US2642309A - Temperature responsive actuator - Google Patents

Description

June 16, 1953 J. A. WASSER TEMPERATURE RESPONSIVE ACTUATOR 3 SheetsSheet 1 Filed July 7, 1950 June 16, 1953 w ss 2,642,309

TEMPERATURE RESPONSIVE ACTUATOR Filed July 7, 1950 3 SheetsSh eet 2 FIG. 2.

June 16, 1953 WASSER TEMPERATURE RESPONSIVE ACTUATOR 3 Sheets-Sheet 3 Filed July 7, 1950 IN l/ENToP: JOSE-PH ,q. wnsssre, WM

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FIG. 7.

Patented June 16, 1953 TEMPERATURE RESPONSIVE ACTUATOR Joseph A. Wasser, Kirkwood, Mo assignor to Missouri Automatic Control Corporation, St. Louis, Mo., a corporation of Missouri Application July 7, 1950, Serial No. 172,547

2 Claims.

This invention relates to control devices for gaseous fuel burners, and more particularly to control devices for this purpose which respond to a change from flame to no-flame and vice versa at a controlling pilot burner to automatically control the fuel supply to the main burner.

In burner control devices of this character, there is an appreciable lag in the closing of the main burned fuel valve following the extinguishing of the flame at the controlling pilot burner. This lag is due in part to the high temperatures which usually exist ambient to the pilot burner, and in part to the inherent thermal inertia which characterizes any suitable type of temperature responsive actuator which would ordinarily be employed for the actuation or the control of the main burner fuel supply valve.

In burner control systems for domestic gas range ovens, for example, which employ control devices of this type together with the usual manual shut-off cock by which the fuel supply to both the main and pilot burners may be shut off or turned on at will, thereis the possibility that hazardous accumulations of unburned gas may occur in the oven chamber. These accumulations may occur if the manual shut-off cock is first closed, for any reason, thereby extinguishing the main and controlling pilot burners, and then opened again before the temperature responsive actuator has had time to close the automatically operated main burner fuel valve.

In order to preclude this possible hazard it has been proposed to provide-an auxiliary or standby pilot burner, at which flame may be maintained under any conditions as long as any fuel is capable of passing the automatically operated main burner fuel control valve. The standby pilot burner having a fuel supply conduit which bypasses the usual manual shut-offcock and includes a control valve which is coordinated with that of the automatically operated main burner fuel supply valve so as to open and close substantially at the same time.

Such burner control systems may further include automatic ignition devices for igniting the controlling pilot burner, and it is desirable that such ignition devices operate only for an interval sufficient to insure ignition of the controlling and standby pilot burners and main burner, in order to prolong the service life of the igniter device.

The present invention has for an object the provision of a generally new and improved burner controlling the flow of fuel to the main burner and to an auxiliary or standby pilot burner, and for controlling the operation of an intermittent pilot ignition device so as to permit its operation only for a period sufficient to insure ignition of all burners.

It is a further object to provide a control device of the above character having a flame sensitive actuator and a pair of control valves arranged to be opened and closed substantially simultaneously by the actuator, and a switching device arranged to be operated to an open circuit position by the actuator upon further movement of the actuator after the valves have been moved to their full open positions.

A further object is to provide a control device as above in which the operative relationship between the switching device and the control valves is conveniently adjustable.

A further objectis to provide a particularly compact and dependable temperature responsive actuator employing a relatively small quantity of a high boiling point thermally expansible fluid such as mercury and an expansible chamber having a flexible metal diaphragm of relatively limited movement, thereby to provide a relatively small, though substantially positive, movement in response to a small economical pilot flame, and having novel means for substantially multiplying the actuating movements of the flexible diaphragm and for transmitting the multiplied movements in a direction substantially perpendicular to and coincident with the center of the diaphragm for the actuation of control members.

