US2584419A

US2584419A - Thermostatically actuated pilot operated valve

Info

Publication number: US2584419A
Application number: US44525A
Authority: US
Inventors: Charles D Branson
Original assignee: Robertshaw Fulton Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1948-08-16
Filing date: 1948-08-16
Publication date: 1952-02-05
Anticipated expiration: 1969-02-05

Description

Feb. 5, 1952 c. D. BRANSON 2,584,419

THERMOSTATICALLY ACTUATED PILOT OPERATED VALVE Filed Aug. 16, 1948 IN V EN TOR.

Charles D. Bransow.

Ai-tonwys Patented Feb. 5, 1952 THERMOS'EATICALLY ACTUATl ID PILOT OPERATED VALVE Charles D. Branson, Knoxville, Tenn., assignor to Robertshaw-Fulton Controls Company, Knoxville, Tenn., a corporation of Delaware Application August 16, 1948, Serial No. 44,525

2 Claims. (Cl. 236-80) 1 This invention relates to thermostatically actuated pilot operated valves and more particularly to such pilot operated valves which move rapidly between closed and wide open positions.

There are various services to which pilot operated valves are desirably put wherein the main valve should be either in closed position or in wide open position. For example, in a sprinkler system wherein water is discharged as a spray through nozzles when a predetermined control temperature has been reached, the main valve controlling the supply of water should move quickly to wide open position when the desired temperature is reached so that the nozzles may 'function efficiently in producing the desired sprays, and when the sprays are to be cut off. said valve should close quickly so as to avoid a period wherein the water is dribbling through the nozzles.

To obtain rapid opening and closing of a main valve it has heretofore been proposed to provide a pilot valveactuated by a thermostat of the snap acting type. Devices of this character have been open to several objections among which are the lack of power derivable from thermostats of the snap acting type, the difliculty of rendering the thermostatic actuator of the pilot valve responsive to temperatures at points relatively remote from the pilot operated valve, the

- complexity and cost of the construction it grad- .ual opening and closing of the pilot operated valve are to be avoided, etc.

It is an object of this invention to provide an improved thermostatically actuated pilot operated valve wherein the lattermoves quickly withstanding variations in the pressure of the fluid being controlled. 7

Another object of this invention is to provide an improved device of the type characterized. wherein the pilot valve will be positively moved to open position in the event that it fails to respond to pressure difierentials as contemplated for normal operation.

Another object of this invention is to provide an improved device of the type characterized which is simple and rugged in construction, composed of parts that are inexpensive to manufacture and assemble, and highlyeflicient when applied to a wide variety of services in which the pilot operated valve should move quickly between closed and wide open positions.

The invention is capable of receiving a variety of mechanical expressions only one of which has been shown on the accompanying drawing, and therefore it is to be expressly understood that the drawing is for purposes of illustration only, and is not to be construed as a definition of the limits of the invention, reference being had to the appended claims for that purpose.

The accompanying drawing shows somewhat schematically a cross section through a thermostatically actuated pilot operated valve embodying the present invention.

As shown, a valve housing ill, of any suitable size, construction and material, has an inlet H and an outlet l2 and, interiorly, a partition l3 through which passes a valve port It. As illustrated, the rim of the port It is properly formed to provide a valve seat l5, but if desired a separate valve seat member may be used.

Mounted in the chamber It at the inlet side of port It is an expansible and collapsible chambeer I! the movable end wall of which is operatively connected to any suitable main valve memher. As shown, said chamber I1 is formed by an expansible and collapsible corrugated tubular wall or bellows l8 suitably secured at one end to a movable end wall l9 and at its opposite end to an annular member 20, here shown as clamped to the wall 2| surrounding a lateral opening 22 in said housing, as by a threaded collar 23. While the movable end wall l9 may itself be' a valve member, the construction shown includes a valve disk 24 of any suitable material secured to the outer face of end wall l9 by a plate 25 and nut 2" the latter being threadedly mounted on a s ud 21 secured to or formed on said movable wall l9. Annular member 20 is provided in any suitable way with a bleed opening 28 for a purpose to be explained.

Also secured in position by the threaded collar 23, as by means of an interposed annular member 29, is the housing 30 of the pilot valve proper. As here shown, said housing takes the form of a hollow or tubular member providing an interior chamber 3| which is in communication with chamber I! through a pilot valve port 32. Said chamber 3| also has a drain pipe opening at 33.

