Year: 1889

page_text: I, SCHUYLER SKAATS WHEELER of No. 141 West 34th Street New York City,
United States of America, 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
My invention relates primarily to governors or automatic regulators for electric
motors and dynamo electric machines; and the object of this part of my invention is
the controlling of the speed, current, potential &c. in spite of variations in the load
and other conditions which occur in practice.
Many forms of governors for motors and dynamos have been invented and used,
which have generally operated either by shifting the commutator brushes or by
varying the strength of the field magnetism. The first of these methods,-shifting
the commutator brushes, has the difficulty that it causes sparking, which is extremely
objectionable, since the commutator is the weakest point of a motor or dynamo. The
other method-varying the field magnetism by introducing dead resistance, shunting
the current or changing the field connections, is also objectionable, because it
involves constant making and breaking electrical circuits, which also causes sparking.
In fact, the constant opening and closing of electrical contacts introduces an element
of great unreliability in electrical machinery, since the very act itself tends to destroy
the contact points.
Another very serious, if not fatal objection to governing motors or dynamos by
varying the magnetic intensity, is that the field cannot be magnetized nor demagnetized
with sufficient rapidity, and when the load changes suddenly, as it often does in
practical work, the magnetism is sluggish and does not change quickly enough to
prevent the machines froin running away or slowing down, as the case may be.
The object of my invention is, therefore, to overcome these objections, and to make
an automatic speed governor which operates mechanically, so to speak and does not
involve changing the electrical arrangements or varying the field strength To this
end my invention consists in mechanism hereinafter described and particularly
pointed out in the claims, through the agency of which mechanism I am enabled to
determine or regulate the number of magnetic lines of force which shall at any time
P 871

page_text: pass through the armature, and to do this without substantially altering the magnetic
strength of the field itself, thereby providing an automatic regulator which possesses
extreme delicacy of operation under all conditions of load
In the accompanying drawings, which illustrate several modifications of my
invention Fig. 1 represents a plan view partly in section of one of the simplest
forms of my apparatus Fig 2 is a side view and Fig. 3 an end view partly in
section of my governor combined with a magnetic thrust plate designed to balance
the end thrust on the shaft due to the magnetic attraction between the field magnets
and the armature Fig 4 is a side view partly in section of one form of my
governor in which the armature has combined with it a supplemental magnetic core
which I denominate a dummy amature," the function of which I will point out
hereinafter Similar letters of reference indicate corresponding parts in all the
figures
"
In Fig. 1, N & S are respectively the field pole-pieces of an electric motor or
dynamo electric machine. A is the armature, the commutator, and B, B the
brushes The armature A is carried upon a shaft D turning in suitable bearings E & F
The armature A is mounted upon the shaft D in such a manner that it is capable of
sliding longitudinally upon the shaft, and can thus be drawn out of the pole-piece
space but the armature A is prevented from turning upon the shaft D by a slot and
spline, or in any other suitable way The governor consists of ball G connected to
the armature by link II, pivotted both in the ball and at the point where it is attached
to the armature. The ball G is connected in the opposite direction by a similar
pivotted link J to a collar K rigidly attached to the shaft D This construction is
duplicated on the opposite side, in order to secure balance. A spiral spring L,
surrounding the shaft D, is attached at one end to the amature A, and at the other
end to a collar M which may be adjusted and fixed at any point by means of a set
screw in the collar, as represented.
"
race
the
Let us assume that the above described machine is running as a motor upon a
constant curient oi <
series" circuit, and that it is working under full load, in which
case the armature will be entirely within the field, as represented by the dotted lines.
If now, the machine had no governor and the load decreased, the armature would
tend to increase its speed, and if the load were thrown off entirely, it would
away" at such a high speed as to be very objectionable and even dangerous.