Other objects and advantages will become apparent upon reading the following complete-description in connection with the accompanyin drawings. 1

In the drawings:

Fig. 1 is a schematic illustration of the burner control system incorporating a burner control device constructed in accordance with the principles of the present invention;

Fig. 2 is a plan view of the burner control device shown in Fig. 1;

Fig. 3 is a side elevation of the burner control device shown in Fig. 1;

Fig. 4 is a view taken on line 4-4 of Fig. 3;

Fig. 5 is a view taken on line 55 of Fig. 4;

Fig. 6 is a view taken on line 66 of Fig. 3;

Fig. '7 is an enlarged part sectional view taken on line I-'!- of Fig. 8; I

Figs. 8 and 9 are different operative views shown in enlarged section and are taken on line 99 of Fig. 5;

Fig. 10 is a sectional view taken on line l-l0 of Fig. 7; and

Fig. 11 is a perspective view of the diaphragm follower member.

Referring more particularly to the drawings, the burner control system schematically illustrated in Fig. 1 is particularly adapted to the control of a domestic gas range oven burner. The system includes as primary elements a main oven burner In, a controlling pilot burner H, a pilot igniter l2, an auxiliary or standby pilot burner 13, an electromagnetically actuated valve M for controlling the supply of fuel to the controlling pilot burner, a thermostatically actuated control device generally indicated at 5 having a valve l5a, a valve I52), and a switch 50 for controlling the supply of fuel to the main burner and standby pilot burner and for controlling the igniter device, a timer actuated switch device 56, and a modulating control valve I! having incorporated therein a manual shut-off cock and a pilot control switch Ila. The modulating valve i! is of the conventional type which regulates the supply of fuel to the main burner in accordance with requirements in order to maintain a preselected oven temperature and it is provided with the usual fluid filled temperature sensitive bulb Ilb which is located in the oven chamber so as to be sensitive to the temperatures therein.

Fuel is supplied to the system through a fuel conduit l8 in which the modulating control valve I1 is connected as indicated. Fuel is conducted to the standby pilot burner l3 through a by-pass conduit [9 which by-passes the valve device 57. A branch 28 leading from the by-pass conduit i9 supplies fuel to the controlling pilot burner ii. The thermostatically actuated control device 15 is connected in the main fuel burner supply line 18 and in the by-pass conduit it! so as to further automatically control the flow of fuel to the main burner l0 and so as to control the flow of fuel to the standby pilot 13. The branch 28, however, which supplies fuel to the controlling pilot .burnen-is connected to the by-pass 19 at a point anterior to the device l5 and has the electromagnetic valve i4 connected therein to control the supply of fuel to the controlling pilot burner Electrical power is supplied to the time operated switch device it through a pair of conductors 2| and 22 which are connected to a suitable source of electrical energy. A master control switch 23 is included in the conductor 2!. A parallel circuit for the energization of the electromagnetically operated valve [4 is provided and includes the lead 2 1, connected to the conductor 22, the pilot control switch Ila, a lead 25 to the electromagnetic valve M, a lead 26 to the timer switch l6 and a lead 21 to the conductor 2!.

Means for energizing the pilot igniter i2- is provided and includes the lead 24, the switch Ha,

the lead 25, a lead 28, a transformer primary winding 29, a lead 3!], the lead 26 to the timer actuated switch [G and the lead 2'! to the conductor 2l completing a primary circuit, and a secondary circuit comprising a secondary transformer winding 3 i, a lead 32, the switching device 150, a lead 33, the resistance type pilot igniter l2, and a lead 33a back to the other side of the secondary winding 3!.

From the foregoing it will be seen that the fuel supply to the main burner Ill maybe modulated or completelyshut off manually at the modulating valve l1 and that it is further controlled by the thermostatically actuated control 15.- It will 4 also be seen that the fuel supply to the standby pilot burner 13 is controlled only by the thermostatic control device l5 and that the fuel supply to the controlling pilot burner II is, through the energizing circuit for the electromagnetic valve In, under the control of both the manual switch Ila which is associated with the modulating control valve I? and the timer actuated switch It which is in series with the switch Ila.

