US2672292A

US2672292A - Combined thermostat and automatic pilot control

Info

Publication number: US2672292A
Application number: US239554A
Authority: US
Inventors: Michael J Caparone; Charles M Vaughn
Original assignee: Robertshaw Fulton Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1951-07-31
Filing date: 1951-07-31
Publication date: 1954-03-16
Anticipated expiration: 1971-03-16

Description

March 16, 1 M. J. CAPARONE ET AL 2,672,292

COMBINED THERMOSTAT AND AUTOMATIC PILOT CONTROL Filed July 31, 1951 3 Sheets-Sheet l INVENTORS Me'afiael Jfiz aa oue dud March 16, 195.4 M. J. CAPARONE ET AL 2,672,292

COMBINED THERMOSTAT AND AUTOMATIC PILOT CONTROL iled July 31, 1951 3 Sheets-Sheet 2 LNVENTURS Me'cfiaeZ 1. dk oar'ozze me March 16, 1954 M. J. CAPARONE ET AL 2,672,292

COMBINED THERMOSTAT AND AUTOMATIC PILOT CONTROL Filed July 31, 1951 3 Sheets-Sheet I5 68 62 64 76 66 5 60 Z48 5'6 M 5'6 16] 5'0 I I 5 20 46 I I Z 46 I? I0 INVENTORS Mzbael J agoamlze ma y Lhzzvs M Vzqy/m mare AYTOHA/H Patented Mar. 16, 1954 COMBINED THERMOSTAT AND AUTOMATIC PILOT CONTROL Michael J. Caparone, Arcadia, and Charles M. Vaughn, Santa Monica, Calif., assignors to Robertshaw-Fulton Controls Company, Greensburg, Pa., a corporation of Delaware Application July 31, 1951, Serial No. 239,554

Claims.

This invention relates to combination controls for gaseous fuel burners wherein the temperature controlling device and the pilot cut-0.1T both opcrate upon a single control valve.

The present invention is particularly adapted, although not limited, for use with gas burning water heaters and the like wherein Water temperatures are controlled within precise limits.

The thermostatic device which is responsive to the water temperature is preferably of the rod-and-tube type having temperature adjustment means located on the control body for ready access by the user. The automatic pilot control in this embodiment includes an expansible thermal element of the mercury vapor pressure type responsive to the flame of the pilot burner.

Since provision may be made for complete shutofi of fuel to both the main and pilot burners under automatic control, a separate pilot valve can be provided for conjoint operation to closed position with the main burner valve. Operation of such a pilot valve to open position can conveniently be efiected by a control handle on the body adjacent the temperature adjustment means. An interlock between the main gas cook and the pilot valve will permit operation of the latter to open position only when the gas cock is in the pilot position and is thus positioned for preventing flow of fuel to the main burner valve. Thereafter, the pilot valve is maintained opened by operation of the automatic pilot control whenever the pilot burner is producinga flame for heating the expansiblethermal element.

The invention includes a pivoted lever member operably engageable with the main burner valve which is biased toward closed position and is operable toward open position by the thermostatic device. The lever member is engageable by an actuating member biased for moving it to an active position for holding the main valve closed irrespective of the thermostatic device. Manually operable means are efiective for overcoming the bias of the actuating member for movement of the lever member to an inactive position and freeing the main valve for an opening operation. Means are also provided for opcrating the pilot valve to open positionwhile the lever member is in the inactive position. The expansible thermal element responsive to a flame at the pilot burner member in said inactiveposition upon release of the manually operable means.

The device provides safe lighting since the manually operable means is effective for holding the pilot valve open serves to maintain the lever only when the "interlock is i eifective. Moreover, a complete shut-oil of fuel to both main and pilot burners occurs upon extinguishment of the pilot burner flame. These objects are accomplished with a fail-safe type of unit which prevents leakage of gas under abnormal conditions of damage to the automatic pilot control.