If however the machine is provided with a governor, as shown in Fig. 1,
balls G, G tend to fly out by centrifugal force with an increase in speed, and pull
the armature out of the field, thus reducing the torque or turning power of the
armature, and thereby counteracting the tendency to speed away The spring L is
adjusted, (which may be done by sliding the collar M back and forth, as already
stated) so that the centrifugal force of the balls G, G is practically balanced in every
position, and thus a small change in speed will make them move the whole extent of
their path It is to be remembered, however, that the magnetism tends to draw the
armature into the pole-pieces, and in cases where this force is greater than that of
the governor, the spring L should be adjusted to pull instead of push. It will be
seen that the commutator C is made longer in order to allow of the longitudinal
motion of the armature
It is evident that in the form of governor above described, in which the armature
1s moved out of the field space, there will be an end pressure on the shaft due to the
magnetic attraction of the field for the armature, tending to draw the latter into the
field. In some cases this end pressure is not seriously objectionable, and may be
carried by collars on the shaft D which press against the main bearings of the
machine, E & F (Fig. 1). But in most cases such end pressure is objectionable, and
I overcome it in various ways. For example, in Fig 4 I mount a supplementary iron
drum or 66 dummy armature a alongside of the real armature A. This dummy a
1s attached to and moves with the armature A, and is made similar in magnetic
effect and capacity to the iron core of the armature. When the armature A 18
pulled out of the field by the action of the governor, the dummy a is drawn in,
thus
the attraction of the field for the armature is balanced by the attraction of the field

page_text: for the dummy, and by properly proportioning the dummy, as already stated, the end
thrust may be practically eliminated It is also evident that when the dummy a
enters the field it will magnetically short circuit the armature more or less, which
is desirable since it effects the reduction of power of the machine more quickly
than by the withdrawal of the armature alone Thus the dummy a performs two
functions.
In Figs. 2 & 3, I show another organization for eliminating the end thrust of
the shaft. In this construction the governo balls G act through knee-joints to
push the armature A out of the field when the speed increases, as is perfectly
evident from the drawing, (Fig 2). The plate O, preferably composed of
laminae of sheet iron, is mounted upon and rigidly attached to the shaft D and is
adjusted in such a position that there is tho maximum force tonding to draw it
into the field.
I find that a comparatively thin plate O, placed in the most effective position, as
stated, will practically balance the magnetic force tending to pull the armature into
the field. This is because the change in the number of lines of force passing through
the armature is only gradual, whereas to force the plate O out of the field it would be
necessary to sever all its lines of force at once. A certain amount of magnetic leakage
occurs through this thrust plate O, but this is insignificant because the plate may be
made even thinner than is represented in the drawing say one eighth of an inch
thick. In some cases I either modify the shape of the armature or turn out the field,
as indicated by the dotted lines, in order to equalize variations in the magnetic
attraction and in the pressure of the governor on the armature in any given case,
all of which, of course, depends upon the form of the field and armature as well as
the proportions of the governor, &c.
In the forms of governor which have been described above, the amature is moved
out of the field by sliding it longitudinally upon the shaft but it is evident that
precisely the same results may be obtained by mounting the armature rigidly upon
the shaft in the usual manner and sliding the shaft longitudinally in the bearings In
Fig. 4 it is shown how this form of governor may be constructed in practice. The
armature A and the commutator Care both fixed upon the shaft D as is also the
dummy armature a which is preferably laminated. The bearings are put at such a
distance apart and the shaft is made of such length as to allow the latter to slide
longitudinally in the bearings far enough to bring the armature core out, or partly
out of the held. In this form of apparatus it is preferable to make the dummy
armature of somewhat greater magnetic capacity than the armature proper, hence
the tendency is for the dummy to be pulled into the field. This tendency is opposed
by the compression spring L which is made of sufficient power to resist this excess
of attraction of the dummy and also to balance the centrifugal force of the governor
when running at the normal speed The governor is similar to the form shown in
Fig. 1 except that in addition to the links J & H which operate in the usual manner,
there is an arm G made in one piece with the link H which exerts little or no
centrifugal force at first, but, when the link H flies out until it loses its effect, the
arm G comes into action and carries the link H still further around, and thus increases
the stroke of the governor. The operation of this form of governor is substantially
the same as those already described. When the speed rises above the normal, the
governor arms H, H fly out and the armature A is drawn out of the field against the
compression spring L the resisting force of which as already stated is equal to
the centrifugal force of the governor at the normal speed plus the amount that the
attractive force of the field for the dummy armature exceeds its attraction for the
armature proper. Hence these forces are exactly balanced at the normal speed and
at higher speeds the armature is moved out, thereby reducing the speed, and at lower
speeds it is moved into the held thereby increasing the speed. The dummy acts to
balance the attraction of the field for the armature and also to shunt or divert the
lines of magnetic force from the latter. Furthermore it has been stated that the
dummy is preferably constructed to be attracted a little more by the field than is
the armature itself; the object of this excess of attraction is to regulate for the

page_text: variations in strength which almost always occur in practice in the so-called constant
current circuits. Assuming for example that the current strength rises from the
normal of ten amperes to ten and a half amperes, this will of course strengthen the
field magnetism, and the dummy which is magnetically stronger will be drawn into
the field and the armature proper will be forced out, thus counteracting the
tendency to run faster as would otherwise be the case with increase of field strength.
