US2232467A - Compound valve - Google Patents

Description

Feb. 18, 1941. MORlN HAL 2,232,467

' COMPOUND VALVE Filed Sept. 5, 1940 INVENTOR GZQRGEQMORINMA I'M/LE J-Qmurofl Patented. Feb. 18, 1941 COMPOUND VALVE George G. Morin and Emile J. iUarleton,

Holyoke, Mass.

Application September @1940, Serial No. 355.432

6 Claims.

This invention relates to hydraulic control valves of the general type shown in our Patent 2,121,389, June 21, 1938. The valve described in that patent received fluid under pressure from a constant pressure source and delivered it' at a pressure'which could be regulated accurately to any degree desired under both static and moving conditions. The regulation of pressure in that valve depended upon the comprehsion of a spring 1 which maintained the fluid pressure at all times when the source was out off by the regulating valve, In many instances it has proved desirable to use a higher pressure than can economically be controlled by a. compression spring mounted as described in that prior patent since the heavier types of springs are harder tomake and more difllcult to maintain inaccurate condition. I

It is the object of the present invention to provide a valve by which a, relatively high unit hydraulic pressure at the delivery end of the valve may be controlled by a compression spring of moderate size. A further object is to produce a valve of this character of simple construction and in which those valve parts which have to be made in concentric relation can be kept large enough to permit accurate and ready machining. Additional objects will appear from the following description and claims. l 3 Referring to the drawing:

Figs. 1, 2, and 3 are longitudinal sections through a. valve construction in accordance with the invention-Fig. 1 showing the valve in discharging position; Fig. 2 in a. position feeding pressure fluid from the inlet line directly to the exhaust; and Fig. 3 showing the valve in balanced or static position.

The valve is composed of two sections, a low pressuresection which is constructed substan- 49 tlally in accordance with our prior patent, and

a highpressure section connected to and operated by it. The low pressure section is contained wl-thina cylinder Ill within which runs a piston ll having an annular groove or channel i2 around its central part which in all operative positions overlies an inlet port It. The piston i-l may have suitable rings to preserve fluid tightness which are not necessary to illustrate in the drawing. Within the piston His a bore M in 2 whiclra pilot valve I5 may slide. The pilot valve has a central circumferential channel 16 which maybe shifted into alignment with an inlet port I! extending trom the bore i4 into the channel l2; and which may also come into registration with a delivery port I! o'pening'at ll at theend of the piston l l. The pilot valve I5 is fitted with a control handle 20 extending outwardly through a stuffing box 2| at the end of the casing and has a hole 22 through its centerso that the pressures pressure into aohamber 23, located at the left hand end of the piston and which may beconsidered at the present stage of the description as being blocked off in any suitable way so that 15 a pressure may be built up. This will cause the piston I I to move toward the right against the resistance of a compression spring 24 mounted between the piston and the end of the casing. When 7 the piston hasmoved into the position of Fig. 3, 2 in which the exhaust port l8v is blocked off bythe end 25 of the pilot valve, the total pressure in the chamber 23 will balance the force exerted by thecompressed spring 24. The valve will remain in this condition, with the unit pressure in the g5 chamber 23 fixed at the .point determined by the setting of the rod 20, unless some outside conditions disturb this equilibrium. In order to prevent the piston H being moved so far to the right that the spring 24 will be compressed beyond a 3 safe limit, a stop 50 is preferably secured to the rod 20 to limit its movement.

. The arrangement as described above is substantially that covered by our prior patent referredto with the exception that in that prior 35 patent the chamber 23 was directly connected to the delivery line in which the'iluid pressure was to be controlled. In the present case it is desirable to achieve a higher unit pressure than can be given in the chamber 23 by the mecha- 0 nism already described. For this purpose a second piston valve 26 is located within a bore 2 1 of a casing 28 mounted in fixed relation to the casing III as by tie bolts 29. The piston valve 2-6 p is made of a cross-sectional area substantially less than that of the low pressure piston valve 1 I and at its end bears against an intermediate piston 30 sliding in a .bore 3! which may be a continua-' tlon of the bore" within the casing ill ii desired.

This piston 30 is subjected on one side to a hy- 50 m draulic'pressure within the chamber 23 and at its otherslde to the mechanical-pressure of the pisfton valve 26. At the end where it contacts with.

the intermediate piston the high pressure piston valve is solid, but its other end is hollow asshown 68 at 3| in Fig. l, and the two pistons 26 and 30 form in effect a single differential piston although made separate for purposes of convenience in manufacture. Between the two sections 26 and 3| there is a ported or slotted portion 32 which may be shifted into registration with an annular inlet port 33, an annular exhaust port 34, or an intermediate unported section of the bore 21. The port 33 is connected to an inlet port 36 which may receive fluid pressure from the same source as the port i3 or from a higher pressure source, if desired; and the port 34' is connected to a discharge line 31 which may join the discharge line 38 into which the chamber 23 is vented when the low pressure valve is in the condition of Fig.

