Year: 1896

page_text: EVERSHED & VIGNOLES, LTD., of Woodfield Works, Harrow Road, in the
County of London, Electrical Engineers, and SYDNEY EVERSHED, of the same
address Electrical Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to meters of the type in which the speed of a motor is a
measure of either the current passing or the power supplied through the meter,
and is applicable to motor meters in which mercury or other conducting liquid is
employed to lead the current between the fixed and the rotary parts of the meter.
The objects of our invention are:-
(1.) To make such motor meters readily portable.
(2.) To enable such meters to be sealed after having their accuracy certified.
(3.) To protect the mercury from atmospheric and other influences.
(4.) To relieve the motor from the work required to drive the counting
mechanism.
་་
One form of enclosed motor meter made according to our invention is as
follows:-
The rotary armature is a vertical, 'hollow cylinder of copper, having its lower end
closed by a copper disc in the centre of which is a pivot projecting upwards into a
jewelled cup so as to form a centre about which the cylinder can rotate on its
vertical axis. The armature rotates in a radial magnetic field which is produced
by a fixed magnet having one pole in the form of a solid cylinder within the
armature, and the other pole in the form of a ring outside and concentric with the
armature and cylindrical pole. The aforesaid jewelled cup is fixed in the lower
end of the cylindrical pole of the magnet. Suitable caps of insulating material are
fixed above and below the pole pieces so as to completely enclose the annular space
between them, the lower cap being formed so as to leave a clear space for the lower
end of the armature; and the whole of this annular and lower space being filled
with mercury the armature floats upwards and is kept concentric with the annular
space by reason of its pivot resting in the jewelled cup. The current is passed
into the armature by means of two electrodes which pass through the insulating
caps and end in the mercury as close as possible to the copper arinature; the electric
resistance of mercury being many times greater than that of copper nearly all the
total current will traverse the armature and cause it to rotate. In order to make
the largest possible fraction of the total current traverse the armature the internal
faces of the pole pieces are covered with a non-conducting varnish so that the
current from one electrode to the other has only two alternative paths, viz. :-that
of very low resistance through the copper armature, and the high resistance path
through the mercury. Since the mercury completely fills the inter-polar space it
is necessary to provide for its expansion, and this is doue by means of a small elastic
reservoir in communication with the inter-polar space. In order that the speed of
the rotary armature may be proportional to the current traversing it the force
resisting the motion may be produced by means of eddy currents either in the
armature itself or in a copper disc or cylinder attached to the armature and rotating
within a powerful magnetic field.

page_text: The counting mechanism will consist of the usual train of wheels consimonly
employed in electric meters but according to our invention the greater part of the
power required to drive the train may be provided by means of the attraction
between an iron core or permanent magnet attached to one of the axles of the train
and a coil carrying the main current which is traversing the meter. Thus one of
the axles of the train, preferably the one which rotates most slowly,-herein called
the last axle of the train,-may carry a drum on which is wound a flexible cord
having one end fixed to the drum and the other hanging vertically downwards and
carrying an iron core adapted to be attracted towards and within a coil fixed below
the drum and carrying the main current. Provided the coil and core both have
sufficient length along their common magnetic axis the total range or stroke of the
core within the coil may be made to cover several revolutions of the drum. The
coil will attract a core of soft iron with a force roughly proportional to the square
of the current while it will attract a core consisting of a permanent magnet with a
force simply proportional to the current so that by combining a permanent magnet
and a soft iron core a force may be produced proportional to some function of the
current value between the first and second powers. In other words the force may
be made to vary with the current according to a law which shall tend to drive the
train at a speed roughly proportional to the current. In this way the rotary
armature is practically relieved of the work of driving the train and merely has to
control its speed so that the first axle of the train shall rotate at exactly the same
speed as the armature. The necessary connection between the armature and the
train we provide in the following way
We fix the train so that its first axle is vertical and beneath the bottom insulating
cap of the motor part of the meter, so that it rotates on a prolongation of the axis
of rotation of the armature. This axle carries at its upper end a horse-shoe
magnet having its poles upwards with their ends in a horizontal plane immediately
beneath the non-conducting cap. A soft iron bar is attached to the copper disc
forming the lower end of the armature in such a position as will enable it to form
a keeper of the horse-shoe magnet, and providing the non-conducting cap is
sufficiently thin the horse-shoe magnet and the keeper can be brought so close
together as to secure a very considerable magnetic induction between them, and
when this condition is fulfilled the rotating armature will carry the horse-shoe
magnet round with it, the latter with its keeper forming what may be called a
magnetic clutch. By suitably proportioning the various parts the force by which
the horse-shoe magnet is attracted towards the keeper may be made to relieve the
first axle of the greater part of the weight of the magnet at the same time that the
keej er is attracted downwards so relieving the armature pivot from a portion of
the upward force due to the flotation of the copper cylinder in the mercury..
