Improvements in Electric Meters.
Year: 1898

page_text: Date of Application, 11th Feb., 1898
Complete Specification Left, 4th Nov., 1898-Accepted. 23rd Dec., 1898
Improvements in Electric Meters.
We, EVERSHED & VIGNOLES LTD. and SYDNEY EVERSHED, both of Woodfield
Works, Harrow Road, London, W., Electrical Engineers, do hereby declare the
nature of this invention to be as follows:-
This invention relates to the means described in Application No. 9127 97
for magnetically supporting and pivotting the axles of electric supply meters of
the motor type.
The object of our invention is to enable the size of the supporting magnet to
be diminished without decreasing its supporting power; to increase the supporting
power of the magnet without increasing its size; and to prevent the stray field
of the unused poles of the magnetic unipolar system as used for supporting the
axle as described in said Application No. 9127 of 1897, from affecting the working
of the meter.
In the unipolar magnetic system for supporting the axle, described in the
aforesaid application, the magnetic induction which leaves the supporting pole
having traversed a short air gap, enters the axle and returns thence through an
undefined path in the surrounding space back to the magnet.
"
According to our present invention the magnetic induction may be caused to
return by a defined path through an iron tube (herein called the return tube)
adapted to complete the magnetic circuit of the supporting magnetic system,
leaving only the necessary air gap (hereinafter called the supporting gap ")
between the supporting pole and the upper end of the axle, and a second annular
air gap (herein called the "annular gap") between the axle and a ring of iron
fixed to the return tube and concentrically surrounding the axle at a little distance
below its upper end. This ring is herein called the "ring pole."
The ring pole may be made in a form of a hollow cylinder of sufficient length
to allow of a low induction density in the annular gap so that any magnetic
attraction of the axle due to want of perfect coincidence between the axis of the
ring pole and that of the axle, may be small and easily overcome by the pivotal
guidance afforded by the supporting pole.
In a modification the ring pole may be formed by a round hole in a flat plate
of iron fixed to the lower end of the return tube with its plane normal to the
rotational axis of the axle. A disc of iron a little smaller than the hole in the
fixed plate is fixed on the axle so that it is in the same plane as the ring pole or
plate when the pivot or point at the lower end of the axle is resting on or in the
jewel bearing. When the ring pole and the disc on the axle are in the same
plane the attractive forces between them have no vertical component, but in the
event of the attractive force of the supporting pole being a little greater than the
weight to be supported the axle will rise and by lifting the disc above the plane
of the ring pole produce a vertical component in the forces acting between the
disc and the ring pole tending to draw the axle down. Thus the axle may be
caused to float in stable equilibrium between the lower bearing and upper stop
or bearing, without touching either of them, the essential condition for stable
equilibrium being that the downward force due to displacement of the plane of

page_text: the disc above that of the ring-pole should increase at a greater rate than the
upward force of the supporting pole increases as the length of the supporting air
gap diminishes.
With this modification the higher induction density in the
annular gap which is necessary in order to secure a sufficiently rapid increase of
downward force as the axle rises, necessitates the most perfect coincidence between
the axes of the ring pole and the axle and also perfect mechanical truth in the
disc fixed to the axie and in the ring pole.
In a second modification, the disc on the axle may be larger in diameter than
the pole forming the ring pole, and it may be fixed either above or below the
piane of the ring pole, so that the induction in the annular gap is in a vertical
direction and opposes or assists the upward attractive force of the supporting pole
according as the disc is above or below the ring pole. In the latter case the total
magnetizing force required by the magnetic supporting system to support a given
weight may be greatly reduced for not only is the magnetic resistance largely
diminished by substituting the return tube for an undefined air path, but the
induction in the annular air gap being made to assist the supporting pole the
total induction required will also be less.
In a third modification the ring pole may be a short hollow cylinder of iron,
fixed in a hole in, & projecting downwards from, a plate of iron which serves
to close the lower end of the return tube. A similar cylinder is fixed to the axle
with its upper end immediately beneath but not touching the ring pole and with
its lower end closed by an iron disc attached to the axle. The two cylinders and
the annular gap between them being concentric and of the same diameter will
not only add to the total upward attractive force acting on the axle but will afford
a certain amount of pivotal guidance in addition to that due to the supporting
pole.
In order that the addition of a return path and consequent second air gap may
introduce no appreciable turning moment due to want of perfect mechanical truth
in the annular gap, it is necessary to make the axle and the annular gap of the
smallest possible diameter consistent with the required lifting force. For the
same reason the iron used for the axle and disc thereon and for the ring pole
must be of the most uniform permeability obtainable. If the iron of the ring
pole and that of the axle or of the disc or cylinder attached thereto has an
appreciably greater permeability in one direction than another the axle will tend
to turn until the direction of maximum permeability in the fixed and rotary parts
of the magnetic system coincide. Moreover whilst in rotation parts of the iron
of the disc or cylinder will go through small magnetic cycles involving dissi-
pation of energy through hysteresis and so produce a small constant moment
tending to oppose rotation.
The magnetising force of the system may be either a permanent magnet or a
coil carrying a current. In the latter case the coil may surround the supporting
pole and be enclosed by the return tube. The return tube may be replaced by
several rods of iron, preferably not less than three in number, arranged symmetri-
cally round the supporting magnet and parallel thereto. The rods are fixed at
their upper ends to a circular plate of iron having its centre attached to the upper
end of the supporting magnet. The lower ends of the rods are attached to the
iron used for the ring pole. When the supporting system is magnetised per-
manently these rods may be made of hardened and permanently magnetised steel.
When the meter to which our invention is applied is controlled by a Foucault
current brake the herein described magnetic circuit for supporting the axle may
form part of the magnetic circuit of the brake magnets, and will then require no
separate magnetising force.
Dated this 1141
c
יד
1
1000
FELL & JAMES,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicants.

