US3367572A - Pilot and burner valve construction and method for an oven and the like - Google Patents

Description

Feb. 6, 1968 c, BRANSON ET AL 3,367,572

PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKE Original Filed June 15, 1962 5 Sheets-Sheet l FlG-l co (\1 m 9 2 3- m Y. F I 1 T fir \i I *""m ll 8 Q q l N 9 Q I no N) g d' N O INVENTORS Q CHARLES DAVID BRANSON JAMES ROBERT WILLSON m to 5 ARTHUR HARRY MALCOM r 9* ATTORNEY Feb. 6, 1968 c. D. BRANSON ET AL 3,367,572

PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKE Original Filed June 15, 1962 5 Sheets-Sheet 2 l I I r I I44 I50 /l58 I60 (I56 I55 I54 I52 4 INVENTORS CHARLES DAVID BRANSON F JAMES ROBERT WILLSON I ARTHUR HARRY MALCOM BYW I ATTORNEY Feb. 6, 1968 v c. D. BRANSON ET L 33 5 PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKE Originai Filed June 15, 1962 Sheets-Sheet 5 INVENTORS CHARLES DAVID BRANSON I JAMES ROBERT WlLLSON H6 5 ARTHUR HARRY MALCOM ATTORNEY United States Patent 3,367,572 PILOT AND BURNER VALVE CONSTRUCTION AND METHOD FOR AN OVEN AND THE LIKE Charles D. Branson, James Robert Willson, and Arthur Harry Malcom, Greensburg, Pa., assignors to Robertshaw Controls Company, a corporation of Delaware Original application June 15, 1962, Ser. No. 202,789, now

Patent No. 3,233,830, dated Feb. 8, 1966. Divided and this application Dec. 7, 1965, Ser. No. 578,915

Claims. (Cl. 236-68) ABSTRACT OF THE DISCLOSURE This disclosure relates to a control system for a main burner means wherein a supply of fuel is adapted to be thermostatically controlled and passed to a safety valve means that is intermediate the thermostatic valve and the main burner means, the safety valve means only permitting the fuel to pass therethrough to the main burner means when the safety valve means senses that a heater flame is present at a pilot burner means. The pilot burner means has a first outlet means and is normally supplied with a continuous flow of standby fuel to produce a small standby flame at the first outlet means thereof. The thermostatic valve means increases the flow of fuel to the pilot burner means to cause a large ignition flame at a second outlet means of the pilot burner means and a heater flame spaced from and below the ignition flame at a third outlet means of the pilot burner means whereby the heater means causes the safety valve means to open and permit fuel to flow to the main burner means to be ignited by the ignition flame.

This application is a divisional patent application of its co-pending parent application, Ser. No. 202,789, filed June 15, 1962, now issued as US. Patent No. 3,233,830 on Feb. 8, 1966.

This invention relates to an improved pilot construction and an improved burner valve construction and combination and method of operation thereof.

One of the features of this invention includes the use of a single pilot nozzle to produce a standby pilot flame when main burner ignition is not needed and to produce an igniting pilot flame when main burner ignition is required.

Another feature of this invention includes an inverted channel-shaped shield for a pilot construction which is eflective in maintaining a standby flame and an igniting flame to promote efficient igniion of the main burner when needed.

Another feature of this invention includes an inverted channel-shaped shield for a pilot construction which is eifective to heat a thermostatic bulb in an eflicient manner when needed to open a burner valve and is effective to maintain the thermostatic bulb sufficiently cool during standby conditions not to open the burner valve. The shield also promotes quick cooling of the thermostatic bulb when the igniting flame is not produced.

Another feature of this invention provides a burner valve construction in.which the closing spring action on the valve increases in strength as the valve moves toward its valve seat and decreases in strength as such valve moves away from its valve seat.

Another feature of this invention provides a substantially snap-action by the combined action of a local vaporizing thermostatic action in a liquid line to a thermostatic motor in combination with a spring action on the valve which increases in strength as the valve closes and the thermostatic vapor condenses, and which spring action decreases in strength as said portion of thermostatic liquid vaporizes to receive a quick yielding impulse to open said valve as the liquid vaporizes.

Another feature of this invention provides a lever and spring construction acting on a valve in a manner to apply an increasing valve closing torque as the valve moves toward its valve seat and vice-versa.