The means we have described for providing the power necessary for driving the
train may be made to provide in addition the power necessary to overcome liquid
friction between the arinature and the mercury. Since the resisting force due to
liquid friction is nearly proportional to the square of the speed the required force
will be readily provided by a soft iron core acting on the drum and attracted by
the fixed coil carrying the main current.
Detold this 21st doy of Monah 1000
EVERSHED & VIGNOLES, LIMITED,
W. E. AYRTON,
ERNEST B. VIGNOLES,} Directors.
SYDNEY EVERSHED.

page_text: Improvements in Electric Meters.
We, EVERSHED & VIGNOLES LTD., of Woodfield Works, Harrow Road,
London, W., Electrical Engineers, aud SYDNEY EVERSHED of the saine address
Electrical 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 following statement :-
This invention relates to meters of the type in which the speed of a motor is a
measure of either the current passing or the power supplied through the meter,
and is more particularly applicable to motor meters in which mercury or other
conducting liquid is employed to lead the current between the fixed and the rotary
parts of the meter.
The objects of our invention are:-
(1.) To make such motor meters readily portable.
(2.) To enable such meters to be sealed after having their accuracy certified.
(3.) To protect the mercury from atmospheric and other influences.
(4.) To relieve meters of the motor type from the work required to drive the
counting mechanism.
One form of enclosed motor meter made according to our invention is as
follows:-
The rotary armature is a vertical hollow cylinder of copper having its lower
end closed by a copper disc in the centre of which is a pivot projecting upwards
into a jewelled cup so as to form a centre about which the cylinder can rotate on
its vertical axis. The armature rotates in a radial magnetic field which is produced
by a fixed magnet having one pole in the form of a solid cylinder within the
armature and the other pole in the form of a ring outside and concentric with the
armature and cylindrical pole. The aforesaid jewelled cup is fixed in the lower
end of the cylindrical pole of the magnet. Suitable caps of insulating material
are fixed above and below the pole pieces so as to completely enclose the annular
space between them the lower cap being formed so as to leave a clear space for
the lower end of the armature, and the whole of this annular and lower space
being filled with mercury the armature floats upwards and is kept concentric with
the annular space by reason of its pivot resting in the jewelled cup. The current
is passed into the armature by means of two electrodes which pass through the
insulating caps and end in the mercury as close as possible to the copper armnature;
the electric resistance of mercury being many times greater than that of copper
nearly all the total current traverses the armature and causes it to rotate.
order to make the largest possible traction of the total current traverse the
armature the internal faces of the pole pieces are covered with a non-conducting
varnish so that the current from one electrode to the other.has only two alternative
paths, ris.-that of very low resistance through the copper armature, and the
high resistance path through the mercury. Since the mercury completely fills the
inter-polar space it is necessary to provide for its expansion and this is done by
means of a small elastic reservoir in communication with the inter-polar space. In
order that the speed of the rotary armature may be proportional to the current
traversing it the force resisting the motion may be produced in the manner disclosed
in the specification of a Patent granted to.. W. E. Ayrton and J. Perry
numbered 2642 and dated 1882, that is to say by means of eddy currents either in
the armature itself or in a copper dise or cylinder attached to the armature.and
rotating within a powerful magnetic field.
