US 2126564 A
Description (OCR text may contain errors)
Aug. 9, 1938.. o.'J. L ElNs- SAFETY PILOT SHUT-OFF Filed Feb. 4, 1955 w ////y////////////////////i// PMMA, `s, 193s SAFETY Pll'l SHUT-OFF p oscar J. Lemcrmwaukee. wie.. minor to nmwaukee Gas Specialty Company Milwaukee, Wis., a corporation of Wisconsin f Application February 4,1935, Serial No. 4,741` l scams. (c1. 1st-4) t This invention relates to safety pilotshutoifs, and more particularly is directed to shutois of this type for use in connection with pilot burners for hot water heaters, 4gas-fired furnaces, con- 5 version burners, gas ranges, space heaters and the like.` v
In the 'application of automatic control means tohurners of this type, whereby the flow of fuel tothe burners is automatically controlled in accordance with the sensings of aremotely disposed thermostatic device, it is essential' that ignition of the fuel at the burner be positive. Also,.if ignition does not occur uponl the passage of fuel to the burner under the control of a remote l5 thermostat due to failure of the pilot burner, it is of the utmost importance that the fuel supply be positively'shut ofi. This prevents danger` of 'asphyxiation or explosion. The primary purpose of my invention is to 29 provide a shutoi for automatically preventing flow of fuel to the burner except when the pilot burner is in operation.
In a preferred embodiment of the present invention, I provide a pilot burner head, which may be generally of the type shown in the patent to Bauger, No. 1,960,777, issued May 29, 1934, and mount on this pilot head a. thermocouple having its hot junction disposed in proximity to the burner port and subject to the heat of the 30 pilot llame issuing therefrom. The heat of this pilot llame generates a current in the thermocouple which flows to a holding coil of a magnetically controlled valve placed inthe fuel supply line. When the pilot fails, the thermocouple cools and ceases to generate current. This deenergizes the holding coil, and the valve thereupon snaps shut under spring pressure, preventing any iiow of fuel through the supply line to the main burner.
` One object of the invention'is to provide a convenient and simplied mounting of the ther- ,mocouple upon the pilot burner head and independently of the particular burner structure controlled by the pilot burner. v
Another object of the present invention is to provide a novel and advantageous connection of the thermocouple to the holding coil of the shutoff. valve. In a preferred form of the invention, the two conductors leading from the hot thermocouple junction disposed in the path of the pilot flame comprise an insulated wire' carried within a copper tube which itself forms the second conductor. 'I'he coil Wound about the magnet which controls operation of the valve 5l has its terminals soldered to the tube interior-ly of the valve housing vand to the conductor carried Within this tube. The adaptability of the safety shutoff unit to any type oi burner renders its use practically universal for all types of heating equipment, and "'5 its positive automatic action assuressafety'of operation of any equipment upon which it may Y be installed. It is relatively simple in design. 'l
can be easily and quickly installed into operative l position with respect to a burner, and has no 10 moving parts except the valve member and hold- Y ing amature therefor. The useV of bimetallic actuating members, rods and tubes,- liquid-in-bulb expansion members and other control mechanisms has been entirely' eliminated by the pres- 15 ent construction. As there is no rigidity necessary to be maintained forl operation of the device, the structure is extremely exible in its adaptability to the partie burner or heating equipment upon which 1t 1ste be mstsued. 2
Further, the unit is self-contained, requiring no auxiliary external batteries or circuit connections, relays, or the like, and the control is eifected within the unit only by means of the 'current generated by a relativelysmall pilot a-me. 25 There is no necessity for adjusting or calibrating the unit to each installation, as it is independent of the particular type of burner or heating equipment to which it is applied.
Other objects and advantages of the present 30 invention' will appear more fully from the following detailed description, which, taken in connection with the accompanying drawing, will disclose to those skilled in the art the particular construction and operation of a preferred form 35 Y of the present invention.
