US3682382A

US3682382A - Thermostatically operated valve assembly

Info

Publication number: US3682382A
Application number: US243A
Authority: US
Inventors: Jay R Katchka
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1970-01-02
Filing date: 1970-01-02
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08

Abstract

A thermostatically operated valve assembly including a pair of valves in a cascade arrangement with one of the valves being a relatively small flow valve movable between closed and opened positions with a snap action in accordance with minor temperature variations and with a relatively larger valve being provided with a gradual opening movement in accordance with major temperature variations.

Description

United States Patent Katchka 1451 Aug. 8, 1972 [54] THERMOSTATICALLY OPERATED 3,159,346 12/1964 .Caparone et a1 ..236/48 X VALVE ASSEMBLY 3,190,314 6/1965 Visos et al. ..236/48 X 3,236,262 2/1966 Dobbin ..236/48 X [72] Invent Jay 1mg Beam 3,275,035 9/1966 Freeby et a1 ..236/48 x [73] Assignee: Robertshaw Controls Company,

Richmond, Va. Primary Examiner-William F. ODea Assistant Examiner-P. D. Ferguson [22] Filed 1970 Attomey-Auzville Jackson, Jr., Robert L. Marben [21] Appl. No.: 243 and Anthony A. O'Brien [52] US. Cl ..236/48 R, 137/630.15, 251/75 [57] ABS CT 51 1111. c1. ..'.....G05d 23/10 A h py operated valve assembly mcludmg 581 Field of Search ..137/630.14, 630.15; 236/48; 3 P of valves m a caspade arrangement wlth one of 251/75 the valves bemg a relatlvely small flow valve movable between closed and opened positions with a snap action in accordance with minor temperature variations [56] References cued and with a relatively larger valve being provided with UNITED STATES PATENTS a gradual opening movement in accordance with 2,073,168 3/1937 Newell ..236/48 x temperature vanamns' 2,889,990 6/1959 Loveland et a1. ..236/48 6 Claims, 3 Drawing Figures IIIIIIIIIIIII IIA III.

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PATENTEDAus 8 I972 FIG. I

INVENTOR, Jay R. Korchkc BY W 74.

ATTORNEY THERMOSTATICALLY OPERATED VALVE ASSEMBLY BACKGROUND OF THE INVENTION springs for the two separate valve elements with the result that a high spring force is applied to the main valve and a low spring force is applied to the smaller or supplemental valve.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to improve prior art devices in such a manner that a high spring force is applied to both large and small valves for closure thereof.

This invention has another object in that a single high force spring is utilized to affect closure of a pair of concentrically arranged valves.

A further object of this invention is to reduce the possibility of leakage through a pair of valves in a cascade arrangement.

It is another object of the present invention to open the smaller of serially arranged valves with a snap action and to open the larger of such valves with a gradual movement.

The present invention is summarized in a thermostatic control device including a casing having inlet and outlet ports with a flow passage therebetween, a main valve movable between opened and closed positions for controlling a main flow through such passage, a supplemental valve carried by the main valve to permit a supplemental flow through such passage when the main valve is in its closed position, a snap acting mechanism for operating the main and supplemental valves, thermal responsive means operatively connected to the snap acting mechanism for moving it between actuated and released positions in accordance with temperature variations, the snap acting mechanism having an initial snap movement applying an impact force on the supplemental valve for opening it with a snap action and having a subsequent gradual movement applying a gradually increasing force on the main valve for opening it with a gradual action, and spring means biasing both the main and supplemental valve to closed positions when the snap acting mechanism is released by the thermal responsive means.

Other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying draw- BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation view of a thermostatically controlled device with parts broken away'and parts in section embodying the present invention;

FIG. 2 is an enlarged section of a detail of Fig. l but showing it in another controlling position; and

Fig. 3 is similar to Fig. 2 but showing the components in still another controlling position.

