Automatic Electric Switches.
Year: 1893

page_text: Date of Application, 29th Nov., 1893
Complete Specification Left, 7th Aug., 1894-Accepted, 20th Oct., 1894
PROVISIONAL SPECIFICATION.
Automatic Electric Switches.
JOHN HOPKINSON F.R.S. of Westminster Chambers 5, Victoria Street
London S.W. do hereby declare the nature of this invention to be as follows :―
My invention is more particularly addressed to rendering the switches which
vary the number of cells of a battery, through which current is passed, automatic,
but parts of the invention are applicable to other automatic switches in which
connections have to be varied when certain electric events take place.
In a switch which has to be actuated automatically, it is desirable that the
pressure of the contacts shall be as light as is possible consistently with certainty
of contact, and be known in amount. This I find it convenient to secure by making
a contact piece in the form of a lever freely pivoted on a fulcrum carried by a shaft
which is forced up to its work by a spring or weight, this ensures that the pressure
on the two contacts shall have a definite value and be divided between them in a
definite proportion.
It is necessary in accumulator switches, that if the switch move at all it shall
move an entire step and not stop in an intermediate position. I move the switch
by any power, according to one method I move it by the fall of a weight, and I
determine the times at which it shall move, by an electromaguet acting on an
armature, this armature operates a detent which stops a quick moving part of the
apparatus. This detent is also controlled by a cam on a slow moving part in such-
wise that it cannot stop the apparatus after being once released until the proper
time.
Generally an accumulator requires two switches one for charging, the other for
discharging. The charging switch is best controlled by the electromotive force of
the cell next to be cut out in suchwise that the contact piece moves to cut out this
cell when its electromotive force attains to a value indicating that it is fully
charged. I may connect the cell by a contact piece on the main switch. In a
discharging switch the switch must be moved in a direction to diminish the number
of cells used or to increase the number, according to the current passing or more
generally to the electromotive force of the battery. To attain this I drive the
discharging switch by two trains of clockwork through differential bevil or spur
gear. When one train is released, the switch moves in one direction, when the
other train is released in the other direction. Each train may be controlled by its
own electromagnet operating a detent which is also controlled by a cam, but a
single electromagnet will do equally well arranged so as to lift one detent when
the current or pressure is too low and to lift the other detent when it is too high.
The discharging switch may be arranged to carry back with it the charging
switch when it returns on completion of the charge.
If the shock of the rapidly moving part of the apparatus on the detent is too
great on the detent the latter may take the form of a spring which will act as a
buffer.
I
may vary the mode of actuation, of the switch, for example, I may make use
of a small dynamo machine to move and send a current through the armature of
the dynamo in one direction or the reverse by means of a contact operated by an
electromagnet but in that case I provide that a contact once made shall be
maintained until the switch has completed its step. I also provide that the contact
shall be a rubbing contact.
Dated this 28th day of November 1893.