An object of this invention is to provide a pilot construction having one or more of the features herein disclosed.

Another object of this invention is to provide a burner valve construction having one or more of the features herein disclosed.

Another object of this invention is to provide a system for burner operation having one or more of the features herein disclosed.

Another object of this invention is to provide a method of burner control having one or more of the features herein disclosed.

Other objects are apparent from this description and the accompanying drawings in which:

FIGURE 1 is a diagrammatic representation of a burner system embodying this invention.

FIGURE 2 is a diagrammatic representation, on enlarged scale, of a part of the main gas burner, the pilot burner, the burner gas valve, and the thermostatic control for the gas valve.

FIGURE 3 is a perspective view of the nozzle construction for the discharge conduit of the burner gas valve.

FIGURE 4 is an enlarged longitudinal vertical cross section of the pilot burner construction.

FIGURE 5 is a view of a portion of FIGURE 2 with the valve in open position.

FIGURE 6 is an end view of the main gas burner and pilot burner.

FIGURE 7 is an enlarged cross section of the valve actuating means shown in FIGURE 2 taken from the opposite side.

FIGURE 8 is a top view of the valve actuating lever.

FIGURE 9 is a top view of the supporting fulcrum lever.

FIGURE 10 is an enlarged view of the fulcrum c0n struction.

Certain words indicating direction, relative position, etc., are used in this application for the sake of brevity and clearness. However, such words are not intended as limitations and apply only to the illustrations in the drawings. The actual constructions used may have different directions, relative positions, etc. Words such as vertical, horizontal, upper, lower, etc., are types of words which are used in this manner.

Referring first to FIGURE 1, an oven 20 may be provided with a main gas burner 22, a pilot construction 24, a main burner gas valve construction 26, a gas supply pipe 28. A thermostatic control construction 30 may have a thermostatic bulb 32 in the oven 20 which causes said thermostatic control construction 30 to control the heating action of the burner 22 to produce desired temperatures in the oven 20. A main gas valve 33 may control the flow of gas to the system shown in FIGURE 1.

The pilot construction 24 may be of a character such that it produces a stand-by pilot flame 34, FIGURE 4, incapable of igniting the burner 22, and an igniting flame 36 capable of igniting the burner 22.

The stand-by pilot flame 34 is incapable of heating the thermostatic bulb 35 sutficiently to cause such bulb 35 to cause gas to be supplied to the main burner 22 by the gas valve 26. The flame 36 is of such size, or construction, or shape, that it is capable of heating the thermostatic bulb 35 to cause gas to be supplied to the burner 22 by the valve 26 so the burner may be ignited by the igniting flame 36.

The pilot construction 24 may include a nozzle 38, which receives gas from the pipe 40 and discharges it through an orifice 42 in sufiicient quantity to produce the stand-by flame 34 under one type of control, and to produce the igniting flame 36 under a different type of control.

The gas is discharged from the orifice 42 as a jet 44 which entrains a quantity of atmospheric air entering through one or more orifices 46 in the side of connector 48.

When the stand-by flame 34 is to be produced, the gas entering the nozzle 38 is of limited quantity and pressure so that only a small amount of gas and air are fed to the shield 50. The shield 50 may be inverted channel-shaped in cross section, and may have a downwardly open elbow 52 which guides the gas and air mixture to the first pilot burner aperture 54 through which the limited amount of gas and air pass and form the stand-by pilot flame 34. The aperture 54 may be provided with a small hood 56 which aids in controlling the formation of the flame 34.

The stand-by calibrating valve 58, FIGURE 1, may be adjusted so that the standby pilot flame 34 is a small blue flame, and the small blue flame is the calibration indicator to show that the pilot flame has been adjusted to the desired size.

The production of the standby pilot flame on top of the shield 50 prevents undesired heating of the thermostatic bulb 35 during the standby conditions.

The hood 50 has a downwardly slanting channel 60 with an open end 62 and one or more additional small hoods 64, and igniting flame apertures 65. The construction is such that when a larger quantity of gas is fed through the nozzle 38, by the thermostat construction 30, then the igniting flame 36 is produced, which burns at 36, 36A and 36B as gas and air mixture are fed under the small hood or hoods 64, and out of the end 62, and these i niting flame portions are sufficiently high to ignite the burner gas which is discharged through the burner orifices 66. If desired, the orifices 66 may be slightly downwardly slanted along the side 68 of the burner. The end 70 of the burner 22 may also be provided with orifices 66 which carry the ignition to the other similar side 68A of the burner.

