US3799730A

US3799730A - Electric ignition system

Info

Publication number: US3799730A
Application number: US00384534A
Authority: US
Inventors: N Das; E Strain
Original assignee: Raytheon Co
Current assignee: Raytheon Co
Priority date: 1973-08-01
Filing date: 1973-08-01
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26

Abstract

A cooking range of the fluid-fueled type having at least a front burner and a rear burner with an electric ignitor therebetween, and flash tubes between each burner and the ignitor for supplying fuel from the respective burners to the ignitor for igniting the burners, the burners being located nonequidistant from a fuel supply manifold whereby unequal fuel pressure is applied at the burners and particularly at the flash tubes, the ignitor being located closer to the flash tube containing the lower fuel pressure whereby to ensure reliable ignition of the associated burner.

Description

United States Patent 1191 Das et al.

[451 Mar. 26, 1974 1 ELECTRIC IGNITION SYSTEM [75] Inventors: Nalini R. Das, Bethlehem; Edwin H.

Strain, Allentown, both of Pa.

[73] Assignee: Raytheon Company, Lexington,

Mass.

22 Filed: Aug. 1, 1973 21 Appl. No.: 384,534

[52] us. Cl. 431/191 58 Field of Search 431/191, 192, 193,194; 126/39 [56] References Cited UNITED STATES PATENTS 2,537,692 1/1951 Mueller 431/191 2,654,359 10/1953 Reeves.... 431/191 X 2,667,605 1/1954 Massier 431/191 X 3,298,420 1/1967 Blanzy 431/191 Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-Harolld A. Murphy; Joseph D. Pannone; Jon T. Meaney [5 7] ABSTRACT A cooking range of the fluid-fueled type having at least a front burner and a rear burner with an electric ignitor therebetween, and flash tubes between each burner and the ignitor for supplying fuel from the respective burners to the ignitor for igniting the burners, the burners being located noneqmidistant from a fuel supply manifold whereby unequal fuel pressure is applied at the burners and particularly at the flash tubes, the ignitor being located closer to the flash tube containing the lower fuel pressure whereby to ensure reli- 1 able ignition of the associated burner.

10 Claims, 7 Drawing Figures ELECTRIC IGNITION SYSTEM BACKGROUND OF THE INVENTION a common manifold which is suitably connected to a source of fuel.

It is the usual practice to provide such burners in pairs front and rear, with an ignitor located between the burners of each pair. Eachburner is independently and individually connected to the: manifold by a separate valve and venturi. Each valve is located in a suitable position for operation by a control knob which, for convenience, is preferably located at the front edge of the cooktop. Thus, the valve is connected into a pipe leading from the manifold.

It is known, of course, that gas in the manifold is maintained under pressure, and the exit of gas from the manifold to a selected burner is regulated by the valve. However, before entering the burner the gas must be mixed with air, as is well known, and this is achieved by providing a venturi between the burner and the valve. In order to take advantage of an adequate supply of fresh air for this purpose, the venturi is located near the front of the range where the supply of fresh airis most plentiful. Therefore, a short pipe or orifice extends from the valve into the end ofa cooperating venturi which is provided in the adjacent end ofa tube connected to the burner.

Since the venturis are all located near the front of the range, it will be apparent that the tubes leading to rear burners will be considerably longer than the tubes leading to the front burners. Accordingly, a substantial drop in fuel pressure occurs within the tubes leading to the back burners in comparison to that within the front burner tubes.

The fuel in a selected burner is ignited by means of an ignitor which is located between the burners ofa respective pair of front and rear burners. To achieve this, each burner is provided with a number of ignition ports in its wall directed toward the ignitor, and a flash tube spans the space between the ignitor and the burner, with one end of the flash tube being positioned adjacent the ignition ports so that gas within the burner will flow into the flash tube toward the ignitor.

When a pilot is used as the ignitor, it will efficiently ignite gas emerging from the adjacent end of the flash tube, causing a flash back to the burner whereupon the burner will be ignited. However, when an electric ignitor is used, ignition is often unreliable for several reasons. The glow coil of such an ignitor is relatively small compared to a pilot and it must be well shielded to prevent contact by stray air currents which might cause it to darken. Therefore, gas flowing from the flashtube of a back burner, being low pressure, sometimes becomes dissipated in the space between the flashtube and the burner and thus fails to reach and become ignited by the coil.

