Heat Motor Operated Gas Valve Construction And System And Method

Abstract

A heat motor operated gas valve construction having a housing for the passage of gaseous fuel therethrough and a bimetal member for operating a valve member of said housing and carrying an electrical heater that is utilized to cause warpage of the bimetal member to move the valve member to one operating position thereof when the heater is energized to heat the bimetal member. Means are disposed between the bimetal member and the electrical heater with such means not acting as a catalyst with the gaseous fuel to prevent the bimetal member when heated from acting as a catalyst with the gaseous fuel to "crack" the fuel and cause carbon to build up between the bimetal member and the heater. BACKGROUND OF THE INVENTION It has been found that in heat motor operated gas valve constructions that when the gaseous fuel is permitted to pass adjacent the heated bimetallic member of a heat motor, the gaseous fuel, whether the same is natural gas or LP gas tends to be "cracked" by the heat of the bimetallic member and causes a carbon build up between the bimetallic member and the heater wire disposed thereon. This build up of carbon between the bimetal member and the heater wire thereon has been found to reach the point where the wire is stressed sufficiently to cause it to break and thereby require a replacement of the heat motor for the gas valve construction. SUMMARY This invention provides a heat motor operated gas valve construction of the above type that eliminates the aforementioned cracking problem by providing means between the bimetal member and the electrical heater thereon that does not act as a catalyst on the gaseous fuel to prevent the bimetal member when heated from itself acting as a catalyst with the gaseous fuel to crack the fuel and cause the aforementioned carbon to build up between the bimetal member and the heater wire. In one embodiment of this invention, such means comprises a chrome coating electrolytically plated on the bimetallic member and on which the heater wire is subsequently wound or disposed. Accordingly, it is an object of this invention to provide an improved heat motor operated gas valve construction having one or more of the novel features set forth above or hereinafter shown or described. Another object of this invention is to provide an improved fuel control system utilizing such a heat motor operated gas valve construction. Another object of this invention is to provide an improved method for making a heat motor operated gas valve construction. Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings show schematically an embodiment of the invention, in which:

FIG. 1 is a top perspective view of the improved valve construction of this invention.

FIG. 2 is an enlarged cross-sectional view taken on line 2--2 of FIG. 1 with FIG. 2 schematically illustrating the improved fuel control system of this invention.

FIG. 3 is a top perspective view of part of the valve construction of FIG. 2.

FIG. 4 is a fragmentary, cross-sectional view taken on the line 4--4 of FIG. 2.

FIG. 5 is an enlarged, fragmentary, cross-sectional view taken on line 5--5 of FIG. 4.

FIG. 6 is a view similar to FIG. 1 and illustrates the valve construction in its open position.

FIG. 7 is a view similar to FIG. 2 and illustrates the valve construction in its closed position and upon a rise in ambient temperature.

FIG. 8 is an exploded perspective view of the various parts of the valve member of the valve construction.

FIG. 9 is a fragmentary cross-sectional view taken on line 9--9 of FIG. 8.

While the various features of this invention are hereinafter described and illustrated as being particularly adaptable for providing a valve construction for a fuel control system of a cooking apparatus or the like, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide a valve construction for other devices as desired.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIGS. 1 and 2, the improved valve construction of this invention is generally indicated by the reference numeral 10 and comprises a housing means 11 formed of two housing parts 12 and 13 suitably secured together with gasket means 14 therebetween to seal around a chamber 15 defined between the housing members 11 and 13.

The valve construction 10 is utilized in a fuel control system of this invention that is generally indicated by the reference numeral 16 in FIG. 2 and comprises a fuel source 17, burner means 18 and a control device 19. The fuel source 17 is interconnected to an inlet 20 formed in the housing means 11 of the valve construction 10 by a conduit means 21 whereas an outlet 22 of the valve construction 10 is interconnected by a conduit means 23 to the burner means 18.

