Improved Magnetic Apparatus for Counteracting Longitudinal Thrust in Rotary Shafts and the like.
Year: 1897

page_text: Date of Application, 26th Aug., 1897
Complete Specification Left, 29th Apr., 1898-Accepted, 4th June, 1898
PROVISIONAL SPECIFICATION.
TROVISIONAL SPECIFICATION.
Improved Magnetic Apparatus for Counteracting Longitudinal
Thrust in Rotary Shafts and the like.
I, ADOLF SENGEL, of 4, Hölgesstrasse, Darmstadt, Germany, Engineer at The
Electric Engineering Institute, Darmstadt, do hereby declare the nature of this
invention to be as follows:-
The footstep or collar bearings usually employed to resist the tendency to longi-
tudinal movement of a revolving shaft not only consume, on account of friction,
a considerable proportion of the power transmitted by the shaft but are moreover
subject to rapid wear. These disadvantages are obviated by substituting for such
bearings the resistance to longitudinal thrust offered by the attraction of a magnet
acting in a direction parallel to the axis of the revolving shaft.
The idea of employing magnetic attraction for this purpose is not new. But the
incans heretofore proposed for utilizing this force have not obviated the loss of power
due to the phenomenon known as "hysteresis" and moreover present mechanical
and other difficulties. These disadvantages have been overcome in the apparatus
forming the subject of my invention which comprises an electro-magnet having
annular pole pieces co-axial with the shaft in connection with which the apparatus
is to be used, the pole piece of one sign being concentric with, and external to, that
of the opposite sign. The annular pole pieces are carried by a circular disc which
forms the yoke of the magnet, the exciting coil being contained in an annular space
separating the pole pieces whilst the armature is in the form of a circular disc also
concentric with the shaft. Usually the armature would be mounted to rotate with
the shaft, the magnet being a fixture, but these positions might be reversed.
On current being passed into the coil the two poles are formed at the annular
terminal surfaces of the electro-magnet for instance the south pole at the outer, and
the north pole at the inner, annulus. The lines of force pass for the most part
through the armature disc which is attracted towards the poles with a certain force
dependent upon the size of the apparatus and the strength of the energizing current,
the attractive force remaining unaltered whether the magnet and armature are at rest
or are rotated relatively to one another.
As a proof that no loss whatever of magnetic force occurs either in the armature or
in the electro-magnet during the rotary movement, the following considerations may
serve-As both the electro-magnet and the armature disc are perfectly symmetrical
with reference to all plane axial sections the power of the magnet is independent of
the angular inovement of the disc relatively to the magnet, remaining constant so
long as the distance between the inagnet and the disc is unaltered. Consequently
all those particles of the electro-magnet, as also of the disc, which are situated at the
same distance from the axis are constantly magnetized equally and in the same
direction. Now as these particles move in circular paths around the axis their magnetic
condition remains unaltered throughout the entire revolution of the magnet or
armature and therefore no loss of efficiency takes place in consequence of any reversal
of the magnetism (hysteresis) of the iron. Further there is no waste of energy in
consequence of the setting up of secondary electric (whirling) currents.
imagine a closed line of any shape in the iron of the electro-magnet as well as in
If we

page_text: the iron of the armature, then a definite number of lines of force will pass through
the surface enclosed by the said lines. If in the rotation of the disc, electromotive
forces can be proved to exist along the said line injurious secondary currents must
be produced. But the number of the lines of force which pass through any closed
line is necessarily the same on account of the perfectly symmetrical arrangement
both of the armature as well as of the electro-magnet with relation to the axis of
rotation for all angular positions of the armature relatively to the electro-magnet.
Therefore no electromotive forces, and consequently no whirling currents, can be
produced by the revolution of the electro-magnet and armature disc relatively to one
another. For this reason neither the electro-magnet nor the armature disc need be
built up of segments or sub-divisions as is usual in the case of dynamos and electro-
motors and thus the construction of the apparatus is rendered very much cheaper.
Two or more electro-magnets as described may be arranged concentrically, one
within the other, so as to exert attractive force upon the same dise armature, the
exciting coils of each magnet being contained within the annular space separating
the pole pieces of that magnet. By arranging annular electro-magnets as above
described on the opposite sides of the disc arinature the direction in which the
magnetic attraction is exerted may be reversed at will.
In the event of the power transmitted by a revolving shaft and tending to produce
longitudinal movement of the shaft being subject to variation, it may obviously be
desirable to automatically regulate the resistance to the longitudinal thrust pro-
portionately to such variations. This can readily be effected through the medium of
my improved apparatus, in cases where the power transmitted by the shaft is derived
from, or communicated to, such a machine as for instance an electro-motor or dynamo,
by utilizing the whole or a portion of the electric current generated by the dynamo
or supplied to the motor for the purpose of energizing the annular electro-magnets
above described.
Should alternating currents be employed these must first be rectified or given the
same direction.
In cases where the variable power transmitted as above described is derived from
such a source as a steam engine or the like, the automatic regulation of the resistance
to longitudinal thrust in the revolving shaft. can be effected through my improved
magnetic apparatus by so connecting the governing mechanism of the steam or like
engine with a variable electrical resistance interposed in the circuit of the annular
electro-magnet, as to cause any variation in the power given out by the engine to
produce proportionate variation in the strength of the electro-magnet.
Dated this 26th day of August 1897.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
Improved Magnetic Apparatus for Counteracting Longitudinal
Thrust in Rotary Shafts and the like.
I, ADOLF SENGEL, of 4, Hölgesstrasse, Darmstadt, Germany, Engineer at The
Electric Engineering Institute, Darmstadt, do hereby declare the nature of this
invention and in what manuer the same is to be performed to be particularly
described and ascertained in and by the following statement :-
Footstep or collar bearings usually employed to resist longitudinal thrust of a
revolving shaft not only consume in friction a considerable proportion of the power
but are subject to rapid wear. These disadvantages are obviated by substituting for