DESCRIPTION OF THE PREFERRED EMBODIMENT As is illustrated in Fig. 1, the present invention is embodied in a thermostatic control device including a casing, indicated generally at 10, having an inlet port 12 for receiving fuel from a gas source (not shown) and an outlet port 14 for delivering fuel to burner apparatus (not shown). Such control devices conventionally include a second outlet port for delivering a smaller flow of fuel to a pilot burner of the burner apparatus whereby thermostatic cycling thereof is permitted due to the pilot burner flame which effects reignition; a manually resettable thermoelectric safety device is retained in a flow permitting position in response to the pilot burner flame and shuts off all fuel flow upon extinguishment of the pilot burner flame. Since any type of pilot flow control device may be utilized, a detailed description is being omitted for the sake of brevity.

The flow of fuel into the casing 10 is controlled by a manually operated on-off valve 16 disposed adjacent the inlet port 12, as is well known in the art; the downstream side of the on-off valve 16 communicates with an inlet chamber 18, from which the fuel flow to the outlet port 14 is thermostatically controlled. A temperature selection dial 20 is mounted on the external end of an adjusting shaft 22 which is threaded through a bushing fixed to a front wall of casing 10. Shaft 22 is axially movable in a sleeve 24 extending across the flow passage adjacent the outlet port 14 and being sealed at both ends. The free end of shaft 22 abuts one end of an operating lever 26.

The thermostat for actuating the lever 26 includes a conventional rod and tube type in which a rod 28 is concentrically disposed in a tube 30. The tube 30 is made of material that has a relatively high coefficient of thermal expansion while the rod 28 is made of material that has a relatively low coefficient of thermal expansion. The tube 30 has a threaded end for fastening it to the mounting shank 32 of the casing 10 and the opposite end of the tube 30 is fixed to the adjacent end of the rod 28 whereby the rod 28 follows the longitudinal movement of the tube 30 due to thermal expansion and contraction. The free end of the rod 28 engages the lever 26 intermediate its ends while the other end of lever 26 engages an operating button 34. It should be noted that any other suitable type of thermostatic means may be utilized to cause movement of lever 26 in response to variations in temperature from a desired set point of the medium in which the tube 30 is disposed. I

The operating button 34 engages a snap action mechanism sealingly mounted in a recess on the rear wall of casing 10. As is conventionally utilized in thermostatic control devices, the snap action mechanism includes a fulcrum disc 36 having a flat surface engaged by the operating button 34 and an annular knife edge or fulcrum on its opposite surface adjacent its periphery. A clicker disc 38 has a bowed portion centrally carrying a headed stud 40 which is disposed adjacent the central portions of lever arms 42. For a more detailed description of the snap action mechanism, reference is made to the above mentioned US. Pat. No. 3,159,346.

The rear wall recess for the snap action mechanism also has a centrally bored, guide bushing 44 which is concentric with an internal wall of casing that defines an annular valve seat 46. The downstream side of the valve seat 46 defines the flow passage leading to the outlet port 14. A circular valve member 48 cooperates with the valve seat 46 and is integrally formed on the end of a cylindrical valve stem 50 that has its other end slidably mounted in the guide bushing 44. The left end of stem 50 (as viewed in Fig. 3) is centrally bored to define a flow chamber 52 having an outlet aperture 54 communicating with the outlet flow passage leading to the outlet port 14.

As is illustrated in Figs. 2 and 3, the valve member 48 and the valve stem 50 are integral elements having a generally T-shape configuration in cross section and a rubber facing is affixed to the surface of valve member 48 for cooperation with the valve seat 46. The peripheral lip of the stem chamber 52 is raised to define an annular valve seat 56. A circular valve element 58 cooperates with the valve seat 56 and is integrally formed on the end of a valve shaft or plunger 60 that has its other end slidably mounted in the valve stem 50. The plunger 60 is concentrically carried by the valve stem 50 and extends through the chamber 52, a shaft bore in stem 50 and the right end of valve stem 50 (as viewed in FIG. 2) whereby the end of the valve plunger 60 is disposed adjacent the snap lever arms 42. Coil spring 62 in the chamber 52 surrounds the adjacent portion of valve plunger 60 and is mounted in compression between the bottom wall of chamber 52 and the valve element 58. A rubber facing is affixed to the surface of valve element 58 for cooperation with the valve seat 56.