SUMMARY OF THE INVENTION The above and other objections to prior art devices of the character described are overcome by the present invention wherein there is provided an ignitor which is located substantially closer to the flash tube associated with a rear burner than to the flash tube associated with the front burner.Thus, low presure fuel exiting from the rear burner flash tube will become ignited ina reliable manner, while the front burner flash tube is maintained sufficiently remote from the ignitoras not. to affect the operation of the. glow coil.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objectives of this invention are achieved by the-structures described herein and shown in the accompanying drawings, wherein:

FIG. 1 is an isometric view, partly fragmentary, of a cooking appliance embodying the invention;

FIG. 2 is a top plan view of the appliance shown in FIG. 1;

FIG. 3 is an enlarged top plan view of a burner arrangement in the appliance of FIG. 1;

FIG. 4 is a side elevational view of the arrangement shown in FIG. 3;

FIG. 5 is a side elevational view partlyin section showing the valve and venturi portions of a burner arrangement;

FIG. 6 is a side elevational view of an ignitor structure; and

FIG. 7 is a top plan view of the ignitor structure shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, wherein like characters of reference designate like parts throughout the several views, there is shown in FIGS. 1 and 2 a cookingappliance of a fluid-fueled type. Although only the top cooking portion of the appliance is shown and described herein, it is to be understood that the invention may be applied to the top, burner cooking portion of any fluid-fueled cooking appliance or range, whether of free standing, countertop or other type.

The illustrated range is a gas-fueled appliance having a main cooking top 10 which mounts a number of manually controlled surface burners such as front burners l2 and rear burners 14. Two pairs of such front and rear burners are shown. Below the main cooking top 10 is a burner box 16 beneath which may be normally located the usual oven and/or broiler and storage compartments (not shown) which form no part of the present invention.

The burners l2 and 14 are preferably positioned within a depressed portion 18 of the cooking top 10 be neath a suitable grate 20 on which utensils maybe sup- .ported above the burnersin the well-known manner.

Front burners 12 are hollow and supplied with gas and primary combustionair by venturi tubes 22, and the rear burners 14 are similarly suppliedby venturi tubes 24. Each pair of venturi tubes 22-24 extend-in substantially parallel fashion forwardly of the range and each tube terminates in a respective venturi 26-28.

At the front of the range beneathapanel 30 adjacent the front edge of the cookingtop 10 is a manifold 32 which is adapted tobe suitably connected to a source of gaseous fuel. The burners I2 and 14 are supplied .with gas from themanifold 32by

individual pipes

34 and 36. The burner valves 38and 40 are operatively connected inturnby respective orifices orpipes 42 and 44 to

respective venturis

26 and 28 where the gas is mixed with primary combustion air for passage to the burners.

On panel 30 are located a number of

knobs

46 and 48 which are connected to the valves for manual operation to control flow of gas from the manifold to the respective burners.

Ignition of the burners is achieved by a pair of igniting devices 50 each of which is located between adjacent front and rear burners as shown best in FIGS. 3 and 4. The igniting device 50 comprises a small glow coil 52 of high electrical resistance wire which is supported on an insulating block 54 and which carries at its ends terminals 56 to which leads 58 are secured whereby the ignitor may be conveniently connected into a suitable electrical circuit. Glow coil 52 is partially enclosed within a hood 60 which is provided with apertures in its sides disposed toward the respective front and rear burners l2 and 14. Other apertures in the top and other sides of the cap may be provided for exit of flue products from the interior of the hood.

The electric ignitor 50 further includes a base 62 having an aperture 64 (FIG. 7) in its upper surface through which the cap, block and coil assembly projects. A flange (not shown) extends downwardly from an edge of the aperture, and fastening means such as a bolt 64 functions to secure the assembly to the flange. The base 62 is screwed or otherwise secured by opposite end portions 66 to a channel-shaped bracket 68 which is bolted or otherwise mounted on the burner box 16.

In the usual construction ofa device of this character there is provided an elongated flash tube 70 (FIGS. 3 and 4) which extends between the front burner 12 and the ignitor 50. For properly retaining the burner, flash tube and ignitor in fixed spaced relationship, there is provided a bracket 72 which is fixed at one end to the bottom of burner 12 and which is provided at its opposite end with tabs 74 removably located in openings 76 provided therefor in the bracket 68. The flash tube 70 is fixed to bracket 72 by any suitable means such as support 78.

To achieve gas ignition ofa front burner 12 when the glow coil 52 is activated, the gas is turned on by manual rotation of knob 48 and consequent operation of the respective valve 38. This causes eventual passage of the required gas-air mixture into the interior of the burner head 12. The burner head 12 is provided with a number of main burner ports 80 at which the normal blue flame is produced when the gas is ignited. Additional ports 82 are provided near the base of the burner head 12 opposite the adjacent end of flash tube 70. Thus, gas will escape from the burner head 12 through ports 82 and will flow, by reason of normal gas pressure, through flash tube 70 to the glow coil 52 where it will become ignited and will flash back to the burner head to ignite the gas at ports 80.

A second flash tube 70a for the rear burner 14 is similarly mounted on a support 78a fixed to bracket 72a which is connected between rear burner 14 and the ignitor bracket 68a. One end of the second flash tube 70a is located adjacent the ignitor 50 while its other end is positioned adjacent lower ports 82a in rear burner head 14.