The increase of current in the armature will produce little lateral attraction because
its poles are nearly at right angles to the field poles. In order that this action should
take place properly it is obvious that the field should be constructed and worked
so that it is not magnetically saturated at the normal current but is capable of
increasing in magnetic strength up to the highest current that it is likely to carry.
In this form of governor in which the shaft slides lengthwise in the bearings,
carrying the pulley with it, it is necessary to employ a pulley having a face some-
what wider, and the belt will travel on one side or the other according to the position
of the pulley. It is found that the pulley moves easily from one side to the other
under the belt since it is going at a high rate of speed. The commutator moves to
and fro under the brushes in a similar manner and in this case as well as in the
case of the shaft in the bearings, this end motion is a decided advantage and makes
them work much more evenly.
It might appear at first sight that the above described machines are open to the
objection that when the armature is partly out of the field there would be a great
deal of sparking at the commutator because the magnetic effect of the field upon
the armature would be reduced and the direction of polarity would be distorted by
the armature current in the well known manner. But this is not the case because
the strength of the field itself is not reduced and whatever portion of the armature
remains in the field is under the same conditions of relative magnetic power as
when the whole amature is within the field; the part of the armature which is
outside of the field is neit and would produco no sparking it being like an armature
revolving in the open air without any field at all. It is only where the armature
and field act upon each other that any sparking or other effect can be produced and
when the current remains practically constant in both armature and field their
relative magnetic strength is substantially the same whether the armature is in one
position or another.
01
It is obvious that the above described forms of apparatus are equally applicable to
dynamo machines for governing them with respect to speed, load, current
electromotive force and that the construction and operation would be substantially the
game.
The second portion of my invention relates to a new form of field magnets for the
above described electric motors and dynamos.
In the designing and construction of field magnets for dynamos and electric motors
a number of limitations and conflicting considerations are encountered. If, for
example, the magnet is made so that it can be taken apart and the cores easily wound
with wire, then there are necessarily a number of joints which are decidedly
objectionable for three reasons, they are troublesome and expensive to fit properly,
they weaken the construction mechanically and introduce breaks into the magnetic
circuit If on the other hand it is attempted to make a field magnet of one piece
or only a few pieces it is usually clumsy and difficult to wind, each turn of wire
requires to be placed in position by hand as in winding the rounded horse shoe form
for instance. In short it the magnet is simple and strong mechanically it is hard to
wind and vice versa.
The object of this part of my invention is therefore to overcome these difficulties
and to make a field magnet which is as strong as possible mechanically, and capable
of being easily wound, and at the same time simple and cheap to construct.
In the accompanying drawings which illustrate my invention:-
Figs 5 & 6 are side and end views of a held magnet made all in one piece but
which is formed, according to my invention, so as to be capable of being easily and
freely wound in its integral state. Figs. 7 & 8 are diagrams representing the above

page_text: form of field being wound. Fig. 9 is a vertical sectional view similar to that shown
in Figs. 3 & 4 but especially designed to be gorged out of bar iron.
Sunlar letters of reference indicate corresponding parts in all these figures.
In Figs. 5 & 6 I have shown a form of field magnet inade according to my invention.
This field magnet consists of pole pieces N & S and main field magnet cores Q & R.
The pole pieces N & S are connected across the top by a magnetic brace P, according
to my invention. This brace P is made of sufficient strength for the purpose and
may be bolted or otherwise attached to the pole pieces I prefer however to cast the
whole field magnet as represented in Fig 5 in one piece and make the cores Q & R
at such an angle with respect to each other that either may be wound freely without
interference from the other, as represented in Fig. 7. The magnetic brace or supple-
mentary core P can also be wound freely as represented in Fig. 8 thus all three cores
can be easily wound and a form of field is obtained which is very strong and rigid
mechanically and in which the magnetic circuits are very short. The yoke joining
the cores Q&R which is required to complete the main magnetic circuit through
them may be a separate piece bolted on to them in the usual minner, but I usually
prefer to cast it as part of the base, in fact an ordinary base plite may be used simply
thickened at that point In either case the magnet is attached to the base at the
neutral portion of the former, which is always desirable. A field magnet made all
in one piece in this way is a decided advantage in a great many respects It can be
bored out and fitted to the base as one solid piece and after it is once made properly
it is always the same. Whereas a magnet made of several pieces has to be care-
fully fitted together again and adjusted each time the machine is taken apart for
transportation or repairs. It is obvious that the proportion of the cores to the field
magnet may be varied if desired The relative diameters for example, of the
cores P&Q may be made different from that represented in the drawing and the upper
core or brace need only be made sufficiently large to give the requisite strength,
the lower cores Q & R being made large enough to pro luce the greater part of
the field magnetism, in this way the large and heavier portions of the field are brought
as low as possible
The relative amount of wire with which the cores P Q & R in Fig 5 should be
wound, depends upon their relative sizes It will be seen that there are two magnetic
circuits in multiple arc, one being formed by the upper core P with the pole
pieces N & S and the armature and the other being formed by the two large
cores Q&R the yoke or baso B and the armature. These two circuits being
preferably of different cross sections as I have explained it is necessary to propor-
tion the windings on them so as to obtain a magnetic bilance between them and
have each magnet work at the proper point of saturation to get the most
econom cal effects. This balance can be calculated by well known formulas, or
found by trial one circuit being varied while the other is kept constant and vice
versa.