The outlet 22 of the housing means 11 is defined by a tubular part or fitting 24 carried by the plate-like housing member 13 and has a reduced cylindrical portion 25 thereof sealingly passing through an opening 26 in the plate 13 whereby the upper end 27 of the tubular member 27 projects above the upper surface 28 of the plate part 13. A cup-shaped member 29 has its cylindrical side wall means 30 press-fitted into the reduced part 31 of the outlet passage 22 that passes through the fitting 24 so that the upper open end 32 of the cup-like member 29 can extend above the end 27 of the fitting 24 to the desired distance, the upper end 32 of the cup-like member 29 being outwardly flanged at 33 and defining a valve seat separating the inlet 20 from the outlet 22. The cup-like member 29 has an opening 34 passing through the closed end 75 thereof so as to fluidly interconnect the upper end 32 thereof with the outlet 22.

Thus, it can be seen that by the press fit relation of the cup-shaped member 29 with the outlet fitting 24, the height of the valve seat 32 into the chamber 15 can be adjusted by merely forcing the cup-shaped member 29 to the desired position.

While the housing member 11 is illustrated as having another inlet or outlet 35 at the right hand end thereof similar to the inlet 20, it is to be understood that the inlet or outlet 35 can be utilized in the same manner as the inlet 20 or can be utilized as an outlet that leads to a desired location. Of course, the outlet 35 can be suitably plugged, if desired, whereby only one inlet 20 and one outlet 22 need be provided for the valve construction 10.

A valve member 36 is provided for the valve construction 10 and includes a plural leg bimetal member 37 having two legs 38 and 39 joined together at adjacent ends 40 and 41 thereof by a yoke portion 42 bent out of the plane of the legs 38 and 39 at a right angle thereto and being suitably stiffened or reinforced by rib means 43 formed therein. The legs 38 and 39 of the bimetallic member 37 are so constructed and arranged that with the high expansion side of the bimetal member 37 facing upwardly in the drawings, the leg 39 is bent out of the plane of the leg 38 in a downward direction in the drawings so that when the legs 39 and 38 are disposed in the coplanar relationship illustrated in FIG. 2, the natural bias of the leg 39 is in a downard direction to insure valve seating and sealing as will be apparent hereinafter.

The free end 44 of the leg 38 is adapted to be secured to an insulating post 45 disposed on the surface 28 of the housing part 13 and be not only fastened thereto by rivet-like means 46, but also be electrically interconnected by the rivet means 46 to an external terminal 47 also fastened to the housing part 13 by the rivet-like means 46 and being engaged against insulating members 48 and 48' whereby the terminal 47 is electrically interconnected to the leg 38 of the bimetal member 37.

A valve seating part 49 is formed of non-bimetallic material and has an end 50 spot welded at 51 to the free end 52 of the leg 39 of the bimetal member 37, the valve part 49 being angularly disposed relative to the leg 39 of the bimetal member 37 toward the leg 38 while being coplanar with the leg 39 in order to render the valve member 36 relatively compact as will be apparent hereinafter. The valve part 49 includes a circular section 53 being dished on the side 54 thereof as illustrated in FIG. 3 and being opposite dished at 55 on the other side thereof. In this manner, a flexible membrane 56 is adapted to be carried on the dished side 55 of the valve part 49 so as to be stretched across an annular ridge means 57 thereof and normally be spaced from the circular central flat area 58 of the valve part 49, the membrane 56 having its outer periphery 59 held against the valve part 49 by an annular ring 60, FIG. 5, held in place by bent over tab means 61 of the circular part 53.

In this manner, the flexible membrane 56 is adapted to be compressed into sealing relationship against the open and flanged end 32, 33 of the valve seat member 29 when the bimetal member 37 is disposed in the position illustrated in FIG. 2 because the natural bias of the leg 39 is in a downward direction beyond the coplanar relationship illustrated in FIG. 2 so that positive sealing of the valve seat 32, 33 is provided since the flexible membrane 56 can be deformed toward the flat area 58 of the valve member part 49 without engaging against the same so as to positively seal completely around the flanged end 33 of the valve seat member 29.

A heating device 62 is carried on the leg 38 of the bimetal member 37 and comprises an electrical resistance wire 64 wound in coil fashion on suitable electrical insulating means or plates 65 between which the leg 38 of the bimetal member 37 is to be inserted. A pair of lead clamps 66 and 67 are respectively and electrically interconnected to the opposed ends 68 and 69 of the resistance wire 64 with the clamps 66 and 67 respectively having eyelet connectors 70 for interconnecting to desired terminal means.