' With these and other objects and advantages in view, a preferred embodiment of the invention is illustrated in the accompanying drawings, wherein;

Fig. l is a plan view of the control device;

Fig. 2 is a longitudinal section on an enlarged scale taken on the line 11-11 of Fig. 1;

Fig. 3 is a cross-section on an enlarged scale taken on the line III--III of Fig. 1, but revolved Fig. 4 is a crosssection taken on the line IV-IV of Fig. 3;

Fig. 5 is a partial section taken on the line VV of Fig. 3;

Fig. 6 is a section on an enlarged scale taken on the line VI-VI of Fig. 2;

Fig. 7 is a plan view of a detail, and

Fig. 8 is an elevation of the detail shown in Fig. 7.

M az'n shut-01f cock Referring more particularly to the drawings, the control device comprises a casing ill provided at one end with a lateral inlet opening 12 for fuel and at the other end with an outlet opening M for the fuel. A main fuel passage I 8 through the casing I 0 provides communication between the inlet 12 and the outlet I4. As is customary in such devices, suitable pipe connections may be provided at the inlet !2 and the outlet [4 to ably, the knob 22 carries the usual indicia (not shown) for the on, off and pilot of the main shut-oil cock it which are adapted to register selectively with a pointer 24 carried by a stop plate 25 secured to the casing H3 in an appropriate location.

The knob 22 is also adapted for axial movement relative to the cock It for a purpose appositions 2,672,292 H r e parent hereinafter. As shown more clearly in Figs. 6, '7 and 8, the knob 22 is provided on its underside with a substantially annular recess 28 which however, is interrupted by an unrecessed or land portion 28 and a cam portion 30 which lies opposite the indicia pilot." An arcuate adjustable stop element 32 is secured to the underside of the knob 22 by a screw 34 which is accessible from the exterior of the knob 22. A second stop element 36 projects from the stop plate into the recess 26.

The structure described serves to limit the rotation of the knob 22 to an arc of approximately 180 between the off and on positions. Thus, when the knob 22 is rotated to the off position, the land portion 28 abuts the stop element 36 and further rotation is prevented. Likewise, when the knob 22 is rotated to the "on position then the adjustable stop 32 abuts the stop 36. It will be apparent that the position of the stop 32 can be altered by loosening the screw 34,setting the stcp 32 to the desired position and then tightening the screw 34.

A plunger 38 projects from the casing I0 underneath the knob 22 for alignment with the cam element in the pilot position. Thus, when the knob 22 is rotated to the pilot" position and moved axially relative to the shut-oil? cock I8 then the cam element 30 will engage the plunger 38 and move it inwardly of the casing I0. Movei ment of the plunger 38 outwardly of the casing I0 is limited by engagement of a collar 40 formed on the plunger 38 with the interior bottom wall of a. cap nut 42 on the casing is and through which the plunger 38 projects. A coil spring 44 serves to bias the plunger 38 outwardly of the casing I0, but such movement is limited as described.

Pilot valve As shown more clearly in Figs. 3 and 5, the

casing I0 is provided with an integral hollow boss 48 disposed on one side of the shut-off cock I8 and provided with a hollow filter cartridge 48 for the pilot fuel. The bottom wall of the filter cartridge 48 is suitably sealed, as at 50, in fluid-tight connection with the bottom wall of the hollow boss 46. The outer wall of the cartridge 48 is, however, spaced from the inner wall of the boss 46 to provide for passage of fuel therebetween.

To this end, a passage 52 is formed in the casing I0 for communication at one end with an arcuate groove 54 in the side wall of the shut-01f cock I8 forming an extension of the port 20 therethrough. The groove 54 affords communication between the port 20 and the passage 52 when the f shut-off cock is in the on position and fuel is passing directly from the port 20 to the main fuel passage I6.

The opposite end of the passage 52 communicates with the hollow boss 46 adjacent the side wall of the filter cartridge 48 which thereby receives fuel in its upper end to be filtered and emitted from the lower end thereof adjacent the seal 50. A pilot passage 58 formed in the boss 48 communicates at one end with the lower end of the filter cartridge 48 and at the opposite end with a pilot valve chamber 58 formed in the casing I0. A pilot valve member 6!! is mounted in the chamber 58 and is reciprocable on an axis substantially normal with that of the plunger 38 to open and close a passage through a pilot valve seat member 82 which is supported in the chamber 50.

