Improved Valve Gear for Oscillating Steam and other Motor Engines Worked by Compressed Air or other Fluid Pressure.
Year: 1891

page_text: Date of Application, 29th Dec., 1891
Complete Specification Left, 16th Aug., 1892-Accepted, 17th Sept., 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by PRAGER MASCHINENBAU ACTIEN GESELL-
SCHAFT, in Prague, Bohemia.]
Improved Valve Gear for Oscillating Steam and other Motor Engines
Worked by Compressed Air or other Fluid Pressure.
I, CHARLES DENTON ABEL of No. 28 Southampton Buildings, Chancery Lane
in the County of London, Chartered Patent Agent, do hereby declare the nature
of this invention to be as follows:-
This invention relates to apparatus for actuating the slide valve or other devices
for distributing the steam, air or gas in the oscillating cylinders of motor engines,
in which the motion is derived either from eccentrics or from the crank motion,
combined in a variable manner with the oscillating motion of the cylinder or with
a motion derived therefrom, whereby a compound motion is obtained which is
available for effecting variable expansion or for reversing the motion of the
engine.
I will proceed to describe various arrangements for carrying out the said invention
with reference to the accompanying drawings.
Fig. 1 shews a side elevation of an oscillating engine, in which the crank shaft
carries an eccentric a the ideal angle of which relatively to the crank is either
0° or 180°, and which is connected by means of the eccentric rod b to the pivot
piece h. This piece is guided either by a radius rod g or by sliding between
fixed guides, and is pivotted to a guide link c, the other end of which is connected
by a pivots to the rod x. This rod is pivotted to a lever v fixed on the regulating
shaft w actuated by a governor or by a reversing lever, so that by the turning of
the shaft w and lever through a certain angle, the path of the joints will be
correspondingly shifted.
To the hinge-joint is pivotted the guide link d, the other end of which is
pivotted at t to the sway beam f.
This is carried by a pivot fixed to the oscillating cylinder of the engine so as to
partake of the motion thereof and it has its other end connected to the slide valve
or other device for distributing the steam, air or gas under pressure to the
cylinder.
On the rotation of the crank-shaft, the joint t of the link d will, owing to the
above described connections, be made to describe closed curved paths which will
assume different forms, according to the position of the regulating lever v, or
according to the path of the joint s.
In Fig. 1 three such paths are shewn. The proportions of the gear are so chosen
that the points and coincide with each other at the middle position of the
cylinder, that is to say, for the two dead centre positions of the crank, this being
the case when the two links c and d are of equal length; as the motion of the
joint only depends upon the eccentric motion, the positions of the joint t which
correspond to the two dead centres of the crank, and consequently those of the
sway beam and of the distributing device are independent of the position of the
regulating lever v, and consequently all the different curves described by the point t
corresponding to the different positions of the regulating lever will intersect each
other at two points, which correspond to the lead positions of the distributing device
when opening to steam.
The distributing device consequently opens for both the dead centre positions of