The coil spring 62 is a relatively low force spring that biases the valve element 58 away from the valve seat 56 toward a valve open position but mainly the spring 62 assists in holding the larger valve member 48 closed when the smaller valve element 58 is open. A second coil spring 64 is a relatively high force spring mounted in compression between the front wall of casing 10 and that surface of valve element 58 which is opposite the surface cooperating with the valve seat 56. Thus, the spring 64 biases the valve element 58 to the valve seat 56 toward a valve closed position. The

springs

62 and 64 are disposed along a common axis and are in opposition to each other. However, because the spring 64 has a higher spring force than the spring 62, the valve element 58 is normally closed on its valve seat 56; since the valve seat 56 is an integral part of the valve member 48, the same large spring force causes the valve member 48 to be normally closed on its valve seat 46 (see Fig. 1).

In the following description of a sequence of operation of the above thermostatic control device, it is assumed that manual on-ofi valve 16 is opened permitting a pilot flow of fuel to a pilot burner which provides a pilot burner flame for ignition of the main flow of fuel during thermostatic cycling. At the same time, there is a main flow of fuel from the inlet port 12 and through the on-ofi" valve 16 to the inlet chamber 18 whence it is controlled thermostatically according to the demand sensed by the thermostat 28-30. In addition, it is assumed that the temperature setting knob 20 has been moved to a selected temperature setting e. g., F.) which defines the set point that is desired to be maintained in the medium sensed by the thermostat 28-30.

The relative positions of the

valves

48 and 58 in Fig. 1 represent the sensed thermal condition when there is no demand for burner operation; thus, the thermostat 28-30 is in its expanded condition so there is not sufficient force on operating lever 26 to cause actuation of the snap action mechanism. As the thermostat 28-30 cools, the tube 30 contracts and the rod 28 is moved inward or to the left as viewed in Fig. l; the continued inward movement of rod 28 causes the lever 26 to pivot counterclockwise about the end of shaft 22. The force on the operating button 34 thus increases moving the fulcrum disc 36; such initial movement is transmitted to the snap acting disc 38 causing it to move overcenter and be flexed in a direction opposite to that shown in Fig. 1.

Fig. 2 illustrates the respective positions of the

valve elements

48 and 58 upon completion of the initial movement of the snap acting disc 38. The disc 38 is now flexed to the left causing the arms 42 to move the plunger 60 whereby the supplemental valve element 58 is moved to its open position with a snap action. During such snap movement, the force from the snap acting mechanism supplements the biasing force of the light coil spring 62 to overcome the relatively high biasing force of the larger coil spring 64. A relatively small flow of fuel is now permitted from the inlet passage 18, past the small valve seat 56, through the flow chamber 52 and the outlet aperture 54 to the outlet port 14, thence to the burner apparatus (not shown) where it is ignited.

If the burner apparatus supplies sufficient heat to the medium in which the thermostat 28-30 is disposed to cause the thermostat to release the snap mechanism, the larger coil spring 64 will close the small valve 58 on its valve seat 56 to cut off the fuel flow. Thus with only minor temperature variations from the set point fixed by the dial 20, the small valve 58 will cycle thermostatically to maintain the desired temperature.