The thermostatically controlled device l5, shown in Figs. 2 to 11 inclusive, includes an inverted U-shapedframe member 34 which is rigidly attached at its lower open ends to a rectangular base member 35 by means of attaching screws 36. Attached to the lower surface of the base member 35 is an expansible chamber comprising a rigid outer cup member 31 and an inner flexible metal cup member 38. The inner cup member 38 is closely fitted in the outer cup member 3! and the side Walls of the cup members are continuously connected by welding as indicated at '39. The outer cup element 3'! is provided with a flange am through which pass attaching screws 40 for attachment of the cup to the base member 35.

The bottoms of the inner and outer cup members are normally substantially contiguous as indicated in Fig. 9. The outer cup member has an aperture M in the bottom thereof which is in communication with one end of a capillary tube Q2. The other end of the capillary tube is connected to a bulb 43. The complete system which comprises the expansible chamber, the capillary tube and the bulb, is filled with liquid mercury and the bulb 43 is disposed with relation to the controlling pilot burner so as to be heated thereby, as indicated in Fig. 1. Upon being sufliciently heated by the controlling pilot burner flame, the liquid mercury is expelled from the bulb 43 and forced in between the bottoms of the inner and outer cup members 31 and 38 which displaces the flexible inner cup member 38 as indicated in Figs. 7 and 8. The volume increase of the ex- I pansible chamber between its contracted and expanded positions is sufficient to receive all of the liquid contained in the bulb 43, so that when the bulb 43 is sufficiently heated all liquid mercury may be expelled therefrom and excessive pressures on the thin metallic diaphragm due to continued heating of the bulb are thereby avoided.

The base member 35 is provided with a large circular opening 44 therethrough which receives in sliding fit relationship a lower cup-shaped follower member 45. The bottom of follower member 45 is tapered to a short relatively, small diameter cylindrical portion 46 at its center which rests in a shallow accommodating circular recess 3811!; at the center of the inner cup member 38. The lower follower member 45 is therefore moved vertically as the inner cup member or diaphragm member 38 is displaced by the mercury expelled from the bulb 43. Slidably fitted in the cup-shaped follower member 45 is a second invertedcup member 4'! having a vertical shaft .ing 4.9. which is supported in the, horizontal leg portion of the U-shaped frame member 34. The

upper end of shaft.48- has -a longitudinally threaded boreiil which receives an adjustable abutment member 5| having rigidly fastened thereon a collar member 5| a.

The base member is further provided with a pair of slots- 52, see Figs. 7 and 10, each of which receives one end of one of apair of curved levers 53. The curved levers 53 are pivoted at their outer ends in the base member 35 on horizontal pivot pins 54. The side walls of the follower member as well as the side walls of the inverted cup member 41 are also provided with corresponding slots and 55a respectively so as to receive the curved levers 53 and permit their rotation about their pivots 54. The curved levers 53 bear on their lower curved surfaces against an upper flat bottom surface of follower member 45. The free inner ends of levers 53 are rounded andbear against the flat bottom under surface of inverted cup member 41. As the follower member 45 is moved upward or downward the levers 53 rotate, and their engagement with the bottoms of follower member 45 and inverted cup members? is maintained through a smooth rolling and sliding action. It will be understood that the vertical movement of follower .5 is relatively small, in the order of .030 of an inch. The shaft 48 has threaded thereon near its lower end an adjustable collar member 58 having an annular recess 56a. A spring 57 is provided which surrounds the shaft 48-and is biased between the guide bushing 49 and the collar member 55 so as to normally urge the members 45 and 41 together and downwardly against the inner cup member 38. The strength of spring 5'? determines the temperature at which the mercury in bulb 43 is expelled and therefore, the temperature at which the control is actuated. The strength of spring 51 is preferably made such that the control actuating temperature is sufficiently higher than anticipated ambient temperatures to insure reasonably rapid response to a change from flame to no flame at the controlling pilot burner.

