IMPROVEMENTS IN VALVE-GEARS
Year: 1884

page_text: I HERMANN BORGSMÜLLER, of 13, Lützowstrasse, Berlin, Prussia, German
Empire, Engineer do hereby declare the nature of my invention for IMPROVEMENTS
IN VALVE-GEARS to be as follows:-
-
In order to shift slide valve eccentrics, even when the resistances. are very
considerable, without fail perpendicularly to the crank shaft, so as to change the
eccentricity and the lead-angle and thereby the cut-off, I employ, according to the
method constituting my invention, the power exerted by the engine shaft itself,
whilst the governor has merely to introduce or instigate the changes and, being
moreover quite independent of reactions, always assumes a position corresponding
exactly to the velocity of the engine.
Conformably to the said method, the engine shaft as it rotates takes with it a
screw which, carrying a friction wheel at its free end, passes through a projection
on the eccentric and can be turned in a bolder secured to the crank shaft, but not
'displaced therein longitudinally. At every revolution of the shaft the friction
wheel passes between the two jaws of a slide, which permits of being shifted
through the agency of a governor in a guide below the crank shaft and in the
longitudinal direction of the latter, so that the friction. wheel rolls sometimes along
the one, and sometimes along the other jaw of the slide, turning thereby the said
screw now to the left and now to the right, the eccentric is in this manner caused
to pass to and fro, its centre being placed at different distances from the centre of
the engine shaft, thus changing its eccentricity and lead-angle, and consequently
also the cut-off, whilst the lead of the slide-valve remains nearly constant.
.
For shifting the aforesaid slide, a weighted governor may be arranged directly
upon the engine shaft and connected with the slide by levers and rods; or the
engine shaft may actuate an ordinary statical governor which by means of a lever
and rod imparts oscillating motion to an axis having a screw thread which gears
into a slanting groove at the underside of the slide. With this arrangement the
governor is entirely relieved from reactions during the adjustement of the eccentric
by the crank shaft.
The advantages of this method are the following: Slide-valves, including the
largest sizes, permit of being properly worked without balancing them, even when
the resistances are very considerable. Expansion-valves being superfluous, there is
less frictional resistance and less wear of the valves which consequently remain
longer in working order: ..

page_text: I, HERMANN BORGSMÜLLER of 13, Lützowstrasse Berlin, Prussia, German
Empire do hereby declare the nature of my invention for IMPROVEMENTS IN VALVE
GEARS and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
•
In order to vary in steam engines the cut-off of the steam by slide or lift valves
under a constant outside lead and in a quite exact proportion to the power required,
the eccentric is shifted at a right angle to the crank shaft on a straight guide upon
the latter. The power required for such shifting is exerted by the shaft itself.
And the governor has merely to instigate the shifting, thereby remaining quite
independent of reactions from the steam power. To this end the crank shaft as it
rotates takes with it a screw, carrying a friction wheel at its free end and passing
through an ear on the eccentric, so that the screw can be turned but not be dis-
placed. In such rotating with the crank shaft the friction wheel rolls sometimes
along the one and sometimes along the other jaw of a slide which is mounted upon
'a guide underneath the shaft and which can be moved to and fro in the direction
of the shaft by the play of the governor. This causes the friction wheel to turn
with its screw now to the right, now to the left, and so displace the eccentric upon
its guide. The lead angle and eccentricity of the eccentric are thereby simul-
taneously changed. To cut off the steam entering the cylinder sooner or later after the
piston having commenced its stroke, it is not necessary as in other valve gears, that
the governor balls assume greatly different positions, but the position of the balls
remains nearly the same, quite independent of the measure of resistance to be
overcome.
Figures 1, 2 and 3 of the accompanying drawing.show different views and
sections of the valve gear with its straight guide for the eccentric and its slide under
the shaft for the friction wheel to roll upon, the eccentric rod, not fully represented,
being connected with the slide valve rod in the ordinary manner, figure 4 shows]
this slide for the wheel from below.
The eccentric a is provided with a slot b and guided upon the straight guide c
which is fixed upon the crank shaft 8.
Through an ear d of the eccentric extends a screw e which can be turned in the
guide c, but not be displaced therein. The screw e carries on its free end a friction
wheel and rotates with the crank shaft. The friction wheel then passes between
the two jaws of the slide g which is mounted upon a guide / underneath the crank
shafts and which can be displaced in the longitudinal direction of the latter by
means of the governor h. To this end the governor is connected with the lever i
mounted upon an axis k in the guide of the slide g, and this axis carries a worm m
which enters a groove n on the underside of the slide g. By but little rising or
falling of the governor balls the slide g is therefore moved in the one or other
direction and consequently the friction wheel f in passing between the two curved
jaws t of the slide g will roll sometimes upon the one and sometimes upon the other
of these jaws. The screw e is thereby turned either to the right or left, the
eccentric a shiited upon its guide c and the steam entering the cylinder cut off

page_text: sooner or later after the beginning of the piston stroke according to the power
required. Curved rails a are preferably mounted on the jaws t upon elastic.
material and tho slide g is provided with plugs z entering eyes w of the guide, so
as to allow of shifting,
The friction wheel may be provided with a packing of compressed leather rings p,
so that it will roll noiseless upon the said rails.
Reaction against the governor h, that should be a statical one (preferably Porter's
system) is prevented by the worm m, and contrary to ordinary valve gears, not the
governor, but the crank shaft exerts the power for shifting the valves in their
stroke. The power of shifting can therefore be raised to more than the fiftyfold of
the direct power of the governor, and on the other hand, expansion valves and
other auxiliary parts are superfluous.
Moreover, as the cut off of the steam is effected only by very little rising or
falling of the governor balls, it is evident that the engine will always run, with
uniform speed. It needs not to run much faster or slower to give the governor
great power for enabling it to change the point of cut off as other valve gears
require. Slide valves including the largest sizes can by these means be properly
worked without balancing them, the connection of the eccentric rod a¹ with the
slide valve rod being as is the ordinary manner.
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
1) Shifting eccentrics at a right angle to the crank shaft on a straight guide upon
the latter by means of a screw mounted in said guide, extending through a part of the
eccentric and carrying at its free end a friction wheel which rotating with the shaft
passes between two jaws of a slide that can be shifted by the governor in the
direction of the shaft, so that the friction wheel will roll either upon the one or
other jaw and shift the eccentric on its guide by means of the said.
screw, substan-
tially as and for the purpose herein before described.
2) The improved valve gear for working valves herein before described and
represented in the accompanying drawings.
Dated this 7th day of September 1885.
"
HERMANN BORGSMÜLLER.