If the demand for heat is greater than can be satisfied by the small valve 58, the thermostat 28-30 continues its movement to the left (as viewed in Fig. 1). Accordingly, the lever arms 42 of the snap action mechanism are gradually moved into engagement with the end of valve stem 50. Since the width of the lever arms 42 is considerably greater than the diameter of the recess in the right end of the valve stem 50, the lever arms do not reach into such recess which only serves the purpose of allowing the end of the valve stem 60 to enter into the end of the valve stem 50 without restriction due to burrs. The lever arms 42 thus move the stem 50 causing large valve member 48 to move gradually away from its fixed valve seat 46 to a valve open position. A larger flow of fuel is now permitted from the inlet passage 18 and past the valve seat 46 to the outlet port 14.

With the additional heat being supplied as a result of the larger valve 48 being opened, the thermostat 28-30 will commence to expand whereupon the movement of the snap action mechanism causes the

valves

48 and 58 to throttle downward from their full open positions of Fig. 3 to their small flow positions of Fig. 2. Further expansion of the thermostat 28-30 allows the snap action mechanism to snap overcenter from its position of Fig. 2 to its position of Fig. 1 wherein the small valve 58 is closed on its valve seat 56 with a snap action.

The above arrangement has the particular advantage that a single coil spring 64 is utilized to close both

valves

48 and 58. In addition, the single high force spring 64 eliminates the need for a separate spring to close the small valve 58 whereby leakage possibility past either valve is virtually eliminated. It should be noted that the foregoing terminology of main and supplementary adjectives for the

valves

48 and 58 is merely arbitrary since such adjectives could be utilized vice ve rsa for such valves.

Inasmuch as the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a thermostatic control device, the combination comprising a casing having inlet and outlet port means and a flow passage therebetween,

main valve means movable between open and closed positions in said flow passage for controlling a main flow therethrough,

said main valve means including a fixed valve seat in said casing and a movable valve member cooperating with said fixed valve seat,

supplemental valve means carried by said main valve means to permit a supplemental flow through said flow passage when said main valve means is in its closed position,

said supplemental valve means including a valve seat on said movable member and a movable valve element cooperating therewith,

snap acting means operatively disposed adjacent said main and supplemental valve means,

thermal responsive means operatively connected to said snap acting means for moving the same between actuated and released positions in accordance with predetermined temperature variations,

said snap acting means having an initial snap movement applying an impact force on said supplemental valve means for opening the same with a snap action and having a subsequent gradual movement applying a gradually increasing force on said main valve means for opening the same with a gradual action, and spring means biasing both said main and supplemental valve means to closed positions when said snap acting means is released by said thermal responsive means,

said spring means including a pair of coil springs acting in opposition to each other on opposite sides of said valve element, one of said coil springs exerting a relatively low biasing force on said valve element and the other of said coil springs exerting a relatively high biasing force on said valve element whereby said valve element and said movable valve member are normally closed on said supplemental valve seat and said fixed valve seat, respectively.

2. The invention as recited in claim 1 wherein said movable valve member includes a stem having a flow chamber and outlet means from said chamber communicating with said flow passage downstream of said fixed valve seat, and wherein said supplemental valve means is disposed upstream of said fixed valve seat to control the supplemental flow to said flow chamber.

3. The invention as recited in claim 2 wherein said valve element includes a plunger slidably extending through the stern of said movable valve member whereby said movable valve member and said valve element are concentrically arranged.

4. In a thermostatic control device, the combination comprising a casing having inlet and outlet port means and a flow passage therebetween,

main valve means including a fixed valve seat in said casing and a movable valve member cooperating with said fixed valve seat through said flow passage,

said movable valve member including a stem having a flow chamber and outlet means from said flow chamber communicating with said flow passage downstream of said fixed valve seat,

said snap acting means having an initial snap movement applying an impact force on said supplemental valve means for opening the same with a snap action and having a subsequent gradual movement applying a gradually increasing force on said main valve means for opening the same with a gradual action,

said supplemental valve means including a supplemental valve seat on said movable valve member defining inlet means for said chamber and a valve element cooperating with said supplemental valve seat to control the supplemental flow to said flow chamber,

said valve element including a plunger slidably extending through the stem of said movable valve member whereby said movable valve member and said valve element are concentrically arranged,

spring means biasing both said main and supplemental valve means to closed positions when said snap acting means is released by said thermal responsive means,

said spring means including a pair of coil springs acting in opposition to each other on opposite sides of plunger to supplement the relatively low biasing force to overcome the relatively high biasing force on said valve element and hold the same in an open position independently of said movable valve member.