The valves generally indicated at l5a and 15b in Fig. l comprise a relatively large cylindrical valve housing 58 attached to the right vertical leg, Fig. 3, of the frame member 34, and a smaller cylindrical valve housing 58a attached to the left ver tical leg of the frame member 34. The valve housings are provided with flanges 59 and 59a. respectively through which pass attaching screws 60 and 53a for attachment of the housings to the frame member 34. The valve housings EB-and 58a and their internal valve mechanisms are similar except for size. Each being provided with an inlet chamber 6| and Bla respectively and an outlet chamber 62 and 62a respectively which are formed by longitudinal bores and counter bores, see Fig. 5. Valve seats 63 and 63a respectively are formed at the shoulders between the outlet and inlet chambers and are adapted to be engaged by valves 64 and 64a respectively. The counter bores, which form the inlet valve chambers BI and Bid, are internally threaded at their outer ends to re ceive inlet closing plugs 65 and 65a respectively. These inlet closing plugs have internally threaded central openings therethrough which receive in threaded engagement the main fuel line [8 and by-pass line [9. The valves 64 and 64a are normally held in a closed position by valve closing springs 56 and 66a respectively. Laterally proiecting hollow outlet bosses 6'! and 61a having communication with the outlet chambers 62 and 62a and being internally threaded to receive in threaded engagement the ends of conduits I 8 and I9 respectively are also provided.

The valve housings are further provided with longitudinally bored internal guide bosses 68 and 68a which slidably receive and guide the valve stems 69 and 69a. The valve stems are loosely received at one end in central recesses in the faces of the valves 64 and 64a to facilitate assembly, cleaning or inspection of the valves. The valve stems extend inwardly and exteriorly ofthe valve housings and through relatively large perforations Hi and 76a in the vertical legs of the frame member 34. Recesses H and Ha are provided at the inner ends of the valve housings. corresponding in size tothe perforations '10 and 10a in the frame member, and flexible diaphragm members 12 and 52a clamped at their peripheries between the inner ends of the valve housings and the frame member 3d are provided to seal the valve housings and to permit the reciprocating movement of the valve stems. The valve stems have reduced threaded portions at their inner ends and pass through central perforations in the diaphragms. These central diaphragm perforations, as best seen in Fig. 7, are sealed on one side by washers 1'3 and 13a which bear against the shoulder formed by the reduction in the diameter of the valve stems, and by washers i4 and 14a on the other side of the diaphragm. The diaphragms being held firmly between the washers and the washers being held firmly against the shoulder by nuts i5 and 15a.

Each of the vertical legs of frame member 34 is provided with a pair of inwardly and right angularly formed portions it and 76a at their edges, which portions are perforated and receive and support pivot pins Ti and Tia respectively. Mounted for rotation on these pivot pins are a pair of wide levers iii and 78a having widely spaced angularly formed and perforated ear portions "i9 and 75a formed at their edges through which pass the pivots l1 and Tia. The ear portions 19 and 'i9a are so located on the levers as to form relatively short inner lever leg portions and relatively long outer leg portions. The inner leg portions of the levers l8 and 18a are formed substantially horizontal at their ends and are adapted to engage the lower side of the recess 55a in the adjustable collar member 58. The ends of these horizontal leg portions are provided with arcuate recesses Bil and 88a which generally conform to the diameter of the adjustable collar 56 at the base of its recess 55a, thus permitting the point of engagement between the inner ends of the levers and the adjustable collar to more closely approach the axial center of the shaft 48. The outer longer leg portions of levers 78 and 18a are formed substantially vertically and are adapted to be engaged near their outer endsby the inner ends of the valve stems 69 and 69a. Thus as the shaft i8 is moved upward by expansion of the expansible chamber, the valve stems 69 and 69a are moved outwardand the valves 64 and 54a are movedopenward, and as the shaft 48 is moved downward upon contraction of the expansible chamber by the spring 51, the valves are closed and the levers are maintained in engagement with the lower side of the recess in the collar 53 by the valve return springs 66 and 66a.

