Improvements in Electro-magnets.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electro-magnets.
I, MAURICE BOUCHET, of 22, Rue Alphonse de Neuville, Paris, France, Engineer,
do hereby declare the nature of this invention to be as follows:
This invention relates to an electro-magnet whereby to obtain a better utiliza-
tion of the energy expended by increasing the work as well as to better utilize
this work by making the attractive effort proportional at each point in the move-
ment of the armature to the resistance to be overcome.
The invention permits of obtaining either a uniform effort during the whole
stroke of the armature or of modifying the effort at any given point of such
course, the work done being in both cases the same.
My invention is essentially characterized by the combination of a core of decreas-
ing section preferably hollowed and of a coil of which the two ends of magnetic
metal are united by an intermediate armouring also of magnetic metal with the
object of facilitating the return of the lines of magnetic force, 'the attraction of the
core in this case taking place opposite one of the end pieces which may, or may
not, be provided with a polar extension of decreasing section.
Reference is to be had to the accompanying drawings forming part of this
specification wherein Figure 1 represents my improved electro-magnet in section
with the core in its highest position. Figure 2 is a similar view with the core in
its lowest position. Figures 3 and 4 shew the core in two intermediate positions.
Figure 5 shews a modification in which one end of the coil carries a polar extension.
Figure 6 shews a series of these coils mounted end to end. Figure 7 is a modifi-
cation of this arrangement. Figure 8 is a similar arrangement shewing a series
of cores. Figure 9 shews a modification for obtaining alternating movement.
The same letters of reference denote like parts.in all the figures.
The electro-magnet consists essentially of a coil a enclosed in an armouring of
magnetic metal 6 to the ends of which are fixed two pole pieces c c (see Figure 1).
d is a soft iron core hollowed out at dwhich traverses the pole pieces c c with
only the necessary play between the parts to prevent contact. The core slides 'in
guides, collars, or bearings of non-magnetic material suitably arranged either at
the ends of the core or on the frame of the apparatus. In Figure 1 the coil itself
serves as a guide for the core. The work developed by the electro-magnet depends
upon the flow of force existing at the commencement of the stroke and on the
variation of the flow produced by the movement of the core. The flow of force
being equal to the quotient of the magneto-motive force by the reluctance, the
electro-magnet is so arranged as to diminish as much as possible the reluctance
(magnetic resistance) in order to obtain a maximum flow for a given coil pro-
ducing a definite magneto-motive force. If we examine the magnetic circuit of
the electro-magnet (derivations apart) it will be seen that the lines of force traverse
the core d, the upper "interferricum gap" intermediate space e, the upper pole
piece c. the armouring b, the lower pole piece c', and the lower intermediate
space e. The parts cb c¹, are such that their reluctance is a negligable quantity
whilst the reluctance of the intermediate space e is inversely proportional to the

page_text: sectional area presented to the passage of the lines of force and it is with this
object that the part c is provided with a polar extension p whereby to augment at
will the area by utilizing the lateral surface of the core within this polar extension.
Nearly the whole of the ampère turns developed in the coil are thus concen-
trated ate and the passage of the lines of force is facilitated by the great
proximity of the end of the core and the pole piece. The initial flow at the com-
mencement of the stroke is therefore very important and the core may be almost
saturated. If the current be passed through the coil the core d takes up the
position shewn in Figure 2 the stroke being sensibly equal to the depth of the
cavity d¹.
By examining the two intermediate positions of the core shewn in Figures 3
and it will be seen that at the commencement. the section presented to the
passage of the flow (without considering derivations) is represented by the cross
sections in Figure 3 and that towards the end of the stroke the section increases
as represented by the cross sections in Figure 4. The flow is therefore greater
when the core d is at the end of its stroke and the power developed between these
two positions of the core depends on the increase of the section s s¹.
The core having arrived at the position shewn in Figure 2 its whole section is
utilized for the flow of the lines of force and it is therefore at the end of its stroke.
