US790115A - Relief-valve. - Google Patents

Description

No. 790,115 PATENTED MAY16,1905.

J. L. DOHBRTY.

RELIEF VALVE.

APPLIOATION FILED JAN. 13, 1905.

UNITED ST ATEs Patented May 16, 1905.

PATENT OFFICE.

RELIEF-VALVE.

SPECIFICATION forming part of Letters Patent No. 790,115, dated May 16, 1905. Application filed January 13, 1905. Serial No. 240,908.-

To all whom it may concern.-

Be it known that I, J OHN L. DOHERTY, a citizen of the United .States, residing in Baton, Territory of New Mexico, have invented certain Improvements in Relief-Valves, of which the following is a specification.

time causing a reduction of wear on the engine.- It is further desired to provide a valve which shall while accomplishing the abovenoted objects also serve to automatically per- Init of the discharge of water from either one or both of the cylinders.

It has frequently been noted that compound locomotive-engines of all types had their cylinders, pistons, or cylinder-heads broken or cracked when drifting or directly thereafter, 25

and this I believe to have been due to the freezing action caused by the expansion ofthe air in the cylinders after the steam had. been cut off and the subsequent admission'to such cooled cylinders of a fresh supply of ing drawings, in which Figure is a sectional elevation of the preferred form of my improved valve, and Fig. 2

is a sectional plan view of the valve shown in Fig. 1 and taken on the line 2 2 of said figure.

In the above drawings, Ais a casting in form not unlikethe well-known pipe-cross,

havin four tubular branches to a, a and a of which the first is threaded, so as to permit of its being screwed into one of the cylinderheads of the engine, while the three remaining branches are threaded to receive unions,

to the compound engine on which the device is employed. Within the casting are two partitlons a, intersecting one another so as to form a separate chamber for each of the branches at a, &c., while the upper portion of said casting A is formed as a cylinder (0*, open at one end and having within it a piston or plunger 5, fixed to a spindle B, hereinafter referred to.

Screwed upon what is the under face of the casting A is a second casting (3, having within it two cylindrical recesses c and c of different diameters. into the first of which open the various chambers of the casting A. There is, however, in the cylinder 0 a valve 6, acting upon a suitable seat so as to prevent communication when in its elevated position between the above-noted chambers of the casting A. Attached to or formed integral with the valve 6 is a piston 6 operating in the cylinder 0, said piston being in the present instance held to said valve 6 by means of a nut o screwed upon a spindle b, which should preferably be formed integral with said valve. It will be noted that the spindle B is also attached to the valve t,- so that it and the two pistons b and b are rigidly connected. There are two passages 6 extending through the valve hand each is provided with a check-valve 6, whereby communication may be automatically established through the cylinder 0 between the chambers connected'to branches (0 and (0 whenever the pressure in said cylinder exceeds that in said chambers. The area of the check-valve openings is such that when one of the valves 6 is open air can pass from cylinder 0 into one of the chambers faster than it can leak into the said cylinder. In order that there may be no possibility of the valve 6 turning relatively to the various chambers a a, &c., I form a slot 6 in the side of the piston b and provide a set-screw, passing through the wall of the casting O and entering said slot.

Under operating conditions the cylinder a is connected to the starting-valve of the locomotive by means of a pipe (not shown) which communicates with said cylinder through an opening (4 while the cylinderc' is similarly connected to a source of steam-supply by means of a pipe coupled to a threaded projection 6.

There are openings b on the sides of the castingC,whereby theinterior of the cylinderc and the various chambers of the casting A may be placed in communication with the atmosphere, and I- also provide a small opening 5 through the casting C for the discharge of water or steam leaking past the rings of the piston 6 When in use, the branch (I, of the device may be screwed into the front head of the high-pressure cylinder, while the branch at is connected to the rear end of the same cylinder. Similarly the branches a and a are respectively connected to the front and rear heads of the low-pressure cylinder or to the passages or chambers communicating therewith. If desired, the appropriate branch may be screwed into the front low-pressure cylinder-head.

