US2171767A - Draft regulating device for orchard heaters - Google Patents

Description

Sept, 5, 1939.

w. c. SCHEU DRAFT REGULATING DEVICE FOR ORCHARD HEATERS Filed Aug. 4, 1936 4 Sliets-Sheet 1 INVENTORT ATT NEYS.

ZJVLY-ST Se t. 5, 1939. w c. SCHEU DRAFT REGULATING'DEVICE FOR ORCHARD HEATERS Filed Aug. 4, 1936 4 Sheets-Sheet 2 l- BY ATTORN YS.

pt 1939- w. c. S CHEU DRAFT REGULATING DEVICE FOR ORCHARD HEATERS 4 Sheets-Sheet 3 Filed Aug. 4, 1936 will ' IN V EN TOR.

GScZeu,

I TOR S.

Sept. 5, 1939. w. c. S'CHEU DRAFT REGULATING DEVICE FOR ORCHARD HEATERS Filed Augf4, 1936 4 Sheets-Sheet 4 INVENTOR.

ATTORNEYS.

Patented Sept. 5, 1939 I HEATE William C. Scheu, Upland, CaliL, assignor to Schcu Products Company, Limited, Upland, Calif., a corporation of California Application August 4, 1936, Serial No. 94,167

Claims. (01. s- 91) This invention relates to temperature-controlled draft-regulating devices for liquid fuel orchard heaters and pertains particularly to a heatresponsive device for automatically establishing 5 a controlled influx of combustion air to the fuelvaporizing chamber of such a heater for normal burning operation thereof following the starting or ignition period-of such heater.-

The principal object of the invention is to proio vide a heat-controlled draft-regulating device for use in connection with a vaporizing type liquid fuel orchard heater, which is operable to provide a substantially unrestricted inflow of air to the vaporizing chamber during a preliminary ignition 16 period and to automatically restrict the admission of air to said vaporizing chamber when the ignition is completed, in response to a temperature increase resulting from combustion within the heater, so as. to thereafter maintain a relatively restricted admission of air to said chamber, sufiicient to maintain the desired normal burning rate during subsequent operation of the heater.-

A further object of the invention is to provide a device of the character described, for associa- 2 tion with the vaporizing chamber of a liqued fuel orchard heater and adapted to effect a draftregulating control of the combustion within said vaporizing chamber in response to the heating efi'ect of such combustion.

A further object of the invention is to provide a movable draft-regulator mechanism disposed in position to control admission of air to the yaporizing chamber of a liquid fuel orchard heater,

'which may be manually positioned to establish 3;, a relatively large air inlet opening for substantially unrestricted supply of air to such vaporizing chamber when the heater is first lighted, and which, in response to the heat produced by combustion within said vaporizing chamber, will automatically move to partially close said relatively large opening and supply a predetermined restricted quantity of combustion air to said vaporizing chamber for maintenance of normal burning operation of said heater.

The heat-responsive mechanism which controls the operation of the draft-regulating device is preferably disposed in heat-receiving relation to the vaporizing flame which is established and maintained within the body portion or vaporizing chamber of the heater, whereby the desired change in the volume of admitted air is directly dependent upon the proper establishment of this vaporizing flame.

A further object of the invention is to provide 55 improved means for admitting air to the vaporizing chamber of an orchard heater, for maintaining a vaporizing. flame within said chamber, in which the position and manner of introduction of such air are such as to provide stable operation of the vaporizing flame, and pre- 5 vent said flame from being extinguished, either due-to the action of the draft produced by the main combustion which takes place within the main combustion chamber of the heater, usually within the stack, or due to outside influences such 10 as atmospheric air currents.

The device of the present invention may comprise, in generaL. thermostatically controlled draft regulating means disposed across and above or within the air-admitting opening which supi5 plies air to the vaporizing chamber of a liquid fuel orchard heater for establishing a vaporizing flame therein, said draft regulating means providing one or more restricted air-admitting openings which are preferably subject to manual 20 adjustment to establish an air influx which is adequate for the maintenance of the desired normal burning rate of the heater. Said draftregulating means may be so mounted with respect to the first-mentioned air-admitting opening as 25 to be movable to a position providing substantially free access of air through a substantial portion of said opening and to another position partially closing the said opening and permitting air to reach the vaporizing chamber solely 3 through the above-mentioned restricted air-admitting openings, said air-regulating means being preferably biased toward said last-mentioned position by suitable means such as gravity or spring-biasing means. Thermostatically controlled positioning means are provided to cooperate with the above-mentioned draft-regulating means to cause the same to maintain the first-named position, said positioning means being so disposed as to be subject to an increase I in temperature caused by combustion within the heater, preferably being disposed in heat-receiving' relation to the vaporizing flame, and operable to cause said draft-regulating means to change from said first-named position to the second-narned position preferably in conjunction with said gravity or spring bias, when the vaporizing flame has established a desired operating or vaporizing temperature condition within the heater body. 553

a narrow stream at an angle to the normal path of the air through the vaporizing member. Such air, furthermore, is preferably admitted in a plurality of narrow s reams which are disposed at an angle to one anotherwhereby an augmented turbulence is obtained.