page_text: We, EVERSHED AND VIGNOLES LIMITED and SYDNEY EVERSHED, all of Wood-
field Works, Harrow Road, London, W., Electrical Engineers, 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 following statement:-
This invention relates to the means described in Application No. 9127 of 1897
for magnetically supporting and pivoting the axles of electric supply meters of
the motor type.
The object of our invention is to enable the size of the supporting magnet to
be diminished without decreasing its supporting power; to increase the supporting
power of the magnet without increasing its size; and to prevent the stray field
of the unused pole of the magnetic unipolar system as used for supporting the
axle as described in said Application No. 9.127 of 1897 from affecting the working
of the meter.
In the unipolar magnetic system for supporting the axle, described in the
aforesaid application, the magnetic induction which leaves the supporting pole,
having traversed a short air gap, enter the axle and returns thence through an
undefined path in the surrounding space back to the magnet.
"
According to our present invention the magnetic induction may be caused to
return by a defined path through an iron tube (herein called the return tube)
adapted to complete the magnetic circuit of the supporting magnetic system,
leaving only the necessary air gap (herein called the supporting gaps")
between the supporting pole and the upper end of the axle, and a second annular
air gap (herein called the "annular gap ") between the axle and a ring of iron
fixed to the return tube and concentrically surrounding the axle at a little distance
below its upper end.
This ring is herein called the "ring pole."
The ring pole may be made in the form of a hollow cylinder of sufficient length
to allow of a low induction density in the annular gap so that any magnetic
attraction of the axle due to want of perfect coincidence between the axis of the
ring pole and that of the axle, may be small and easily overcome by the pivotal
guidance afforded by the supporting pole.
In a modification the ring pole may be formed by a round hole in a flat plate
of iron fixed to the lower end of the return tube with its plane normal to the
rotational axis of the axle.
A disc of iron a little smaller than the hole in the fixed plate is fixed on the
axle so that it is in the same plane as the ring pole or plate when the pivot or
point at the lower end of the axle is resting on or in the jewel bearing. When
the ring pole and the disc on the axles are in the same plane the attractive forces
between them have no vertical component, but in the event of the attractive force
of the supporting pole being a little greater than the weight to be supported the
axle will rise and by lifting the disc above the plane of the ring pole produce a
vertical component in the forces acting between the disc and the ring pole tending
to draw the axle down. Thus the axle may be caused to float in stable equi-
librium between the lower bearing and upper stop or bearing, without touching
either of them, the essential condition for stable equilibrium being that the
downward force due to displacement of the plane of the disc above that of the
ring pole should increase at a greater rate than the upward force of the supporting
pole increases as the length of the supporting air gap diminishes. With this
modification the higher induction density in the annular gap which is necessary