For example, the end 68 of the resistance wire 64 is interconnected by its eyelet member 70 to a terminal rivet means 71 supported through an insulating post means 72 in the same manner that the post means 45 supports the free end 44 of the bimetal leg 38 whereby an external terminal 47' is directly interconnected to the end 68 of the resistance wire 64. The other end 69 of the resistance wire 64 is interconnected by its connector clamp 67 to the bimetal leg 38 at the yoke portion 42 which, in turn, is electrically connected by the rivet 46 to the terminal 47 at the free end 44 of the leg 38 so that, in effect, the bimetal leg 38 is directly interconnected to the end 69 of the resistance wire 64. Thus, the resistance wire 64 of the heater 62 is placed across the terminals 47 and 47'.

As illustrated schematically in FIG. 2, the ends 68 and 69 of the resistance wire 64 are respectively adapted to be interconnected by the terminals 47 and 47' to the control deivce 19 which is adapted to interconnect the wire 64 across power source leads L.sub.1 and L.sub.2 when the control device 19 senses that the output temperature effect of the burner means 18 is below a selected temperature effect. The interconnection of the resistance wire 64 to the power source leads L.sub.1 and L.sub.2 causes the resistance wire 64 to heat up and, thus, heat up the bimetal leg 38 in such a manner that the same warps as illustrated in FIG. 6 and through such warping and the stabilizing yoke portion 42 thereof cause the leg 39 to lift the valve part 49 away from the valve seat 29 so that the fuel source 17 will be adapted to be interconnected to the burner means 18 and thereby increase the temperature output of the burner means 18. Conversely, when the control device 19 senses that the output temperature effect of the burner means 18 is above the selected temperature effect, the control device 19 disconnects the power source leads L.sub.1 and L.sub.2 from the ends 68 and 69 of the resistance wire 64 so that the resistance wire 64 is no longer heating the bimetal leg 38. Thus, the leg 38 subsequently cools and warps back to its coplanar position illustrated in FIG. 2 to thereby carry the leg 39 downwardly and, through the natural resiliency of the prebent leg 39 that tends to move the same further downwardly in FIG. 2, completely seal close the valve seat 29 to disconnect the fuel source 17 from the burner means 18.

Should the ambient temperature surrounding the valve construction 10 increase even though the control device 19 is not attempting to operate the heating device 62, no false opening of the valve seat 29 will take place because both legs 38 and 39 of the bimetal member 37 will be warped downwardly in the manner illustrated in FIG. 7 in unison through the stabilizing effect of the yoke portion 42 of the bimetal member 37 whereby the valve member 36 remains in its sealed closed position against the valve seat member 29 even though the ambient temperature has increased over that normally encountered by the bimetal member 37.

Such previously described heat motor operated gas valve construction 10 is fully disclosed and claimed in the copending patent application Ser. No. 91,438, filed Nov. 20, 1970, now U.S. Pat. No. 3,685,729 and is assigned to the same assignee to whom this application is assigned.

As previously stated, it has been found that when the bimetal member 37 for the heat motor 62 is formed of conventional bimetallic making materials, the same when heated tends to crack the gaseous fuel passing around the same so that a carbon build-up is created between the bimetal member 38 and the insulating plates 65 to cause the plates 65 to push outwardly relative to leg 38 and, thus, stress the wire 64 coiled thereon to the point of actually breaking the wire 64 through such carbon build-up.

However, it has been found according to the teachings of this invention, that if the bimetal member 38 in at least the area underneath the insulating plates 65 on the opposed sides of the leg 38 is covered with a material which itself does not act as a catalyst and can prevent the leg 38 from itself acting as a catalyst and cracking the gaseous fuel passing therearound, then the problem of carbon build-up that breaks the heater wire of the heat motor arrangement will be prevented or substantially eliminated.

According to the teachings of this invention, it has been found that when the leg 38 is plated with chrome, such as by a conventional electrolytic chrome plating process, the chrome covering on the leg 38 prevents the leg 38 from acting as a catalyst in cracking the passing of gaseous fuel through the gas valve construction 10.

