Note: Descriptions are shown in the official language in which they were submitted.
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NWT Management S.A.
S p e c i f i c a t i o n
Magnetic power tran~mi~sion device
The invention relates to a power tr~n~mi~sion device in accordance with the generic part
of claim 1.
Magnetic power tr~n~mi~ion devices are known with which a driving power is
transmitted from one pivoted body to another pivoted body. The bodies are parallel to
each other in axis and positioned next to each other; and the power tran~mi~sion is
performed due to the magnetic effect according to the manner of toothed wheels which
mesh together and which form a gear. The problem with this known type of power
tr~n~mission devices is that the tr~n~mi~sion losses increase as the amount of power to be
tr~n~milte~l increases. On the other hand, magnetic power tr~n~mi~sion devices are
superior to mechanical power transmission devices as regards freedom from or lowdegree of wear.
It is further known to use magnetic forces for the provision of magnetic clutches. Such
clutches can, if designed accordingly, be made to have a comparatively low degree of
play and can ensure a variable clutch function due to the realisation of electromagnets
without mechanical adjustment movements. The activation of the electromagnets requires
d corresponding con~llmption of energy. Nevertheless, such clutches are used if the low
degree of wear, but also the neutralisation of vibrations and similar is relevant.
For example, magnetic agitators work according to the principle of magnetic clutches and
here the low efficiency is justified by the mechanical neutralisation.
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For the provision of power tr~n~mi~sion devices with the lowest possible degree of loss
as a rule mechanical gears are used whose effective surfaces are worked to high
precision. Degrees of efficiency of around 99% can be reached in this way. Such high-
quality gears do, however, require a continuous control as regards lubrication, bearing
play and, if necessary, as regards wear for the maintenance of their high degree of
efficiency.
In contrast, it is the object of the invention to create a magnetic power tr~n~mission
device in accordance with the generic part of claim 1 which is improved substantially in
its degree of efficiency, particularly by orders of magnitude over known power
tr~n~mi~sion devices of this type, and which is also suitable for very high revolutions.
This object is solved in accordance with the invention by claim 1. Advantageous
embodiments result from the dependant claims.
With the magnetic power tr~n~mi~.~ion device in accordance with the invention it is
particularly favourable that the magnetic spirals in accordance with the invention work
slightly offset to each other and that they possess a shape which at least approaches that
of an ideal spiral. As like poles of the roll bodies which are neighbours to each other
point outwards in each case, the opposite identical poles are repulsed. A sliding of the
magnetic spirals past each other is performed where the essential factor is that the
opposite fields of the perm~nent magnets do not intersect, but practically enter into each
other along the direction of the field lines and move out away from each other. Field
lines do not intersect and no eddies arise.
With the magnetic power tr~n~mi~sion device in accordance with the invention the'extremely high degree of efficiency obtained with a corresponding design which is
practically de~ ed by the bearing friction is especially favourable with the power
tr~n~mi~sion device also being suitable for operation in a vacuum. During operation
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under atmospheric pressure, the body in each case is preferred to be exactly cylindrical
so as to keep the air resistance as low as possible.
In accordance with the invention driving powers with very high revolutions can also be
transmitted. This is due to the fact that the pure power tr~n~mission is performed with an
extremely low degree of loss and - under practical points of view - practically with no
loss.
Thermographic studies with a high-resolution thermograph showed that the warming in
the power tr~nsmi~sion area, that is the warming of the actual bodies, is at most 5% of
the bearing w~rming This was determined under the following parameters:
Powers tr~n~mitted: 1.1 KW
Roll diameter 16 cm
Roll length 25 cm
Revolutions 3,200 r.p.m.
Magnetic track width 8 mm
Magnetic track distance (pitch) 8 cm
Spiral Two-wind
Magnet material Neodym 370
Air gal) 0.2 mln
Coating material Brass
Coating thickness 0.2 mm
Bearings Commercial roll bearings
It is further particularly favourable if the effective width of the magnetic tracks is
substantially lower than the distance between the magnetic tracks in an axial direction,
that is the pitch with one-wind spirals or the half-pitch with two-wind spirals. Jn this
way, it is prevented that the magnetic tracks which are neighbours to each other have an
effect on each other. Simultaneously, such a play is created in the tr~n~mission of power
as is desired in accordance with the invention for the further reduction of losses. The
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initiation of the power tr~n~mission begins gently, that is with a slowly increasing
opposing force with nevertheless no slip arising - even with a low pitch - due to the
highly effective magnetic elements.
