IMPROVEMENTS IN APPARATUS FOR REGULATING THE DISTRIBUTION AND THE EXPANSION OF STEAM IN STEAM ENGINES
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Edward Gedge at the Office
of the Commissioners of Patents on the 3rd June 1878. A communication
from abroad by Prosper Nosbaume and Laurent Bénistant, of Paris, France.
WILLIAM EDWARD GEDGE, of No. 11, Wellington Street, Strand, in the County
of Middlesex, Patent Agent. "IMPROVEMENTS IN APPARATUS FOR REGULATING THE
DISTRIBUTION AND THE EXPANSION OF STEAM IN STEAM ENGINES."
A com-
munication from abroad by Prosper Nosbaume and Laurent Bénistant, of Paris,
France.
This Invention relates to improved steam distributing apparatus without springs
and with variable expansion by the governor.
Engineers engaged in the construction of steam engines have long sought a good
method of expansion; they generally go no further than the system which consists
in causing the variation of the expansion by the action of the governor. In this
method springs are often used, which, under the repeated strains to which they are
subjected, quickly deteriorate and then only exert a very irregular power.
The great difficulty of properly manufacturing these pieces is also well known,
and the frequent renewal which thus becomes necessary makes the cost of keeping
the engine in working order very onerous. On the other hand, these movements
are invariably connected with the regulator, that is to say, this latter has its fixed
corresponding elevation for a certain degree of expansion. It is then necessary in
order to secure practical regularity, to take for basis a very slight departure of the
governor from its mean position to cause a very sensible variation of the expansion
movement, and to remove this expansion to have recourse to balls of considerable
weight, and consequently to a governor of large proportions.
.
The apparatus which I will now proceed to describe obviates these defects.
The admission of steam may take place by different kinds of openings.
Figures 1, 2, 3, and 4, Sheet 2 of the accompanying two Sheets of Drawing,
show valves composed of a fixed disc of bronze perforated with several orifices in a
ring. This disc is readily opened or closed by an axle having at each end a
moveable disc pierced with orifices in the same manner as the fixed disc, and keyed
D

page_text: on this axle, so that for a slight oscillation the openings. of the moveable disc may
come and face those of the fixed disc, and the steam be permitted to enter at full
pressure into the cylinder. This movement is operated by a small crank by means
of small intermediate levers.
The exhaust is regulated by very similar valves, but having only one moveable
disc on the side towards the cylinder, worked directly by a crank keyed on the
same axle. This keying is done in such a manner that one of the valves opens
when the other shuts.
The cranks of the steam valves and of the exhaust valves have a reciprocating
motion operated by special novel expansion apparatus, by the aid of a certain
number of levers depending upon the system and the arrangements of the engine to
which the mechanism of this Invention is to be applied.
The following is a description of the main parts of this movement, shown Figures
5, 6, 7, 8, 9, 10, and 11 of the Drawing..
A, cast-iron frame, either separate or of one piece with one of the main parts of
the engine, and carrying a main shaft receiving its rotary motion by means of
toothed gearing from the horizontal shaft of the engine, and turning at exactly the
same speed as this shaft.
B, exhaust cam fixed on the same shaft having a single tooth.
C, cam for opening the steam valves fixed upon the shaft, carrying two teeth
shorter than the thickness of the cam, starting respectively from each edge and
diametrically opposed.
•
D, cam closing the steam valves; it is keyed on the shaft by a key or feather
which may slide in a helicoidal groove, and so permit the cam to shift its position
by a similar movement when it is submitted to a pressure parallel with its axis.
E, exhaust lever of an oval form, oscillated by the cam B, operating upon the two
rollers.
F and F', levers opening the steam valves, each carrying a friction roller actuated
by the cam C and both hung upon a same axle f, f', which may move vertically in
a slot in the frame.
G and G¹, levers closing the steam valves, each carrying a friction roller actuated
by the cam D, hung or set upon a fixed axle, and coupled respectively to the
levers F and F¹ by connecting rods F 1, G 1, F 1, G 1', and the small rocking levers
f1, 91, and f1, g 11, see Figures 12 and 14.
Hand H¹, connecting rods set at one end on the same axle at h and h¹, and
having at the other end two screws and v³ engaged in a circular groove or collar
on the cam D.
v, screw also fixing the rod T to the connecting rod H.
T, rod which may slide longitudinally in the frame carrying a slot of a particular
form combined with the helicoidal groove of the shaft, and giving by its inclined
part a vertical movement to the axle f, ƒ¹.
.
J, lever keyed on the axle / actuating the connecting rods H, H'.
K, lever keyed on the same axle at 1, oscillated by a nut 6.
L, screw fixed longitudinally in the frame carrying the nut e.
M, pinion with fine teeth keyed on the screw L
N, similar pinion set loosely on an axle attached to the wheel plate Q.
O, larger wheel keyed on the cam shaft.
P and P¹, loose pinions set on wheel plate Q
Q, wheel plate set in the axle q and carrying a lever R.
S, small rod guided in the frame and passing freely in the lever K. It may in
certain limited positions of oscillation of this lever receive by the projections 8
and sa slight shifting movement, compelling, by means of the inclined planes
randon its end, the wheel plate to resume its normal position.
Working. The exhaust is effected on each side of the piston, by turns at equal
fixed periods, by the contact of the cam B with each of the friction rollers of the
lever E. The admission of steam is also operated at equal and fixed periods by the
cam C. which acts alternately upon the levers F and F', and the duration of
:

page_text: the expansion is regulated by the cam D, which by its variable position acts more
or less rapidly upon the levers G, G¹, to operate the closing of the valves. This
variation of the cam D is obtained from the regulator or governor in the following
manner-
First Case. The engine runs too fast, the governor rises with its socket, causes
the wheel plate Q to oscillate in one direction by the lever R, thus bringing the
toothed wheel O which is always rotating in gear with the pinion M, and gives a
rotary motion to the screw L, which by the aid of the levers K and J and the
connecting rods H and H', causes the cam D to advance along its axle. This cam
in advancing receives a helicoidal movement, and then its teeth or projections
coming nearer to the generatrix of those of the cam C act more rapidly upon the
closing levers, and consequently lessen the duration of the admission of steam.
When the teeth of the cams C and D are near placing themselves on the same line,
they might interfere with each other, that is to say, that the friction rollers could
not obey their respective movement. This is prevented by the rod T, which at this
moment by the inclined part of its slot compels the axle ff, to lower. The friction
rollers of the admission of steam then recede from their cam C, and permit the
cam D to lessen the time of admission to the stoppage.
Second Case. The engine relaxes its speed, the governor then causes the wheel
plate Q to oscillate in the contrary direction, and by reason of the additional
toothed wheels between the wheel O and the pinion M causes this latter to turn in
a contrary direction, and consequently the cam D slides so as to increase the
duration of the admission of steam.
When the maximum variation of the expansion is insufficient to bring the
machine quickly enough back to its regulated speed by reason of the inertia of its
parts, the lever K gives a slight impulsion to the small rods by its projections 8
and 8, which by their small inclined planes r, rl, compel the wheel plate Q and
consequently the governor to resume its normal position.
To sum up, the expansion takes place without shock, without springs, is directed
or thrown into gear by the governor, takes its power from the machine, and
therefore may be produced as rapidly as may be desired.