IMPROVEMENTS IN ROTARY SLIDE VALVES
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Imray at the Office of the
A communication
Commissioners of Patents on the 15th November 1879.
'
from abroad by Wilhelm Siller, of Berlin, in the German Empire.
JOHN IMRAY, of No. 28, Southampton Buildings, Chancery Lane, in the County
of Middlesex. "IMPROVEMENTS IN ROTARY SLIDE VALVES." [A communication
from abroad by Wilhelm Siller, of Berlin, in the German Empire.]
This Invention relates to a construction, arrangement, and mode of working
rotary slide valves applicable for governing the ingress and egress of steam or other
working fluid in engines, or of water or other fluid in pumps; the object being to
obtain full passage for the fluid in small space, and rapidity of action in alternating
the passages. As an illustration of the Invention the slide valve for a double acting
steam cylinder may be thus described. At the side of the steam cylinder is a
cylindrical cavity constituting the slide jacket having a steam supply passage to its
middle and steam discharge passages at each end. Centrally within this jacket is
mounted an axis which can be caused to revolve or to turn partly round to and fro
by external mechanism, the axis for this purpose being extended through stuffing
boxes in the ends of the jacket. On this axis are fixed two discs coned a little on
their outer periphery so as to fit correspondingly coned seatings in the jacket.
These discs separate the jacket into three compartments, the middle compartment
being that of supply, and the two end compartments being for exhaust. In
the thickness of each disc are formed two sets of alternating radial cavities, both
open mouthed at the periphery of the disc, the one set opening on the one face of
the disc from the supply compartment, and the other set similarly opening on the
opposite face of the disc to the exhaust compartment. Around the seating of each
dise there is formed in the casing of the jacket an eccentric annular passage opening
at its widest part to the steam port, and having apertures in its inner periphery
corresponding in number with that of one set of the cavities in the disc. When by
turning the axis of the discs one set of these cavities is brought to face the apertures
of the annular passage, steam flows to the cylinder port, all passage for exhaust
being closed; and when by turning the axis partly round the other set of
cavities of the disc are brought to face the apertures of the annular passage,
exhaust flows from the cylinder port; all passage for supply being closed. Thus
by turning the disc axis round either by a rotation always in one direction or by &
partial rotation to and fro, the steam supply and exhaust is alternated at both ends

page_text: of the cylinder. As the one disc may be made larger in area than the other for
convenience of introducing the slide into the jacket the pressure will tend to slack
the discs off their seatings, but their tightness thereon can be adjusted by an
external setting screw bearing against the end of the extended axis. The
movement of rotation may be imparted to the axis in the following manner:-On
the extended external part of the axis is fixed a toothed wheel or segment which
gears with cam grooves in the periphery of a wheel on the engine shaft. As this
wheel revolves the oblique portions of these grooves cause the toothed wheel to
turn partly round, whilst the portions that are not oblique retain the wheel
stationary. This wheel may be loose on its shaft and driven by stops so as to
reverse the engine by changing the relative position of the wheel on its shaft.
A similar arrangement of coned discs and apparatus for turning them is obviously
applicable to pumps worked from a revolving shaft. Also a similar construction of
slide having dises with only one set of radial cavities can be used as an expansion
or cut off valve in conjunction either with a rotary slide of the kind above described,
or with known slides of other kinds. Farther, instead of fixing both discs upon
one axis in a jacket parallel to the cylinder, two discs may be fixed on each of two
separate transverse axes, one at each end of the cylinder, and near each such axis
may be arranged a rotary expansion slide of the kind described.
When this arrangement is adopted in order to avoid large clearance spaces in the
cylinder ports, the cylindrical slide jackets may project partly into the body of the
cylinder at each end thereof, the piston being made with hollows to clear them at
each end of its stroke.