In the drawing: f
Figure 1 is a diagrammatic view of the present invention as applied to a hot waterheater;
Figure 2 is an enlarged view, partly in section, 40 showing the safety shutoff unit and its mounting upon a pilot burner; Y
Figure 3 is a. vertical sectional view through the shutoff valve; and
Figure 4 is a detail sectional view through the 45 thermocouple tip. In Figure 1 II have disclosed a. hot water heater structure comprising a housing or drum 5, having a fire box 6 and a suitable supporting base 1. The burner for heating the water is shown 50 at 8, and is connected through the mixing chamber 9 to a fuel supply line shown generally at Il). Mounted in the fuel supply line l0 is the safety shuto valve indicated generally at i2, and anterior to the valve is the pilot burner.
conduit I3 leading from the fuel supply pipe I0 to the pilot burner head. 'I'he thermocouple I5 is carried by the head I4, and is connected to the valve I2, wherebyupon extinguishment of the pilot burner at the head I4, the current generated by the thermocouple ceases, and the valve I2 closes, shutting o the ow of the fuel from the supply line I0 to the mixing chamber 9 of the burner 8, whereby no fuel will escape to the burner. l
Considering now in detail the structure of the shutoi unit, in Figure 2 I have shown the pilot burner head I4 in section. This head includes an air inlet opening I8, a bushing I9 threaded into one end of the head and adapted to receive the threaded end of the pilot burner conduit I3 leading to the fuel supply line, a. pilot jet or spud 20 within the bushing I9 and directed substantially axially of the head I4, the jet 29 having a small jet opening 22 for directing a jet of gas from the conduit I3 into the Venturi bushing 23 carried within a reduced portion of the head I4. The jet of gas passing into the bushing 23 draws with it 'air from the air intake chamber I8, and the mixture of gas and air passes into a mixing chamber 24, from which it issues through the laterally and vertically directed ports 25 and 26 respectively, and is ignited to burn as a pilot flame, shown at 21. This pilot flame is preferably relatively small, of the order of B. t. u. to provide economy in the operation of the unit.
The inrush of relatively cool air into the air intake chamber I8 caused by the suction produced by the jet of gas 22 passing into the Venturi bushing 23 serves to cool the .iet 20, whereby it does not become excessively heated, and fouling and choking of the supply nozzle is eliminated. The Venturi bushing 23 provides for sufcient suction to produce an adequate amount of air ow into the mixing chamber 24, whereby the proper amount of air will be mixed with the fuel to give the desiredpilot flame at the ports 25 and 28.
The burner head I4 has an upwardly projecting clamping portion 28, which is provided with a suitably recessed portion receiving the exterior tubular portion 29 of the thermocouple, there preferably being a clamping screw 30 passing through the clamping support 28 to secure the thermocouple 29 positively in position upon the burner head I4. 'Ihe shoulder 32 of the tube 29 provides an abutment whereby the positioning of the thermocouple junction 33 with respect to the burner port 26 is positively determined.
Considering now in detail the structure shown in Figure 4, the thermocouple junction 33 cornprises a welded junction between two dissimilar metals, there being an outer enveloping tubular member 34, which may be formed of constantan, or chromel, and the enclosed member 35, which is formed of the opposite metal.
The welded junction 33 being disposed directly in the path of the pilot flame from the port 26, comprises the hot junction of the thermocouple, and the .enclosing tubular member 34 is connected with thecopper tubing member 29, which is preferably enlarged adjacent the clamped portion thereof whereby the member 34 is received in telescoping engagement therewith, the two members being preferably welded or otherwise suitably secured together. The outer element 34 is highly resistant to heat, and completely encloses and protects the irmer element from the heat of the pilot flame. 'I'he Considering now in detail Figures 2 and 3, A
rwhich disclose' the internal construction of the valve I2, the cup-shaped housing 39 is provided, at its upper end, with an inwardly extending boss portion 40 forming a central rib or web. This web provides a supporting base for a bracket member 42 which is secured thereto by means of the screws 43. The bracket member 42 is adapted to support a. U-shaped magnet 44 in depending position below the web 40. The magnet is preferably of a special alloy which is noncorrosive, and has high permeability, with minimum retentivity of magnetism. Each leg of the magnet 44 has mounted thereon a coil of insulated Wire, indicated at 45, and the end terminals of the coils 45 are connected to the conductor 31 at 46 and to the inner projecting portion of the bushing 38 at 41, preferably by soldered connections thereto. 'I'his connects the thermocouple I5 to the coils 45 surrounding the legs 4of the magnet 44. Preferably an insulating sleeve 4I extends about the conductor 31 enclosing the connection 46, projecting a considerable distance inwardly of the housing 39.
The cover or dome shaped housing 39 is preferably threaded on to a projecting boss 48 formed integral with a. valve housing member 49. The valve housing 49 is provided with an inlet chamber 50 and an outlet chamber 52 separated by a partition wall 53 having a valve seat 54 formed about the valve opening therethrough. The inlet chambers 50 and 52 are adapted to be connected to the fuel conduit IU in any well known manner, and the fuel passes from the inlet chamber 50 past the valve opening and then through the outlet chamber 52 to the burner 8.
Pinned or otherwise suitably secured within the lower end of the dome-shaped housing 39 is a guide member 55, which member has upwardly projecting spaced leg portions 58 serving as guides for reciprocatory movement of the carrier member 51 therein. Preferably four such guiding legs are provided.
The carrier member 51 is adapted to provide suitable carrying means for the armature 58, which armature is preferably formed of a special alloy which is noncorrosive, has a high degree of permeability, and minimum` retentivity. 'I'he armature 58, as shown in Figures 2 and 3, is securely held by the carrier member 51, the upwardly projecting portions of the carrier member being bent over, as shown at 58' in Figure 2, to secure the armature in position.
'I'he lower end of the carrier member 51 is provided with a downwardly and inwardly offset portion 59, which is adapted to have universal movement about an annular groove 60 formed in the valve stem member 62. This valve stern member 62 has axial reciprocatory movement within the guide member 55, and at its lower end is provided with a valve member 63 universally mounted about an annular groove in the lower end of the stem 62. The valve member 63 has an upwardly extending recessed portion in its lower surface receiving the nut 64, which nut is adapted to secure a leather facing member 65 to the annularly recessed portion of the valve member 63,
. .the coils I of whereby a leather faced valve member is provided for engagement with the valve seat 54.
The valve member 83 is provided with an upwardly extending cylindrical boss portion about which is biased a coiled spring member B8, which spring member at its opposite end seats against a washer 81 press-ntted into an annular recess formed in the lower extending end of the guide member 35. The washer 51 serves as an additional guide for the valve stem 62, and is adapted to place the packing disposed thereabove within the recess in compression about the valve stem to prevent leakage of gas from the inlet chamber 50 upwardly past the valve stem into the domeshaped housing 39.
The spring member 8K5 is adapted to urge the valve member 83 constantlyinto engagement with the valve seat 5I. so that upon deenergization of the coils 45, the magnet M becomes deenergized, releasing its grip upon the amature 58, and allowing the valve member 53 to seat against the valve seat 54 under the pressure of the spring 63. In the operation of the device. during such times as the pilot flame from the ports 25 and- 26 is ignited, the heat imparted to the thermocouple junction 33 will be sufficient to maintain themagnet 44 energized, whereby the magnet is sufficiently energized to maintain the armature 58 in attracted position across the lower end of the leg portions thereof, against the tension of the spring member 66. This holds the valve open during all times that the pilot burner is ignited. Upon extinguishxnent of the pilot burner, the thermocouple 33 rapidly cools, and as a resultthe generation of current is discontinued, and the magnet 44 becomes deenergized. Due to the minimum retentivity of the magnet and armature, the armature is immediately released from the lower end of the magnet, and drops downwardly therefrom under the pressure of the spring 66, the valve member 63 at the Sametime shutting off ow of fuel through the valve l2 to prevent further flow of fuel to the burner 8 should the secondary thermostatically controlled anterior fuel metering valve be in open position.
Although the magnet 44, when the armature 58 is in engagement therewith. may be suiliciently energized -to maintain the armature in attracted position against the pressure of the valve spring 66, nevertheless it is not capable of drawing the armature 58 upwardly from valve 'closed position. In order, therefore, to provide for opening of the valve during initial operation, a reset button 10 is provided, which button 10 is mounted at the upper end of a reset plunger 12 extending through the lower end of the valve 49. The plunger 12, at its lower end, is provided with a push button 13, which button is preferably recessed as shown at 1l to provide a seat for a spring member 15 normally urging the plunger outwardly of the valve housing.
Outward movement of the plunger is limited by engagement of the lower annular end of the button 1li upon the boss forming the guide for the plunger 12. 15, at its upper end, is biased against a washer 16, which washer is adapted to engage suitable packing disposed in an annular recess about the plunger 12 and to force this packing into engagement with the lateral surface of the plunger, whereby leakage of gas from the outlet chamber 52 of the valve housing I9 past the lateral surface of the plunger 12 is prevented.` In order to prevent accidental opera-tion of the reset button 10, and to protect the reset plunger and push button 13 against mechanical injury, a gas tight cap 11 is threaded about the lower extending portion oi' the valve housing I9, and serves to form an enclosure about the push button 13, so that it is necessary to remove the cap member 11 before the plunger 12 can be actuated to provide for engagement of the button 1D with the nut 64 of the valve member to provide for moving the valve member upwardly to place the armature 58 in attracted position.
After the valve i2 has once been closed due to failure of the pilot ilame, no fuel can flow to the burner 8, until the pilot flame has been reestab- Ylished. Thus, when the pilot flame 21 is to be to unthread the cap reignited, it is necessary member 11, and manually push the plunger 12 upwardly toV move the valve stem 82 upwardly into position whereby the armature 58 is engaged with the lower end of the magnet M. By holding the plunger 12 in raised position until such time as the pilot ame has suiclently heated the thermocouple 33 to provide for completeenergization of the coils 35 by the current generated at the thermocouple, it is possible to have the magnet d4 thereafter hold the armature 58 in attracted positionfand the plunger 12 can then be released, and the enclosing cap 11 rethreaded over the lower end thereof. As long as the pilotfiame remains ignited, thereafter, the thermocouple will energize the coils 45 the armature will be maintained in attracted position Vacross the ends of the magnet Il. Thereafter, upon extinguishment of the pilot flame, the magnet 44 becomes deenergized and the valve 53 closes under spring pressure.
It is thus apparent that I have provided a novel type of pilot shutoff unit, which is capable of producing a positive and accurate control of the ow of fuel to a main burner or the like directly in accordance with the operation of the pilot burner, and which employs no moving parts at the pilot burner, and therefore is relatively flexible and capable of easy installation, and can be employed without the necessityof separate supporting means or the like. In addition, the tube 29 can be made of any desired length, so that the valve I2 may be disposed in any desired position in the fuel conduit i8 independently of the positioning of the thermocouple, whereby the adaptability of the unit to varioustypes of heating equipment is increased. Further, it will be noted that, by reason of the novel manner in which the current generated at the thermocouple junctionis transmitted to the coils of the electrically controlled valve, only one insulated conductor is required, and the use of the copper tube as a conductor simplifies the design of the unit, and at the same time provides a substantially secure and positive connection between the thermocouple and the valve. The inherent rigidity of the tube is such that it may independently support the thermocouple if desired. The particular construction of the valve is such that it is capable of rapid and positive operation in accordance with the actuation of the armature, and will positively shut oif the ow of fuel through the valve when the thermocouple is not being heated by the pilot flame.
It is apparent that certain modifications in design and construction of the component parts of the present invention may be made without in anywise departing from the underlying princlples thereof, and I therefore do not intend to be limited to the exact details shown and described, but only insofar as defined by the scope and spirit of the appended claims.
to an extent such that I claim:
1. A thermocouple and lead connection therefor comprising an inner metallic thermocouple member, an internally disposed lead conductor connected to said inner thermocouple member to form an internal thermal junction, single wall metallic tubular means enclosing said inner thermocouple member and said internal thermal junction and comprising an outer metallic tubular thermocouple member joined to said inner thermocouple member to form a second thermal junction adapted to be heated and an outer tubular lead conductor connected to said outer tubular thermocouple member to form a third thermal junction, said outer tubular thermocouple member having its outer surface externally exposed throughout substantially its entire length and with said outer tubular lead conductor constituting a single Wall enclosure about said inner thermocouple member and said internal thermal junction of a character throughout the extent of said inner thermocouple member and said internal thermal junction thermally to insulate said internal thermal junction and maintain the heat transmitted to said internal thermal junction when said second thermal junction is heated so that the difference in temperature between said internal thermal junction and said second thermal junction is more quickly reduced when the heating of said second thermal junction is discontinued.
2. A thermocouple and lead connection therefor comprising an outer metallic tubular thermocouple member, an inner metallic thermocouple member disposed within said outer thermocouple member and rigidly joined at one end to one end of said outer thermocouple member to form a thermal junction adapted to be heated, the opposite end of said inner thermocouple member extending beyond the opposite end of said outer thermocouple member, an inner lead conductor joined to the extending end of said inner thermocouple member to form an internal thermal junction beyond the end of said outer thermocouple member, and an outer tubular lead conductor enclosing said inner lead conductor and said internal thermal junction and rigidly joined to said outer thermocouple member between said rst and second thermal junctions, said outer tubular lead conductor forming a single wall enclosure about said internal thermal junction and the adjacent end of the internal thermocouple member with the inside of said single wall enclosure directly exposed to the internal thermal junction and the outside of said single wall enclosure externally exposed, said single wall enclosure being of a character thermally to insulate said internal thermal junction and maintain the heat transmitted to said junction when said rst thermal junction is heated so that the difference in temperature between said first thermal junction and said internal thermal junction is more quickly reduced when the heating of said first junction is discontinued.
3. A thermocouple and lead connection therefor comprising an outer metallic tubular thermocouple member, an inner metallic thermocouple member disposed within said outer thermocouplemember and rigidly joined at one end to one end of said outer thermocouple member to form a thermal junction adapted to be heated, the opposite end of said inner thermocouple member extending beyond the opposite end of said outer thermocouple member, an inner lead conductor joined to the extending end of said inner thermocouple member to form an internal thermal junction beyond the end of said outer thermocouple member, an outer tubular lead conductor enclosing said inner lead conductor and said internal thermal junction and rigidly joined to said outer thermocouple member between said rst and second thermal junctions, said outertubular lead conductor being of reduced diameter closely to enclose said inner lead conductor and enlarged adjacent the end joined to the outer thermocouple member to form a single wall enclosure of enlarged diameter about said internal thermal junction and the adjacent end of the inner thermocouple member with the inside of said single wall enclosure Vdirectly exposed to the internal thermal junction vand the outside externally exposed, said single wall enclosure being of a character thermally to insulate said internal thermal junction and maintain the heat transmitted to said junction when said rst thermal junction is heated so that the dierence in temperature between said rst thermal junction and said internal thermal junction is more quickly reduced when the heating of said first junction is discontinued.
4. In combination, a burner head adapted to be connected to a fuel supply conduit and having flame port means therein, a thermocouple comprising an outer metallic tubular thermocouple member, an inner metallic thermocouple member disposed within said tubular thermocouple member and joined to the end thereof to form a rst thermal junction, a tubular conductor member connected to said outer tubular thermocouple member to form a second thermal junction, an internally disposed conductor extending through said tubular conductor and connected to said inner thermocouple member to form an enclosed third thermal junction for the thermocouple, said tubular conductor member and said `internally disposed conductor forming a lead cir- `cuit connection for the outer and inner members of the thermocouple, and a bracket member on said burner head and cooperating with one oi' said tubular members to support the thermocouple in position on said burner head with the first thermal junction between said inner thermocouple member and said tubular thermocouple member in proximity to the flame port means in said burner head.
5. In combination, a burner head adapted to be connected to a fuel supply conduit and having a flame port therein, an outer tubular conductor member constituting a lead tube, an inner lead conductor extending through said'lead tube,
joined to said outer thermocouple member to form a thermal junction, said outer tubular conductor member being joined to the outer tubular thermocouple member to form a second thermal junction and said inner lead conductor being joined to said inner thermocouple member to form a. third thermal junction, and a bracket member on said burner head and cooperating with one of said tubular members to support the thermocouple with the thermal junction between the inner thermocouple member and the outer thermocouple member in proximity to the llame port means in the burner head, said bracket member enclosing the thermal junction between the outer tubular conductor member and the outer tubular thermocouple member.
OSCAR J. LEINS.