It will be understood that the area of surface of the valve 7) exposed to fluid-pressure exerted in the various chambers a a, &c., is made to bear a definite relation to the area of its under face which is exposed to atmospheric pressure within the cylinder 0, as well as to the areas of the pistons b and b, the design of the device being such that as soon as steam is admitted to the steam-chest of the engine pressure is exerted upon the piston Z2 which'causes the valve 6 to seat against the partitions a, and the body of the casting A, so as to cut off communication between the various chambers in said casting. Under these conditions steam enters the chambers communicating with the branches (6 a, &c., in the first of these branches acting upon the valve Z) at apressure practically equal to that in the steam-chest. The pressure in the branches a and c is the pressure at which steam is exhausted from the high-pressure cylinder and delivered to the low-pressure cylinder, while that in the chamber connected to the branch (4 is equal to the back pressure from the engine. Owing to the atmospheric pressure upon the piston b there is also a downward pressure transmitted through the spindle B, which tends to force the valve 6 away from its seat. On the other hand, force is exerted in an opposite direction by the atmospheric pressure acting upon the under face of valve 6 and by steam at full pressure acting upon the piston 5 the result being that under the conditions noted, which are those found when in operation, the valve 6 is kept seated and the engine operates in the well-known manner. Similarly when working simple the valve 6 is kept seated, it being understood that under these conditions steam at full pressure is admitted to the under side of piston 5 through the pipe connected to the opening a. As soon, however, as steam is shut off from the steamchest the pressure falls in cylinders c and (0*, as well as in the various chambers communieating with branches (6 a, &c. Under these conditions the valve 7) would still be held to its seat by the atmospheric pressure upon its under face were it not that the check-valves I) open and permit said valve 7/ to fall from the position shown in Fig. 1 to the bottom of cylinder 0, thereby placing the four ends of the two cylinders in communication with the atmosphere and with each other. It will be understood that this is the condition which exists when the engine is drifting, so that any excessive expansion of the air in the cylinders and consequent cooling are certainly prevented. Considering, for example, the case of a Vauclain compound engine in which the high-pressure piston is at the front end of the cylinder ready to begin its backward stroke, the relief-valve will be open, and as the piston moves back air will be drawn into the front end of the cylinder through the branch (0 of said relief-valve throughout the entire stroke. \Vhen the piston starts on the return stroke, air will similarly be drawn into the rear end of the cylinder through the branch a of the valve, and the air in the front end will be delivered through the steam-chest to the rear end of the low-pressure cylinder, it being noted that air continues to [low to the front end of the high-pressure cylinder through the branch (L until the pressure therein is equal to that of the atmosphere.

hen the point of cut-off is reached, it will be noted that by far the greater part of the air still in the high-pressure cylinder is forced through branch (0 and cylinder 0 into the branch (6 of the casting A, and hence into the rear end of the low-pressure cylinder. The advantage of this action will be appreciated by those skilled in the art when it is remembered that the air so entering the low-pressure cylinder is warmed by its passage through the high-pressure cylinder and steam-chest, with the result that excessive fall of temperature and pressure in the low-pressure cylinder is thereby prevented. If the engine under consideration be of the balanced compound type, the warmed air will pass from the front end of the high-pressure cylinder into the front end of the low-pressure cylinder.

As soon as the throttle of the engine is opened the valve 7) is immediately seated by the action of the steam upon the piston I), and the engine is thereby permitted to operate under normal conditions. If at any time while the engine is in operation there is suilicient water in the cylinders to cause excessive pressure, this is at once exerted upon the valve 6, which is forced from its seat against the action of the steam-pressure in the cylinders c and (t and the water allowed to escape from the openings 5 I claim as my invention- 1. A relief-valve for compound engines including a casing having four communicating chambers,.means whereby said chambers may to automatically cut off communication be tween the chambers and movable by pressure exerted in said chambers, said valve having a cylinder connected to a source of steam-pressure, substantially as described.

2. A relief-valve including a casing having within it four communicating chambers respectively connected to the ends of thecylinders of a compound engine, and a valve for automatically cutting off communication between said chambers, said casing having a cylinder connected with the steam-chest of the engine and a piston in the cylinder operative on the valve, said valve being movable by pressure exerted in said chambers, substantially as described.