The igniting flame 36 burns at 36B, under the end of the hood 50, so that the flame 36B heats the bulb 35 either by direct contact, or because of close proximity, so that a portion of the liquid mercury, or other thermostatic fluid in the bulb 35, has its liquid phase changed to a gaseous phase to produce a quickly increasing thermostatic fluid pressure in the thermostatic fluid enclosure of which the bulb 35 is a part. The tube 72 and thermostatic motor 74 form the remainder of the thermostatic fluid enclosure.

When the ignition flame 36, 36A and 36B ceases to be produced, the channel-shaped shield or hood promotes the upward flow of cooling air in contact with the thermostatic bulb 35 to cause quick cooling action of the bulb 35. The notches 51 at the elbow 50 promote this cooling action.

The bulb 35 is connected by a tube 72, which forms a part of the thermostatic fluid enclosure, and which is connected to the thermostatic motor 74, in the burner gas valve construction 26, to cause burner gas to be supplied by the burner gas valve construction 26 to the burner 22 in response to temperatures produced by the burner 22, as elsewhere further described. The size of the igniting flame 36, 36A and 36B may be regulated by an igniting flame regulating valve 76, FIGURE 1.

The construction is such that when the temperature in the oven 20, as produced by the burner 22. is below a selected level, the thermostatic bulb 32 causes the thermostatic construction 30 to feed an igniting flame producing amount of gas through the igniting gas pipe 78, FIG- URE 1. The pipe 78 is connected to the pilot burner pipe 40. This causes the large igniting flame 36, 36A and 36B to be produced in the pilot construction 24. This heats the pilot thermostat bulb 35, which in turn actuates or expands the thermostatic motor 74 and causes burner gas to be fed by the burner gas valve construction 26 to the burner 22.

This heats the oven 20 until the temperature in the oven 20 reaches the desired maximum, at which time the thermostatic bulb 32 causes pilot gas to cease to be fed through the pipe 78, which in turn causes the igniting pilot flame 36, 36A and 368 to cease to be produced. This permits the pilot bulb 35 to cool and thereby restore the thermostatic fluid to the liquid phase throughout the fluid enclosure, and to cause the burner gas valve construction 26 to cease feeding burner gas to the burner 22.

The thermostatic motor 74 may include a pair of telescoped resilient cup-shaped diaphragms 75A and 75B, which are sealed together at the flanges 75C to form an expandable motor 74 into which the liquid mercury is forced when the mercury in bulb 35 is vaporized.

A suitable bracket construction 80, of any desired shape, may be provided to hold the hood 50, the nozzle construction 49 which holds nozzle 38, and the bulb 35 adjacent to the burner 22. If desired, this bracket construction 80 may be secured by the flange 82 to the top of the burner by one or more screws 84.

The thermostatic control construction 30, FIGURE 1, may be of any suitable character capable of controlling the flow of igniting burner gas through the pipe 78 in response to the temperatures registered by the thermo static bulb 32. A suitable knob 36 may be included, which adjusts the thermostat valve construction 88, so the construct-ion 88 causes gas to be fed from the pipe 90 and gas supply 28, through the regulating valve 76 and pipe 78 to the pipe 40 and nozzle 38.

Standby pilot gas may be fed through standby pipes 92 and 94, and the standby flame regulating valve 58, t0 the pipe 40 and from thence to the nozzle 38. The regulating valves 58 may be supported on the thermostat casing 96, or the pipes 92 and 94, and valve 58 may be entirely separate and independent from the casing 96, as desired.

The thermostat control construction may feed standby gas continuously through the pipes 92, 94 and 40, as regulated by an adjustable orifice valve 58, so the standby flame 34 only is formed when no gas is fed through the pipes 90 and 78 when the thermostat valve 88 is closed by bulb 32 when the oven 20 is sufliciently warm. However, when the oven cools below a desired level, the bulb 32 opens the valve 88 and feeds a larger amount of gas through pipes 96, 78 and 40, and regulating valve 78 to produce the igniting flame 36, 36A and 36B.