A closure cap 84 provides access to the valve :member 60 and also forms a seat for one end of a 4 coil spring 66 serving to bias the valve member 60 toward its seat 62. An outlet passage 88 communicates with the passage in the valve seat member 82 and thus receives a supply of fuel from the inlet passage 56 when the valve member 60 is in open position. The oposite oroutlet end of the passage 68 terminates in a suitable connection 10 for a pilot conduit for supplying fuel to a pilot burner (not shown). The usual adjusting means 12 is provided in the passage 68 for flow of fuel to the pilot burner.

Movement of the pilot valve member 50 between open and closed positions is effected by operation of a pilot valve stem I4 which projects through the passage in the pilot valve seat member 62 and is suitably fluted or noncircular to permit passage of fuel thereby. The usual sealing diaphragm I8 is provided for the operating end of the valve stem 14 to prevent leakage of fuel from the chamber 58. An operating head 18 is carried on the valve stem 14 on theopposite side of thesealing diaphragm "I5 therefrom to provide convenient means for moving the valve member to open position when desired Control valve mechanism As shown more clearly in Fig. 2, an annular main valve seat member 80 is formed in the cas-. ing I0 in position to intersect the passage of fuel from the inlet I2 to the outlet I4 throughthe main fuel passage I6. An axial hollow boss 82 is formed within the annular valvev seat 80 and provides a bearing for a main valve stem 84 which is reciprocable therein. A valve stem-84 is axially bored to accommodate an override mechanism comprising a plunger 86. and an override spring 88. The plunger 86 is biased outwardly of the valve stem 84 by the spring 88, but such relative movement is limited by a stop in the form of a bushing 90 which engages a collar 92 formed on the plunger 86. A disc-type main valve member 94 is mounted on the valve stem 84 for axial reciprocable movement therewith between open and closed positions relative to the valve seat 80 as will be described more fully hereinafter.

The axial hollow boss 82 forms one wall of, a chamber I00 in the casing In which houses a snap-action means of conventional form comprising clicker mechanism I02 and an annular thrust element I04 for operating the valve member 94 to open position. The clicker mechanism I02 operatively engages the plunger 86 of the override mechanism which normally acts as a solid unit as hereinafter described. The thrust element I04 carries a thrust button I06 which projects through a sealing ring I08 forming an opposite wall for the chamber I 00.

Temperature regulation Thermally responsive means for operating the valve member 94 through the clicker disc mechanism I02-I06 is carried by a thermostat housing H0 which is secured to the exterior of the casing I0 adjacent the thrust button I06. The housing IIO may be of conventional formfor securing the casing I0 to the tank of the water heater. The usual rod-and-tube thermally responsive element II2--I I4 projects from the housing IIO into the tank of the water heater and, as is customary in such devices, the rod IIZ has a relatively low coeflicient of expansion while the tube II4 has a higher coefficient of expansion. The differential under the influence of the heat of the water in the tank causes the rod element H2 to move outwardly of the casing I0.

acetate The rod element II2 projects toward the thrust button I06 on one side thereof and epgages a connecting lever H6 having an operating end supported on t, e thrust button 406.

