US3346231A

US3346231A - Ambient compensated bimetal actuated valve

Info

Publication number: US3346231A
Application number: US421803A
Authority: US
Inventors: Lamar J Wall
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1964-12-29
Filing date: 1964-12-29
Publication date: 1967-10-10
Anticipated expiration: 1984-10-10
Also published as: GB1130377A

Description

Oct. 10, 1967 L. .2. WALL. 33%6331 AMBIENT COMPENSATED BI-METAL ACTUATED VALVE Filed Dec. 29, 1964 "ml? .ZA MAE J Mu:

F390 By M w 47'70E/VEV United States Patent 3,346,231 AMBIENT COMPENSATED BIIVIETAL ACTUATED VALVE Lamar J. Wall, Norwalk, Calif., assignor to Honeywell Inc., a corporation of Delaware Filed Dec. 29, 1964, Ser. No. 421,803 2 Claims. (Cl. 251-11) ABSTRACT OF THE DISCLOSURE An electrically energized, ambient compensated, bimetal actuated fuel control valve having the bimetal actuator, and the electric heater associated therewith, disposed in the fuel flow passage through the valve.

Background of the invention Fuel control valves utilizing a bimetal actuator which is heated by an electrically energizable heater are broadly old. Also, it is known to utilize, in combination with a heater of this type, a compensating bimetal to offset the ambient temperature eifects upon the actuating bimetal. However, I have found that bimetal actuators utilized in gas control valves utilize the same material for the compensating bimetal as for the actuating bimetal.

Fuel control valves of the types described must be small in size and relatively inexpensive if they are to be acceptable. Also, the actuators for these valves must operate with standard voltages and currents, the voltage customarily being about 24 volts and the current being limited by the current capacity of the device controlling the valve, usually a room thermostat. It is essential that, while staying within the above noted requirements, the valves open and close relatively rapidly and that, when the actuator is energized, the valves open to a prescribed distance sufficient to allow a substantially full flow of gas through the valve. In valves of this type it is customary to mount the bimetal actuator in a gas flow passage so that it is cooled by the fuel flowing over it. It has been apparent for some time that one of the shortcomings of the valves presently available is that, should for some reason the valve be energized when the flow of fuel over the actuator is interrupted, the actuating bimetal is overheated and it becomes distorted and consequently the actuator is rendered useless.

Brief summary of invention By my invention I provide a fuel valve utilizing a specific actuator construction which includes an actuating bimetal with an associated electric heater and a compensating bimetal which is substantially unaffected by the electric heater but which is eflective to offset the eifect of ambient temperature upon the actuating bimetal member. The actuating bimetal has a relatively low deflection constant and has its maximum temperature sensitivity range relatively low so that the heater, although operating on a relatively low voltage and with limited current input, is effective to cause relatively rapid deflection of the bimetal even though this heating is counteracted by the cooling effect of gas flowing over the actuator. The compensating bimetal is formed of a diiferent bimetal material having a substantially greater deflection constant but also having its maximum temperature sensitivity at relatively low temperatures so that it deflects in response to ambient temperature changes within the gas flow passage. In order to insure that the actuating bimetal member will not be damaged should no gas flow through the passage while the heater is energized, the actuating bimetal is made of a material which, in addition to the characteristics noted above, also is able to withstand relatively high temperaice tures such as those which might be encountered when the gas flow is so interrupted.

By so constructing the actuator, it is small in size and hence readily adaptable to typical gas valve installations. Also, it gives relatively rapid response under the limited voltage and current conditions available and opens to a position to allow a substantially full flow upon energization of the heater. It is able to withstand the high temperatures encountered should the gas flow through the valve be interrupted when the actuator is energized.

It is therefore an object of my invention to provide an improved bimetal actuated, ambient temperature compensated, fuel control valve.

Another object of my invention is to provide in combination with a fuel control valve, an ambient compensated bimetal actuator which gives relatively rapid response and substantial deflection with limited voltage and current inputs and which is capable of withstanding relatively high temperatures at the actuating member without damage thereto.