Preferably the magnetic elements are small and positioned in a row so that they form an
essenti~lly uniforrn magnetic track outwardly. The power tr:~n~mission between magnetic
spirals positioned diagonally opposite to each other is performed in such a way that the
rounded characteristic of a single magnet in each case does not yet become effective, but
that rather the individual magnetic elements work as one elongated magnet. Acceleration
and braking losses due to a non-uniform magnetic characteristic are thus definitely
avoided.
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The invention can be used particularly favourably for highly effective energyneutralisation in motor/generator systems. In all cases 90% of the power tr~n~mission
losses can be saved over known systems whereby completely new fields of application
are opened up.
Preferably, the spirals of bodies which are neighbours to each other are directed in
opposing directions so that an opposing roll rotation direction is produced. It is naturally
also possible to use spirals with the same direction so that a roll direction in the same
direction is produced. It is particularly favourable that any direction of rotation can be
chosen simply and with one and the same driving spiral depending on the design of the
driving spiral. The opposing spiral produces even slightly more reductions in losses
under non-vacuum conditions as the air current generated by the rolls in the direction of
the ci-~iw~elellce is in the same direction in the neighbouring area with opposing spirals.
~It is essenti~l for a tr~n~mi.c~ion with a low degree of loss to keep the surface roughness
of the bodies approaching ideal rolls as low as possible. In this way, the pick-up effects
for the ambient air are kept low. It is understood that with only slightly reduced air
pressure the losses caused by the air pick-up can be further reduced.
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The design of the magnetic spirals in accordance with the invention can be adapted to the
requirements in many areas. A pitch of, for example, around 15 with a two-wind spiral
creates such a distance between the individual magnetic spirals, seen in each case in the
axis-parallel direction, that the neighbouring spirals have no effect on each other, that a
very uniform sliding of the magnetic spirals of the neighbouring bodies past each other
can be performed, and that nevertheless - assuming the use of correspondingly powerful
magnets - no slip is created.
It is possible to adapt the ~limensions of the bodies in accordance with the invention to
the requirements in many areas. If a length of the bodies is desired which exceeds the
diameter by a multiple factor, each body can be supported as required by several support
beanngs.
The powers which can be transmitted increase as the angle of pitch increases, with,
however, the losses being Im~ f~ctorily high even with very long rolls, for example,
for an angle of pitch of 60 . If desired, the play during power tr~n~mi.~sion can be
reduced despite a low pitch thanks to a multi-wind spiral, which is also often termed a
multiple spiral, with a play-free position of the driving roll, i.e. a defined adjusting
position of the driving roll in free wheel to exactly one position, being possible.
Furthermore, the same choice for the angle of pitch of rolls opposite each other is
important.
Provided the angle of pitch is the same, the diameter of rolls opposite each other can be
different. This leads to the possibility of creating step-up or step-down gearing with the
power tr~n~mission devices in accordance with the invention.
Further advantages, details and features of the invention are produced from the following
description of an embodiment using the drawing.
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Fig. 1 shows a slightly schematic, perspective view of a magnetic power tr~n~mission
device in accordance with the invention in one embodiment;
Fig. 2 a slightly schematic, perspective view of a magnetic power tr~n~mi~sion device in accordance with the invention in a further embodiment;
Fig. 3 a view of a development of an essentially roll-shaped body in accordance with
the invention, to show the positioning of the magnetic spirals, in a one-wind
design of a power tr~n.cmi~sion device in accordance with the invention; and
Fig. 4 a pres~nt~tion of a further design of a power tr~n~mi~sion device in accordance
with the invention in a top view of opposite roll-shaped bodies.
A power tr;lnsmi~sion device 10 in accordance with the invention comprises two roll-
shaped bodes 12 and 14 which face each other. One of the bodies, for example, body 12,
is provided as the driving roll and the other, for example, body 14, as the driven roll.