In
The counting mechanism consists of the usual train of wheels commonly
employed in electric meters, but according to our invention the greater part of the

page_text: ower required to drive the train may be provided by means of the attraction
between an iron core or permanent magnet attached to one of the axles of the
train and a coil carrying the main current which is traversing the meter. Thus
one of the axles of the train preferably the one which rotates most slowly (herein-
after called the last axle of the train) may carry a drum on which is wound a
flexible cord having one end fixed to the drum and the other hanging vertically
downwards and carrying an iron core adapted to be attracted towards and within a
coil fixed below the drum and carrying the main current. Provided the coil and
core both have sufficient length along their common magnetic axis the total range
or stroke of the core within the coil may be made to cover several revolutions of
the drum. The coil will attract a core of soft iron with a force nearly proportional
to the square of the current while it will attract a core consisting of a permanent
magnet with a force simply proportional to the current so that by suitably
combining a permanent magnet and a soft iron core a force may be produced
proportional to some function of the current value between the first and second
powers. In other words the force may be made to vary with the current according
to a law which shall tend to drive the train at a speed roughly proportional to the
current. In this way the rotary armature is practically relieved of the work of
driving the train and merely has to control its speed so that the first axle of the
train shall rotate at exactly the same speed as the armature.
The necessary connection between the armature and train we provide as
follows:-
A
We fix the train so that its first axle is vertical and beneath the bottom insulating.
cap of the motor part of the meter so that it rotates on a prolongation of the
axis of rotation of the armature. This axle carries at its upper end a horse-shoe
magnet having its poles upwards with their ends in a horizontal plane immediately
henenth or on opposite sides of the circular non-conducting or insulated cap.
soft iron bar is attached to the copper disc forming the lower end of the armature
in such a position as will enable it to form a keeper of the horse-shoe magnet and
provided the insulated cap is sufficiently thin the horse-shoe magnet and the keeper
can be brought so close together as to secure a very considerable magnetic induction
between them and when this condition is fulfilled the rotating armature will carry
the horse-shoe magnet round with it, the latter with its keeper forming what may
be and is herein called a magnetic clutch.
The means we have described for providing the power necessary for driving the
train may be made to provide in addition the power necessary to overcome liquid
friction between the arinature and the mercury. Since the resisting force due to
liquid friction is nearly proportional to the square of the speed the required force
will be readily provided by a soft iron core acting on the drum and attracted by
the fixed coil carrying the main current.
In order that our invention may be the better understood we will now proceéd
to describe the same in relation to the drawings hereunto aunexed, reference being
had to the letters and figures marked thereon. Like letters refer to like parts in
the two figures.
Fig. 1 shows the essential features of a meter made in accordance with our
invention, the annular space in which the armature rotates being shown in section.
The radial magnetic field in the annular space is produced by means of permanent
magnets N N abutting on an iron ring R which forms one pole the central core P
forming the other pole. The annular space is completely enclosed by means of
caps of insulating material CC the lower cap having a metal tube B projecting
beneath it. The cylindrical armature A is attached to an axle pivotted at its upper
end in a jewelled centre fixed within the lower end of the central core P and at its
lower end it is pivotted at J at the bottom of the tube B. This axle carries a sof
iron rod F near its lower end the length of the rod being such as to leave a very
small clearance within the tube.
The counting mechanism or meter train G has its first axle vertical and in-lin
with the armature axle the worm gearing W serving to transmit motion betwee

page_text: the first and second axles of the train. The first axle carries a permanent magnet M
having its poles at such a height as will bring the iron rod F between them,.
M and F forming a magnetic clutch connecting the armature axle with the first
axle of the train.