The variation of flow available between the two extreme positions being given
one may thus obtain with this arrangement:-
(1) Any required stroke by distributing the variation of section of core d over
a given length, that is to say by varying the depth of the cavity d¹, the work done
being always the same:
(2) A constant effort throughout the course traversed. The effort may be modi-
fied at any part of the stroke at will by adopting a suitable profile, the effort at
each point depending on the ratio of the increase of section to the distance
traversed.
The core may be conical but the internal cavity has the advantage of facilitating
the passage of the lines of force at e¹, at the beginning of the stroke. In the
modification shewn in Figure 5 the end c¹ is provided with a polar extension of
decreasing section enabling the effort to be regulated or modified at every point
of the stroke of the core, the stroke being in this case equal to about the
distance+m.
This last described arrangement enables by placing several coils end to end,
the section of the intermediate space to be increased whilst leaving the stroke in-
dependent of the length 7.
The electro-magnet shewn in Figures 1 to 5 may he used separately or several
coils may be mounted upon the same frame b of magnetic metal so as to act in
succession with a view to reduce the expenditure of energy.
Figure 6 shews coils of the type shewn in Figure 1, i.e. without polar extensions,
while Figure 7 shews coils of the type shewn in Figure 5, that is to say whose ends
are provided with internal polar extensions. The core is in either case attracted
by coil a from 1 to 2 and then by coil a² from 2 to 3 and so on. Supposing
coil a³ to be in work the magnetic circuit of the coils a², a', will have the same
polarity and thus allow the lines of force to reach the core through the pole picces
of the coils, the circuit of these coils playing the part of the polar extension of the
end coil and thus reducing the reluctance of the intermediate space.
. The combination shewn in Figures and 7 permits of obtaining a uniform
effort throughout the travel of the core, the field of action of a coil being capable
of being made equal to the distance from axis to axis of two coils. The current
is sent through the several coils in succession at the proper instant, by any suitable
switch. For example the switch may consist of a conductor f mechanically con-
nected to core d and successively connecting the terminals corresponding with the
several coils a¹, a², a³, a, to a bar g electrically connected with one of the poles of
the source of electricity.
'

page_text: เล
In Figure 8 is shewn a series of solid cores so combined that coil a¹ actuates
core d' from 1 to 2, the core d² being at this moment at 3 and coil a' causing the
series of cores to move from 3 to 4. Coil a³ then acts on d¹, coil a³ upon dand
so on. The length of a coil is thus traversed in two stages the available space for
the winding of a coil being of double length compared with Figure 6. Generally
speaking the length from axis to axis of each core should be such that the action
of the first coil upon the following core should continue the action of the last coil
upon the preceding core, thus reducing the number of coils to a minimum for a
given travel.
An alternating rectilinear movement may also be obtained by acting successively
on the two ends of the core as shewn in Figure 9, in which the coil a¹ acts upon
one end of core d, and at the end of its stroke the core may be moved in the reverse
direction by the coil a² acting on the opposite end.
For producing alternating rectilinear movement the hollow-ended cores and pole
pieces of decreasing section may be used with one or several coils acting in opposite
directions. In all cases the magnetic metal may be suitably divided to avoid
induction currents. The return flow in all cases may be through either an armour-
ing or any other connection of magnetic metal between the two ends of the coil
of such section that its reluctance or magnetic resistance is negligable.
The dimensions and details of arrangement of the apparatus may be varied to
suit the particular purpose to which the apparatus may be applied.
1000
A. M. & WM. CLARK,
Chartered Patent Agents.
53, Chancery Lane,, London.
A. M. & WM. CLARK,
Chartered Patent Agents.
53, Chancery Lane,, London.
I, MAURICE BOUCHET, of 22, Rue Alphonse de Neuville, Paris, France, Engineer,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be particularly described and. ascertained in and by the follow-
ing statement:
:
This invention relates to improvements in electro-magnets and it has for its
object to obtain a better utilization of the energy expended by increasing the work
developed as well as to better utilize this work by making the attractive effort
proportional at each point in the movement of the armature to the resistance to
be overcome.
The invention permits of obtaining either a uniform effort during the whole
stroke of the armature or of modifying the effort at any given point of such
course, the work done being in both cases the same.