page_text: such bearings the resistance to longitudinal thrust offered by the attraction of a magnet
acting in a direction parallel to the axis of the revolving shaft.
The idea of employing magnetic attraction for this purpose is not new but the
means heretofore proposed for utilizing this force have not obviated the loss of power
due to the phenomenon known as "hysteresis" and moreover present mechanical and
other difficulties.
These disadvantages have been overcome in the apparatus forming the subject of
my invention which as compared with known magnetic apparatus of the same kind,
presents the following advantages:-
1. It does not necessitate any greater consumption of energy beyond the
inappreciable amount of electrical power required for the purpose of excitation ;
and
2. In consequence of the use of an armature of solid iron without lamination, or
subdivision, it is considerably more easy to construct.
The apparatus comprises an electro-magnet having annular pole pieces co-axial with
the shaft to which the apparatus is to be applied, the pole piece of one sign being.
concentric with, and external to, that of the opposite sign. The annular pole pieces
are carried by a circular disc which forins the yoke of the magnet the exciting coil
being contained in an annular space separating the pole pieces and receiving current
from an external source. The arinature is a circular disc and is usually mounted on
the shaft, the inagnet being a fixture but these positions might be reversed.
In the accompanying drawings forming part of this Specification Figure 1 illustrates
an arrangement of this kind in longitudinal section and Figure 2 is a section taken
through the electro-magnet at right angles to the shaft.
A designates the outer pole, B the inner pole, C is the yoke of the electro-magnet,
1) the exciting coil, E the revolving shaft, and F the armature which is fixed to
the shaft. The current is supplied to the coil from the source of current G, is
measured by means of the current ineter H, and is regulated by means of the
resistance R..
On current being passed into the coil D the two poles are formed at the annular
terminal surfaces of the electro-magnet for instance the south pole at the outer, and
the north pole at the immer, annulus. The lines of force pass for the most part
through the armature disc F which is attracted towards the poles with a certain force
dependent upon the size of the apparatus and the strength of the energizing
current, the attractive force remaining unaltered whether the magnet and armature
are at rest or are rotated relatively to one another.
As a proof that no loss whatever of magnetic force occurs either in the armature
or in the electro-magnet during the rotary movement, the following considerations
may serve As both the electro-magnet and the armature disc are perfectly symme-.
irical with reference to all plane sections taken through the axis x-x the power of
the magnet is independent of the angular movement of the disc relatively to the
magnet, remaining constant so long as the distance between the magnet and the disc
is unaltered. Consequently all those particles of the electro-magnet, as also of the
disc, which are situated at the same distance from the axis are constantly
magnetized equally and in the same direction. Now as these particles move in
circular paths around the axis their magnetic condition remains unaltered through-.
out the entire revolution and therefore no loss of efficiency takes place in consequence
of any reversal of the magnetism (hysteresis) of the iron. Further there is no
waste of energy in consequence of the setting up of secondary eddy or Foucault
currents. If we imagine a closed line of any shape in the iron of the electro-magnet
as well as in the iron of the armature, then a definite number of lines of force will
pass through the surface enclosed by the said line. If in the rotation of the disc,
electromotive forces can be proved to exist along the said line injurious secondary
currents must be produced. But the number of the lines of force which pass through
any closed line is necessarily the same on account of the perfectly symmetrical
arrangement both of the armature as well as of the electro-magnet with relation to
the axis of rotation x-x for all angular positions of the armature relatively to the

