An Improvement in Dynamos or Electric-generators, by Means of which a Constant Pressure is Maintained under Varying Speeds.
Year: 1895

page_text: Date of Application, 7th Jan., 1895
Complete Specification Left, 7th Oct., 1895-Accepted, 14th Dec., 1895
PROVISIONAL SPECIFICATION.
An Improvement in Dynamos or Electric-generators, by Means of
which a Constant Pressure is Maintained under Varying Speeds.
I, GEORGE EDWIN FLETCHER, of "The Homestead "Cale Green, Stockport,
in the County of Chester, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
-
An improvement in dynamos or electric-generators by means of which a constant
pressure is maintained under varying speeds. To obtain this result, I construct
the armature of the dynamo in the following manner :-(1) using either an ordinary
armature-drum or ring type-having placed close up to it a laminated iron cylinder,
or (2) by making the armature conical & the bore of the field-magnets conical
to correspond and control the position of either of these types of armature in
between the pole pieces by means of a pendulum or other type of mechanical
governor.
The result attained is as follows:-in the 1st case it will be seen that if
the speed increases, and the armature & cylinder are moved by means of the
governor, so that the iron cylinder travels in between the pole pieces while the
armature moves out, the cylinder takes up a certain proportion of the magnetic
lines thus leaving fewer magnetic lines to cut the armature winding, & consequently
the pressure does not rise, although the speed is increased. With regard to the
2nd case, the governor acting on this in the same manner as in the previous case,-
that is-driving the conical armature out of the conical cavity of the field-magnets,
the air space is increased, consequently fewer magnetic lines pass through the
armature & here again the pressure is kept constant.
Dated this 5th day of January 1895.
GEO. EDWIN FLETCHER.
An Improvement in Dynamos or Electric-generators, by Means of
which a Constant Pressure is Maintained under Varying Speeds.
GEORGE EDWIN FLETCHER of "The Homestead" Cale Green, Stockport in
the County of Chester, 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:—
For the purpose of my invention 1 prefer the use of an armature as illustrated
in the drawings owing to its efficiency being practically the same for all speeds
between the limits for which the dynamo may be designed.
The following is a description of the drawings:-
Fig. 1 is a sectional plan and Fig. 2 a sectional elevation of a machine having its
field magnet pole pieces bored out conically and its armature turned conical mounted
on a spindle which is free to rotate aid at the same time to travel endways so far
as it is allowed by the controlling governor; in each fig. the same letters are used
for the same parts; A is the yoke. B the field magnet cores.
C. the field magnet
021

page_text: windings. D the armature which may be wound either drum or ring. E the
commutator F the pole pieces. G the air gap between armature D & pole-
piece F. HH2 & H³ the bearings in which the spindle revolves & at the same
time is free to slide end ways. J is any pendulum or other governor having balls K
connected to the rocking centres by arms S, & actuating the spindle through
extended arms R geared to the spindle by double dise L. The frame of the
governor revolves with the spindle but does not travel endways with it except at
the point L where it is geared to it. M is the bed plate, N the driving pulley
which is geared to the spindle O by means of a key in the keyway P, so that the
spindles may slide through the pulley endways when so actuated by the governor
as bereinafter described.
Having now described the drawings it will be seen that the governor J being so
designed & arranged that, at the normal speed at which the machine is designed to
run, with armature as in the drawing, would exert just sufficient power to maintain
the armature in this position, exactly balancing the pull endwise of the polepieces,
but as soon as this speed is increased, the power of the governor balls also rises,
and will cause the armature D to travel with the spindle O out of the polepieces F
end wise, thus by so doing the air gap G becomes larger, owing to the armature D
being conical, causing the magnetic resistance of the machine to be increased:
therefore with the same magnetising force the number of magnetic lines passing
through the air gap G & the armature are reduced, whilst the speed is increased,
thus keeping the pressure constant at the terminals of the dynamo.
Having now described the nature of my said invention, I claim
1. The method of construction of a dyname or electric generator as herein
set forth.
2. The use of conical armatures in dynamos or electric generators revolving in
pole pieces bored out conically, & controlled substantially in the manner as herein
set forth.
Dated this the 5th day of October 1895.
GEO. EDWIN FLETCHER.