Other objects and features of the invention will be brought out in the following description thereof or will be apparent therefrom. The accompanying drawings illustrate certain embodiments of the invention, and show the application thereof to a conventional type liquid fuel orchard heater, and referring thereto:

Fig. 1 is a vertical section of a complete orchard heater provided with draft-regulating means according to the present invention;

Fig. 2 is an enlarged fragmentary vertical median section of the draft-regulating means alone, showing a preferred form of the invention;

Fig. 3 is a plan view of the draft-regulatin means, taken on line 3--3 of Fig. 2;

Fig. 4 is a detached elevation of the draftregulating means, taken on line 4-4 of Fig. 2;

Fig. 5 is a plan view, as on line 33 of Fig. 2, showing the device in a position corresponding to that shown in the dot-dash lines of Fig, 2;

Fig. 6 is a side elevation similar to Fig. 4, showing the device in the position represented by the dot-dash lines in Fig. 2; and

Fig. '7 is a fragmentary vertical median section through a variational form of the invention, showing a modified form with a different location of the thermostatic control means.

Referring to the drawings, a standard form of vaporizing liquid fuel orchard heater is indicated at I, comprising a reservoir 2 adapted to contain a body of liquid fuel 3 and provided with a cover member 4 having a centrally disposed collar portion 5 carrying a suitable stack assembly. The stack assembly may comprise a lower portion 6 carrying an air-admitting intermediate portion 1 which may be provided with a plurality of airadmitting openings 8 and 9 at itslower and upper end portions, respectively.

The space H enclosed by the reservoir 2 and the cover 4, above the body of fuel 3, constitutes a vaporizing chamber, and a suitable opening I2 is provided in the cover 4 for admission of air to said chamber for maintenance of a vaporizing flame therein. This opening may conveniently be defined by a raised collar portion l2a (see Figs. 2 and '7) formed in said cover, said collar portion serving to position the hereinafter described draft-regulating device with respect to said openmg.

if desired, mounted on the collar 12a and de-' pendent therefrom, to facilitate the maintenance of a vaporizing flame within the chamber II. A suitable wick member is preferably also provided adjacent the opening H, as shown at ll, for example, and such wick member may be formed of an absorbent material such as fibrous asbestos, and is preferably wrapped or enclosed in a wire or metal fabric envelope as indicated at a.

The draft-regulating device comprises a housing 64 in the shape of a short tubular member that fits snugly around the up-raised collar In and is held in place by frictional engagement with the sides of the collar. Housing 64 is preferably provided with a weather cap I l hingedly mounted thereto as at l8, and which may be disposed over the draft opening 65 and the draft-regulating portions of the device as shown in Fig. 1 when the heater is not in operation, in order to prevent A suitable draft-tube or flame-stabilizing I baffle I3 may be provided adjacent the opening l2,-

ingress of atmospheric moisture, such as rain or Housing 64 is provided with a draft opening 65.

in its upper end, the opening preferably being semicircular in shape as shown in Fig. 3. A suitable draft-regulating means is provided in order to control or restrict the flow of air through opening 65, and this means comprises semicircular plate 62 located adjacent opening 65 in a position to cover the opening when lowered, and pivotally mounted on the housing at one edge of the opening by.hinge 63. Draft-regulating plate 62 is movable about its pivot 63 to a first or open position which it normally occupies at the time a heater 'is started. In this first open position, which is shown by the full lines in Fig. 2, substantially free access of air to the vaporizing chamber is provided thorugh opening 65. Since plate 62 is mounted with its axis of pivotal movement 63 at one side of the center of gravity of the plate, it will be apparent that'the plate is biased by gravity toward a second or lowered position indicated by the dot-dash lines in Fig. 2. A spring or the like may be used to bias the plate toward the lowered position, but in general gravity will be found fully effective and much more convenient. 'When plate 62 is in this second or lowered position, opening 65 is partially closed to a greater or lesser extent but not completely closed, as will be more fully described, and thepassage of air through said opening is restricted accordingly. This second position is the onenor mally occupied by the plate when the heater is in operation.