My invention is essentially characterized by the combination of a core of de-
creasing section preferably hollowed and of a coil of which the two end cheeks of
magnetic metal are united by an intermediate armouring also of magnetic metal
with the object of facilitating the return of the lines of magnetic force so that the
attraction of the core will take place opposite one of the end cheeks which may,
or may not, be provided with a polar extension of decreasing section.
Reference is to be had to the drawings accompanying my Provisional Specifi-
cation wherein Figure 1 represents my improved electro-magnet in section, the
core being in its highest position. Figure 2 is a similar section of the end portion
of the electro-magnet, the core being in its lowest position. Figures 3 and 4 shew
two intermediate positions of the core. Figure 5 shews a modification in which

page_text: one end of the coil has a polar extension. Figure 6 shews a series of coils mounted
eend to end, and Figure 7 is a modification of the same, whilst Figure 8 is a further
bmodification of this arrangement having a series of cores. Figure 9 shews a modifi-
cation for obtaining alternating movement. The same letters of reference denote
like parts in all the figures.
B. The electro-magnet consists essentially of a coil a enclosed in an armouring of
magnetic metal b, to the ends of which are fixed two pole pieces c c constituting
the cheeks of the coil, as shewn in Figure 1. d is a soft iron core hollowed out
at d, which traverses the pole pieces c with only the necessary play to prevent
contact therewith. The core slides in guides, collars, or bearings of non-magnetic
material suitably arranged either at the ends of the core or on the frame of the
apparatus. In Figure 1 the coil itself serves as a guide for the core. The work
developed by the electro-magnet depends upon the flow of force existing at the
commencement of the stroke and on the variation of the flow produced by the move-.
ment of the .core. The flow of force being equal to the quotient of the magneto-
motive force by the reluctance, the electro-magnet is so arranged as to diminish as
much as possible this reluctance (magnetic resistance) in order to obtain a
maximum flow for a given coil producing a definite magneto-motive force. If we
examine the magnetic circuit of the electro-magnet (derivations apart) it will be.
seen that the lines of force traverse the core d, the upper "interferricum gap
space e, the upper pole piece c, the armouring b, the lower pole piece c', and the
lower interferricum gap" or space e. The parts c b c¹ are so con-
structed that the reluctance is a negligable quantity whilst the reluctance
of the intermediate space e is inversely proportional to the sectional area pre-
sented to the passage of the lines of force and it is with this object that the part c
is provided with a polar extension 2 which enables the sectional area presented at
the "interferricum gap "to be augmented at will, by utilizing the lateral surface
of the core within this polar extension.
88
"
or
Nearly the whole of the ampère turns developed in the coil are thus concen-
trated at and the passage of the lines of force is facilitated by the close
proximity of the end of the core and the pole piece. The initial flow at the com-
mencement of the stroke is therefore very great and the core may be almost
saturated. If the current be passed through the coil the core d takes up the
position shewn in Figure 2 the stroke being sensibly equal to the depth of the
cavity d¹
If the two intermediate positions of the core , shewn in Figures 3 and 14, be
examined it will be seen that at the commencement, the sectional area presented to
the passage of the flow (without considering derivations) is represented by the
cross section sin Figure 3 and that towards the end of the stroke
the section increases as represented by the cross sections in Figure 4.
The flow is therefore greater when the core d is at the end of its stroke and the
power developed between these two positions of the core depends on the increase of
the section s¹ - S.
The core having arrived at the position shewn in Figure 2, the lines of force How
through its whole sectional area and it is therefore at the end of its stroke.
The variation of flow available between the two extreme positions being given
one may thus obtain with this arrangement:-
(1) Any required stroke by distributing the variation of the section of the core d
over a given length, that is to say by varying the depth of the cavity d', the work
developed being always the same;
(2) A constant effort throughout the course traversed. The effort may be modi-
fied at any part of the stroke at will by adopting a suitable profile, the effort at
each point depending on the ratio of the increase of section to the distance
traversed.
