US3764181A - Thermoelectric ignition safety device - Google Patents

Abstract

A system of levers controls the main gas solenoid valve switch and ignition burner valve whereby depression of a starting pushbutton opens the ignition valve while keeping the switch closed, at the same time forcing the armature of a thermoelectric control device into engagement with the ignition flame sensitive magnet. After the interval required to activate the magnet, the pushbutton is retracted to close the switch and render the system operative subject to shutdown by release of the armature upon failure of the ignition flame. A shutdown push-button is also provided.

Description

United States Patent 1191 11] 3,764,181 Friedrich Oct. 9, 1973 [54] THERMOELECTRIC IGNITION SAFETY 3,e7 ,o41 7/1972 Mobus ..431/2ss DEVICE [75] lnventor: Peter Friedrich, Remscheid,

Germany [73] Assignee: Joh. Vaillant KG, Remscheid,

Germany [22] Filed: Feb. 1, 1972 [21] Appl. No.: 222,486

[30] Foreign Application Priority Data Feb. 20, 1971 GermanyP 20 46601.7

[52] U.S. Cl 431/81 [51] Int. Cl.F23n 5/10 [58] Field of Search 431/255,'8l, 77

[56] References Cited UNITED STATES PATENTS 2,443,891 6/1948 Caparone 431/81 Primary Examiner-Edward G. Favors Attorney-l-loward H. Darbo et al.

[5 7] ABSTRACT tive magnet. After the interval required to activate the magnet, the push-button is retracted to close the switch and render the system operative subject to shutdown by release of the armature upon failure of the ignition flame. A shutdown push-button is also provided.

7 Claims, 3 Drawing Figures 'PAIENTEDBEI 91m SHEET 1BF 2 6lull Q H H Ill 5 Mo l THERMOELECTRIC IGNITION SAFETY DEVICE German Pat. No. l 205 923 discloses a thermoelectric ignition safety device, in particular for circulation gas water heaters, in which a manually operated push- -button acts on a pair of levers, joined in scissorslike manner, one of the levers returning into its initial position together with the push-button while the other lever is retained by the armature of a magnet which is thermoelectrically energized by the ignition flame heat to keep open a pilot gas valve and in which one of the levers supports a switch with a resiliently depressable switch pin for controlling the main gas valve, said switch pin being supported on the lever.

This scissors system functions so that the closing of the switch, that is to say opening of the main gasvalve when the push-button is released, takes place only if the levers can be spread, that is to say if one of the levers is retained by the thermoelectrically energized magnet. I

The improvement of a patent of addition of the said German patent (German application Pat. No. P 46 60l.7) seeks to avoid the frictional forces which are present in the device of the parent patent between the armature and the switch in order to improve the response reliability of the thermoelectric ignition safety device. These forces, which inhibit the motion of the lever, also include the stiffness of the electric leads connected to the switch and passing through the wall of the casing, frequent flexure of such leads possibly causing fracture thereof.

According to the parent patent, the magnet armature with its control pin is disposed axially relative to the switch pin of the switch mounted on the switch housing to act only on said switch in the event of circumstances calling for safety action. Even if the pilot gas valve should fail to return into its closed position when the ignition flame is extinguished, the electric circuit of the main gas valve is still interrupted by the dropped out magnet armature and unburnt gas cannot escape from the main burner.

Since depressing the push-button and application of the armature to the magnet by means of the first lever accompanied by opening of the pilot gas valve through the second lever, simultaneously pivoted with the first lever, causes the switch pin of the switch for the ignition safety device to follow the armature pin and to close the electric circuit of the main gas valve, a further embodiment of the invention proposes that a second switch be connected electrically in series with the first switch, the second switch interrupting the electric circuit through the first lever of the pivoted pair of levers for as long as the push-button remains depressed. The first lever together with the push-button returns into its starting position and closes the circuit of the main gas valve to the second switch only when the magnet is sufficiently energized and retains the armature plate when the push-button returns so that the main gas valve releases gas to the burner. The relative position of the switches are such that the contact of the second switch is already open when the push-button is depressed before the first switch, for the safety system, closes the electric contact.

The object of the present invention is to providea construction which, by contrast to the parent German Pat. No. l 205 923, substantially avoids force deflections and accompanying disturbing frictional forces in circumstances calling for the operation of the safety device and by contrast to the patent of addition utilizes only a single switch.

The invention therefore relates to a thermoelectric ignition safety device in which a manually operated push-button acts on a pair of levers, joined to each other in scissors configuration, one of the levers returning together with the push-button into its starting position while the other lever is retained against the action of a loading spring by the armature ofa magnet which is thermoelectricaily energized by the ignition flame heat and thus maintains a pilot gas valve in the open position, a switch fixed relative to the housing being provided, the switching pin of said switch being actuable in the sense of opening said switch by means of a tappet which is joined to the armature and extends in parallel to the switching pin when the armature drops out under the effect of the loading spring, and comprising a system inwhich the tappet acts on a switch lever bearing FIG. 2 is a schematic view showing the device in the switched-on state, and

FIG. 3 is a. schematic view showing the device in the operative state.

Anelectromagnet 2, thermoelectrically energized in known manner when the ignition flame, not shown, is burning, is disposed in a housing 1. Thearmature 3 of theelectromagnet 2 is guided so as to be axially slideable and, in a manner to be described hereinbelow, may be thrust by means of a push-button 4 against the poles of theelectromagnet 2. The housing 1 also contains apilot gas valve 5 whose valve plate 5' is biased by avalve closingspring 6. Arocker lever pair 7, 8, joined to each other in scissors configuration, is pivotably supported in common at 9 on the housing 1. Thelever 7 is retained on the push-button 4 in its inoperative state by the restoringspring 10 of the push-button 4 via thepin 11.

Thedisc 12 is mounted on the push-button 4. It functions as an abuttment for thespring 13. It acts via thesliding disc 14 and the lever arm 15' of-the two-armed lever 15 in the opening sense on the switch pin 16' of theswitch 16. Thearmature spring 17 acts in the same sense via therod 18 on thelever arm 15" of thelever 15; The spring bears on thehousing 19 of themagnet 2 and thrusts therod 18 against thelever arm 15" via thedisc 20, fixedly mounted on therod 18. The extended position of therod 18 is defined when the arm ature 3 bears on thehousing 19 of themagnet 2. Thespring 13 is weaker than the spring which biases theswitch pin 16 of the switch. The off position of theswitch 16 is defined by thearmature spring 17.

One lever arm 8' of thelever 8 grips in bifurcated manner under thedisc 20 while thesecond lever arm 8 is disposed opposite to therod 5" of the valve plate 5'. The end of thelever arm 8" is also positioned opposite to the ofl'push-button 21 which is retained by the restoringspring 22 in the stand-by position.

To place the safety device in operation, the pushbutton 4, see FIG. 2, is depressed against the force ex erted by the restoringspring 10. At the same time thelever 7 is pivoted via thepin 11, thus causing thelever arm 7 to abut thearmature 3 against themagnet 2 through thedisc 20 and therod 18. Furthermore, the lever arm 15' of thelever 15 is pivoted via thedisc 12 and thespring 13 as well as thesliding disc 14, so that theswitch 16 remains open although therod 18 is separated from the lever arm 15'. Thespring 13 is designed so that in the illustrated position it willovercome the force exerted by the switch. The residual spring travel of the spring is provided to accomodate the overrun of the push-button 4.

Furthermore, thelever 8 is rotated in the clockwise direction by virtue of thedisc 20 and thelever arm 8 so that thelever arm 8" moves therod 5" of thevalve plate 5 against the force exerted by thevalve closing spring 6 in the upward direction to open a passage for the ignition gas.

When the thermocouple has sufliciently energized theelectromagnet 2 after ignition of the ignition or pilot flame, thearmature 3 will be retained in known thus cleared for the event which gives rise to the ne for eas ier th safstx 192 2;.

Retraction of the push-button 4 causes the spring 13 V to relax so that because of the slight force exerted by it thelever 15 with its lever arm 15' is driven by the switch pin 16' through the spring force of the switch thus closing the electric circuit of the gas solenoid valve. Thelever 8 remains in its position and maintains thepilot gas valve 5 in the open position through thelever arm 8".

The circuit controlled by the switch may also be used to control the pump of a circulating heating system in which opening of the main gas valve depends on the circulating water. In addition it is possible for both the gas solenoid valve and the pump to be simultaneously controlled.

It is common practice to control a relay by means of a small capacity switch. The relay may be employed to control two or more circuits which are DC isolated, for example, in order to control the pump and the gas solenoid valve. However, this arrangement is too expensive because of the relay necessarily required for it. By

using the ignition safety system described hereinabove it is however possible to control at least two circuits, DC isolated from each other, in a less expensive manner by disposing a second switch adjacent to the first switch so that both may be actuated by thelever 15. To this end it is merely necessary to allow for the fact that the force of thespring 13 must be adapted to the total force exerted by the two switches. Furthermore, the switching moments of the switches may be adjusted with respect to timerelative to each other by means of a relative offset between the switches. If the last mentioned features were to be achieved by means of a relay If the ignition flame is extinguished and the magnet releases the armature, therod 18 will pivot thelever 15 so that the switch pin 16' interrupts the circuit. Thevalve closing spring 6 also causes thelever 8 to return into its position illustrated in FIG. 1 so that the passage of ignition gas is interrupted.

The control circuit controlled by the thermoelectric ignition safety device may be changed, if required, from the operative state into .the. inoperative state by disposing adjacent to the push-button 4 for taking the thermoelectric safety device into operation, a second push-button by means of which the armature is forcibly detached from the magnet. The push-button 21 in the drawing is provided to this end, said push-button being depressed against the force of the restoringspring 22 to detach thearmature 3 from themagnet 2 via thelever arms 8", 8'. Thepilot gas valve 5 is closed by thevalve closing spring 6. After the push-button 21 is released, thespring 22 returns same into the starting position.

I claim:

1. Thermoelectric ignition safety device in which a manually operated push-button acts on a pair of levers, joined to each other in scissors configuration, one of the levers returning together with the push-button into its starting position while the other lever is retained 1 against the action of a loading spring by the armature this would result in further additional and substantial 4 costs.

of a magnet which is thermoelectrically energized by the ignition flame heat and thus maintains a pilot gas valve in the open position, a switch fixed relative to the housing being provided, the switching pin of said switch being actuable in the sense of opening said switch by means of a tappet joined to the armature and extending in parallel to the switching pin when the armature drops out under the effect of the loading spring, characterized in that a tappet (l8) acts on a switch lever (15) bearing on the switching pin (16) said lever'( 15') being retained in a position which keeps the switching pin (16) in the open position through a further lever arm (15) of said lever (15) when the push-button (4) is depressed.

2. Thermoelectric ignition safety device according to claim 1, characterized in that the levers (7, 8), joined to each other in scissors configuration, are constructed as rocker levers, the direction of motion of the manually operated push-button (4) and of the pilot gas valve (5) extending perpendicularly to the direction of motion of the armature (3) and of the rod (18) and of the switch pin (16').

3. Thermoelectric ignition safety device according to claim 1, characterized in that the push-button (4) acts on the aforementioned further lever arm (15') of the switch lever (15) through a spring (13) which is stressed when the push-button (4) is depressed and whose spring stress then overcomes a spring force which normally maintains the switch pin (16') and the switch (16) in the closed position.

4. Thermoelectric ignition safety device according to claim 1, characterized in that a shutdown push-button is provided which acts on the lever (8) associated with the lever pair in opposition to the retaining force of the magnet (2) of the armature (3).

5. Thermoelectric ignition safety device according toclaim 2, characterized in that the push-button (4) acts on the aforementioned further lever arm (15') of the switch lever (15) through a spring (13) which is stressed when the push-button (4) is depressed and whose spring stress then overcomes a spring force which normally maintains the switch pin (16) and the switch (16) in the closed position.

6. In a gas ignition safety device including a spring loaded normally closed main valve solenoid control switch, a spring loaded normally closed ignition burner gas valve, a thermoelectric device having a magnet sensitized by the heat from the ignition flame and an armature controlled by said magnet, a spring loaded'normally retracted starting push-button having a shaft, and means for the safety control of said switch and ignition gas valve, the improvement wherein said means comprises a pivotally mounted switch control lever having a first arm in control engagement with the solenoid valve switch and an extension of said arm adapted to engage said armature, said lever having a second arm in operative engagement with said push-button shaft, a pivotally mounted ignition valve control lever having a first arm in control engagement with said valve and a second arm connected with said armature for movement therewith, and a pivotally mounted starting lever having a first arm connected to said push-button shaft for movement therewith and a second arm arranged to push said armature toward said magnet, the arrangement being such that depressionof said push-button holds said switch open through said switch control lever, pushes said armature into engagement with said magnet through said starting lever and opens said ignition valve through said ignition valve control lever for ture from said magnet.