Both bodies are supported on the front sides in roll bearings not shown in detail here.
High-quality components are used as the roll bearings which are superior to the industry
standard both as regards the low degree of wear and as regards the bearing friction. The
bodies 12 and 14 consist of a material which is also comparatively faithful to llimension
under temperature change. In the example case they are formed from aluminium. An air
gap 16 is provided between the bodies 12 and 14 with the air gap simultaneously serving
to compensate any deformations of the bodies 12 and 14 due to temperature. In the
present embodiment it has a size of 0.2 mm with a diameter of the bodies 12 and 14 of
162 mm.
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The bodies 12 and 14 each possess magnetic spirals 18 and 20 which in the example case
point in opposing directions. If the body 12 is driven on a drive shaft 22 in a clockwise
direction, the transmitted power can be taken up on a drive shaft 24 on the body 14 in a
counter-clockwise direction.
As can be seen from Fig. 1, in the area of the air gap 16 the magnetic spirals 18 and 20
are closely next to each other in operation and as such asymmetrical in an axial direction.
The magnetic spiral 18 of the driving body 12 practically pushes the corresponding part
of the magnetic spiral 20 of the driven body 14 in front of it as like magnet poles are
facing each other so that to this extent a repulsing effect exists. This pushing is
perfonned with an extremely low degree of loss as the power of individual magnets from
which the magnetic spirals 18 and 20 can be formed, is negligible.
The magnehc spirals 18 and 20 are positioned respectively on the circumference of the
bodies 12 or 14. However, this does not mean that they are exposed outwardly. Rather,
they are covered by a coaling 26 made of a non-magnetic material which possesses low
friction to air. For example, a polished ceramic, plastic or titanium coating can be used
with a thickness of 0 2 mm being fully sufficient.
The radial distance of the magnetic spirals 18 and 20 in the neighbouring area is thus
very low, for example around 0.6 mm.
The magnetic spirals 18 and 20 are provided as one-turn spirals. As small, lumped
magnetic spirals are used, the effective area of the magnetic spirals 18 and 20 is
subst~nli~lly lower than the pitch, i.e. the distance of the neighbouring pitches of the
magnetic spirals 18, 20 viewed in an axial direction. This causes corresponding play
~which is favourable in accordance with the invention. Nevertheless, in the start-up phase,
irrespective of the position in which the driving body is sil~l~te-l over the driven body, no
knocking occurs as the neighbounng magnetic spirals work like a spring with a
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progressive characteristic curve in their power transmission effect.
A further embodiment of the invention can be seen from Fig. 2. In this embodiment, four
roll-shaped bodies are provided with further driven bodies 28 and 30 being used
additionally to the bodies 12 and 14 respectively. The same reference numbers represent
the same parts here and in the further figures.
Each neighbouring body turns in an opposing direction. Thus a power distribution of a
particularly low degree of loss or with no loss can be realised with even more than four
bodies being able to be used for the power distribution if required.
It is not necessary to have the bodies 12, 14, 28 and 30 positioned on top of each other in
a row. Rather, they can be provided in any geometrical arrangement with the axes in
principle also being able to be positioned in a square so that dual power tr~n.cmis.sion
paths exist in each case.
From Fig. 3 an exemplary positioning of the magnetic spirals, for example of magnetic
spiral 18 in its development can be seen. The magnetic spiral 18 consists of a number of
magnetic elements 32 positioned in a row where in the embodiment shown in Fig. 3 the
angle of pitch is around 8. Here, it is a one-wind sp*al so that correspon(lin,~ly high
play obtains as the area between the individual pitches of the magnetic spiral 18 is
substantially larger than the effective width of each row of individual magnets 32.
From Fig. 4 a further embodiment of the power tr~n~mi~sion device in accordance with
the invention can be seen. In contrast to the embodiment examples in accordance with
Figures 1 and 2, here magnetic spirals 18 and 20 with the same directions are neighbours
'to each other. Thus, the body 12 turns in the same direction as the body 14. The air gap
16 in this embodiment has been chosen to be slightly larger, but in such a way that no
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slip between bodies 12 and 14 is possible.
Furthermore in the embodiment in accordance with Fig. 4 three-wind magnetic spirals 18
and 20 are used.