The burner gas valve construction 26 may have a burner gas discharge connection 100, which has an adjustable orifice 102, which discharges the burner gas in the form of a jet stream past the well known gas and air mixing construction 104. The rate of discharge at the orifice 102 may be regulated by turning the gas connector 100, to cause the threaded construction 101 to regulate the jet 102, as desired.

The burner gas valve construction 26 may have a discharge valve seat connected in gas flow relationship to the burner 22, as by the connector 110, which discharges into the nozzle construction 100.

The jet construction may include a lower passageway 100A which is threaded on the upper portion 101 of connector and is adjustable up and down by said threaded construction.

A jet piece 100B has a larger bore 100C and the minimum flow passage 100D. The upper end 100E of construction 100 has an internal conical bore 100E which may seal against the upper conical end 100G to force all the gas through passage 100D.

The conical bore 100H is tapered so it does not seat against the upper slanting ends 100] of wings 100K so a tight seal may be formed at 100B.

The wings 100K are driven in the bore 100L and against the shoulder 100M.

The construction 100 may be turned to its lowest position to produce a minimum discharge through passage 100D or construction 100 may be adjusted upwardly by the threaded construction to produce a bypass between 100F and 1006 so a larger amount of gas may be fed to the mixer 104.

A valve 112 may seat on the valve seat 108, and, if desired, may have a sealing disc 114 to engage the seat 108 in effective sealing relationship.

A guide pin 116 may have a head 118 to guide valve 112 through the medium of a cylindrical opening 120. The downward movement of the valve 112 may be limited by the end wall 122 of the opening 120 when the wall 122 engages the head 118. The pin 116 may be fluted and driven into the cylindrical opening 124 of the valve casing 126, to the proper level properly to limit the downward movement of valve 112.

The thermostatic motor 74 may have means to move the valve 112 toward said valve seat 108 when the igniting flame 36, 36A, 36B, or a similar flame, ceases to be produced. Such means may also move the valve 112 away from the valve seat 108 when such igniting flame 36, 36A and 36B is produced. This action is indirectly in response to the control of the ignition gas by the thermostatic bulb 32 and thermostat 30 in response to the temperature in oven 20. The action maintains the temperature in the oven 20, or other heated object, within selected temperature limits.

The means to move the valve 112 may include a spring construction 128, FIGURE 7, acting to aid in moving the valve 112 toward the valve seat 108, and increasing the valve seating strength as the valve 112 moves toward the valve seat 108 and decreases in strength as said valve 112 moves away from said valve seat 108.

The construction is such that the valve 112 is qiuckly opened when a portion of the mercury in bulb 35 is vaporized and is quickly closed when the vaporized portion is cooled and condensed. This quick opening and closing of valve 112 is in response to the existence or nonexistence of ignition flame 36, 36A, 3613, or similar control flame.

The thermostatic motor 74, tube 72 and bulb 35 form a thermostatic fluid casing which is heated by the igniting flame 36, 36A, and 36B. A portion of the thermostatic fluid in the thermostatic casing, such as in bulb 35, may change phase when it is heated by said igniting flame 36B or similar flame. For example, the bulb 35 and the tube 72 and the thermostatic motor 74 may contain mercury in liquid form at normal atmospheric temperature, and the fluid casing so produced by these members may be charged with liquid mercury through the opening 130, FIGURE 7, after which the ball 132 may be welded to the opening 130, on the motor head 134, which is secured to the diaphragm 75B.

A suitable wire 136 may be placed in the tube 72 to reduce the amount of mercury used in the tube 72, and may be chosen of such material, that it may compensate for the expansion and contraction of the tube 72 and liquid mercury due to surrounding temperatures, so such atmospheric temperature changes, and other temperatures which do not vaporize mercury (below 700 F. more or less) do not affect the valves 112.

The portion of the thermostatic fluid, or mercury, which is in the bulb 35 may change phase. For example, the liquid mercury in bulb 35 may be vaporized at temperatures of 700 F., more or less, and the production of this vapor causes a quick and elastic movement of the ball 132 to produce a substantially snap-acting opening and closing of the valve 112, depending upon the change from liquid mercury to mercury vapor and vice-versa.

The valve moving means or spring construction 128 may include a valve actuating lever 136 having a lever fulcrum 138 and a valve actuating portion 140, Which are separated from each other. The thermostatic motor 74 has means, such as the ball 132, to move the lever 136 and valve 112 toward and away from the valve seat.108.