. C UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,764,181 Dated October 9, 1973 In n Peter Friedrich It is certified that error appears in the above-identified patent and that said Letters Patentere hereby corrected as shown below:

Col. 3, line 26 after "performed" insert by Col. '3, line 30 delete" after "disc" Col, 3, line 36 insert -out-- after "driven" Col. 3, line 51 "DC" should be -d.c.--

Col. 3, line 57 V I "DC" should be -d.c.--

Signed and sealed this 19th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR, 0. MARSHALL DANN Attesting Officer I Commissioner of Patents F ORM PC1-1050 10-69) USCOMM'DC BD375'P69 ".5. GO ERN MENT PRINTING OFFICE: IN! 0-306-331.

Claims (7)

1. Thermoelectric ignition safety device in which a manually operated push-button acts on a pair of levers, joined to each other in scissors configuration, one of the levers returning together with the push-button into its starting position while the other lever is retained against the action of a loading spring by the armature of a magnet which is thermoelectrically energized by the ignition flame heat and thus maintains a pilot gas valve in the open position, a switch fixed relative to the housing being provided, the switching pin of said switch being actuable in the sense of opening said switch by means of a tappet joined to the armature and extending in parallel to the switching pin when the armature drops out under the effect of the loading spring, characterized in that a tappet (18) acts on a switch lever (15) bearing on the switching pin (16'') said lever (15) being retained in a position which keeps the switching pin (16'') in the open position through a further lever arm (15'') of said lever (15) when the push-button (4) is depressed.

2. Thermoelectric ignition safety device according to claim 1, characterized in that the levers (7, 8), joined to each other in scissors configuration, are constructed as rocker levers, the direction of motion of the manually operated push-button (4) and of the pilot gas valve (5) extending perpendicularly to the direction of motion of the armature (3) and of the rod (18) and of the switch pin (16'').

3. Thermoelectric ignition safety device according to claim 1, characterized in that the push-button (4) acts on the aforementioned further lever arm (15'') of the switch lever (15) through a spring (13) which is stressed when the push-button (4) is depressed and whose spring stress then overcomes a spring force which normally maintains the switch pin (16'') and the switch (16) in the closed position.

4. Thermoelectric ignition safety device according to claim 1, characterized in that a shutdown push-button is provided which acts on the lever (8) associated with the lever pair in opposition to the retaining force of the magnet (2) of the armature (3).

5. Thermoelectric ignition safety device according to claim 2, characterized in that the push-button (4) acts on the aforementioned further lever arm (15'') of the switch lever (15) through a spring (13) which is stressed when the push-button (4) is depressed and whose spring stress then overcomes a spring force which normally maintains the switch pin (16'') and the switch (16) in the closed position.

6. In a gas ignition safety device including a spring loaded normally closed main valve solenoid control switch, a spring loaded normally closed ignition burner gas valve, a thermoelectric device having a magnet sensitized by the heat from the ignition flame and an armature controlled by said magnet, a spring loaded normally retracted starting push-button having a shaft, and means for the safety control of said switch and ignition gas valve, the improvement wherein said means comprises a pivotally mounted switch control lever having a first arm in control engagement with the solenoid valve switch and an extension of said arm adapted to engage said armature, said lever having a second arm in operative engagement with said push-button shaft, a pivotally mounted ignition valve control lever having a first arm in control engagement with said valve and a second arm connected with said armature for movement therewith, and a pivotally mounted starting lever having a first arm connected to said push-button shaft for movement therewith and a second arm arranged to push said armature toward said magnet, the arrangement being such that depression of said push-button holds said switch open through said switch control lever, pushes said armature into engagement with said magnet through said starting lever and opens said ignition valve through said ignition valve control lever for an interval sufficient for the ignition flame to activate said magnet and hold said armature in operating position whereafter retraction of said push-button permits retraction of said switch control lever to allow said switch to open and retraction of said starting lever.

7. Structure in accordance with claim 6 and including a spring loaded normally retracted shutdown push-button having a shaft adapted to engage said first arm of said ignition valve control lever whereby depression of said shutdown push-button closes said ignition burner valve and simultaneously detaches said armature from said magnet.

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