Mounted on an upturned portion 8! of the horizontal leg of the frame member 34, as by attachingscrews 82. is the switching device generally indicated at I50 in Fig. 1. The switch comprises a pair of flexible contact carrying blades 83 and 84. The blades are stacked in the usual manner on screws 85 with suitable separating insulators as indicated. The flexible switch blades carry at their outer free ends contacts 86 and 81 and the blades are so formed that the contacts are normally held in engagement by the inherent resiliency of the blades. The circuit leads 32 and 33 of Fig. 1 which form a part of the pilot igniter circuit are connected to the blades 83 and 84 respectively as indicated. At its outer free end the switch blade .83 has attached thereto a right anegularly formed member 88 constructed of insulating material and adapted to be engaged by the outer free end of a switch actuating lever 89. The switch actuating lever. 89 is pivoted on a pivot 98 which passes through perforated angularly formed ears 9| at the sides of the lever 89. The pivot 98 is supported at its end by a U-shaped bracket 92 attached to the upturned portion 8| of the frame 34 by the screws .82.

The pivot point of the switch actuating lever 89 is so located as to provide a short inner lever leg portion and a longer outer leg portion. The inner leg portion of the lever is formed substantially horizontal at its end and is adapted to engage the collar Ia of adjustable abutment member 5|. The horizontal lever portion is also provided at its end with an arcuate recess 93 which generally conforms with the diameter of the threaded adjustable abutment member 5| thus permitting the point of engagement between the lower horizontal lever portion and the collar 5| a to more closely approach the axial center of the shaft 48. The outer longer leg of the lever 89 provided to definitely limit the leftward travel of this resilient blade as viewed in Fig. 8.

In operation When it is desired to operate the oven burner for a selected interval to be started at a selected time, the timer actuated switch It is adjusted so as to close at the preselected time and remain closed for the preselected interval in the usual manner. The dial of the conventional modulating device I! is also rotated; first opening the manual cock and closing the incorporated switch IIa, and then being further adjusted to the selected temperature to be maintained within the oven chamber during the interval of operation. It will be understood that the master control switch 23 must also be closed. When this has been done and the timer actuated switch I5 closes the circuit at that point, the electromagnetic valve I4 will be energized through a circuit comprising the lead 24 connected to the conductor 22, the switch I'Ia, the lead 25, the lead 26, the timer actuated switch It and the lead 21 connected to the conductor 2|. When the valve I4 is energized fuel is permitted to flow through the by-pass I9 and the branch 28 to the pilot burner I I. At the same time the igniter I2 will be energized through the primary and secondary circuits described. The primary circuit comprising the lead 24' connectedto the conductor 22, the switch Ila, the lead 25, the lead 28, theprimary winding 29, the lead 38, the lead 26, the timer actuated switch I6, and the lead 2l-connected to the conductor 2| The secondary circuit comprising the secondary winding 3I,- a lead 32 to the normally closedswitch I5c, the lead '33 to the igniter I2 and the lead 33a back to the secondary winding 3|. It will be understood that theswitching device I5c is normally closed when the system is in a cold condition,

The controlling pilot burner will therefore be ignited and the mercury filled bulb 43 will be heated by the controlling pilot burner flame. When the bulb 43 is sufficiently heated the liquid mercury will be expelled therefrom to deflect the flexible expansible chamber member 38 upwardly causing the valves 64 and 64a to be opened. This permits the flow of fuel through the conduit I8 to the main burner I0 and through the conduit I9 to the standby pilot I3. The main burner is then ignited by the controlling pilot burner II and the standby pilot burner is ignited by either the main burner ID or by the controlling pilot burner II dependin upon the preferred location. When the bottom of the flexible cup member 38 has been deflected upwardly sufliciently to substantially open the valves 64 and 64a, the switch I will be opened, thus breaking the energizing circuit for the igniter I2. Under normal conditions operation of the burner I0 under the modulating control of the device I'l will continue until the timer actuated switch I6 is again opened at the end of the preselected interval.

When the timer actuated switch is opened at the end of the selected interval, the energizing circuit for the electromagnetically actuated valve I4 is broken and the valve I4 closes extinguishing the controlling pilot burner. Following the loss of flame at the controlling pilot burner the bulb 43 will begin to cool and the shaft 48 and element 33 will move downward under the urging of the spring 57, thereby first permitting the closing of the ignition controlled switch I50 and then the closing of the valves 64 and 54a. The time required for the bulb 43 to cool sufiiciently to permit closing of valves 64 and 64a will vary to some extent with the temperature at which the oven is being operated at the time the controlling pilot burner is extinguished, but in any event suflicient time will elapse to permit the flow of a considerable amount of gas from the main burner.