page_text: ՀԱՄԱՅՆՆ ԵՆՆԱՆ IO,
1 JOHN HOPKINSON F.R.S., of Westminster Chambers 5 Victoria Street,
London, S. W., 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 :-
My invention is more particularly addressed to rendering the switches which
vary the number of cells of a battery through which current is passed automatic
but parts of the invention are applicable to other automatic switches in which
connections have to be varied when certain electric events take place.
In a switch which has to be actuated automatically it is desirable that the
pressure of the contacts shall be as light as is possible consistently with certainty
of contact and be known in amount. This I find it convenient to secure by making
a contact piece in the form of a lever freely pivoted on a fulcrum carried by a
shaft which is forced up to its work by a spring or weight. This ensures that the
pressure on the two contacts shall have a definite value and be divided between
them in a definite proportion.
It is necessary in accumulator switches that if the switch move at all it shall
move an entire step and not stop in an intermediate position. I move the switch
by any power. According to one method I move it by the fall of a weight and I
determine the times at which it shall move by an electro-magnet acting on an
armature, this armature operates a detent which stops a quick moving part of the
apparatus. This detent is also controlled by a cam on a slow moving part in such-
wise that it cannot stop the apparatus after being once released until the proper
time.
Generally an accumulator requires two switches one for charging the other for
discharging. The charging switch is best controlled by the electromotive force of
the cell next to be cut out, in suchwise that the contact piece moves to cut out this
cell when its electromotive force attains to a value indicating that it is fully
charged. I may connect the cell by a contact piece on the main switch. In a
discharging switch the switch must be moved in a direction to diminish the number
of cells used or to increase the number according to the current passing or more
generally to the electromotive force of the battery. To attain this I drive the
discharging switch by two trains of clockwork through differential, bevil or spur
gear. When one train is released the switch moves in one direction, when the
other train is released in the other direction. Each train may be controlled by its
own electro-magnet operating a detent which is also controlled by a cam, but a
single electro-magnet will do equally well, arranged so as to lift one detent when
the current or pressure is too low and to lift the other detent when it is too high.
The discharging switch may be arranged to carry back with it the charging
switch when it returns on completion of the charge.
I may vary the mode of actuation of the switch for example, I may make use of
a small dynamo machine to move the switch and send a current through the
armature of the dynamo in one direction or the reverse by means of a contact
operated by an electro-magnet but in that case I provide that a contact once made
shall be maintained until the switch has completed its step. I also provide that
the contact shall be a rubbing contact.
The switch arm A (Figs. 1 & 2) which makes connection between the contact
pieces 1, 1, 2, 2*, &c., and the contact piece 7 is carried loosely upon a shaft F
and is pressed into contact with the said pieces by means of a pin 8 passing through
the shaft F, the shaft F being acted upon through a set screw and bell crank lever 9

page_text: by a weight 10 or spring whereby a certainty of contact is assured and with a
known pressure.
Figs. 1, 2, & 3, show an arrangement for a charging switch. The contact
pieces 1, 2, 3, 4, 5, 6, are connected to the end cells of the series as shown
diagramatically in Fig. 9. The switch arm A, which makes contact with one
pole of the last cell being charged carries an insulated piece B which makes
contact with the other pole of the same cell. Wires lead from the arms A, B, to
terminals C, D, (Fig. 3) of the coils of an electro-magnet E. The switch arm A
is actuated through a shaft F by a pulley G and weight H. Upon the shaft F
is mounted a spur wheel J which drives through spur gear a fan K. The
armature L of the magnet E is mounted on a carrier M free to turn on a
pivot N.
The carrier M carries a stud O which engages in cams Q on the
periphery of the pulley G and also carries a detent P which engages with the
fan K. Adjustable springs R. S, are provided for the purpose of controlling
the action of the armature L. The intermediate contact pieces 1, 2, 3, 4ª, 5ª, are
connected to the contact pieces 1, 2, 3, 4, 5, respectively through resistances to
avoid short circuiting the cell as the contact arm passes from one cell to the
next.
The operation is as follows:-) -When the cell between the arms A, B, becomes
fully charged the current passing round the magnet E will attract the armature L
against the pull of the spring S and drawing the detent P away from the fan K
and the stud O out of the cam Q will allow the weight H to rotate the shaft F
and carry the switch arm round until the cell is out of circuit. As soon as the
arm A has moved from the contact piece the current round the magnet falls and
the armature is drawn back by the spring S. The arm A is prevented from
stopping in an intermediate position as the detent P can only engage with the
fan K when the stud O is engaged in one of the cams Q and these cams are
so arranged that this can only occur when the switch arm A is in a correct
position.
Figs. 4, 5, & 6, show a discharging switch arranged according to my invention.
The switch arm A is actuated by the shaft F which is driven through gearing by
an electric motor G. The coils of the electro-magnet H are connected to the leads,
the potential between which it is required to keep constant. The armature I is
mounted on an arm J fixed on a shaft K and fitted with a counterpoise W and a
riding weight X. Upon the shaft K are also carried two contact pieces L, M,
insulated from each other. On the intermediate shaft N is mounted an insulated
ring O bearing on which is a contact piece P connected to one of the brushes Q
of the commutator R. The other brush S is connected to the middle point of a
series of batteries while the contact pieces L, M, are connected respectively to the
positive and negative terminals of the said batteries.
The operation is as follows:-When the potential difference between the leads
connected to the magnet H is too great the armature I is attracted and raising the
weights W,X, brings the contact piece M against the ring O thus completing the
armature circuit of the motor G and causing it to turn the switch arm A to cut out
one or more cells until the proper potential is obtained. If the potential difference
is too low the weight W operates to bring the contact piece L against the ring O
thereby causing the motor to turn the arm A to put in one or more cells until the
proper potential is obtained. The weight X is suspended from a bracket Y so that
it is relieved from the arm J when the arm reaches its normal position and the
counterpoise W alone operates on the arm to bring the contact piece L against the
ring O. By adjusting the weight Y the extreme limits at which the switch operates
may be regulated.
In order to prevent the arm A resting in an intermediate position on the contact
pieces, an arm T is fixed to the shaft K and carries a projection U which engages
against a cylinder V carried on the shaft N. The cylinder has a slot in which the
projection U lies when the potential difference is normal and both the contact
pieces L, M, clear of the ring U. If either contact piece is brought against the