The core may be conical but the internal cavity has the advantage of facilitating
the passage of the lines of force at el, at the beginning of the stroke. In the

page_text: modification shewn in Figure 5, the end cheek c¹ of the coil is provided with a
polar extension of decreasing section enabling the effort to be regulated or modified.
at every point of the stroke of the core, the stroke being in this case equal to about
the distance + m.
وو
This last described arrangement permits of placing several coils end to end and,
thereby enabling the section presented at the "interferricum gap or space to
be increased whilst leaving the stroke independent of the length 1.
The electro-magnet shewn in Figures 1 to 5 may be used either separately or by
inounting several such coils upon the same frame of magnetic metal so as to
act in succession with a view to reduce the expenditure of energy.
Figure 6 shews a number of coils of the type illustrated in Figure 1, i.e. without
polar extensions, while Figure 7 shews a number of coils of the type illustrated in
Figure 5, that is to say whose ends are provided with internal polar extensions.
The core dis, in either case, attracted by coil a¹ from 1 to 2 and then by coil a²
from 2 to 3 and so on. Supposing coil to be in work, the magnetic circuit of
the coils a², al; will have the same polarity and will thus allow the lines of force
to reach the core through the pole pieces of these coils, the circuit of these coils
then playing the part of the polar extension of the end coil and thus reducing the
reluctance of the "interferricum gap."
This arrangement of Figures 6 and 7 permits of obtaining a uniform effort
throughout the whole travel of the core since the field of action of a coil may be
made equal to the distance from axis to axis of two coils. The current is sent
through the several coils in succession at the proper instant, by the intervention
of any suitable switch. For example the switch may consist of a conductor f
mechanically connected to the core d and successively connecting the terminals
corresponding with the several coils a¹, a, a, a, to a bar g electrically connected
with one of the poles of the source of electricity.
In Figure S is shewn a number of cores so combined that coil a¹ 'actuates
core d¹ from 1 to 2; the core 2 being at this moment at 3, the coil at causes it to
move from 3 to 4. Coil a² then acts on d and coil a on d² and so on. The
length of a coil is thus traversed in two stages.
In the arrangement represented in Figure 8, a coil produces an attraction of the
core for a distance equal to half the distance of attraction obtained in the arrange-
ment shewn in Figure 7. Consequently by comparing Figures 7 and 8 it will be
seen that in order to obtain the same stroke of core, the arrangement shewn in
Figure 8 requires double the number of coils; thus with this arrangement an
available space is obtained for the wire which is double that obtained with the
arrangement shewn in Figure 7.
Several successive cores may also be employed with the arrangement shewn in
Figure 7, in which case it is simply necessary that the length from axis to axis of
each core should be such that when one core has been subjected to the successive
actions of all the coils, another core rigidly connected to the preceding core will
be presented to the action of the end coil, and similarly for a third and fourth
core in succession.
An alternating rectilinear movement may also be obtained by acting successively
on the two ends of the core, as shewn in Figure 9, in which the coil al acts upon
one end of core d, and at the end of its stroke the core may be moved in the reverse
direction by the coil a² acting on the opposite end.
For producing alternating rectilinear movement the hollow-ended cores and pole
pieces of decreasing section may be used with one or several coils acting in cach
direction. In all cases the magnetic metal may be suitably divided to avoid
induction currents. The return flow in all cases may be through either an armour-
ing or any other connection of magnetic metal between the two ends of the coil
of such section that its reluctance or magnetic resistance is negligable.
The dimensions and details of arrangement of the apparatus may be varied to
suit the particular purpose to which the apparatus may be applied.
་

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I claim
is:-
!!
The improved system of electro-magnet consisting essentially in the combination
of a core of decreasing section, preferably by being hollow-ended, and of a coil
of which the two end cheeks of 'magnetic metal are united by an armouring also
of magnetic metal with the object of facilitating the return flow of the lines of
force, so that the attraction of the core will take place opposite one of the end
cheeks which may, or may not, be provided with a polar extension, all substantially
as hereinbefore described with reference to the drawings.
Dated this 7th day of Decomber 1908
A. M. & WM. CLARK, .
Chartered Patent Agents,
53, Chancery Lane, London.