Under normal conditions of operation, when the controlling pilot burner is extinguished by the opening of the timer actuated switch,-the main burner would continue to burn until the valve 84 closed. However, if without the provision of the standby pilot burner this normal sequence of operation is interrupted by manipulation of the valve device IT, a hazardous accumulation of gas within the oven chamber could occur. For example, if during a period of automatically controlled burner operation, an operator thoughtlessly or for any reason manipulates device I! so as to close the shut-off cock and open the switch I la which is incorporated therewith thereby cutting olf the supply of fuel to the main burner and the controlling pilot burner, and then again for any reason immediately reverses the manipulation so as to open the shut- 01f cock and permit fuel to again flow to the main burner, a volume of unburned gas would accumulate in the oven chamber during the interval required for the bulb 43 to cool sufficiently to permit closing of the thermostatically operated valve 64. With the provision of the standby pilot burner I3, however, a flame for the ignition of any gas flowing from the main burner is maintained so long as the thermostatically actuated valve 54a remains open.

The thermostatically actuated control I5 is so constructed that the valve 64 and 64a are simultaneously opened and closed. The time of opening and closing of the pilot igniter control switch 150 with relation to the opening and Closing of the valves 94 and 64a is variable by reason of the adjustable abutment member The abutment member 5| is however preferably adjusted so that the igniter energizing circuit is broken slightly after the valves reach their full open position and is again closed before the valves reach their full closed positions.

It will be seen from the foregoing that I have provided a particularly compact and dependable safety control device for use in a burner control system as described, for controlling the supply of fuel to a main and a. standby pilot burner and for controlling a pilot igniter device. It will also be seen that the valves 15a and [5b are each complete and sealed individual units detachably mounted on the frame member 34, and that the valve 151) may be omitted from the control without in any way affecting the operation of the main burner fuel control valve 15a or the igniter control switch 150. By this arrangement the control is rendered readily adaptable to uses in other systems not requiring a second or standby pilot control valve by merely omitting the valve [5b, and the economy of wider usage is thereby achieved.

The foregoing description of the device is intended to be illustrative and not limitin the scope of the invention being set forth in the appended claims.

I claim:

1. In a device of the class described, a temperature responsive actuator including a cup-shaped expansible chamber having a displaceable inner bottom wall, a base member for supporting said cup-shaped chamber at its open end and having a bore therethrough concentric with said chamber, a cup-shaped follower member slidably fitted in said bore and adapted to engage said displaceable wall, an actuating member having an inverted cup-shaped portion slidably received in said cup-shaped follower member in telescopic relationship, and a pair of levers lying between the bottom walls of said follower member and said actuating member portion, said levers extending laterally through the side walls of said follower member and said actuator member portion and being pivotally mounted at their outer ends in said base member, and said levers being slightly curved so as to be engaged at one side by the bottom of said follower member at a point intermediate of their ends and so as to engage the bottom of said cup-shaped actuator member portion at a point near their free ends.

2. In a device of the class described, a temperature responsive actuator including an expansible chamber having a flexible wall, an actuating member adapted to move in a path perpendicular to and coincident with the center of said flexible wall, a follower member between said actuating member and said flexible wall, said actuating member and said follower member having adjacent surface portions which are parallel to and coextensive with said flexible wall, a plurality of curved levers lying between said actuating member and follower member, said levers being arranged so as to extend outward from the center of said surfaces beyond the periphery of said surfaces, and means for pivotally supporting said levers at their outer ends, said levers having rounded inner ends and said levers being curved so as to engage the surface of said actuating member at their rounded inner ends and so as to be engaged at a point intermediately of their inner and pivoted ends by said follower member surface, whereby a smooth sliding and rolling movement of the levers on the surfaces occurs as linear motion of the follower member is multiplied and transmitted to the actuator member.

JOSEPH A. WASSER.

References Cited in the file of this patent UNITED STATES PATENTS

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