Mounted in the chamber 3| is a cup-shaped 3. member 34, snown as depressed at to provide a seat for a purpose to be explained, having a central portion which is shaped or recessed to provide a chamber 38 having an aperture 31 through its bottom wall. Extending through said aperture 31 and provided in any suitable way, at

. or adjacent its end, with a collar 38 in chamber 36 is a pilot valve stem 33 to which is suitably secured a pilot valve member 40 for cooperation with the port 32. A coil spring 4| reacts between a shoulder 42 on said valve member and the bottom wall 43 of the chamber 36 so that the collar 38 on stem 33 is normally held in contact with said bottom wall 43. A second and stronger coil spring 44 reacts between the cupshaped member 34 and the wall of the chamber 3| surrounding the valve port 32 and normally urges said cup-shaped member 34 together with the pilot valve member mounted thereon in the direction for closing said pilot valve member 40. Pilot valve member 40 is preferably so constructed that it presents a surface 45 of substantialarea to the pressure in chamber Also mounted in the chamber 3| is the motor vessel of a thermostat of the type wherein the motor vessel is in communication with a bulb that may be disposed at any suitably remote distance from the motor vessel. As illustrated, chamber 3| is closed by a block 46, secured to the end of the pilot valve housing 30in any suitable way, and .has formed thereon or secured thereto a flange 41 to which is hermetically sealed an expansible and collapsible corrugated tubular wall or bellows 48 whose opposite end is inte-' grally formed with or suitably attached to a movable end wall 43. The chamber enclosed by the bellows 48, its movable end wall 49 and the stationary block 41 constitute an expansible and collapsible chamber or motor vessel whose movable end wall 43 is so disposed that it is adapted to engage seat 35 on the cup-shaped member 34 and move the latter downwardly, as viewed in the drawing, when said chamber 50 is expanded as hereinafter explained. A collar 5| is shown as secured to the block 46 within chamber 50 and projects into proximity of the movable end wall 43 to limit the extent to which chamber 50 may be contracted.

Block 46 is provided with a suitable passage 52 which communicates with motor vessel 50 at one end and which communicates at its opposite end with a conduit 53, which may be of any suitable size, length and construction, and either rigid or flexible, leading to a bulb 54 of any suitable construction and size and mountable in position in any suitable way. As shown, bulb 54' has an overrun provision in the form of an expansible and collapsible corrugated tubular wall or bellows hermetically sealed at one end to 'a flange 53 secured interiorly to the wall of the bulb and at its opposite end having a movable end wall 51 to which is attached in any suitable way a post 53 that extends through an opening 53 in the end wall 50 of the bulb, where it is provided with a collar 8| A coil spring 52 reacts between the movable end wall 51 and the end wall 50 of the bulb and normally holds the collar 5| against the exterior of said end wall 60. In the event of excess pressure in the bulb 51, however, the expansible and collapsible chamber 53 interiorly of the bellows 55 can be collapsed by the pressure on the movable end wall 51, causing the post 58 to slide downwardly as viewed in the drawing through the opening 59 until the excess pressure is relieved. The exterior chamher in which collar 6| is disposed may be closed by any suitable threaded cap 64.

Bulb 54, tube 53 and chamber 5!! are filled with any suitable thermostatic liquid so that upon increase of temperature at the bulb 54 the resulting expansion of the liquid will effect expansion of the motor vessel 50 and operate the pilot valve in a manner to be explained.

If it is desired to limit the extent to which the main valve may be opened a collar 65 may be mounted in any suitable way on the pilot valve housing 30 and have its inner end so disposed with respect to the movable end wall IQ of chamber l1 that a predetermined limit of contraction of chamber I1 is prescribed.

Assume that the bulb 54 is subjected to any suitable source of temperature and that the inlet II to housing- I0 is connected to any suitable source of liquid while outlet I2 is connected to any suitable provisions for utilizing such liquid. If the temperature at the bulb 54 is such that motor vessel 50 is not expanded, coil spring 44 reacts on the cup-shaped member 34 to hold the pilot valve member 40 in its position for closing port 32. The liquid to be controlled entering through'the inet II can bleed through aperture 23 into the chamber l1 and thereby produce an unbalanced pressure in said chamber on the movable end wall I 9, in a downward direction as viewed in the drawing, holding the main valve member 24 in contact with seat |5 to prevent flow of liquid through the port H. The pressure in the chamber I! also acts upwardly, as viewed in the drawing, on the face 45 of pilot valve member 40, acting adjunctively with the spring 44 to urge member 40 into its position for closing th P rt 32.

Nowsuppose the temperature at the bulb 50 approaches that degree. at which main valve member 24 should move to its wide open position permitting maximum flow of liquid through the port l4. Expansion of the charge in the

thermostat

50, 53, 54 will gradually develop pressure in the motor vessel 50 and, when the movable end wall 43 of said vessel is in engagement with the seat 35 of the cup-shaped member-34, the latter member develops resultant tension in the springs 44 and 4 When the tension of spring 4| slightly exceeds the pressure in the chamber 11 on the face 45 of pilot valve member 40 the latter will be opened to a small amount. This effects a release of pressure in the chamber l1, because only a slight opening of the pilot valve member 4'0 permits an outflow of liquid through the port 32 well in excess of what enters the chamber I! through the bleed opening 23. This diminution of pressure on the face 45 of pilot valve member 40 in turn permits the stored tension of spring 4| to open the pilot valve member 40 rapidly, by snap action, whereupon the pressure in the chamber I1 is rapidly released, the liquid therein flowing out through port 32, chamber 3| and drain opening 33, and the main valve member 24 is thereby moved to its wide open position by the unbalanced fluid pressure acting on the main valve member, or by the tension developed'in bellows 3 when it is extended by the pressure in chamber I! to close the main valve member, or by any suitable spring associated with said chamber if preferred.