page_text: the crank to an equal extent for the different positions of the regulating lever v,
that is to say, the linear extent of lead-opening is constant.
As the lever f assumes the same positions relatively to the cylinder for the
closing as those for the corresponding opening, the positions of the point t corre-
sponding to the closing positions of the distributing device will fall in the circular
ares (a) which can be described from the centre of, oscillation o of the cylinder
through the positions of the point t corresponding to the commencement of the lead-
opening. These arcs cut off different lengths from the curves described by t, so
that the duration of the opening, and consequently the degree of expansion will be
different for the several positions of the regulating lever.
On moving the lever from the right hand towards the middle position, corre-
sponding to the direction of rotation of the crank shaft marked "forward" on the
drawing, the cut-off will be increased, and will become a maximum on reaching the
middle position of v, the extent of filling then amounting to that due to the amount
of the lead only, and consequently nearly zero. On the further movement of the
lever " to the left, the extent of filling will be increased for the reverse motion of
the engine, indicated by "backward on the drawing.
For motor engines running only in one direction, the valve gear can also be so
arranged that the coincidence of the points h and t shall not correspond to the dead
centre positions of the cranks, but shall be in advance thereof to the extent of the
lead, in which case constant lead will be obtained, and the filling can be brought to
absolute zero.
The said valve gear permits of all degrees of filling from zero to full steam, and
is also suited for motor engines running in both directions.
The working of the distributing device can of course also be effected directly
from the joint t, in which case, with the same construction of the distributing
device, the eccentric would have to be in a position diametrically the opposite of
that shewn at Fig. 1.
The sway beam f can also be replaced by a slide working in guides as shewn by
way of example at y Fig. 3.
In order to allow of the joints h and t being constructed with simple pins passing
through them, a central arrangement of the links cd, in which the forces acting
thereon all lie in one and the same plane may be adopted by making the length of
the two guide links c and d unequal, as shewn at Fig. 2.
Of course with this arrangement the lead is not constant for all degrees of
expansion, but the variations will only be small, if the difference in the lengths
of the links is not too great.
Fig. 2 also shews the arrangement of the valve gear for a motor engine with main
and expansion slide valves.
•
The main slide is worked by the eccentric a by means of the guide links C, d which
in this case only serve for reversing, the variation in the expansion being effected
by shifting the laps of the expansion slide, which is worked from the eccentric a by
means of the radius rod g, coupling link m, radius rod. n, link q (which is used in.
place of a so called neutralising piece) and sway beam r.
The possibility of using a single eccentric for working both the main and the
expansion slide results from the fact that the eccentric is fixed on the shaft at an
ideal angle of 0° or 180° to the crank.
It will be readily seen that in the above described valve gear there may be
employed in place of the oscillating motion of the engine cylinder itself, an
oscillation derived therefrom. Fig. 3 shews such an arrangement in which the
guide link d is connected to a lever which, on the one hand is connected by a
pin y sliding in guides on the engine cylinder and actuating the distributing device,
and on the other hand is connected to the radius rod k working on a fixed centre.
As, with the arrangement at Fig. 3, the middle position of the eccentric rod does
not lie in the plane passing through the axes of the crank shaft and of the cylinder
trunnions, the actual angle between the eccentric and the crank will have to vary

page_text: from the ideal angle of 0° or 180° to the extent of the angle formed by the middle
position of the eccentric rod, with the said plane passing through the crank shaft
and trunnion axes.
Dated thie 29th day of December 1891
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Valve Gear for Oscillating Steam and other Motor Engines
Worked by Compressed Air or other Fluid Pressure..
I, CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery
Lane, in the County of London, Chartered Patent Agent, 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 apparatus for actuating the slide valve or other devices
for distributing the steam, air or gas in the oscillating cylinders of motor engines, in
which the motion is derived either from eccentrics or from the crank motion, com-
bined in a variable manner with the oscillating motion of the cylinder or with a
motion derived therefrom, whereby a compound motion is obtained which is
available for effecting variable expansion or for reversing the motion of the
engine.
I will proceed to describe various arrangements for carrying out the said
invention with reference to the accompanying drawings.
Fig. 1 shews a side elevation of an oscillating engine, in which the crank shaft
carries an eccentric a the ideal angle of which relatively to the crank is either
0° or 180°, and which is connected by means of the eccentric rod b to the pivot
piece h. This piece is guided either by a radius rod g or by sliding between fixed
guides, and is pivotted to a guide link c the other end of which is connected by a
pivot s to the rod a. This rod is pivotted to a lever v, fixed on the regulating
shaft to actuated by a governor or by a reversing lever, so that by the turning of
the shaft w and lever through a certain angle, the path of the joint s will be
correspondingly shifted.
C
To the hinge joint s is pivotted the guide link d, the other end of which is pivotted
at t to the sway beam f
This is carried by a pivot I fixed to the oscillating cylinder of the engine so as to
partake of the motion thereof and it has its other end connected to the slide valve
or other device for distributing the steam, air or gas under pressure to the
cylinder.
On the rotation of the crank-shaft, the joint t of the link d will, owing to the
above described connections, be made to describe closed curved paths which will
assume different forms, according to the position of the regulating lever v, or
according to the path of the joint 8.
In Fig. 1. three such paths are shewn. The proportions of the gear are so chosen
that the points h and t coincide with each other at the middle position of the
cylinder, that is to say, for the two dead centre positions of the crank, this being
the case when the two links c and d are of equal length; as the motion of the
joint only depends upon the eccentric motion, the positions of the joint t
which correspond to the two dead centres of the crank, and consequently those
of the sway beam f and of the distributing device are independent of the position
of the regulating lever v, and consequently all the different curves described by the
point corresponding to the different positions of the regulating lever will
intersect each other at two points, which correspond to the lead positions of the
distributing device when opening to steam.
The distributing device consequently opens for both the dead centre positions of