3. A relief-valve includinga casing having within it a plurality of communicating chambers respectively connected/to the ends of an engine cylinder or cylinders, and a valve for cutting off communication between said chambers, said casing having a cylinder connected with the steam-chest of the engine and a piston in the cylinder operative on the valve, said valve being movable by pressure exerted in the chambers, with a check valve or valves for permitting fluid to pass from the cylinder to the chamber or chambers, substantially as described. a

4:. A relief-valve including a structure having two cylinders, a plurality of communicating chambers, and means for connecting said chambers to the ends of an engine cylinder or cylinders, a valve in one of the cylinders of said structure constructed to cut of]? communication between the chambers, and a piston connected to the valve and operative in the second cylinder of the casing, substantially as described.

5. A relief-valve including a structure having two cylinders, a plurality of communicating chambers, and means for connecting said chambers to the ends of an engine cylinder or cylinders, a valve in one of the casingcylin ders constructed to cut oil communication between the chambers, a piston connected to the valve and operative in the-second cylinder of the casing, with a check valve or valves in the first valve placed to control the flow of fluid from the valve-cylinder to a chamberor chambers, substantially as described.

6. A relief-valve for compound engines including a structure having a cylinder, a plurality of communicating chambers, and means for connecting two of said chambers to the ends of the high-pressure cylinder and the other two chambers to the ends of the lowpressure cylinder, a valve for cutting oil communication between the chambers, means for causing said valve to be pressed to its seat by steam under'pressure, and means for causing the valve to open when the pressure in the chambers connected to the low-pressure engine-cylinder falls to a predetermined point, substantially as described.

7 A valve including a casing having four chambers, a cylinder communicating therewith and provided with atmospheric ports, and a valve in said cylinder for cutting off communication between the various chambers, there being a cylinder in the casing connected to a source of supply for steam, and a piston therein connected to said valve, with means for connecting the four chambers of the casing respectively to the ends of the cylinders of a compound engine, substantially as described.

8. A valve including a casing having four chambers respectively connected to the ends of the high and low pressure cylinders of a compound engine, a cylinder communicating with all of said chambers and having in it a valve for cutting ofl communication between said chambers, a check valve or valves in said main valve constructed to permit fluid to flow from the cylinder into a definite chamber or chambers, means for preventing rotation of the valve, and means for pressing said valve to its seat, substantially as described.

9. Arelief-valve including a casing having a plurality of chambers, a cylinder open to the atmosphere and communicating with said chambers, a second cylinder connected to a source of steam-supply, a valve in the first cylinder for cutting off communication between the chambers, a piston in the second cylinder connected to said valve, with means for automatically establishing communication between a chamber or chambers and the first cylinder when the pressure in said chamber falls to a predetermined point, and means for connecting the respective chambers of the casing to the four cylinder ends of a cornpound engine, substantially as described.

10. A relief-valveincludinga casing having three cylinders and a plurality of chambers for connection to the ends of an engine cylinder or cylinders, two of said casing-cylinders having means for connecting them to sources of supply of steam under pressure, and the third having an atmospheric port or ports, pistons in the first two cylinders, and avalve in the third cylinder connected to said two pistons, said valve being constructed to cut off or establish communication between the various chambers depending upon the pressure in the first two cylinders, substantially as described.

11. The combination of a casing having four tubular branches for connection to the cylinders of a compound engine and partitions forming chambers in communication with said branches, a valve fitting against the ends of the partitions for controlling communication between the chambers, and a piston connected to said valve, said piston having a cylinder connected to a source of supply for fluid under pressure, substantially as described.

12. The combination of a casing having four tubular branches and partitions forming chambers in communication with said branches, a main valve fitting against the ends of the partitions for controlling communication between the chambers, a piston connected to said valve, said piston having a cylinder connected to a source of supply for fluid under pressure, and tWo check-valves connected respectively to the space containing said main valve and to two of the chambers, for automatically permitting flow of fluid from said space to said chambers When the pressure in the chambers falls to a predetermined point, substantially as described.

13. Thecombination ofacasinghavingcommunicating chambers respectively connected to the ends of the high and low pressure cylinders of a compound engine, with a valve controlling the communication between said chambers, and means for keeping said valve in a closed position as long as motive iiuid is supplied to the engine, said valve being provided with means whereby it is permitted to automatically open both when the motive fluid is cut oil from the engine and the pressure falls in the chambers, and also when the pres sure in the chambers rises above a predetermined point, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

JOHN L. DOHERTY.

Witnesses:

F. G. NASH, ED. Rum).

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