US3189277A

US3189277A - Temperature responsive safety control valve

Info

Publication number: US3189277A
Application number: US244962A
Authority: US
Inventors: Elton B Fox
Original assignee: Amot Controls LLC
Current assignee: Ropintassco Holdings LP; Ropintassco 2 LLC
Priority date: 1962-12-17
Filing date: 1962-12-17
Publication date: 1965-06-15
Anticipated expiration: 1982-06-15

Description

June 15, 1965 Filed Dec. 1'7, 1.952

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the pressure on the safety system and shuts down the compressor.

Nhile the thermostatic actuator of the present invention may have various uses and applications in the thermostat art, it is particularly well adapted to use in a slide valve construction as herein depicted. This structure includes a valve housing 36 formed with an interior valve cylinder 37 having side ports 3S and 39' communicating with conduit receiving portions i4 and 4S adapted for connection to high pressure and venting lines (not shown) of a control system.

Mounted for longitudinal reciprocation in cylinder 37 for selective operation across

ports

38 and 39 is a spool valve heretofore generally referred to as the actuated device 27. This valve herein also referred to as numeral 27 is formed with longitudinally spaced enlarged

shoulders

46, 47 and 48 which extend to the internal wall of cylinder 37 and are formed with seats for receiving the O rings Si, 52 and 53, and which slidably engage the cylinder wall to provide controlled valving action with

respectto ports

38 and 39. When the valve is in the position illustrated in FiGURE 2, shoulders 47 and 4.3 and their() rings S2 and 53 straddle inlet port 38 thereby effecting a closed position of the valve. Upon movement of the valve to the right as viewed in the drawing, shoulder 47 and its O ring 52 move to a position wherein ports 3d and 39 are in. communication, representing the open position of the valve. The stop 3l hereinabove referred to here consists of a set screw, identified by the same number and which is threaded through the body of housing 36 so as to position the internal end of the set screw between shoulders 4d and 47 thereby limiting the reciprocating displacement of the valve.

Displacement of valve 27 is here effected by shaft 8 which is mounted axially through the valve and extends therefrom through an end Wall 49 of the housing. Spring 32 is here mounted around shaft 8 and in compression between the adjacent end 50 of valve 27 and end wall 49 so as to constantly bias the valve upwardly, as viewed in the drawing, and to its terminal position against set screw 3l.

Shaft end 28 projects from one end of valve 27 for mounting of adjustment nut 26 against the adjacent end 5d of the valve, and the opposite end 55 of the shaft projects from the opposite Valve end S0' through spring 32 and end wall 49.

The thermostat discs 6 are mounted on shaft S between a shoulder support llo on wall 49 and collar i8 pinned to the shaft end as above described.

lt is significant to note that upon heating of the elements the latter will bow, as illustrated in FIGURE 3 and hereinabove described, so as to produce a movement of shaft 8 downwardly, as viewed in the drawings, and eventually and at a predetermined elevated temperature cause an open of port 3; to port 39 and a triggering of the control system.

Upon shutting down of the compressor system, the elements will cool and spring 32 will cause the valve to return to closed position, as depicted in FIGURE 2. It is, however, in the nature of bimetal elements, as above explained, that they will bow in an opposite direction when cooled below the temperature at which they are planar. This reverse bowing of the elements will produce a movement of the valve toward opened position in the same manner as when the elements are heated. Consequently, and because of this reverse phenomenon, the discs are formed with an initial pre-set deformation, as hereinabove described, which prevents such a reverse bowing of the discs at the reduced temperatures to which the device may be subjected as to cause an opening of the valve. L

A still further important feature of the construction of the present unit is the fact that the thermostatic actuator may be removed from a high pressure gas line in which it is inserted without opening the line. Applicant has therefore provided a well casing fil for thc receipt of the thermostatic actuator', and which may be threaded or otherwise secured in the wall of the gas line. The actuator housing 36 is machined to slidably fit into this well and is held therein by set screw 42. Accordingly, by backing oit set screw 42, housing 36 may be removed without opening the gas line in which the well casing is mounted.

In order to protect shaft and adjusting screw 26, a cap 6l rnay be provided for attachment to housing 36.

Vent holes

62, 63 and 64 are provided in the housing and the cap to prevent any build-up of pressure to'impede the movement of the valve Z7.