page_text: the crank to an equal extent for the different positions of the regulating lever v,
that is to say, the linear extent of lead-opening is constant.
As the lever assumes the same positions relatively to the cylinder for the closing
as those for the corresponding opening, the positions of the point t corresponding to
the closing positions of the distributing device will fall in the circular ares (a ß)
which can be described from the centre of oscillation o of the cylinder through the
positions of the point t, corresponding to the commencement of the lead-opening.
These arcs cut off different lengths from the curves described by t, so that the
duration of the opening, and consequently the degree of expansion will be different
for the several positions of the regulating lever.
"
On moving the lever from the right hand towards the middle position, corre-
sponding to the direction of rotation of the crank shaft marked "forward
on the
drawing, the cut off will be increased, and will become a maximum on reaching the
middle position of v, the extent of filling then amounting to that due to the amount
of the lead only, and consequently nearly zero. On the further movement of the
lever v to the left, the extent of filling will be increased for the reverse motion of
the engine, indicated by " backward on the drawing.
For motor engines running only in one direction, the valve gear can also be so
arranged that the coincidence of the points h and t shall not correspond to the dead
centre positions of the cranks, but shall be in advance thereof to the extent of the
lead, in which case constant lead will be obtained, and the filling can be brought to
absolute zero.
The said valve gear permits of all degrees of filling from zero to full steam, and
is also suited for motor engines running in both directions.
The working of the distributing device can of course also be effected directly
from the joint t, in which case, with the same construction of the distributing
device, the eccentric would have to be in a position diametrically the opposite of
that shewn at Fig. 1.
The sway beam ƒ can also be replaced by a slide working in guides as shewn by
way of example at y Fig. 3.
In order to allow of the joints h and t being constructed with simple pins passing
through them, a central arrangement of the links cd, in which the forces acting
thereon all lie in one and the same plane may be adopted by making the length of
the two guide links c and d unequal, as shewn at Fig. 2.
Of course with this arrangement the lead is not constant for all degrees of
expansion, but the variations will only be small, if the difference in the lengths of
the links is not too great.
Fig. 2 also shews the arrangement of the valve gear for a motor engine with
main and expansion slide valves.
d
The main slide is worked by the eccentric a by means of the guide links
which in this case only serve for reversing, the variation in the expansion being
effected by shifting the laps of the expansion slide, which is worked from the
eccentric a by means of the radius rod 9, coupling link m, radius rod link
n,
(which is used in place of a so called neutralising piece) and sway beam r.
q
The possibility of using a single eccentric for working both the main and the
expansion slide results from the fact that the eccentric is fixed on the shaft at an
ideal angle of 0° or 180° to the crank.
It will be readily seen that in the above described valve gear there may be
employed in place of the oscillating motion of the engine cylinder itself, an
oscillation derived therefrom. Fig. 3 shews such an arrangement in which the
guide link dis connected to a lever which on the one hand is connected by
a pin y sliding in guides on the engine cylinder and actuating the distributing
device, and on the other hand is connected to the radius rod k working on a fixed
centre.
As with the arrangement at Fig. 3, the middle position of the eccentric rod does
not lie in the plane passing through the axes of the crank shaft and of the cylinder

page_text: trunnions, the actual angle between the eccentric and the crank will have to vary
from the ideal angle of 0° or 180° to the extent of the angle formed by the middle
position of the eccentric rod, with the said plane passing through the crank shaft
and trunnion axes.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. Excentric and link gear for motor engines with oscillating cylinders for
varying the cut off or reversing, or both for varying the cut off and for
reversing, wherein link gear such as c d Figs. 1 2 3, receives the motion of an
excentric or crank a through a pin h moving in a definite path, and is made to
actuate the fluid pressure distributing valve or slide of the engine through a
pin t which participates in the oscillation of the engine cylinder or in a motion
derived therefrom, the path of the pivot a common to the links c and d being
actuated by the engine governor or by the reversing lever, for effecting a
variation of the cut off, or the reversal of the engine, substantially as described
with reference to the drawings.
2. The combination of the mechanism referred to in the preceding claim, with an
expansion gear in such manner that the excentric which actuates the main slide
through the link gear c d is also made to work the expansion slide, substantially as
described with reference to Fig. 2 of the drawings.
Dated this 16th day of August 1892.
ABEL & IMRAY,
Agents for the Applicant.