page_text: electro-magnet. Therefore no electromotive forces, and consequently no whirling
currents, can be produced by the revolution of the electro-magnet and armature
dise relatively to one another. For this reason neither the electro-magnet nor the
armature disc need be built up or laminated as is usual in the case of dynamos and
electro-motors and thus the construction of the apparatus is rendered very much
cheaper.
Figure 3 illustrates an arrangement in which two or more electro-magnets are
arranged concentrically one within the other so as to exert attractive force upon the
same disc armature, the innermost pole being bounded by a cylindrical surface and
having the same polarity as the outermost pole and opposite to that of the inter-
mediate pole, the exciting coils o o, pp, being contained within the annular spaces
separating the three pole pieces. Three or more electro-magnets may be similarly
combined. By arranging annular electro-magnets as above described on the opposite
sides of the disc armature the direction in which the magnetic attraction is exerted
may be reversed at will.
In the event of the longitudinal thrust of the shaft being subject to variation in
consequence of variation of the power transmitted to the shaft, it may obviously he
desirable to automatically regulate the resistance to the longitudinal thrust propor-
tionately to such variations. This can readily be effected through the medium of my
improved apparatus, in cases where the power transmitted by the shaft is derived
from, or communicated to, such a machine as for instance an electro-motor or
dynamo, by utilizing the whole or a portion of the electric current generated by the
dynamo or supplied to the motor for the purpose of energizing the annular
electro-magnets above described. Should alternating currents be employed these
must first be rectified.
Figure 4 illustrates the mode of driving a shaft A by a shunt electric motor B
through a worm C and worm wheel D. The current is supplied to the motor from
an external source E. By the rotation of the motor in the direction indicated there
is produced a pressure in the motor shaft. in the direction of the arrow F. In order
to counterbalance this pressure there is connected with the motor shaft a disc G
which moves in front of an electro-magnet H whose coil is energized directly by the
electrical energy supplied to the motor. Consequently as there is an approximate
proportion between the current supplied and the pressure produced by the worm
gear on the one hand, and the counter pressure produced by the electro-magnet on
the other hand, then for every load there will be produced an automatic counter-
balancing of the thrust of the shaft due to the worm gear. Another kind of automatic
compensation for thrust which varies with the power applied, consists in applying the
part which regulates the supply of power to influence in a positive or constrained
inanner the regulating device of the electro-magnet.
Figure 5 illustrates an arrangement of this kind in combination with a ship's
screw propeller S driven by a steam engine D. The valve which regulates the
supply of steam moves the lever H in a positive manner and thus at the same time
regulates by means of the resistance R the energy which is supplied from
the source
of current G to the coil A. The resistance R can be SO
compensated for, that at each position of the valve V the thrust of the shaft is
counterbalanced.
In the same way the regulating lever H may be connected to the distributing
valve gear of a steam engine, to the regulating apparatus of a turbine, to a speed-
regulating device or governor.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
1. Magnetic apparatus for counteracting longitudinal thrust in rotary shafts and
the like, characterized by the use of one or more electro-magnets composed of non-
laminated iron of circular or annular form arranged co-axially and bounded by
uninterrupted surfaces in combination with an armature disc composed of non-

page_text: laminated iron of uninterrupted circular or annular form for the purpose of generating
a definite force of attraction between the electro-magnet and the armature by the
energization of a coil situated between the poles of the electro-magnet substantially
as and for the purpose described.
2. In combination with the apparatus specified in Claim 1 in operating a dynamo
or in transmitting the power developed by an electric motor by means of a trans-
mitting device of such a kind that a thrust which increases with the consumption of
power by the dynamo or with the delivery of the power by the electric motor is
produced in the driving, or in the driven, shaft the arrangement described having
for object to supply for the purpose of energizing the coil of the electro-magnet an
amount of energy proportionate to the delivery of energy by the dynamo or to the
consumption of energy by the electric motor and consequently also proportionate to
the thrust produced in the shaft whereby to automatically counterbalance the thrust
under all loads.
3. In combination with the arrangement specified in Claim 1 in all cases in which
a thrust dependent on the amount of the transmitted power is produced in the
power-transmitting shaft and the supply of power is varied by means of a hand-
operated or an automatically-acting regulating device, the connecting in a positive
or constrained manner of said device with the regulating device of the
electro-magnet with the object of counterbalancing automatically and at
all loads the thrust produced in the shaft or of producing a pressure of definite.
amount.
Dated Guis 20th day of April 1830.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.