The spring construction 128, may include a relatively strong compression spring 142 which cooperates with the lever 136 to move the valve 112 toward the seat 108. The spring construction 128, which may include the relatively strong spring 142, with or without an additional relatively Weak compression spring 144, cooperates with the lever 136 to move the valve 112 toward the seat 108. The spring construction 128 increases'in valve seating strength as the valve 112 moves toward the valve seat 108 and decreases in strength as the valve 112 moves away from the valve seat 108.

A lost motion notch may be provided in valve 112 to permit the lever 136 to impart an additionally quick opening motion to the valve 112 as the mercury starts to vaporize.

A supporting fulcrum 146 cooperates with the lever fulcrum 138 to hold the lever 136 in pivoting position The lever fulcrum 138 may be hook-shaped as at 148 and engages the knife edge of the stationary or supporting fulcrum 146. The compression spring 142 pulls the hook type fulcrum 138 tightly against the stationary or supporting fulcrum 146, in a rightward direction in FIG- URES 7 and 10.

The supporting fulcrum 146 may be adjustable up and down, for example, to adjust and calibrate the opening and closing action of valve 112. For example, the supporting fulcrum 146 may be carried by a fulcrum lever 150 which is adjustable to adjust the supporting fulcrum 146.

The lever 150 may be pivoted by hooks 152 inserted in openings 154 in the valve casing end wall 155. The lever 150 is adjustable by the pin 156, which may be longitudinally adjusted, as by the threaded construction 158 which has a screw head 160, for longitudinal engagement.

A suitable valve casing cover 157 may be bolted on the end wall 155 after the lever 150 has been positioned. The cover 157 may carry the thermostatic motor 74 so the ball 132 engages lever 136.

The compression spring 142 has a first spring part, such as one end 161 which engages the lever 136, through the medium of a disc 162 which engages the lever 136 at a first spring fulcrum 164.

A second spring part 166, which may be the other end of the spring 142, may engage a second spring fulcrum 168, which is carried at the end of the lever 150.

The spring fulcrums 164 and 168 are so located to produce a valve closing torque, as indicated 'by the dotted line 170 in FIGURE 7, which extends from the fulcrums 138 and 146 to the right angled intersection 172 with the extended line 174 fiom the spring fulcrums 164 and 168.

The first spring fulcrum 164 swings about the arc 176 which is centered about the fulcrums 138 and 146. The fulcrum 168 is stationary during the operation of the device and is movable only for adjustment purposes. Therefore, the extension line 174 moves toward the fulcrums 138 and 146 as indicated at 174A as the valve 112 moves away from the valve seat 108. Hence the intersection 172 likewise moves towards the fulcrums 138 and 146, as indicated at 172A as the valve 112 moves away from the valve seat 108. The line 170 is indicative of the torque produced by the rightward pull of the line 174 (in FIGURE 7) due to the compression spring 142. It produces a counter-clockwise torque about the fulcrums 138 and 146 which increases in length and strength as valve 112 moves toward the seat 108, and decreases in length and strength as the valve 112 moves away from the valve seat 108.

This increase in spring torque 170 as the valve 112 moves toward the valve seat 108 causes a quick closing movement of the valve. Conversely, the decrease in spring torque 170 as the valve moves away from the valve seat 108 causes the valve 112 to have a quick opening movement. This action is amplified by the resiliency of themercury vapor in bulb 135.

The supporting fulcrum 168 cooperates with the adjacent spring fulcrum and is adjustable by the pin 156' to calibrate the action of valve 112. The fulcrum 168 is carried by the lever 150, which is adjustable by the pin 156 about the fulcrums 152 to adjust the supporting fulcrum 168.

The lever 150 is held in locked position by the thrust: of the ball 132, the openings 154, and the pin 156.

The lever 150 may be adjusted by the pin 156 to cause any relative movement between the line 174 and the fulcrums 138 and 146. For example, it may be preferred to cause the extension line 174 to be at, or just slightly below the fulcrums 138 and 170 when the valve 112 is: in the downward fully opened position 112A, and to be a relatively long distance, such as at 172, when the valve 112 is in the fully closed and full line position illustrated in FIGURE 7.