page_text: ring O it is held in such contact by the cylinder V acting on the projection U until
the switch arm A has arrived at a proper position on the contact pieces, the position
of the slot in the cylinder V being suitably arranged.
A similar arrangement may be used to actuate a charging switch instead of the
pulley and weight shown in Figs. 2 & 3.
An
Figs. 7 & 8 show an automatic discharging switch actuated by differential gear
driven by weights. The switch arm A is carried upon and actuated by a shaft F
as before described. The shaft F is actuated by the differential gear G, H, I, the
wheel G being carried on the shaft F and the wheels HI being carried on
sleeves J J and driven through ratchets and pawls by pulleys K, K₁ and
weights L L'. The sleeves JJ also drive through gearing fans M M¹.
electro-magnet N is connected to the leads whose difference of potential it is
required to keep constant. The armature 0 of the magnet is mounted on an
arm P attached to a shaft Q to which is also attached an arm P. Mounted
loosely on the shaft Q are arms R R carrying detents S S¹ which retain the
fans M M', and adjustable studs TT', through which the arms R R¹ are operated
by the arms P P. The arms R R₁ also carry projections U U which enter
cams VV' on wheels W W'fixed on sleeves J J'. The operation of the armature O
is controlled by adjustable springs X X'.
1
The operation is as follows:- If the potential between the leads is too great
the armature is attracted and through the shaft Q and arm P raises the arm R
and so frees the fan M thereby allowing the weight L to turn the shaft F through
the gear HG and so carry the switch arm A over the contact pieces to cut out one
or more cells until the right potential is obtained. If the potential is too low the
armature O is drawn back by the spring X and actuates the shaft Q and arm P¹
thereby raising the arm. R' which frees the fan M' and allows the weight L³ to
turn the shaft F through gearing I G and so carry the switch arm A over the
contact pieces to add one or more cells until the right potential is obtained, when
the armature O returns to its normal position. In order to prevent the switch
arın resting in an intermediate position the detents S S' can only engage with the
fans M M when the studs U U₁ are engaged in the cams V V' and these cams are
so arranged that this can only occur when the arm A is in proper position on the
contact pieces.
Instead of connecting the electro-magnets directly to the leads the potential
difference between which is to be controlled or regulated I may connect the said
leads to a relay which actuates a switch and so, causes a local battery cr batteries
to be applied to the electro-magnet.
I am aware that automatic switches have been described and described too
for charging and discharging batteries as for example in the Patents of Boult
No. 1026 A.D. 1890, Muller No. 2040 A.D. 1891, I make no general claim to such
switches.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
First. An automatic switch in which the movable connecting piece is pivotted
and is forced up to its contacts by a spring or weight in such wise that the pressure
on each contact is always the same substantially as herein described.
Second. A locking gear in an automatic switch combined with a detent in such wise
that the switch will only rest in defined positions substantially as herein described
with reference to Figs. 2, 3, 7. 8.
Third. A locking gear in an automatic switch combined with electric contacts
in such wise that the contacts will be maintained until the switch is in one of
certain defined positions substantially as herein described with reference to
Figs. 4 & 5.
Fourth. An automatic switch constructed substantially in the manner illustrated
by Figs. 2 & 3.

page_text: Fifth. An automatic switch constructed substantially in the manner illustrated
by Figs. 4 & 5.
Sixth. An automatic switch constructed substantially in the manner illustrated
by Figs. 7 & 8.
J. HOPKINSON.