It the brace P in Fig 5 be made quite small in cross section so that the amount
of magnetism which would be short circuited by or leak, it would be small enough
Or in
to be insignificant or allowable, then the brace need not be wound with wires.
other words, the field may be cast in one piece in order to secure the great advantages
which result therefrom, by making the main magnets a little larger in order to make
up for the leakage through the brace In Fig. 9 the form of field magnet represented
is similar to that shown in Figs. 5 & 6 but is specially designed to be easily inade
of wrought iron by simply taking a piece of bar iron and forging it around a form
In this case the lower cores F & G are made parallel to each other instead of at an
angle but they may be just as well be placed at an angle to each other like the
cores Q&R Fig. 5 If these coils F and G are made parallel to one another, the
coils f&g may be wound upon a mandrill, for example, and afterwards shipped on to
them In Fig 9 the yoke Y is represented placed between the extremities of the
cores F, and G the whole being held together by the base B around the outside, as
represented, this makes a very strong construction, but it evident that the cores F & G
may be screwed to the base or yoke from below, as represented in Fig. 5.

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 :-
1. An electric motor or dynamo electric machine having an armature constructed
to be moved out of the magnetic field and a supplementary magnetic core similar to
that of the armature and mechanically connected to it which takes the place of the
armature as the latter moves out of the field, substantially as described.
2. In an electric motor or dynamo electric machine the combination with an
armature constructed to be moved out of the field of a magnetic plate placed with
respect to the field in the position of maximum longitudinal attraction, whereby the
opposition of the armature to movement out of the field is sustained or balanced,
substantially as described.
3. In an electric motor or dynamo electric machine the combination of a field
magnet and armature, which are constructed to have their positions changed with
respect to each other, and means whereby the attraction between said field magnet
and armature is magnetically balanced in the direction of movement, substantially
as described.
4 In an electric motor or dynamo electric machine the combination with the
armature of a dummy armature or supplementary magnetic core mechanically
connected to and rotating with the armature shaft, substantially as described.
5. In an electric motor or dynamo electric machine an armature and field magnet,
which are constructed to have their positions changed with respect to each other, in
combination with a dummy armature or supplementary core and a mechanical
governor or regulator which effects said change of position substantially as described.
6 In an electric motor or dynamo electric machine automatic regulating mechanism
consisting of an armature constructed to move longitudinally into or out of the
magnetic field in combination with and mechanically connected to a supplementary or
dummy core of greater magnetic strength or capacity than the armature itselt, whereby
said dummy is attracted into and the armature forced out of the magnetic field
with an increase of energizing current and vice versa, substantially as described.
7. A field magnet for electric motors or dynamos, made in the general form of a
triangle with a core at the vertex capable of being freely wound through the armature
space and cores near the base at the two sides and placed at an angle to each other so
as to be freely wound without interference with one another, substantially as described.
8. A field magnet for dynamo electric machines or electric motors made in the
general form of the letter A with a core at the top Joining the pole pieces and forming
one magnetic circuit, and a core at each side below, which with the base or yoke
forms another magnetic circuit, substantially as described
9 In a field magnet for a dynamo electric machine or motor a core piece of
horse shoe type made of a single piece of magnetic material with three field coils,
two of which are located near the ends of the core pieco, while the third is located at
an intermediate point, the winding of said coils being such that effective field poles of
opposite polarity are created at points between the opposite ends of the intermediate
coil and the adjacent ends of the other two coils, substantially as described
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.