These and other objects of my invention will become apparent upon reading the following detailed description of a preferred embodiment taken in conjunction with the drawing, wherein:

FIGURE 1 is a longitudinal cross-sectional view of a gas valve constructed according to my invention.

FIGURE 2 is a greatly enlarged view taken generally along line 2-2 of FIGURE 1 and disclosing the inner surface of a cover member and bimetal actuator mounted thereon for the valve of FIGURE 1.

FIGURE 3 is a cross-sectional view of the valve cover and bimetal actuator taken generally along line 3-3 of FIGURE 2.

Detailed description Referring to FIGURE 1, numeral 10 generally designates a valve body having an inlet chamber 11 and an outlet chamber 12 separated by a wall 13. Wall 13 has a port 14 therethrough and around this port, in the inlet chamber, is formed an annular valve seat 15. Removably attached to valve body 10 by appropriate means, such as screws 16, is a cover member 17. In order to insure a gas tight seal between the cover member and the valve body, an appropriate gasket may be used between these members. Cover 17 has an outer surface on which is mounted an electrical connector means 20 which may be of any appropriate type and to which electrical connectors (not shown) which supply power for a bimetal actuator to be described hereinafter, are connected. Cover 17 also has an inner surface 21 which is exposed to the inlet chamber 11 and to which is connected 'by appropriate means, such as welding (not shown), a depending mounting bracket 22 on which is mounted a bimetal actuator generally designated by numeral 23. This actuator operates a fuel control valve 24 which cooperates with the seat 15. The details of the mounting bracket 22, the bimetal actuator 23, and the valve closure member 24 can best be seen by referring to FIGURES 2 and 3.

Mounting bracket 22 includes a pair of downwardly extending legs 22A each having an inwardly struck, transversely extending portion 24, a lower end 25 of which is bent generally tangential to the leg and extending towards the wall of the body. To this portion 25 is attached, by appropriate means, such as welding, one end of an actuating bimetal member 26. As best seen in FIGURE 2, actuating member 26 is a generally rectangular strip of material cantilevered from the bracket 22. The free end of member 26 extends generally horizontally in chamber 11. Actuating member 26 has attached to its free end, by appropriate means, such as rivets 27, one end of an ambient compensating bimetal member 30. Disposed between I the

bimetal members

26 and 30 at their point of connection is a heat insulating means 31 which is held in place by the rivets 27. Actuating member 26 is preferably wrapped with an insulating material 32 which may take of the length of actuating member 26 is wrapped an electrical resistance'heater 33. The electrical leads for heater 33 may be connected to terminals 34 which are mounted on the inside of the cover member 17 and which form a a part of the electrical connector generally designated'by numeral 20. Asseen in FIGURE 3, the insulating material 32 may extend partially over the fixed end of compensating member 30' in order to aid in isolating the compensating member from the heater 33.

Adjacentits free end, compensating member 30 has an aperture 35 through which is mounted a stem 36 which carries the closure member 24. As seen in FIGURES 1 and 3, this mounting may be 'one which permits some relative motion between the compensating member and the closure member to assure good'seating of the closure member on the valve seat. A mounting of this type is conventional and therefore additional description of it is thought to be unnecessary. V As will be noted in FIGURE 1, the actuator 23 is disposed in the inlet chamber 11 and, consequently, normally would be in the path of gas flow when the closure member 24 is opened. In the preferred embodiment of my invention, the

bimetal members

26 and 30 are so constructed that when heater 33 is not energized, the actuator maintains closure member 24 seated against the valve seat 15 with a predetermined seating force. Deflection of the actuating member -26 in response to the heat produced by heater 33 when it is energized is effective to lift the closure member from it's seat. g r

' As noted previously herein, it has been customary in bimetal actuators of this type to utilize an actuating bimetal member and a compensating member which are constructed of identical materials. customarily these have 4- gization. In addition, the compensating bimetal must be such that it is capable of oifsetting the ambient effects upon the actuating member.