access by the user. Yieldable means in the form of a leaf spring I22 is carried by the thrust button I06 for operative engagement with the lever II 6 to maintain it in engagement with the thrust button I06 and the adjusting screw I I6 respectively. Automatic pilot control The vapor-pressure type automatic pilot control of this invention is adapted to render the rod-and-tube element l i2, H4 inefiective for opening the valve member 94 unless the pilot burner of the appliance is producing a flame. The automatic pilot control comprises an actuating device including a bulb element I23, a capillary tube I24 and a diaphragm unit I 26 as is customary in such devices. As shown more clearly in Fig. 3, the device is adjustably connected to the casing It by the provision of a bushing I 28 threaded into a hollow boss I 3.2

formed on the casing I 0. An internally threaded eeve I29 is slid biy mounted in th ushin I28 to abut a houlder I31 on the bushing i211 and en age a suitably threaded connection I 30 secured to the diaphragm unit I26. The hollow boss I32 extends at an angle to the main shut, off cock I8 on the opposite side thereof from the pilot valve opening 58. Provision against leakage of fuel through the boss I32 is made by a packing I34 which is compressed into engagement with the threaded bushing I28 by a packing nut I36 through which the capillary tube I24 extends. The bulb element I23 contains a quantity of mercury which becomes vaporized upon the bulb element I23 being suificiently heated and serves to actuate the diaphragm i.

unit I26 by expansion thereof. The diaphragm unit I26 projects into a chamber I38 commus nicating with the chamber I6 opposite the projection of the plunger 38 therein.

Means are employed for transmitting the movement of the diaphragm unit I26 for main! taining the valve member 94 in closed position irrespective of the rod-antletube element I12, II4. To this end, an angular lever member I40 is pivoted intermediate its ends on a bracket I42 projecting from the casing I into the passage I6. The lever member I40 carries an adjusting screw I44 at one end which is operatively engageable with the valve stem 84. A coil spring I46 serves to bias the lever member I49 and the valve member 94 apart. However, the lever member I 40 is adapted to be maintained in an active position with the adjusting screw I44 in engagement with the valve stem 64 by actuat= mg means which are effective upon the opposite end of the lever I40.

. The actuating means include a plunger I43 which extends from the chamber I into engagement with the opposite end of the lever I40. The plunger I46 is reciprocable in a sup-..--

Port member I50 which is secured in the cham ber I38 by a threaded cap member 152 mounted on the casing I0. .Biasing means for urging the plunger I48 toward the lever I takes the form of a coil spring I54 which is operative between the cap member I52 and a suitably recessed nut I56 carried on the plunger I48 for slidable movement in the support member I 50. The threaded end of the plunger I48 is provided with a screw driver slot to facilitate adjustment of the nut I56 thereon. A yieldable disc I58 may be interposed between the end cap member I52 and the support member I to provide a yieldable mounting .for the latter.

The movement of the diaphragm unit I26 is transmitted to the plunger I 48 by detent means in the form of a bell-crank I60 which is pivoted on the support member I50 for this purpose. One end of the bell-crank I60 engages with the diaphragm unit I26 while the opposite end is 'apertured to extend around the plunger I48 into operative engagement with the nut I56 carried thereon. It will be apparent that the spring I54 N tends to rotate the bell-crank I60 clockwise as viewed in Fig. 3 and maintains it in operative engagement with the diaphragm unit I26.

The end of the lever member I40 engageable by the plunger I48 extends therebeyond and is operatively engageable on the opposite side thereof by the manually operable plunger 38. A projection I6! extends substantially normal to this end of the lever I40 for operative engagement with the operating head 18 of the pilot valve member 60.

Operation The control device is shown in the drawings as in the normal running condition with both the pilot valve member Stand the main valve member 94 in open position. The control device is placed in such condition by manual operation when the knob 22 is rotated to the pilot position and pushed in axially to engage the plunger 38 with the cam element 30 on the underside of the knob 22. The resulting inward movement of the plunger 38 serves to rotate the lever member I40 clockwise, as viewed in Fig. 2, about the bracket I62 on which it is pivoted. The projection I61 on the lover I 40 engages the operating head l8 and moves the pilot valve member 66 to open position.

Fuel now flows from the inlet I2, angular port is in the shut-off cock I6, passage 52, hollow boss '46, filter cartridge 48, passage 56, pilot valve seat 62, passage 60, and through the connection I0 for the pilot burner. Since the angular port 26 in the main shut-off cock I6 is at this time out of alignment with the opening to the passage I6, no flow of fuel to the main outlet I 4 can occur irrespective of whether the rod-and-tube element I I 2, I M is in condition for opening the main valve member 94.

