Improvements in Slide or Distribution Valves of Steam Engines.
Year: 1891

page_text: Date of Application, 29th Dec., 1891
Complete Specification Left, 29th Sept., 1892-Accepted, 17th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Slide or Distribution Valves of Steam Engines.
I ALFRED BLECHYNDEN of Cavendish Park Barrow-in-Furness in the County
of Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:-
The object of the invention is to secure greater economy of steam in engines by
filling the ports and the clearance space of the cylinder, as well as a part of the
working cylinder at the one side of the piston with steam released from the other
side of the piston, while securing an early effective release of steam. For this
purpose I make a valve with clearance or negative lap" on the inside or exhaust
edges and in order to direct the steam as it exhausts from one end into the other, I
make the valve with a passage over the exhaust cavity of the valve which may
consist of a suitably formed plate fixed in the inside or exhaust side of the valve.
The edges of this plate next to the cylinder faces may be, and are by preference,
made clear of the cylinder faces, to direct the escaping steam to the side of the
piston opposite that from which the steam is being released, it may also serve as a
partial exhaust passage when the port at the compression side of the valve is closed.
The effect of this, is to fill the clearance and ports at the compression side of the
piston with steam of a pressure and temperature but slightly different from the
pressure and temperature of release which may be compressed to a still higher
pressure before the period of admission. The directing passage may be of any
suitable form and may either be cast in the valve or be formed by a plate fixed to
the same, and is equally applicable to valves exhausting at the outer edges, to
double ported valves and to slide valves of the piston description.
Dated this 26th day of December 1891.
ALFRED BLECHYNDEN.
COMPLETE SPECIFICATION.
Improvements in Slide or Distribution Valves of Steam Engines.
I, ALFRED BLECHYNDEN of Cavendish Park, Barrow-in-Furness, in the County
of Lancaster, 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 :-
The object of the invention is to secure greater economy of steam in engines by
filling the ports and the clearance space of the cylinder, as well as a part of the
working cylinder at the one side of the piston, with steam released from the other
side of the piston while securing an early effective release of steam. For this
purpose I make a valve with clearance, or "Negative Lap," on the inside or exhaust
edges and in order to direct the steam as it exhausts from one end into the other I
make a valve with a passage over the exhaust cavity of the valve which may
consist of a suitably formed plate fixed in the inside or the exhaust side of the
valve. The edges of this plate next to the cylinder faces may be, and are by
preference, made clear of the cylinder faces to direct the escaping steam to the side
of the piston opposite that from which the steam is being released; it may also
serve as a partial exhaust passage when the port at the compression side of the
valve is closed.
The effect of this is to fill the clearance and ports at the compression side of the
piston with steam of a pressure and temperature but slightly different from the
pressure and temperature of the release, which may be compressed to a still higher

page_text: pressure before the period of admission. The directing passage may be of any
suitable form and may either be cast in the valve, or be formed by a plate fixed to
the same, and is equally applicable to valves exhausting at the outer edges, to
double ported valves, and to slide valves of the piston description.
DESCRIPTION OF DRAWINGS.
On the accompanying 3 sheets of drawings my invention is illustrated as it may
be carried into practical application.
On Sheet 1. Figs. 1. 2 and 3 shew respectively a longitudinal section, transverse
sections and face plan of a valve for an ordinary single ported cylinder admitting
steam from the steam chest to the cylinder from the outside edge at one end and
from the other end by a steam pass-over port the valve being shewn in its central
position and shewing the clearance (or "negative lap") on the inside or exhaust
edges. A A are the steam ports and B the exhaust cavity in the cylinder face.
C is the pass-over port for steam from the opposite end to supplement the steam
supply, as in the "trick-valve," D is the pass-over port or passage over the exhaust
cavity E in the valve, by means of which, combined with the clearance F on the
exhaust side, the cylinder port and clearance space, as also a portion of the cylinder
at one side of the piston, are filled with steam released from the other side of the
piston of a pressure and temperature but slightly different from that of the released
steam, which may be compressed to a still higher pressure before the period of
admission of steam from the boiler, the clearance F, through the port D, giving an
early effective release of steam on the exhaust side in conjunction with the exhaust
cavity E in the valve.
On Sheet 2. Figs. 4. 5 and 6 shew respectively a longitudinal section, transverse
sections and half face and back plans of a valve adapted for a double ported
cylinder in which A A-A' A' are the four ports and B the exhaust cavity in the
cylinder face, D is the pass-over port or passage formed over the exhaust cavity E
in the valve by means of which exhaust steam passes from one side of the piston to
the other to fill the ports and clearance space as also a portion of the cylinder.
In this construction the edges G of the diaphragm or division plate forming the
passage over the exhaust cavity are shewn clear of the face of the cylinder serving
not only to direct the escaping steam from one side of the piston to the opposite
side but also serving, by means of the inside clearance F, as a
partial exhaust
passage when the inside port (A or A¹) is closed. The extent of this clearance
may be adjusted to give the required compression.
On Sheet 3 my invention is shewn as adapted for application to a piston valve
Fig. 7 being one half in section and the other half in elevation and Fig. 8 a
sectional plan through 1-2 of Fig. 7. A A are the steam ports and B the
exhaust cavity in the cylindrical valve chest. D is the pass-over port or passage
over the exhaust cavity E in the valve, to pass exhaust steam to the opposite side
of piston, the edges G of the diaphragm or division plate being as previously
described clear of the lining forming the port faces A. A of the cylinder for the
purpose stated with reference to Figs. 4, 5 and 6 on Sheet 2.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. The improvements in slide or distribution valves consisting in forming the
valve with clearance or "negative lap" on the exhaust edges and with a passage
over the exhaust cavity divided therefrom by a diaphragm cast with or fitted into
the valve, the edges of which next the cylinder face are by preference made clear
of said face but may work close up to the face; with the objects hereinbefore set
forth and operating substantially as described.
2nd. The modified forms of my invention as applied to valves constructed as
shewn by Figs. 1. 2 and 3 Sheet 1, and 4, 5 and 6-Sheet 2 of the drawings

page_text: herewith, adapted for single and double ported cylinders respectively, and shewing,
in the latter case, the edges of the diaphragm clear of the cylinder face to give
greater freedom of exhaust and adjusted to the required compression substantially
as described and shewn.
3rd. The modified form of my invention as applied to piston slide valves
substantially as described and shewn by Figs. 7 and 8 Sheet 3 of the drawings
herewith, or in which the edges of the diaphragm may work close up to the
cylinder face.
Dated this 20th dow of Santember 1802
T. J. DANSON, F. Inst. P.A.,
Chartered Patent Agent,
Newcastle-upon-Tyne, Agent for Applicant.
T. J. DANSON, F. Inst. P.A.,
Chartered Patent Agent,
Newcastle-upon-Tyne, Agent for Applicant.