The lever 136 may be made of a stamping, such as:

shown in FIGURE 8. The lever 136 has extension shoulders 180 which carry a pair of hook fulcrums 138, which act in unison against the pair of knife fulcrums; 146, shown in FIGURE 9. FIGURE 9 shows the lever 150 to be a relatively flat piece of metal with shoulders: or hooks 152 carried by an extension 182. The spring: supporting fulcrum 168 is shown at the right end of FIGURE 9. A downward extension 184 is punched into the lever 150 to engage the pin 156. A strengthening; ridge 186 is formed to make the lever 151) rigid.

If desired, the spring 142 may have a spring strength of 6 pounds, more or less at its normal load. The spring: 144 may be relatively weak, and may have a spring: strength of 1.5 ounces, more or less, when at its normal load. The spring 142 therefore provides a very substantial upward push on the valve 112 when the valve closes- It is strongest in valve closing strength or torque when. valve 112 is in the fully closed position as shown in full lines in FIGURE 7 and has a small valve closing torque: when the valve 112 is open.

The parts which contact the mercury, if used, may be made of material which is not affected by the mercury. For example, the bulb 35, tube 72, wire 136 and. the mercury contacting parts of motor 74 may be made of stainless steel, or the like.

It is thus to be seen that this invention provides new and useful pilot constructions, burner gas valve constructions, and combinations thereof. Also new and useful methods of control are provided.

In the fully closed position of the valve 112, and in. the fully retracted position of the ball 132, not shown, the ball 132 is slightly spaced from the lever 136 to permit the full closing force of the spring 142 to act on the valve 112.

The dotted line position of lever 136 in FIGURE 7 is not its lowest position when the valve 112 is fully opened. Such lowest position is below the dotted line showing. Also the line 174 approaches the fulcrums 138 and 146 to a position closer than 172A when the valve 112 is in fully open position. Hence the counterclockwise torque of lever 136 is less than the torque at 172A when valve 112 is in fully open position.

While the form of the invention now preferred has been disclosed as required by statute, other forms may be used, all coming within the scope of the claims which follow.

What is claimed is:

1. In a fuel control system, a pilot burner means having a first outlet means to normally issue a small standby flame during normal flow of fuel to said pilot burner means, said pilot burner means having a second outlet means spaced from said first outlet means, and means for increasing the flow of fuel to said pilot burner means to create a large ignition flame at said second outlet means for ignition purposes, said pilot burner means having a third outlet means spaced from and below said first and second outlet means to produce a heater flame at said third outlet means only when said increased flow of fuel is directed by said fuel flow means to said pilot burner means.

2. In a fuel control system as set forth in claim 1, said pilot burner means carrying a heater flame detector adjacent said second outlet means.

3. In a fuel control system as set forth in claim 2, said heater flame detector comprising a temperature sensing bulb.

4. In a fuel control system as set forth in claim 1, a main burner means, said pilot burner means being disposed adjacent said main burner means to ignite said main burner means with said ignition flame.

5. In a fuel control system as set forth in claim 4, and means responsive to said heater flame adapted to cause fuel to flow to said main burner means.

6. In a fuel control system as set forth in claim 5, said pilot burner means being positioned so that said heater flame is disposed remote from said burner means.

7. In a fuel control system as set forth in claim 1, a main burner, a safety valve for supplying fuel to said main burner, said pilot burner being disposed adjacent said main burner to ignite said main burner with said ignition flame, and means for sensing said heater flame to open said safety valve to direct fuel to said main burner to be ignited by said ignition flame.

8. In a fuel control system as set forth in claim 7, said pilot burner means including a temperature sensing means that senses said heater flame and causes opening of said safety valve.

9. In a fuel control system as set forth .in claim 7, said fuel flow means being thermostatically controlled in response to the temperature effect of said main burner.

10. In a fuel control system as set forth in claim 1, said pilot burner means including a flame shield against which said fuel impinges when said fuel is directed to said pilot burner means, said flame shield having a free end that defines said third outlet means and having two openings passing therethrough which respectively define said first and second outlet means.

References Cited UNITED STATES PATENTS 1,842,337 1/1932 Te Pas 23668 2,999,535 9/1961 Alger 158-113 3,078,916 2/1963 Loveland 158-115 3,146,823 9/1964 Loveland 158123 3,155,143 11/1964 Jackson et al. 158113 3,166,248 1/1965 Fleer 23668 EDWARD J. MICHAEL, Primary Examiner.

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