I have overcome all of these problems-by'utilizing for the'actuating member a bimetallic material which is ca- 7 pable of withstanding relatively high temperatures, for ex- 7' ample, up to approximately 800 The material which I use also has a relatively low deflection constant. Its

maximum range of sensitivity, that is the range in which 7 it is most sensitive to temperaturechange, falling at relatively low temperatures, for example between 0 F. and 300 P. so that it is responsive to the heat which can be supplied by the heater 33 with the limited voltage and currents available and with the cooling generally encountered due to the flow of gas over the actuator.

To utilize a similar bimetal as the compensating member would be totally unacceptable since the relatively low deflection constant of the material used for the actuating member would mean that an extremely long compens-ating member would be necessary. It should be noted that since the compensating member is'connected to the free end of the actuating member, the displacement of the actuating member due to ambient'temperature results in a much greater displacement of the compensating member. Therefore, in order to compensate for this ambient effect, the deflection of the compensating member must be substantially greater than the deflection of the actuating 7 member. I have overcome this problem by utilizing for 7 been of'a material which has a relatively large tempera- I ture'deflection constant, that is, one which deflects a sub- 'stantial amount in response to a temperature change, and

they have been constructed of a material which has a relatively low maximum operating temperature. When upstream of the valve. This may take place, for example in the case of a valve utilized in a home heating'system, when an upstream plug valve has been shut off during the summer season and then for some reason the controlling thermostat is turned up and consequently the heater'energized. This-results in high temperatures at the actuating bimetal member and this in turn results in distortion of the conventional actuating member so that the entire actuator must be replaced. 7

I have overcome this problem by substituting a bimetal material which is able to withstand relatively high temperatures for a prolonged period without damage thereto. However, it must be remembered that the bimetal materials from which such actuators can be constructed are limited to those which are available from suppliers of such material. Obviously, to devise new materials for each application would be impractical if not impossible. In order to render the valve acceptable for use in the fuel valve market, it must be able not only to withstand such high temperature conditions which may arise, but also it must properly function under normal operating conditions. In other words, the actuator must respond relatively rapidly to the available voltage and current supplied (normally 24 volts and a relatively low current limited by the current capacity of the controlling thermostat), the deflection must be adequate to allow substantially full flow through the valve when the valve is energized and the actuator must respond quite rapidly upon enerthe actuating heater for prolonged periods when the flow the compensating member a different bimetal material having a substantially greater deflection constant so that a change in ambient temperature has a greater effect per unit length upon the compensating member than it does upon the actuating member. Also, the compensating member was'chosen so that its maximum temperature sensi- 1 tivity is within a range which is low enough so that it includes the normally encountered ambient temperatures.

In a preferred embodiment of my invention I have chosen to construct the actuating member 26 from a material known asChace #2400 and the compensating member 30 from a material known as Chace #6650. These materials are manufactured and sold by the W. MI Chace Company. Obviously, equivalent or substantially equivalent materials may be used. By so choosing the materials for these members, the actuating member 26 is capable of withstanding temperatures up to about 800 F. without damage thereto and its maximum temperature sensitivity range is between about 0 F. and about 7 300 F. which would include the range of temperatures which could be expected to result from the energization of heater 33 when gas is flowing through the valve and over the actuator. The compensating bimetal 30, when so chosen, has a maximum temperature sensitivity range between about 0" F. and about 400 F., the lower portion of this range including those temperatures which could normally be expected as ambient temperatures in the inlet chamber of the valve where the actuator is located. The ratio of the deflection constant ofthe actuating member and the compensating member, respectively, is then approximately 3 to 4 so that the deflection per unit length of the compensating member is substantially greater than the deflection of the actuating member for a given temperature change. With the member so chosen the overall length of the actuator is kept to a minimum. For example, in this preferred embodiment of my invention, the ratio between the efiective lengths of the actuating member and the compensating member'respectively, was approximately 6:8.

P Therefore with the construction described above, I have overcome a serious shortcoming found in valves of this type, namely their inability to withstand energization of through the valve is interrupted. This problem has been overcome without incerasing the size of the valve or its cost and without sacrificing any of the desired operating characteristics of the valve.

U While I have shown and described a specific embodiment of my invention, various modifications thereof may become apparent to those skilled in the art in view of my disclosure herein. Therefore my invention is to be limited solely by the scope of the appended claims.

I claim:

1. A full control valve comprising:

a valve body having an inlet chamber and an outlet chamber separated by a wall therebetween, a port through said wall, and a valve seat associated with said port;

a cover member removably secured to said body and having an inner surface adjacent said inlet chambet;

a mounting bracket depending from the inner surface of said cover member and extending into said inlet chamber;

an actuating bimetal member disposed in said inlet chamber in the path of fuel flow, said actuating member having one end fixed to said mounting bracket and having a free end adapted to move in a first direction in response to an increase in temperature;

an ambient compensating bimetal member having one end fixed to the free end of said actuating member and having a free end extending therefrom, said compensating member being arranged with respect to said actuating member so that upon a change in ambient temperature the direction of movement of the free end of said compensating member is opposite to the direction of movement of said actuating member and having an effective length such that relative movement of said actuating and compensating members upon a change in ambient temperature substantially offset each other and result in substantially no movement of the free end of said compensating bimetal;

an electrically energizable heater associated with said actuating member and adapted, when energized, to heat said actuating member without substantially affecting the temperature of said compensating member;

said actuating member being formed of a bimetallic material having a relatively low-temperature deflection constant and maximum temperature sensitivity at relatively low temperatures in a range including the temperatures experienced by said actuating member when said heater is energized and a portion of the heat generated thereby is dissipated by fuel flowing over said actuating member, said actuating member being capable of withstand ing, for prolonged periods without damage, relatively higher temperatures experienced thereby when said heater is energized but no fuel is flowing over said actuating member to dissipate a portion of the heat;

said compensating member being formed of a bimetallic material of a different composition and having a deflection constant substantially greater than said actuating member so that upon a change in ambient temperature the deflection per unit length of said compensating member is substantially greater than the deflection per unit length of said actuating member, so that the effective length thereof is substantially 'less than would be necessary to provide ambient compensation if the actuating and compensating members were constructed of the same material, and said compensating member having a maximum temperature sensitivity at relatively low temperatures including temperatures in the range of ambient temperatures to which it is normally subjected; and

means operably connecting the free end of said compensating member of the closure member.

2. The invention defined in claim 1 wherein said actuating bimetal member is capable of withstanding temperatures up to about 800 F. without damage thereto and has a maximum temperature sensitivity range between about 0 F. and about 300 F. and said compesating bimetal member has a maximum temperature sensitivity range between about 0 F. and about 400 F. and wherein the ratio of the deflection constants of said actuating member and said compensating member, respectively, is approximately 3:4 and the ratio of the effective length of said actuating member and said compensating member, respectively, is approximately 6:8.

References Cited UNITED STATES PATENTS 3,275,285 9/1966 Morris 251-11 M. CARY NELSON, Primary Examiner.

A. ROSENTHAL, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,346,231 October 10, 1967 Lamar J. Wall It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 7, "full" should read fuel Column 6, line 27, "of the" should read to the line 32, "compesating" should read compensating Signed and sealed this 17th day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

Claims

1. A FULL CONTROL VALVE COMPRISING: A VALVE BODY HAVING AN INLET CHAMBER AND AN OUTLET CHAMBER SEPARATED BY A WALL THEREBETWEEN, A PORT THROUGH SAID WALL, AND A VALVE SEAT ASSOCIATED WITH SAID PORT; A COVER MEMBER REMOVABLE SECURED TO SAID BODY AND HAVING AN INNER SURFACE ADJACENT SAID INLET CHAMBER; A MOUNTING BRACKET DEPENDING FROM THE INNER SURFACE OF SAID COVER MEMBER AND EXTENDING INTO SAID INLET CHAMBER; AN ACTUATING BIMETAL MEMBER DISPOSED IN SAID INLET CHAMBER IN THE PATH OF FUEL FLOW, SAID ACTUATING MEMBER HAVING ONE END FIXED TO SAID MOUNTING BRACKET AND HAVING A FREE END ADAPTED TO MOVE IN A FIRST DIRECTION IN RESPONSE TO AN INCREASE IN TEMPERATURE; AN AMBIENT COMPENSATING BIMETAL MEMBER HAVING ONE END FIXED TO THE FREE END OF SAID ACTUATING MEMBER AND HAING A FREE END EXTENDING THEREFROM, SAID COMPENSATING MEMBER BEING ARRANGED WITH THE RESPECT TO SAID ACTUATING MEMBER SO THAT UPON A CHANGE IN AMBIENT TEMPERATURE THE DIRECTION OF MOVEMENT OF THE FREE END OF SAID COMPENSATING MEMBER IS OPPOSITE TO THE DIRECTION OF MOVEMENT OF SAID ACTUATING MEMBER AND HAVING AN EFFECTIVE LENGTH SUCH THAT RELATIVE MOVEMENT OF SAID ACTUATING AND COMPENSATING MEMBERS UPON A CHANGE IN AMBIENT TEMPERATURTE SUBSTANTIALLY OFFSET EACH OTHER AND RESULT IN SUBSTANTIALLY NO MOVEMENT OF THE FREE END OF SAID COMPENSATING BIMETAL; AN ELECTRICALLY ENERGIZABLE HEATER ASSOCIATED WITH SAID ACTUATING MEMBER AND ADAPTED, WHEN ENERGIZED, TO HEAT SAID ACTUATING MEMBER WITHOUT SUBSTANTIALLY EFFECTING THE TEMPERATURE OF SAID COMPENSATING MEMBER; SAID ACTUATING MEMBER BEING FORMED OF A BIMETALLIC MATERIAL HAVING A RELATIVELY LOW-TEMPERATURE DEFLECTION CONSTANT AND MAXIMUM TEMPERATURE SENSITIVITY AT RELATIVELY LOW TEMPERATURES IN A RANGE INCLUDING THE TEMPERATURES EXPERIENCED BY SAID ACTUATING MEMBER WHEN SAID HEATER IS ENERGIZED AND A PORTION OF THE HEAT GENERATED THEREBY IS DISSIPATED BY FUEL FLOWING OVER SAID ACTUATING MEMBER, SAID ACTUATING MEMBER BEING CAPABLE OF WITHSTANDING, FOR PROLONGED PERIODS WITHOUT DAMAGE, RELATIVELY HIGHER TEMPERATURES EXPERIENCED THEREBY WHEN SAID HEATER IS ENERGIZED BUT NO FUEL IS FLOWING OVER SAID ACTUATING MEMBER TO DISSIPATE A PORTION OF THE HEAT; SAID COMPENSATING MEMBER BEING FORMED OF A BIMETALLIC MATERIAL OF A DIFFERENT COMPOSITION AND HAVING A DEFLECTION CONSTANT SUBSTANTIALLY GREATER THAN SAID ACTUATING MEMBER SO THAT UPON A CHANGE IN AMBIENT TEMPERATURE THE DEFLECTION PER UNIT LENGTH OF SAID COMPENSATING MEMEBR IS SUBSTANTIALLY GREATER THAN THE DEFLECTION PER UNIT LENGTH OF SAID ACTUATING MEMBER, SO THAT THE EFFECTIVE LENGTH THEREOF IS SUBSTANTIALLY LESS THAN WOULD BE NECESSARY TO PROVIDE AMBIENT COMPENSATION IF THE ACTUATING AND COMPENSATING MEMBERS WERE CONSTRUCTED OF THE SAME MATERIAL, AND SAID COMPENSATING MEMBER HAVING A MAXIMUM TEMPERATURE SENSITIVITY AT RELATIVELY LOW TEMPERATURES INCLUDING TEMPERATURES IN THE RANGE OF AMBIENT TEMPERATURES TO WHICH IT IS NORMALLY SUBJECTED; AND MEANS OPERABLY CONNECTING THE FREE END OF SAID COMPENSATING MEMBER OF THE CLOSURE MEMBER.