The fuel flowing from the pilot burner is now ignited manually while the knob 22 remains depressed. The pilot flame heats the bulb I23 which is located adjacent to the pilot burner and vaporizeg the mercury contained in the bulb I23. The resulting movement of the diaphragm unit i26 serves to rotate the bell-crank H36 counterclockwise about its pivot as viewed in Fig. 3. Thus, the opphsite end of the bell-crank I66 moves into engagement with the nut I56 and serves to hold the coil spring I54 compressed.

Upon release of manual pressure on the knob 22 the plunger 30 will return to-its' outwardly projecte'd position. Since the coil spring I54 of the lever actuating means is held compressed by the greater force exerted by the diaphragm'unit I26, the return movement of the plunger 38 is unaccompanied by counterclockwise movement of the lever member I40 as viewed in Fig. 2. Dueto this lack of movement of the lever I40, the pilot valve member 60 remains in open position with the projection IIiI of the lever member MD in engagement with the operating head I8.

The knob 22 may now be rotated to the on position for supplying fuel from the inlet I2 through the angular port 26 to the passage It in the casing Ii! as well as continuing the supply to the pilot passage 52 through the arcuate groove 54. It may be assumed that the rod element II2 of the rocl-and-tube thermally responsive device H2, Ht is in an advanced position relative to the thrust button I86 as the water in the tank is still cold and the tube element H4 is contracted. Consequently, the end of the connecting lever H6 in engagement with the trust button I535 is moved by the rod element I I2 in a counterclockwise direction as viewed in Fig. 2 andabout the end of the adjusting screw IIB as a fulcrum.

Such movement of the thrust button it causes the clicker mechanism I52, IE4 to snap over and actuate the valve member to open position. Since the lever member Mil is in its inactive position, such opening movement of the valve member 94 is not interfered with and the devic is placed in normal running condition as shown in the drawings. l v

As the water in the tank increases in temperature, depending on the temperature set by the temperature adjusting knob I28, then the rod element I I2 will be retracted away from the easing ID and the force exerted by the connecting lever Hdonthe thrust button its will cease. Thus, the main valve member 94 will move under bias .of the spring I45-toward closed position relative to the valve seat 8%! to shut-oil flow of fuel through the outlet I4 to the main burner. Such operation of the valve member 94 between open and closed positions will continue as necessary to maintain the temperature set by the temperature adjusting knob I20.

Should the flame at the pilot burner become extinguished then the bulb element I23 will become cooled allowin the diaphragm unit I26 to contract. The actuating means for the lever member I40 is now free to operate under bias of the coil spring I54. Consequently, the plunger I48 will rotate the lever member I40 counterclockwise, as viewed in Fig. 2, to its active position serving to close the main valve member 94 and the pilot valve member 66 under bias of the coil springs I46 and 66 respectively. Thus, a complete shut-oil of fuel to both the pilot outlet iii and the main burner outlet I4 occurs upon operation of the automatic pilot control.

The main valve member 94 will remain closed irrespective of the cooling of the water in the tank and .the resulting movement of the rod element I lz'inwardly of the casing I0. Thus, should such movement of the rod element I I2 occur un der these conditions, then the clicker mechanism I82, I04 will snap over without any damage occurring due to operation of the override mechanism. In this operation the spring 88 becomes compressed by movement of the override plunger 86 relative to the valve stem at instead of this device operating as a solid unit as in normal operation.

, It is apparent that should a leak develop in the actuating element comprising bulb I23, capillary tube I24, and diaphragm unit I26 during normal running conditions, then the actuating element can no longer exert a force tending to rotate the bell-crank ISO to a position for holding the spring I54 compressed. Consequently, a complete shutoff of fuel will occur as in the case of operation of the automatic pilot control upon extinguishment of the flame at the pilot burner. This failsafe feature is utilized in conjunction with the automatic pilot control and the provision for safe lighting to afford complete safety control in device of the described character.