The last axle of the train carries a drum D from which a bar H is hung by a
flexible cord. This bar may be either soft iron or steel of any degree of hardness,.
and if necessary permanently magnetised; it hangs with its lower end within the
coil S the axial length of the coil and of the bar being sufficient to allow the drum D
to make one or more revolutions before H has reached its limiting position.
A ratchet and pawl arrangement not shown in the drawing is provided to enable H
to be wound up to its initial position.
The annular space together with the tube B is completely filled with mercury
or other suitable conducting liquid, the main current being led into the space by
means of a ring electrode E E, the tube B serving as the second electrode..
TT being the main terminals of the meter the current to be measured passes.
through the positive terminal to the electrode E thence through the mercury to.
the upper end of the armature. Leaving the armature at the lower end the current
reaches the tube B and is carried thence to the coil S from which it returns to the
negative terminal.
A
Fig. 2 shows a modification of our meter in which the motor parts are identical
with Fig. 1 but inverted so as to bring the tube B to the top of the meter.
modified form of magnetic clutch is shown having a permanent magnet M attached
to the armature axle with its poles close to the top of the tube B, the first axle of
the meter train carrying at its lower end a bent soft iron rod Q. A further
modification is to make a permanent magnet thus increasing the induction between
its poles and those of the magnet M. It is not necessary for the mercury to fiil the
tube B in Fig. 2 it being an advantage to have the surface of the mercury below.
the magnet M; the latter may then be made of such a weight as will exactly
balance the flotation of the armature thus reducing the wear of the pivots to a.
minimum. The axle should be made as small as possible where it cuts the surface.
of the mercury so that the capillary force may be eliminated as far as possible.
Figs. 1 & 2 are not drawn to scale; for example, the annular space is purposely.
enlarged in order to show the working parts more clearly.
Although we describe our improved means of eliminating the friction of the train-
in connection with a particular type of motor meter, it is obvious that the method
is equally applicable to the counting mechanism of any meter of the motor type.
whether containing mercury or not.
We have also described the application of our invention to a motor meter in
which the armature rotates in a radial field but it is obvious that our invention is.
equally applicable to motor meters in which the armature is in the form of a disc
into which the current is led by means of mercury or other conducting liquid.
In the following claims the phrase "motor meter" signifies an integrating electric
meter of the type in which the tota! number of revolutions made by the motor in
a given time is a measure of the quantity of electricity supplied or of the electrical
work done in a given time. The phrase "liquid electrodes" signifies a conducting
liquid used to maintain electrical connection between the fixed parts and the moving-
parts of a motor meter, the said moving parts being either portions of the said
conducting liquid or solid conductors wholly or partiaily immersed therein. The
phrase "maguetic clutch" signifies a magnetic system consisting of a magnetic
circuit in two separated portions fixed on two adjacent axles and adapted to transmit.
motion from one axle to the other by means of the attraction between the two.
portions of the magnetic circuit.
Having now particularly described and ascertained the nature of our said.
invention and in what manner the same is to be performed, we declare that what
we claim is :-

page_text: a liquid-tight chamber, and a magnetic clutch to transmit motion from the said
moving parts to a counting mechanism outside the said chamber, substantially as
described.
(2.) A motor meter comprising a rotary armature with liquid electrodes enclosed
within a liquid-tight chamber, a magnetic clutch to transmit motion between the
said armature and the counting mechanism, and means for overcoming the friction
of the moving parts, substantially as described.
(3.) In a motor meter a coil and permanently oi temporarily magnetised core acting
on the counting mechanism to overcome friction, substantially as described.
(4.) In a motor meter a magnetic clutch to transmit motion between the moving
parts of the motor and the counting mechanism.
Dated this Eighth day of February 1897.
EVERSHED & VIGNOLES, LIMITED,
SYDNEY EVERSHED,
Managing Director.
SYDNEY EVERSHED
EVERSHED & VIGNOLES, LIMITED,
SYDNEY EVERSHED,
Managing Director.
SYDNEY EVERSHED