page_text: in order to secure a sufficiently rapid increase of downward force as the axle rises,
necessitates the most perfect coincidence between the axes of the ring pole and
the axle and also perfect mechanical truth in the disc fixed to the axle and in
the ring pole.
In a second modification, the disc on the axle may be larger in diameter than
the hole forming the ring pole, and it may be fixed either above or below the
plane of the ring pole, so that the induction in the annular gap is in a vertical
direction and opposes or assists the upward attractive force of the supporting pole
according as the disc is above or below the ring pole. In the latter case the total
magnetising force required by the magnetic supporting system to support a given
weight may be greatly reduced for not only is the magnetic resistance largely
diminished by substituting the return tube for an undefined air path but the
induction in the annular air gap being made to assist the supporting pole the
total induction required will also be less.
In a third modification the ring pole may be a short hollow cylinder of iron
fixed in a hole in, and projecting downwards from, a plate of iron which serves
to close the lower end of the return tube. A similar cylinder is fixed to the axle
with its upper end immediately beneath but not touching the ring pole and with
its lower end closed by an iron disc attached to the axle. The two cylinders and
the annular gap between them being concentric and of the same diameter will
not only add to the total upward attractive force acting on the axle but will afford
a certain amount of pivotal guidance in addition to that due to the supporting
pole.
In order that the addition of a return path and consequent second air gap may
introduce no appreciable turning moment due to want of perfect mechanical truth
in the annular gap, it is necessary to make the axle and the annular gap of the
smallest possible diameter consistent with the required lifting force. For the
same reason the iron used for the axle and dise thereon and for the ring pole
must be of the most uniform permeability attainable. If the iron of the ring
pole and that of the axle or of the disc or cylinder attached thereto has an
appreciably greater permeability in one direction than another the axle will tend
to turn until the direction of maximum permeability in the fixed and rotary parts
of the magnetic system coincide. Moreover, whilst in rotation, parts of the iron
of the disc or cylinder will go through small magnetic cycles involving dissi-
pation of energy through hysteresis and so produce a small constant moment
tending to oppose a rotation.
The magnetising force of the system may be either a permanent magnet or a
coil carrying a current. In the latter case the coil may surround the supporting
pole and be enclosed by the return tube. The return tube may be replaced by
several rods of iron, preferably not less than three in number, arranged symmetri-
cally round the supporting magnet and parallel thereto. The rods are fixed at
their upper ends to a circular plate of iron having its centre attached to the upper
end of the supporting magnet. The lower ends of the rods are attached to the
iron used for the ring pole. When the supporting system is magnetised per-
manently these rods may be made of hardened and permanently magnetised steel.
When the meter to which our invention is applied is controlled by a Foucault
current brake the herein described magnetic circuit for supporting the axle may
form part of the magnetic circuit of the brake magnets, and will then require no
separate magnetising force..
And in order that our invention may be the better understood we now proceed
to describe the same with reference to the drawings hereto annexed and to the
letters and figures marked thereon, which show diagrammatically sections of the
magnetic circuit of the magnetic system employed for supporting and affording
pivotal guidance to a meter axle: like letters in the different figures refer to
similar parts.
In Fig. 1, N, S, represents the supporting magnet having its supporting pole N,

page_text: immediately above the upper end of a meter axle A, the magnetic circuit being
completed through the annular air gap G, ring pole R, and return tube T.
In Fig. 2 we show a modification in which the magnetic circuit is complete by
means of a disc 1) attached to the axle, an annular air gap G, and ring pole K.
With this form of return path the axle may be made to float without touching
either the top or the bottom bearing but for this purpose it is necessary to make
the bottom bearing in the manner indicated in Fig. 2 where a pivot P at the lower
end of the axle A, passes through a hole in a jewel J1, which provides the
pivotal guidance necessary with this modification. A second jewel J 2 serves as
the lower bearing for the pivot; the latter does not however rest against J 2 when
the disc D is properly adjusted with reference to the ring pole R.
Fig. 3 shows a modification in which the return path is provided by means of
a disc D, attached to the axle, an annular air gap G, ring pole R, and return
tube T. In this modification the disc D, may be placed either below the ring
pole or above it as indicated by dotted lines.
Fig. 4 shows a modification in which the return path comprises a disc 1)
attached to the axle, a short cylinder C, attached concentrically to D, an annular
air gap G, and ring pole R. In this modification the magnetic induction return-
ing through the annular gap G, not only assists in supporting the axle but affords
pivotal guidance sideways in addition to that provided by the supporting pole.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is-
1st. In an electric meter having its armature axle suspended by unipolar means
a fixed ring pole surrounding but not touching the said axle and adapted by
means of a return path of iron to complete the magnetic circuit of the supporting
magnet substantially as and for the purpose set forth.
2nd. In an electric meter having its axle supported by unipolar means a disc
attached to the said axle adapted to rotate concentrically within a ring pole and
serving in conjunction with a return tube to complete the magnetic circuit of the
supporting magnet for the purposes set for and substantially as described in
reference to Fig. 2.
I
1 1.
1000
FELL & JAMES,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicants.