Improvements in Valve Gears for Steam-engines..
Year: 1899

page_text: Improvements in Valve Gears for Steam-engines..
I, JOHANN STUMPF, of 27, Ranke Strasse, Berlin, in the Kingdom of Prussia,
German Empire, Professor, do hereby declare the nature of this invention to be
as follows:
The present invention relates to a dash-pot for valve-gears.
An essential
feature of my improved dash-pot is that the force producing its closure results
from a vacuum created when the valve stem is lifted, by a piston moving within
a closed cylinder filled with an almost noncompressible liquid which advan-
tageously is oil. During the rise of the valve the buffer piston rigidly con-
nected with the same is moved upwards within a cylinder completely filed with
oil or other suitable liquid whereby immediately a vacuum is formed. The
cylinder or the buffer receptacle is preferably so formed that there is always a
certain layer of oil, one part of which during the upward movement of the
buffer piston is pressed through the small opening between the piston and the
side wail of the cylinder into the latter.
In order to remove all the oil penetrating at each stroke, I provide at the
highest part of the cylinder a valve through which the oil is removed to the
outside during the descent of the buffer piston. Evidently the removal of
the superfluous oil from the buffer cylinder only takes place shortly before the
end of the closing movement of the valve, that is to say when the vacuum pro-
duced by the rise of the cylinder is destroyed. The work effected by the piston
during the removal of the oil forms already a certain brake-action rendering
slow the closure of the valve shortly before its arrival upon the seat. In order
to reduce the force at the end of the stroke an oil-cushion is provided within the
buffer piston.
The vacuum created within the buffer cylinder by the rise of the piston pro-
duces a force sufficient to ensure the closure of the valve and which always is
exactly of same value for the course of the valve without reference to the size
of the opening.
Owing to this fact my improved apparatus is distinguished from the spring
regulated valves which are generally employed and which for each different stroke
of the valves give a different closing force.
In the drawing a dash-pot according to my invention in combination with
a valve gear is illustrated as an example. The valve a has the form of a double
seat valve, the spindle b at its upper extremity carries the buffer piston c in form
of a plunger piston. The latter in the example is of a W-formed section whereby
into the inner central opening extends a socket d' fixed to the buffer receptacle d.
Owing to this peculiar arrangement of parts the oil is prevented from leaving
the buffer receptacle, and air is not allowed to enter. The buffer-receptacle d
by means of a transverse wall d² which is arranged somewhat inclined, is
divided into two parts, the upper one of which may be open. At the highest
part of this transverse wall d² I provide a valve e; I give an inclined form to

page_text: the wall for the reason, that the air, which in spite of the peculiar arrange-
ment might have entered, can easily leave the apparatus through the valve e.
An angular projection or collar f is provided at the bottom of the buffer recep-
tacle. A perforation fl regulable by an adjusting screw 2 connects the space
within and outside of this projection.
When the valve and its piston c is raised, a complete vacuum will be created
within the buffer casing b, whereas between the piston e and the intermediate
wall a certain quantity of oil enters the buffer space from above. When the
valve is disengaged, the vacuum effects its descent. As soon as the empty
space is filled out, the buffer piston removes the penetrated oil through the
valve e whereby, as already mentioned here-above, a certain brake-action is pro-
duced. Hereafter the piston centers the flat cylinder formed by the collar f
and meets the oil-cushion which only is elastic to a certain degree when the
perforation f is adjusted.
Owing to the oil-cushion acting in the last instance only the movement can
be regulated just before the valve comes upon its seat. The brake-action pro-
duced by the pumping outwards of the penetrated oil can be increased at con-
venience when a certain pressure is exerted upon the valve e. According to the
height from which this pressure is exerted, (for instance by springs, weights or
in other similar manner), the resistance of the valve against the passing oil and
the brake action thereby produced, increases.
The construction illustrated in the drawing shows the buffer in combination
with an inlet-valve for steam-engines. It is evident that the buffer also can be
applied to all other valves and engines.
Dated this 22nd dox f D
1800
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.
I, JOHANN STUMPF, of 27, Ranke Strasse, Berlin, in the Kingdom of Prussia,
German Empire, Professor, 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:-
-
The present invention relates to a dash-pot for valve-gears. An essential
feature of my improved dash-pot is that the force producing its closure results
from a vacuum created when the valve stem is lifted, by a piston moving within
a closed cylinder filled with a liquid, preferably oil. During the rising of the
valve the buffer piston rigidly connected with it is moved upwards within a cylin-
der completely filled with oil whereby a vacuum is formed. The cylinder or
the buffer receptacle is formed with an upper chamber also containing oil, a
part of which during the upward movement of the buffer piston passes between
the piston and the side wall of the cylinder into the latter.
In order to remove all the oil penetrating at each stroke, I provide at the
highest part of the cylinder a valve through which the oil is removed to the
outside during the descent of the buffer piston.
The removal of the super-
fluous oil from the buffer cylinder only takes place shortly before the end of the
closing movement of the valve, that is to say, when the vacuum produced by
the rising of the cylinder is destroyed. The work effected by the piston during

