Improvements in Valves for Compound Engines.
Year: 1895

page_text: Date of Application, 2nd Apr., 1895-Accepted, 4th May, 1895
COMPLETE SPECIFICATION.
Improvements in Valves for Compound Engines.
I, ELLIS JAMES WOOLF, of 912 Guaranty Loan Building, Minneapolis, in the
State of Minnesota, United States of America, Mechanic, 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 said invention relates to valves for compound engines of such construction
as to minimize the drag upon them.
For this purpose the valve and valve seat are situated in a chest containing
low pressure fluid, and the ports are so arranged as to distribute the high
pressure fluid from a limited area under the valve, so that the low pressure
fluid above the valve, holds the valve down to its seat, and substantially balances
the pressures acting on it.
The invention is illustrated in the accompanying drawings in which like letters
and numerals refer to like parts.
Fig. 1 is a part longitudinal section through a double acting compound engine,
having a trunk piston, illustrating one form of the invention, the valve being shown
in its central position.
Fig. 2 shews the valve in a different position.
Fig. 3 is a longitudinal section, through a double acting compound engine having
the cylinders set tandem, illustrating a modified form of the invention, with the
valve shewn in its central position.
Fig. 4 shews the valve in a different position.
Fig. 5 is a section of part of an engine, similar to that shewn in Fig. 3
illustrating another form of the invention, with the valve shewn in its central
position.
Referring first to Figs. 1 and 2, 1 is the cylinder 2 a pair of pistons attached
to the trunk 3, which works through the central packing 5, 6 is the piston rod.
The pistons 2, trunk 3 and partition 5 divide the interior of the cylinder 1 into
the high pressure cylinder spaces 7 and the low pressure cylinder spaces 8. In the
valve-chest 9, are the valve-seat 10 and the valve 11 which is operated by the
rod 12 from any suitable valve gear.
The valve seat 10 has a central supply port a two high pressure ports b, one on
each side of the supply port a, two low pressure ports c, near the outer ends
of the seat, and exhaust ports d directly between the high and low pressure
ports.
The valve 11 has a central section f with a cavity f¹, which co-operates with
the supply port a and the high pressure ports b, to distribute the high pressure
fluid; and has a pair of outside sections g, each with cavity g', which co-operate
with the ports c d to distribute the low pressure fluid. The said three valve
sections fgg are all rigidly connected together being integral with the valve.
Through the valve 11 there is also a pair of passages h, which co-operate with
the ports b, permitting low pressure fluid on its way from to c to pass through
the valve to the space above it on its way from the high to the low pressure
cylinder ends.
When the valve is in the position shown in Fig. 2, at the extreme of its left
hand travel, the high pressure fluid enters by a f¹ and b to the left hand high
pressure cylinder space 7; the low pressure Huid from the right hand cylinder
space 7 passes by and into the case 9, and thence, through the right hand
го

page_text: port c to the right hand low pressure cylinder space 8; and the exhaust takes
place from the left hand low pressure cylinder space 8 through the left hand
set of ports c g'd to the atmosphere. When the valve is moved to the right
to the opposite extreme of its travel, the corresponding actions take place through
the proper ports, for the opposite cylinder spaces.
Thus the high pressure fluid is distributed over a comparatively small area
below the valve, and there is always low pressure fluid above the valve, in the
valve-chest 9, this low pressure being made to overcome the high pressure on the
limited area below the valve, by simply making the relative areas above and
below in proper proportions; the low pressure fluid holding the valve down to its
seat and substantially balancing the pressures on it. A balanced valve is thus
obtained without requiring any appliance beyond the valve itself, and the valve
may therefore be made of any size required to obtain ports of proper area while
the drag on the valve may be reduced to a minimum giving corresponding freedom
of action and economy of work.
Referring now to Figs. 3 and 4, the principle involved is the same, but the form
of the valve and the arrangement of the ports is slightly different from that
described. 13 and 14 are the high and low pressure cylinders set tandem.
15 and 16 the pistons on a common piston rod 17, working through the removable
partition 13 between the two cylinders. The pistons 15 and 16 divide the
cylinders into the high pressure spaces 18 and the low pressure spaces 19. The
valve chest 20 is on the low pressure cylinder 14 and in it is the valve seat 21 and
the valve 22 operated by the rod 23. The valve seat 21 has a supply port a', high
pressure ports b¹ low pressure ports c¹ and exhaust port d'. The valve 22 has a
supply port or passage a³, the left end of which is always in communication with
the supply port a' and the right end of which co-operates with the ports b', to
distribute the high pressure fluid. The valve 22 has also a pair of passages or
openings which communicate laterally with the valve chest 20 and co-operate
with the ports c¹ to distribute the low pressure fluid; the valve also has a central
cavity which co-operates with the ports c¹ and the exhaust port d'.
When the valve 22 is moved to the right to the extreme of its travel, as shown
in Fig. 4, the high pressure fluid passes from the supply port a¹ through a³, to the
outer high pressure port b', and thence to the inner high pressure cylinder space 18;
the low pressure fluid from the outer high pressure cylinder space 18 passes from
its port through the right hand passage into the chest 20 and thence through
the other passage and the left hand low pressure port c' to the left hand low
pressure cylinder space 19; and the valve cavity dis in position to permit the
exhaust from the right hand low pressure cylinder space 19 through the ports c¹ d² d'.
When the valve is moved to the left, the corresponding actions take place for the
opposite cylinder ends. Thus low pressure fluid acts above the valve while high
pressure fluid is distributed over a limited area below the valve, so that the valve
is held down to its seat and yet substantially balanced in respect of pressure.
According to the further modification shewn in Fig. 5, 24 is the valve chest,
25 the valve seat, 26 the valve and 27 the valve rod. The valve seat 25 has a
pair of supply ports a³, a pair of high pressure ports 63, a pair of low pressure
ports c, and a single central exhaust port d³. The valve 26 also has a pair of
outside sections with cavity f³, a central section with cavity, and a pair of
passages between the sections. The sections with their cavities f³ co-operate
with the sets of ports ab, to distribute the high pressure fluid; the central
section and the passages / co-operate with the chest 24 and the ports c², to
distribute the low pressure fluid and admit it over the valve, on its passage from
the high to the low pressure cylinder spaces and the central valve cavity g
co-operates with the ports c, and the exhaust port ds to effect the exhaust.
The arrangement shewn in Fig. 5, may be regarded as the inverse of that shewn
in Figs. 1 and 2 involving merely such changes as are incidental to the substitution
of the two supply ports a³ and the single exhaust port d, for the single supply
port a and the two exhaust ports d. In this case also the high pressure fluid is

page_text: distributed over a comparatively small area below the valve, and the low pressure
fluid acts over the valve, to hold it to the seat substantially balancing the pressures
on it.
As a common principle of construction and a common result are thus involved
in all three of the forms of the invention, the remarks made as to the arrangement
shewn in Figs. 1 and 2 apply with equal force to the arrangement in Figs. 3 and 4,
and to the arrangement shewn in Fig. 5 of the drawings.
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 :-
:-
An arrangement of valve, valve-seat, valve chest and ports of a compound
engine such that the high pressure fluid acts on a limited area below the valve,
and low pressure fluid passing from the high to the low pressure cylinder acts
above the valve holding it to its seat and balancing the pressures thereon
substantially as described.
Dated this 2nd day of April 1895.
ABEL & IMRAY,
Agents for the Applicant.
ABEL & IMRAY,
Agents for the Applicant.