1.- By shifting valve 26 successively to the positions of Figs. 1 and 2, a port 4| towhioh the devices to be operated are connected may be placed in communication with ports 31 and 36 for exhausting or delivering fluid to the devices respectively. If the valve 26 is placed in the mid position of Fig. 3, whatever pressure is already existing in' the devices connected to port 4| is maintained. In order to prevent liquid being trapped v within the chamber 36 at the left hand end of the intermediate piston 30 this chamber is preferably connected as by passages 40 to the exhaust port 34.

i It will be seen that any pressure built up in the dischargeport 4| will act against the solid part of the piston 26. This piston is of relatively small area so that the total pressure will not be large. The piston acts mechanically against tion of piston 26 and intermediate piston 30 causes piston 26 under working conditions, to act like a diflerential piston having working faces of 4I may-by this directly'in the chamber 23.

largeand small areas corresponding respectively to the area of piston 30 and the area of piston 26. The total pressure against the piston 26 is of course ultimately balanced by the compressive force of the spring 24, but the unit pressure in pounds per square inch in the discharge line construction be made substantially greater than that which can be produced Since the latter chamber represented the connection to the exhaust line in our prior patent there is a very substantial increase in the unit pressure available by this means.

We claim:

1. A controller for fluid pressure devices comprising a casing having a port for connection to the devices, a main inlet port and a main outlet port, a supplementary inlet port and a supplemental-y outlet port for admitting and exhausting fluid, a difl'erential piston valve having working faces of large and small area respectively and slidable back and forth in the casing for connecting the main inlet and outlet ports selective- 1y with the port for the devices and bodily movable in one direction by and having its working face of smaller area exposed to the pressure supplied to the devices, a pilot piston slidable in the casing adjacent the diiferential piston and having a channel for connecting the supplementary inlet and outlet ports to deliver fluid to and exhaust fluid from the working face of larger area on the differential-piston for moving vsaid differential piston in a direction opposite to that in which it is moved by the fluid supplied to the devices. said pilot piston being movable in one direction by and exposed on one side ,-to fluid supplied to said working face of larger area, yieldable means acting on the other side of said pilot piston for moving it in the opposite direction, a valve element movable back and forth within said pilot piston to alternately connect the supplementary inlet and outlet ports selectively with the channel in said pilot piston and a control rod connected to said valve element and extending through the casing for moving said valve back and forth.

2. A controller for fluid pressure devices comprising a casing having main inlet and outlet ports, supplementary inlet and outlet ports and a port for connection to the devices, a main piston valve slidable back and forth to connect the main inlet and outlet ports with the port for the de-- vices, and connected to be moved in one direction by fluid supplied to said last named port, and a pilot piston valve slidable back and forth to connect the supplementary inlet and outlet ports to movethe main piston valve in the opposite direction, said pilot piston valve being moved in one direction by and havin one face exposed to fluid admitted to move the main piston in said opposite direction and being moved in the opposite direction by yielding pressureexerted on the second face.

3. A controller for fluid pressure devices comprising a casing having main inlet and outlet ports, supplementary inlet and outlet ports, and a port for connection to the devices, a main ,siston valve slidable back and forth to connect the main inlet and outlet ports with the port for the de-: vices, and connected to be moved in one direction by fluid supplied to said last named port, a pilot piston valve and a supplementary piston valve both mounted in the casing, said last two valves being relatively slidable back and forth to connect the supplementary inlet and outlet ports to move the main piston valve in the opposite directionfrom that in which it is moved by fluid supplied to the port for the devices.

4. A controller for fluid pressure devices comprising a casing having main inlet and outlet ports, supplementary inlet and outlet ports and a port for connection to the devices, a main piston valve having oppositely disposed working faces and slidable back and forth to connect the main inlet and outlet ports with the port for the devices and having a channel to direct fluid supplied to the port for the devices against one working face to thereby rection, a pilotpiston valve and asupplementary piston valve both mounted in thelcasing, said last two valves being relatively slidable back and forth to connect the supplementary inlet and outlet ports to supply fluid to the second working face of the main piston valve to thereby move the main piston valve in the opposite direction.

5. A controller for fluidpressure devices comprising a casing having main inlet and outlet ports. supplementary inlet and outlet ports and a move the main piston in one diarea to thereby move the main piston in one di rection, a second channel in communication with other iace of said pilot piston the working face of large area. a pilot piston valve and a supplementary valve slidable relative to each other to connect the supplementary inlet and outlet ports with said second channel to thereby move the main piston in the opposite direction, said pilot piston valve having oppositely disposed working laces, one of which is in communlcation with the second channel whereby said pilot piston is moved in one direction by fluid in said channel, a yielding member acting on. the to move the pilot piston in the opposite direction, and a control rod connected to said supplementary valve and extending through the casing for moving said supplementary valve back and iorth.

6. A controller for fluid pressure devices comprising a body portion and two end portions. a

substantially constant diameter cylindrical bore in the body portion, a constricted cylindrical bore in one end portion, an inlet port, an outlet port, and a port tor the devices iormedin said last named end portion, and in communication with said constricted bore, a supplementary inlet port formed in said body portion and a supplementary outlet ort i'ormed in said other end portion, both said last ports being in communication with the bore in the body portion, a main piston valve slidable back and forth in said constricted bore to connect the main inlet and outlet ports to the port for thedevices, said main valve having two oppositely disposed working faces. one of large and one oi small area, both iac'es lying in the bore oi the body portion, and a channel in the main piston valve connecting the port tor the devices with the worming iace or smaller area, a pilot piston sliolable back and forth in the bore of the main body having two oppositely disposed iaces the first of which is in communication with the working face oi'large area on the main pis ton, a channel in the pilot piston communicating with said first race, a supplementary valve able back and iorth within the pilot piston to connect the supplementary inlet and outlet ports with the channel in the pilot piston, a yieidable member acting against the second face 01 the pilot piston, and a control rod connected to the supplementary valve and extending coaxially with said bore in the body out through the end portion remote from the main piston valve (or moving said supplementary valve.

GEORGE G. MORAN. EMILE J. CARLETON;

Slick.

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