page_text: the removal of the oil gives a certain brake-action rendering slow the closing
of the valve shortly before its arrival upon the seat. In order to close the valve
very gently, the buffer piston during the last part of its movement is received
by an oil-cushion.
The vacuum created within the buffer cylinder by the rising of the piston
produces a force which can be depended upon to close the valve and which is
always exactly of the same value for any stroke of the valve.
Owing to this fact my improved apparatus is distinguished from the spring
regulated valves which have been lately employed and which for each different
stroke of the valves gives a different closing force.
In the drawing filed with my Provisional Application a dash-pot according
to my invention in combination with a valve gear is illustrated as an example.
The valve a has the form of a double seat valve, the spindle b at its upper
extremity carries the buffer piston c in form of a plunger piston. The latter
in the example is of a W-formed section whereby into the inner central opening
extends a socket d' fixed to the buffer receptacle d.
Owing to this peculiar arrangement of parts the oil is prevented from leaving
the buffer receptacle, and air is not allowed to enter. The buffer-receptacle d
by means of a transverse wall d which is arranged somewhat inclined, is
separated into two parts, the upper one of which may be completely open. At
the highest part of this transverse wall d² I provide a valve e; I give an inclined
form to the wall for the reason, that the air, which in spite of the peculiar
arrangement may have entered, may easily leave the apparatus through the
valve e.
An angular projection or collar f is provided at the bottom of the
buffer receptacle. A perforation f regulated by/an adjusting screw f³ cor neets
the space within and outside of this projection.
When the valve and its piston c is raised, a complete vacuum will be created
within the buffer casing d, while between the piston e and the intermediate
wall a certain quantity of oil enters the buffer space from above. When the
valve is disengaged, the vacuum effects its descent. As soon as the empty
space is filled, the buffer piston removes the penetrated oil through the valve e
whereby, such as already mentioned, a certain brake-action is produced. Here-
after the piston centers the flat cylinder formed by the collar f and meets the
oil-cushion which is elastic to a certain degree when the perforation f¹ is adjusted.
Owing to this oil-cushion the closing movement of the valve can be retarded
shortly before the arrival of the valve upon its seat. The brake-action pro-
duced by the pumping outwards of the penetrated oil can be increased at con-
venience when a certain pressure is exercised upon the valve e. According to
the pressure exercised, (for instance by springs, weights or in other similar
manner), the resistance of the valve against the brake action, increases.
A. tube g connecting the upper chamber with the vacuum receptacle and pro-
vided with a cock h allows of a further regulation of the closing force by an
adjustment of the cock and thus a variation of the vacuum. When, for example,
the cock is slightly opened, a certain quantity of oil will be sucked from the top
chamber into the bottom vacuum receptacle of the dash-pot by the upward
movement of the piston.
The construction illustrated in the drawing shows the buffer in combination
with an inlet-valve for steam-engines. It is evident that the buffer also can be
applied to other valves and engines.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, what I desire to
claim is:-
1. In steam-engines, the combination of a valve gear with a vacuum apparatus
filled with liquid, the vacuum within the apparatus effecting the closure of the
valve.
2. In a valve-gear as per Claim 1, the combination of an oil buffer f within

page_text: a vacuum receptacle d having a adjustable inlet perforation f¹, substantially as
described.
3. In a valve-gear as per Claim 1, a valve e arranged within the cover d² of
the vacuum receptacle d, for the purpose as described.
4. In a valve-gear as per Claim 1, the arrangement of a valve e suitably
weighted for the purpose of increasing the brake-action produced on pumping
back the oil from the cylinder, substantially as described.
Dated this 18th day of September 1900.
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.