If for any reason the pilot valve member 43 is not opened by the tension'of spring 4| as the latter is compressed, member 34 will slide over the pilot valve stem 33, downwardly as viewed in the drawing, until movable end wall 49 engages the collar 38 and positively moves the pilot valve member 40 off of its seat. Therefore, the pilot valve is positively opened to release the pressure in chamber ll before the temperature at bulb 54 can rise very much above that at which the pilot valve is supposed to be opened.

Upon drop of temperature at the bulb 54 the motor vessel 50 contracts and spring 44 moves the cup-shaped member 34, upwardly as viewed in the drawing, until pilot valve member 40 nearly reaches its seat. At this point the pressure in the chamber I! on the inner face 45 of the pilot valve member 40 becomes active to act adjunctively to the spring 44 in moving the pilot valve member 40 rapidly to closed position. Thereupon the pressure quickly accumulates in the chamber I1, moving the main valve member 24 to its seat by reason of the unbalanced pressure that quickly develops in said chamber I! because of inflow of liquid through the bleed opening 28. However, the closing movement of the main valve member 24 is slightly retarded by reason of the necessity of the pressure accumulating in the chamber ll through bleed opening 28, and therefore there is no pounding or water hammer by reason of the main valve being closed too quickly.

It will therefore be perceived that by reason oi the present invention the main valve moves quickly from closed to wide open position and vice versa notwithstanding that the pilot valve is under the control of a thermostat whose rate of expansion and contraction is gradual. Thereby a thermostat of the bulb and motor vessel type can be used to assure adequate power in operating the pilot valve while the bulb may be disposed at any suitably remote distance from the motor vessel so that the pilot operated main valve may respond to temperatures at points relatively remote therefrom. While in the normal operation of the thermostatically actuated pilot operated valve the pilot valve is given a snap action by reason of the existing diflerential pressures when its associated spring has been predeterminately tensioned by the thermostat, positive actuation of the pilot valve from the thermostat is assured if the pilot valve sticks or temporary pressure conditions prevent opening of the pilot valve by differential pressure. The structure is composed of relatively simple parts that are inexpensive to fabricate and assemble, so that a compact and rugged thermostatically actuated pilot operated valve unit is provided, while at the same time the construction is such as to assure efllcient operation of such unit under widely varying conditions where it is desired that the main valve move quickly between closed and open positions.

While the embodiment of the invention illustrated on the drawing has been described with considerable particularity, it is to be expressly understood that the invention is not limited thereto as the same is capable of receiving a variety of mechanical expressions as will now be apparent to those skilled in the art, while changes may be made in the details of construction, arrangement, proportion, size, etc., and parts may be replaced by equivalent parts, without departing from the spirit of this invention. Reference is therefore to be had to the claims hereto appended for a definition of said invention.

What is claimed is:

1. In a device of the type characterized in combination with a main valve. an expansible and collapsible chamber having its movable wall operatively connected to said main valve and provided with a bleed opening, means providing a pilot port in communication with said chamber, and a pilot valve member cooperativelyassociated with said port, a thermostat including an expansible and collapsible motor vessel and a communicating bulb, a movable member associated with the movable wall of said motor vessel, a spring cooperating with said movable member to oppose movement of said member until said motor vessel has overcome the tension of said spring, and an operative connection between said movable member and said pilot valve member including a stem mounted on and movable relatively to said movable member and having a head for engagement with said movable member, and a second spring cooperating with said stem and movable member for normally holding said head in contact with said movable member.

2. In a device of the type characterized, in combination with a main valve, an expansible and collapsible chamber having its movable wall operatively connected to said main valve and provided with a bleed opening, means providing a pilot port in communication with said chamber, and a pilot valve member cooperatively associated with saidport, a thermostat including an expansible and collapsible motor vessel and a. communicating bulb in communication with said motor vessel through an intermediate conduit, a movable member associated with the movable wall of said motor vessel, a spring cooperating with said movable member to oppose movement of said movable member until said motor vessel has overcome the tension of said spring, and an operative connection between said movable member and said pilot valve member including a stem mounted on and movable relatively to said movable member and having a head for engagement with said movable member, and a second spring cooperating with said stem and movable member for normally holding said head in contact with said movable member, said movable member having a recess in which said head is disposed and from which it becomes engaged with the movable wall of .said motor vessel after a predetermined movement of the latter.

CHARLES D. BRANSON.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name Date 1,328,277 Fulton Jan. 20, 1920 1,491,189 Birtch Apr. 22, 1924 1,970,537 Marvin Aug. 14, 1934 2,389,437 Kmiecik NOV. 20, 1945