It will be understood that many changes may be made in the details of the construction and arrangement of parts without departing from the scope of this invention as defined in the appended claims.

We claim:

1. A combined temperature and automatic pilot control comprising in combination, main and auxiliary valve means biased toward closed position, a first thermally responsive means for'operating said main valve means toward open position, a pivoted lever member operably engageable at one end with said main valve means, an actuating member engageable with the opposite end of said lever member, means for biasing said actuating member for moving said lever member to an active position for holding said main valve means closed irrespective of said first thermally responsive means, manually operable means engageable with one of said members for overcoming said biasing means for movement of said lever member to an inactive position and freein said main valve means for said opening operation, means carried by one of said members for operating said auxiliary valve means toward open position in said inactive position of said lever member, detent means cooperable with said actuating member, said detent means having a first position wherein said actuating member is restrained from movement under said bias and a second position wherein said actuating member is free to act under said bias, and a second thermally responsive means including an expansible diaphragm unit for moving said detent means to said first position in one thermal condition thereof and to said second position in another thermal condition thereof. i

2. A combined temperature and automatic pilot control as claimed in claim 1 wherein said actuating member comprises a plunger engageable with one side of said lever member, said manually operable means including a second plunger engageable with the opposite side of said lever member.

3. A combined temperature and automatic pilot control comprising in combination, main and auxiliary valve means biased toward closed position, a first thermally responsive means for operating said main valve means toward open position, a pivoted lever member operably engageable at one end with said main valve means, an actuating member engageable with the opposite end of said lever member, means for biasing said actuating member for moving said lever member to an active position for holding said main valve means closed irrespective of said first thermally responsive means, manually operable means engageable with one of said members for overcoming said biasing means for movement of said lever member to an inactive position and freeing said main valve means for said openin operation, means carried by one of said members for operating said auxiliary valve means toward open position in said inactive position of said lever member, a second thermally responsive means including an expansible diaphragm unit positioned adjacent said actuating member, and a second lever member operatively engageable with said actuating member, said second lever member having a first position wherein said actuating member is restrained from movement under said bias and a second position wherein said actuating member is free to act under said bias, said diaphragm unit being operatively engageable with said second lever member for moving the same between said first and second positions in response to variations in a temperature condition sensed by said second thermally responsive means.

4. A combined temperature and automatic pilot control as claimed in claim 3 wherein said actuatin member comprises a plunger engageable with one side of said lever member, said manually operable means including a second plunger engageable with the opposite side of said lever member.

5. A combined temperature and automatic pilot control comprising in combination, a casing having an inlet and an outlet for fluid, a rotatable valve member controlling a passage for fluid between said inlet and outlet, pilot valve means controlling a passage for fluid from said inlet under control of said rotatable valve member and being biased to a closed position, an axially reciprocable valve means also controlling the passage of fluid between said inlet and outlet and being biased to a closed position, a first thermally responsive means for operating said main valve means toward open position, lever means operably engageable at one end with said reciprocable valve means, a first actuating member engageable with the opposite end of said lever means, means for biasing said first actuating member for moving said lever means to an active position for holding said reciprocable valve means closed irrespective of said first thermally responsive means, a second actuating member engageable with said opposite end of said lever means for overcoming said biasing means for movement of said lever means to an inactive position and freeing said reciprocable valve means for said opening operation, means eiiective in one position of said rotatable valve member for manual operation of said second actuating member, means carried by said lever means for operating said pilot valve means toward open position in said inactive position of said lever means, detent means having a first position for holding said first actuating member against said bias and a second position for freeing said first actuating member for movement under said bias, and a second thermally responsive means including an expansible diaphragm unit operatively engageable with said detent means for moving the same to said first position in one thermal condition thereof and to said second position in another thermal condition thereof.

MICHAEL J. CAPARONE. CHARLES M. VAUGHN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,085,300 Dillman June 29, 1937 2,215,520 Burklin Sept. 24, 1940 2,319,685 Jackson May 18, 1943