Improvements in Automatic Expansion Valves for Steam Engines, and in Gear for Operating the same.
Year: 1893

page_text: Date of Application, 25th Sept., 1893
Complete Specification Left, 19th June, 1894-Accepted, 28th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in Automatic Expansion Valves for Steam Engines,
and in Gear for Operating the same.
I HENRY JAMES HOGG KING of Newmarket Court near Stroud Gloucester-
shire, Engineer do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in automatic expansion gear for steam
engines, and its object is to provide an instantaneous cut off of steam from the
piston as quick in its action as the well known Corliss valve, and which is
applicable to any engine working with the ordinary slide valve over 3 ports in the
valve face.
To effect this object I place a fine grid-iron valve on the back of the high
pressure main valve or use a double beat, or equilibrium valve as a substitute for
the grid valve but as both valves are operated in the same way, I shall describe
the action of the grid valve only. The valve spindle which works this valve passes
through a stuffing box the same as the main valve and the spindle works in the
same line as the main valve spindle, and it is controlled and worked by a bell
crank lever one arm of which is attached to the cut off valve spindle. It is
centred on a pin fixed in a block, which forms part of the main valve spindle, and
as long as the bell crank does not move on its centre the 2 valves will work
together in unison but if the bell crank is moved on its centre a rotative motion
between the 2 valves is produced, and the grid will be opened or closed, and the
steam admitted or cut off from the main valve. To produce this motion, I use a
pair of pawls, which at every half revolution of the engine, through the medium
of a connecting rod moves the bell crank in the same direction, and opens the grid,
just before the piston gets to the end of its stroke, the pawl then continues its
motion and further opens the grid, till it comes into contact with a cam or stop
which is worked by the governor when the pawl is thrown out of gear and the grid
is instantly closed by a spring or weight. The can or stop is made so that,
the throwing out of the pawl does not effect the governor which is one of the
advantages of this arrangement, and another that the cut off takes place on the
main valve which gives a much better result than cutting off outside the steam
chest.
To prevent anything like a blow which might occur through the rapid closing of
the valve I provide an air cushion in the form of a piston which working in a
cylinder with a closed end, checks the fall of the piston after the grid has been
closed and the steam cut off from the piston. The rocking arm which carries the
2 pawls, is usually worked by the same eccentric which works the pump, but it may.
be worked by any motion working at the same speed as the engine or by one pawl
working at twice the speed.
Dated this 22nd day of September 1893.

page_text: Improvements in Automatic Expansion Valves for Steam Engines,
and in Gear for Operating the same.
I HENRY JAMES HOGG KING of Newmarket Court near Stroud Gloucester-
shire 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:-
This invention relates to improvements in automatic expansion gear for steam
engines and its object is to provide an instantaneous cut off of steam from the
piston, as quick in its action, as the well known Corliss valve, and which is
applicable to any engine working with the ordinary slide valve; and in order that
my invention may be properly understood, I have annexed hereunto 2 sheets of
explanatory drawings. These drawings show the application of my improvements
to a vertical and a horizontal engine, but they are equally applicable to all other
types of engines.
Figs. 1: 2. 3 & 4 (Sheet 1) shew the application of the improved valve gear to
one of my patent compound vertical engines No. 21,579, 1892 in which example
the bigh pressure cylinder is fitted with 2 main valves 1 & 2 one at each end
of the steam chest and on which valves work the fine grid expansion valves 3 & 4.
The grid ports in the main valves being usually in. wide. The valve spindle
of the expansion valves 5 is worked by the bell crank 6 which is centred on the
pin 7 on the main valve spindle 8, so that until the bell crank is moved, the main
valve and the expansion valve work in unison. The tendency of the expansion
valve, when free is to come downwards, and close the ports and keep any steam
from passing into the main valves such tendency, being produced partly by the
pressure of steam on the valve spin lle and partly by the spiral spring 9.
At each end of the stroke of the piston it is essential that the grid shall just
begin to open and this is effected by the expansion eccentric 10, which works
the rocking lever 11, on which are centered the steel pawls 12 & 13 which are
balance weighted as shewn or kept up to their work by springs. These pawls
engage 2 teeth or projections on the steel plate 14 and draw it and the connecting
rod 15 in the direction of the arrow till they are pushed out of gear by the
hardened steel rollers 16 & 17 coming into contact with the cam 18 the face of
which cam is inclined as shewn in plan Fig. 4 and the position of this plane as
regulated by the governor, is that which determines the point at which the steam
is cut off, for as soon as the pawl is lifted by the cam clear of the teeth of the
steel plate 14, the spring 9 is free to act and instantly moves the expansion valve
& closes the grid ports on the main valve. In order to avoid a blow in connection
with such a rapid closing movement, the cylinder 19 is provided, in which the
piston 20 works and forms an air cushion after it has passed holes drilled in the
cylinder 19, which holes the piston closes, after it has moved far enough to allow
the ports to be closed.
One of the pawls controls the inlet and cut off of the steam at one end of the
stroke of the piston, and the other pawl the other end.
Figs. 1 & 2 Sheet 2 show the application of this automatic valve gear to a
horizontal engine in which only one main & one expansion valve is used, the bell
crank 6 being centred on the sliding block 8 which has the same movement and is
attached to the main valve spindle. In this example, the pawls are knocked out
by the end of the cam 18 which end is excentric to a radius drawn from the
spindle 21 which consequently varies the time of cut off, as its position changes by
the action of the governor. Instead of a flat grid valve a double beat valve may
be used or any other which works on or in the main valve and which by a small
movement will admit sufficient steam to the main valve.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare what I
claim is
The use of a grid iron or other equivalent valve working on or in the main
valve of a steam engine, and in which valves a differential motion is produced by
means of a bell crank or other similar device, centred on the main valve spindle
and actuated by one or more pawls, which are controlled by the governor;
substantially as described for the purpose of cutting off the steam instantaneously
from the pistons, at the point requisite to maintain the proper speed.
Dated the 16th day of June 1894
H. J. H. KING.