For example, reference is made to FIG. 9 wherein the bimetal leg 38 comprises the conventional two layers of metallic material 100 and 101 having different coefficients of thermal expansion and suitably secured together in a conventional manner. The outer surfaces 102 and 103 of the metallic layers 100 and 101 are respectively plated with a chromium layer 104 and 105 which prevents the layers 100 and 101 from acting as a catalyst in cracking the gaseous fuel whether the same be natural gas or LP gas passing through the heat motor operated gas valve construction 10 of this invention. Such chrome plating of the leg 38 to prevent the aforementioned cracking problem, has been found, according to the teachings of this invention, when applied to a bimetal member made by the H. A. Wilson Company of Union, N.J., and designated as "Wilco" thermal metal "High Heat" bimetal member.

While it has been previously stated that the leg 38 of the bimetallic member 37 is plated in the aforementioned manner, it is to be understood that the entire bimetal member 37 at both legs 38, 39 and cross member 42 thereof could be plated if desired.

Therefore, it can be seen that this invention not only provides an improved heat motor operated gas valve construction, but also this invention provides an improved fuel control system utilizing such a heat motor construction as well as an improved method for making such a heat motor operated gas valve construction.

While the form and method of the invention now preferred have been described as required by the patent statutes, other forms or methods may be utilized all coming within the scope of the appended claims.

Claims

What is claimed is:

1. In a heat motor operated gas valve construction having a housing provided with a passage means for the passage of gaseous fuel from a fuel source therethrough and provided with a valve member and a bimetallic member for operating said valve member of said housing that is operatively associated with said bimetallic member and controls said passage means and carrying an electrical heater that is utilized to cause warpage of said bimetallic member to move said valve member to one operating position thereof when said heater is energized to heat said bimetallic member, said bimetallic member and said heater being disposed in said passage means and thereby being exposed to said gaseous fuel when flowing therethrough, the improvement comprising means disposed between said bimetallic member and said electrical heater that does not act as a catalyst with said gaseous fuel to prevent said bimetallic member when heated from acting as a catalyst with said gaseous fuel to crack the fuel and cause carbon to build up between said bimetallic member and said heater, said means disposed between said bimetallic member and said heater comprising a metallic material plated on said bimetallic member.

2. In a heat motor operated gas valve construction as set forth in claim 1, the further improvement wherein said metallic material comprises chrome.

3. In a heat motor operated gas valve construction as set forth in claim 1, the further improvement wherein said electrical heater comprises a length of resistance wire coiled about said bimetallic member, said means disposed between said bimetallic member and said electrical heater isolating said bimetallic member from said gaseous fuel at least in the area around which said wire is coiled.

4. In a fuel control system having a source of gaseous fuel and a heater motor operated gas valve construction having a housing provided with a passage means for the passage of said gaseous fuel therethrough, said valve construction having a valve member and a bimetallic member for operating said valve member of said housing that is operatively associated with said bimetallic member and controls said passage means and carrying an electrical heater that is utilized to cause warpage of said bimetallic member to move said valve member to one operating position thereof when said heater is energized to heat said bimetallic member, said bimetallic member and said heater being disposed in said passage means and thereby being exposed to said gaseous fuel when flowing therethrough, the improvement comprising means disposed between said bimetallic member and said electrical heater that does not act as a catalyst with said gaseous fuel to prevent said bimetallic member when heated from acting as a catalyst with said gaseous fuel to crack the fuel and cause carbon to build up between said bimetallic member and said heater, said means disposed between said bimetallic member and said heater comprising a metallic material plated on said bimetallic member.

5. In a fuel control system as set forth in claim 4, the further improvement wherein said metallic material comprises chrome.

6. In a fuel control system as set forth in claim 4, the further improvement wherein said electrical heater comprises a length of resistance wire coiled about said bimetallic member, said means disposed between said bimetallic member and said electrical heater isolating said bimetallic member from said gaseous fuel at least in the area around which said wire is coiled.

7. In a fuel control system as set forth in claim 4, the further improvement wherein said fuel comprises natural or LP gas.