Improvements in Centrifugal Governors and Speed-indicators.
Year: 1898

page_text: Date of Application, 24th May, 1898-Accepted, 6th Aug.,
1898
1
COMPLETE SPECIFICATION.
Improvements in Centrifugal Governors and Speed-indicators.
I, WILHELM LYNEN, of 94, Bismarckstrasse, Aachen, in the Empire of Germany,
Professor at the Koniglich Preussischen Technischen Hochschule at Aachen, 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:-
.
A centrifugal governor, as a device for adjusting the valve or other controlling
device of an engine or motor, is itself to be considered as a working engine or
motor whose useful effect is that work which is done in adjusting or operating the
said valve or other controlling device.
With a mean degree E of insensibility of the governor, this useful effect is, as
is known, E-times the work done by the centrifugal force of the governor. Since
the degree of insensibility of the governor always has a small value, the useful
work done by a governor is only a small amount of the total work done thereby,
for example, when E 150, the useful work done is only 2 per cent. of the
=
work done by the centrifugal force.
In view of these relations, the internal friction in a governor assumes an
enormously increased importance, since it very considerably reduces the efficiency
of the governor. If the internal friction amount, for example, to 4 per cent. of
the work done by the centrifugal force, which can very easily take place, the
efficiency of the governor considered as a motor, taking E 150 will amount
; this is a very low value
to n =
useful work done
0.02
0.02+0.041
=
useful work done + internal friction
for a motor.
From this it follows that the utmost efforts should be made to reduce the
internal friction of the governor.
In addition to the forces acting in the plane of the governor, such as centrifugal
force, pendulum weight, and sleeve-load, the forces produced by the inertia of the
parts during variations in the speed of the engine and acting perpendicularly to
the plane of the governor, form a second source of friction in the governor.
These forces, due to the inertia of the parts, tend to interfere with the driving-
power of the governor, since they produce, as indicated in Figure 1 of the accom-
panying drawing, a turning moment Ma, the magnitude of which is given by the
equation, MT, where T is the moment of inertia of the rotating masses of
the governor relatively to the axis of rotation thereof, and the angular accelera-
tion of this axis of rotation. In the governors heretofore employed, this couple
is taken up by a driving-key or feather in the governor-spindle, a nomal pres-
sure N being set up at the place where the couple is transmitted to the said
spindle, the magnitude of which is determined from the equation Nx = Ma,
as indicated in Figure 1.
With the usual small diameters of the governor-spindles, the length of the
lever-arm is small, and the normal pressure N, and consequently the work to be
done in overcoming the friction in moving the sleeve relatively to the driving-key
or feather, is large. This applies more particularly to governors with moving
037
1

page_text: points of suspension of the pendulums and with a sleeve-weight rigidly connected
with the sleeve, as shown in Figure 2 of the accompanying drawing. The feather,
or other device whereby the sleeve is driven, must here accelerate the motion of
the whole of the rotating masses of the governor.
This frictional work to be overcome at the driving-connection is equal to zero,
with any desired value of N, if the transmission of pressure from the shaft; or
spindle of the governor to the masses thereof to be accelerated, takes place at a
point at which there is no relative motion between the governor and the axis of
rotation during deflection or displacement of the parts of the governor which
actuate the valve-gear or the like.
This condition can be approximately fulfilled in a governor such as that shown
in Figures 3 and 4 of the accompanying drawing. This governor comprises a pair
of pendulums, the point of suspension A. of each of which is guided parallel to the
axis of rotation by a sleeve sliding over the said axis of rotation, while its point
of support B is guided perpendicular to the axis of rotation by means of a roller
which rolls on a slide-way secured to the axis of rotation. Each of these pen-
dulums, which can be either simple or cosine pendulums (that is to say, pendulums
each having say, two balls, so arranged that the moment of inertia about the
line joining their centre of gravity to the point of suspension is equal to their
moment of inertia about a line perpendicular to this line and passing through the
point of suspension, the moment of the centrifugal force being then proportional
to the cosine of the angle which the line joining the centre of gravity of the balls
to the point of suspension makes with the axis of rotation) is so mounted in the
governor that the arm A B, in the mean position of the balls, is perpendicular
to the axis of rotation of the governor. As the governor moves down and up, the
point A consequently moves to Au or Ao, and the point M is then deflected to a
considerable degree viz., from Mi to Ma, whilst B only moves slightly away from
the axis of rotation. If the point B of the pendulum is selected as the place where
the driving forces are to be transmitted between the governor and the axis of
rotation, (which, for example, can be effected by allowing a lug cast on the said
slide-way to press at B on the axis of the roller carried by the pendulum) the
relative motion between the governor and the governor-shaft or spindle, at the
place where the pressure is transmitted, is almost equal to zero, even if the
governor-balls are displaced or deflected to their full extent. In this manner one
of the causes of friction in the governor is eliminated.
What has been said with respect to the friction of centrifugal governors applies
in a higher degree to speed-indicators constructed with a centrifugal pendulum
or pendulums, since the useful work done thereby is much less in proportion to
their internal friction than in centrifugal governors for engines or motors.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
A centrifugal governor or speed-indicator in which an angular pendulum has
its point of suspension guided so as to move parallel to the axis of rotation, and
its point of support guided perpendicularly to the said axis of rotation, and is so
arranged in the governor that, in the mean position of the balls, the inner arm
of the said pendulum is perpendicular to the axis of rotation and the pressure is
transmitted between the axis of rotation and the governor through a point at or
near the end of the said inner arm, substantially as herein before described.
Dated this 21st day of May 1898
D. YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.