It will be noted that the thermostatic actuator of the present invention consists solely of the bimetal discs held in a concentric stack for movement upon the central shaft and no extra parts such as mounting or aligning members or movement multiplying devices are required. Conse quently, the stack is active and is capable of producing optimum displacement for a given size of the assembly, and hence, maximum compactness is achieved. The discs deform hemispherically so as to aiford an optimum weight supporting shape and thus provide a maximum force in their displacement for a given thickness or cross-section of their bimetal body. Of equal importance, and as mentioned above, the circular hemispherical form of the discs and their central threading onto an axial supporting shaft insures peripheral edge support between the opposed peripheral edges of the discs in all relatively rotated positions of the discs on the shaft. rThis feature is particularly important where, as here, adjustment of the operating temperature range of the device isV obtained by introducing slack in the disc stack which may cause discs to move out of engaged position. By Way of example, a valve structure as illustrated may be made with a sensitivity range of, say, 15 F. The valve may be mounted in an environment having a normal temperature of about 300 F. and be adjusted so that it will start to open at, say, about 340 F. ln such a structure, the valve may open sutiiciently at about 350 F. so as to trip the control system and thereafter and upon cooling to` close fully at, say, about 335 F. To adapt the foregoing valve to operation at a higher temperature, say, 600, adjustment nut 26 is backed off on shaft end 2S so as to increase the spacing between collar it; and the housing portion i6 which may introduoe slack. In actual construction, this slack so introduced may range up to 1/s to 1A inch, depending upon the number of discs and amount of displacement required in the design.

l claim:

l. A temperature responsive safety control valve comprising, a valve housing formed with an internal cylindrical wall defining a valve chamber and inlet and discharge passages opening to said wall at longitudinally spaced positions and being formed with a transversely extending end wall for said chamber in longitudinal spaced relation to said ports, a spool shaped valve having longitudinaily spaced flanged portions mounted for reciprocation on said chamber wall in sealed relation thereto and having a closed position closing oit connection between said inlet and discharge passages and a longitudinally spaced open position communicating said passages, said hanged portions in both of said positions being disposed on opposite sides of said inlet passage to provide a pressure balanced condition enabling ready movement of said valve from closed to open positions and vice versa, means providing a stop for said valve in closed'position, a valve stern extending axially from one end of said valve and projecting through and being slidably supportedV by said end `wall and having an end portion disposed exteriorly of said end wall remote from said valve chamber, a helical sprlng surrounding said stem and mounted in compression between said end wall and said valve end for constantly urging said valve to closed position, a plurality of bimetal discs formed with central openings mounted upon said stem end portion to provide a stack with one end disposed for engagement with said end` wall, and means on said stem end portion engaging the opposite end of said stack, said discs being arranged in reversely positioned pairs and being so constructed that upon heatingeach pair of discs will bow away from each other to produce longitudinal displacement of said stem and said valve in the direction of closed to open position and against the resistance of said spring.

2. A temperature responsive safety control Valve as characterized in claim 1 and including a second housing formed with an enclosed longitudinally extending chamber having an open end and formed to receive through said open end and to surround and enclose said stem end portion and bimetal disc stack, said second housing having an internal wall adjacent its open end formed for mating attachment to the external wall of said valve housing adjacent said end wall thereof so as to provide a sealed enclosure for said stem end portion and said bimetal disc stack.

3. A temperature responsive safety control valve as characterized in claim 2 wherein said stem is formed as a shaft separate from and threaded axially through said valve for relative displacement of said valve on said shaft Y and having an end extending from an end of said valve opposite to said first named valve end engaged by said spring, and a nut threaded on said last named shaft end and bearing on said valve for adjusting the spacing between said nut and said means engaging the remote end of said stack for controlling the temperature responsive valve displacement.

References Cited by the Examiner UNITED STATES PATENTS EDWARD l'. MICHAEL, Primary Examiner.

ALDEN D. STEWART, Examiner.

Claims

1. A TEMPERATURE RESPONSIVE SAFETY CONTROL VALVE COMPRISING, A VALUE HOUSING FORMED WITHIN AN INTERNAL CYLINDRICAL WALL DEFINING A VALVE CHAMBER AND INLET AND DISCHARGE PASSAGES OPENING TO SAID WALL AT LONGITUDINALLY SPACED POSITIONS AND BEING FORMED WITH A TRANSVERSELY EXTENDING END WALL FOR SAID CHAMBER IN LONGITUDINAL SPACED RELATION TO SAID PORTS, A SPOOL SHAPED VALVE HAVING LONGITUDINALLY SPACED FLANGED PORTIONS MOUNTED FOR RECIPROCATION ON SAID CHAMBER WALL IN SEALED RELATION THERETO AND HAVING A CLOSED POSITION CLOSING OFF CONNECTION BETWEEN SAID INLET AND DISCHARGE PASSAGES AND A LONGITUDINALLY SPACED OPEN POSITION COMMUNICATING SAID PASSAGES, SAID FLANGED PORTIONS IN BOTH OF SAID POSITIONS BEING DISPOSED ON OPPOSITE SIDES OF SAID INLET PASSAGE TO PROVIDE A PRESSURE BALANCED CONDITION ENABLING READY MOVEMENT OF SAID VALVE FROM CLOSED TO OPEN POSITIONS AND VICE VERSA, MEANS PROVIDING A STOP FOR SAID VALVE IN CLOSED POSITION, A VALVE STEM EXTENDING AXIALLY FROM ONE END OF SAID VALVE AND PROJECTING THROUGH AND BEING SLIDABLY SUPPORTED BY SAID END WALL AND HAVING AN END PORTION DISPOSED EXTERIORLY OF SAID END WALL REMOTE FROM SAID VALVE CHAMBER, A HELICAL