both ends of it, cooperating with the second gear and the fourth gear, respectively.
Depending on the design, either the second carrier or the third shaft constitutes either the output or the input of the Compound Planetary Mechanism, inversely depending on the role of the second gear.
The Compound Planetary Mechanism, as a whole, is designed so that the flow of the power, from its input to its output, is performed independently, kinematically and dynamically, of the rotation of the already existing carrier and for this purpose there is a mathematical relation between the teeth numbers of all the gears involved, which is proposed to be named: "Independence Condition"
Since it seems that this mechanism is a really new configuration solving several important problems, instead of its long name-description: "Mechanism for Transmission of Endless Rotation to a Shaft on an Endlessly Rotating Carrier Independently of the Rotation of the Carrier"
, it is proposed to be named "Eleuthero-Strophic Mechanism"
, which means an Independent Rotation Mechanism, or even "Eleuthero-Strophe"
, which means an Independently Rotating Hub; the term "Eleutheros" is already used in English language, in
but not in Engineering, so there is no any possibility to be confused with another meaning, similar or not.
Finally, looking at this issue from a wider perspective, it should be noted that the Mechanism for Transmission of Endless Rotation to a Shaft on an Endlessly Rotating Carrier Independently of the Rotation of the Carrier or Eleuthero-Strophe, while radically differs (especially: in the present invention the amplitude of the involved oscillation is just zero) from the previous cases WO/2007/125373, WO/2009/040588, WO/2018/020279 and WO/2021/165707 (where, also, the amplitude of the involved oscillation is just zero), falls within the broadly defined category under the name:
"DISTRIBUTIVE OSCILLATING TRANSMISSION"
M O R E (complete description, drawings, claims etc) as PDF
M O R E (complete description, drawings, claims etc) at WIPO
The basic configuration of the present invention includes only FIVE
moving parts, namely the action sun, the planetary action shaft, the satellite shaft, the planetary reaction shaft and the planetary carrier, with the addition, of course, of a sixth moving part, which is the central carrier; this central carrier, of course, already exists since the very beginning of the design and in fact is the moving part with the -in some way- undesired motion.
The operation of the basic configuration of the present invention, also, is based on the cooperation of only four pairs of cooperating gears, while all these gears can be and moreover is preferable to be standard ones.
Even more, there is no any other element which must be specialized; therefore the result is the simplest and most cost-effective possible construction and maintenance, while, at the same time, due to the least possible number of moving parts, the highest possible degree of efficiency is achieved, leading to the most productive possible operation.
It is also important that, by the design of the present invention per se, the most balanced arrangement of the diameters of the gears can be achieved, resulting in the avoidance of the problematic pinion, which is the weakest link in any power-train.
Moreover, taking into account some specific applications of the present invention, the advantages become more obvious and understandable:
- relocation of the vast majority of the operating elements of a wind turbine, from its rotating nacelle to its stationary tower, resulting in the drastic lightening of the nacelle and the drastic, also, reducing of the construction and maintenance costs,
- in addition, combining the concept of the application WO/2021/165707 with the one of the present invention, the result is a configuration with a total transmission ratio as high as it is required by the design of the wind turbine as a whole, thus this configuration comprises a highly effective speed increaser, taking low speed from the propeller shaft and providing high speed to the electric generator, superseding the currently used speed increaser, and the achievement of all these is performed by the insertion of five new moving parts only
- transmission of the electric power via the simplest possible way, avoiding an unnecessarily complex configuration, with low performance and short-lived elements, such as the electric slip rings,
- achievement of purely endless rotation of the turret of a large excavator or a battle tank, with respect to their chassis, while with the existing technology either the rotation is finite and with a significantly shorter angular path than a full revolution or it is much more expensive in construction and maintenance if an endless rotation is available but with a special sealing for rotation of the hydraulic piping,
- lowering of the level of the gravity center of the excavator or the battle tank as much as possible, thus rendering the use of the excavator or the battle tank more effective and safe,
- designing of an all-wheel drive and all-wheel steering vehicle, a really holonomic one, as the steering brackets can be rotated, for steering, in an absolutely endless way,
- designing, also, of a vehicle with extremely high clearance from the ground, for special use -for firefighting in rugged and jungly terrain, for instance- as the height of each steering bracket unit can be as great as it is required,
- achievement of the capability of transmitting of a huge amount of power via wheels which propel and steer the vehicle at the same time, even in a classic front-wheel drive car, with a normal steering angle amplitude, because this transmission is performed via robust gears instead of delicate balls of the ball-bearing constant velocity joint, a fact that can render this application of the present invention the new and promising proposal for the propulsion of a vehicle of any type, especially a military one or even a supercar,
- achievement of the most elegant, compact and robust configuration, even in the case of the propeller pitch adjustment, although the currently used mechanisms are effective because of the need of finite operating stroke, rotational or linear,
- achievement of the capability of even endless rotation for the adjustment of the propeller pitch, with whatever this implies.
In conclusion, these are a number of merits of the present invention which are easily contrasted as advantages over a competition, which in fact does not exist, or, in the few and individual cases in which it does exist, is rather moderate