6. The invention as recited in claim 5 wherein said stem is engaged by said snap acting means after said valve element is moved to an open position and is gradually moved relative to said fixed valve seat in accordance with the gradual movement of said snap acting means.

Claims

1. In a thermostatic control device, the combination comprising a casing having inlet and outlet port means and a flow passage therebetween, main valve means movable between open and closed positions in said flow passage for controlling a main flow therethrough, said main valve means including a fixed valve seat in said casing and a movable valve member cooperating with said fixed valve seat, supplemental valve means carried by said main valve means to permit a supplemental flow through said flow passage when said main valve means is in its closed position, said supplemental valve means including a valve seAt on said movable member and a movable valve element cooperating therewith, snap acting means operatively disposed adjacent said main and supplemental valve means, thermal responsive means operatively connected to said snap acting means for moving the same between actuated and released positions in accordance with predetermined temperature variations, said snap acting means having an initial snap movement applying an impact force on said supplemental valve means for opening the same with a snap action and having a subsequent gradual movement applying a gradually increasing force on said main valve means for opening the same with a gradual action, and spring means biasing both said main and supplemental valve means to closed positions when said snap acting means is released by said thermal responsive means, said spring means including a pair of coil springs acting in opposition to each other on opposite sides of said valve element, one of said coil springs exerting a relatively low biasing force on said valve element and the other of said coil springs exerting a relatively high biasing force on said valve element whereby said valve element and said movable valve member are normally closed on said supplemental valve seat and said fixed valve seat, respectively.

3. The invention as recited in claim 2 wherein said valve element includes a plunger slidably extending through the stem of said movable valve member whereby said movable valve member and said valve element are concentrically arranged.

4. In a thermostatic control device, the combination comprising a casing having inlet and outlet port means and a flow passage therebetween, main valve means including a fixed valve seat in said casing and a movable valve member cooperating with said fixed valve seat through said flow passage, said movable valve member including a stem having a flow chamber and outlet means from said flow chamber communicating with said flow passage downstream of said fixed valve seat, supplemental valve means carried by said main valve means to permit a supplemental flow through said flow passage when said main valve means is in its closed position, snap acting means operatively disposed adjacent said main and supplemental valve means, thermal responsive means operatively connected to said snap acting means for moving the same between actuated and released positions in accordance with predetermined temperature variations, said snap acting means having an initial snap movement applying an impact force on said supplemental valve means for opening the same with a snap action and having a subsequent gradual movement applying a gradually increasing force on said main valve means for opening the same with a gradual action, said supplemental valve means including a supplemental valve seat on said movable valve member defining inlet means for said chamber and a valve element cooperating with said supplemental valve seat to control the supplemental flow to said flow chamber, said valve element including a plunger slidably extending through the stem of said movable valve member whereby said movable valve member and said valve element are concentrically arranged, spring means biasing both said main and supplemental valve means to closed positions when said snap acting means is released by said thermal responsive means, said spring means including a pair of coil springs acting in opposition to each other on opposite sides of said valve element, one of said coil springs exerting a relatively low biasing force on said valve element and the other of said coil springs exerting a relAtively high biasing force on said valve element whereby said valve element and said movable valve member are normally closed on said supplemental valve seat and said fixed valve seat, respectively.

5. The invention as recited in claim 4 wherein said valve element is supplied with a force by said snap acting means, when in its actuated position, engaging said plunger to supplement the relatively low biasing force to overcome the relatively high biasing force on said valve element and hold the same in an open position independently of said movable valve member.