A front burner 12 will ignite properly if the adjacent end of flash tube 70 is located at a distance of about 0.25 inch from the ignitor. However, it has been found that the gas pressure within the rear burner head 14 may be substantially lower than in the front burner head 12, especially noticeable when the front burner is ignited. This may be caused by many factors such as, for example, the length of the fuel flow path associated with the rear burner. Therefore, in accordance with this invention, the rear burner flash tube a is positioned substantially closer to the glow coil 52 than is the front burner flash tube. A spacing of about 0.03 inch between the ignitor and adjacent end of flash tube 70a has proved to be satisfactory at normal gas pressures. This permits the low pressure gas from the flash tube 70a to more readily pass directly to the glow coil 52, and aids in preventing slow moving gas exiting out of the flash tube from being dissipated into the ambient before it reaches the coil 52 or from being wafted away from the ignitor before ignition occurs.

These differences in spacings are effected by providing the aperture 64 (FIG. 3) in base 62 offset from the center of the bracket toward flash tube 70a. Thus, when the glow coil, cap and block

assembly

52, 60, 54 is located in place within the aperture it will be automatically positioned properly as desired closer to the rear burner 14 than to the front burner 12.

From the foregoing it will be apparent that all of the objectives of this invention have been achieved by the structures shown and described. It will be apparent, however, that various changes may be made by those skilled in the art without departing from the spirit of the invention as expressed in the accompanying claims. Therefore, all matter shown and described is to be interpreted as illustrative and not in a limiting sense.

We claim:

1. In an appliance having a single supply of fluid fuel and two burner units connected to said supply at different distances therefrom, an ignition system comprising an ignitor between said burner units, a first flash tube located between the ignitor and the burner nearest the fuel supply, one end of the first flash tube being spaced at a predetermined distance from the ignitor, and a second flash tube between the ignitor and the burner unit farther from the fuel supply, said second flash tube having one end located adjacent the ignitor at a predetermined distance therefrom shorter than the distance at which said end of the first flash tube is spaced from the ignitor.

2. An ignition system as set forth of claim 1 wherein said ignitor is an electrically energized wire.

3. An ignition device as set forth in claim 2 wherein a support is located beneath said burner units, and said ignitor further includes an ignitor base mounted on said support, the ignitor wire being carried by said base.

4. An ignition device as set forth in claim 3 wherein said base contains an aperture therein which is spaced closer to said second flash tube than to said first flash tube, and said ignitor wire is located within a hood which is removably positioned within said aperture.

5. An igniting device as set forth in claim 2 wherein the spacing between the first flash tube and the ignitor is about 0.25 inch, and the spacing between the second flash tube and the ignitor is about 0.03 inch.

6. A fluid-fueled top burner system and ignition system therefor, comprising a pair of first and second burner units, a single source of fluid fuel, a first pipe operatively connected at one end to the first burner units and at its opposite end to the fuel source, a second pipe longer than said first pipe operatively connected at one end to the second burner unit and at its opposite end to the fuel source, an ignitor between said burner units, a first flash tube located between the ignitor and the first burner unit, one end of the first flash tube being spaced at a predetermined distance from the igni tor, and a second flash tube between the ignitor and the second burner unit, said second flash tube having one end located adjacent the ignitor at a predetermined distance therefrom shorter than the distance at which said end of the first flash tube is spaced from the ignitor.

7. A system as set forth in claim 6 wherein said ignitor is an electrically energized wire.

8. A system as set forth in claim 7 wherein a support is located beneath said burner units, and said ignitor tube and the ignitor is about 0.03 inch.

Claims

6. A fluid-fueled top burner system and ignition system therefor, comprising a pair of first and second burner units, a single source of fluid fuel, a first pipe operatively connected at one end to the first burner units and at its opposite end to the fuel source, a second pipe longer than said first pipe operatively connected at one end to the second burner unit and at its opposite end to the fuel source, an ignitor between said burner units, a first flash tube located between the ignitor and the first burner unit, one end of the first flash tube being spaced at a predetermined distance from the ignitor, and a second flash tube between the ignitor and the second burner unit, said second flash tube having one end located adjacent the ignitor at a predetermined distance therefrom shorter than the distance at which said end of the first flash tube is spaced from the ignitor.

8. A system as set forth in claim 7 wherein a support is located beneath said burner units, and said ignitor further includes an ignitor base mounted on said support, the ignitor wire being carried by said base.

9. A system as set forth in claim 8 wherein said base contains an aperture therein which is spaced closer to said second flash tube than to said first flash tube, and said ignitor wire is located within a hood which is removably positioned within said aperture.

10. A system as set forth in claim 7 wherein the spacing between the first flash tube and the ignitor is about 0.25 inch, and the spacing between the second flash tube and the ignitor is about 0.03 inch.