The position of plate 62 is normally determined or controlled by thermostat means associated with the plate and adapted to hold the plate in the open, tilted position. The thermostatic means is placed'in heat-receivingrelation with respect to the vaporizing flame within the heater and is operable in response to heat received therefrom to release the plate from its tilted position and permit the plate to lower itself into the sec- 0nd position. This heat-responsive thermostatic means comprises a pin member 80 rigidly secured to a bimetallic thermostat bar 6|. Pin member 60 is so positioned as to bear against the angular depending portion 19 of plate 62, as illustrated in Fig. 2, the pressure exerted against plate portion 19 being in a direction transverse to the axis of hinge 63, whereby movement of said pin member causes a rotational movement of the draftregulating plate about axis 61. The regulation of the draft opening is obtained by a control of the extent to which the draft-regulating plate closes or covers opening 65, and for this purpose I provide cooperating movement-limiting means on said plate and on said housing member. Such means comprises typically an inclined ramp member 66 formed integrally with housing 64, and a movable limiting member 61 pivotally mounted on plate 62, although I am not limited to the shapes of members 66 and 61 shown. Member 6! may comprise a tab or the like pivotally mounted on plate 62 at 68 and is preferably provided with a flat plate portion 69 parallel to and lying against the upper surface of plate 62, the function of which will be brought out later.

The limiting member 61 is provided with a projecting portion 10 which extends outwardly of the plate 62 a sufficient distance to engage the member 67. construction is such that the ramp 66 is disposed upper edge ll of the ramp member 66 in a lowered position of the regulating plate 62, as is shown in dot-dash lines in Fig. 2 and in full lines in Fig. 6. It will be appreciated that the ramp 66, while shown as arcuate in shape, may be of any desired configuration such as to provide the necessary inclined upper surface H in position to be engaged by the portion 10 of the limiting In its preferred embodiment, the

in an are having a center corresponding roughly to the position of the pivot 68 when the'plate 62 is in lowered position, whereby the projecting portion it may be made of a minimum length.

A vaporizing tube or flame stabilizing baflie I3 is preferably provided as shown in Figs. 1 and 2. In this embodiment the thermostatic element 6! is disposed within the tube i3 and is preferably shielded from the direct flame by means of a tube member l2 which may be secured to the cover 64. in any suitable manner as by means of rivets or the like indicatedat 13. The thermostatic element 6! may be mounted within the tube '52 in any suitable manner, such'as by means of a spider i l abutting against the lower end of the upper portion 72a of the tube Hand secured in place through the agency of a cap portion 12b threadedly disposed on the portion 12a. The pin member 60 is carried by the upper or free end of the element'fii and may extend through a suitable slot or other opening '85 at the upper end of the tube portion 52a. In order to position the element 6i and the pin 60 in correct relation, the spider M is preferably provided with a tongue portion 76 engaging within a suitable slot H at the lower end of the tube 12a. The pin 50 extends laterally from the element 6! through the opening 35 to a suflicient distance to engage a depending tab member 19 secured to the plate 62. As further brought out hereinafter, the tab portion 19 is extended somewhat beyond the point of engagement by the pin (iii to provide a flame stabilizing action.

The operation of the device may be as follows:

. Assuming the reservoir 2 to be filled with a body of liquid fuel a to a suitable level, an attendant who desires to light the heater can lift weather cap H and swing the same away from the position of Fig. l to uncover the draft opening and regulating means as shown in Fig. 2 by grasping a tab or. handle ila. on the top of the weather cap. When draft opening is thus exposed, the attendant can then insert the tip of his lighting torch through the draft opening and inject a suitable quantity of burning ignition fluid, which may comprise a mixture of gasoline and kerosene or the like, into the heater through openings 85 and i2 and tube it. A portion of this burning fluid falls onto wick it, while the remainder passes down tube it onto the surface of the main fuel body 3. A substantial portion of this burning ignition fluid burns adjacent wick i l and establishes within tube l3 a vaporizing flame which burns at the surface of fuel 3 and heats the fuel body sufficiently to efiect generation of fuel vapor therefrom, which vapor is carried upwardly through the stack assembly by the draft created within the heater. When the rate of evolution of fuel vapors is adequate, the main combustion of the heater will be established within or above the stack assembly, it being appreciated that some of the lighting-fluid may be poured down the stack, if desired, to facilitate ignition of the main combustion flame. Air inlet 65 provides air for the vaporizing flame and also the main combustion flame, the latter being able to establish a very strong draft through the heater from inlet 65. The vaporizing flame is maintained within tube [3 at a place within the heater removed from the main combustion which occurs within or above the stack assembly, and the bimetallic element St is in a position to receive heat from the vaporizing flame maintained adjacent wick I4, rather than from the main combustion flame.

When a heater provided with this embodiment of the device is lighted, the thermostat will be cold and will be in the position shown in full.

lines in Fig. 2, forcing the regulating plate up to its full line position. When cold, the thermostat means acts as a detent means to hold the plate in the tilted position against gravity. When the burning lighting-fluid is introduced against the wick M through the opening 65 as above described, the flame from the wick M will heat the tube I2 principally by radiation and the thermostatic element 6! will be gradually raised in temperature. There is little direct metallic contact between the tube 12 and the element 65 and for this reason there will be some lag in the movement of the element GI as the tube 12 is brought to temperature. The main heating of the element 5! results from direct radiation'from the tube 12, and as the element 6 l. becomes heated it will bend to the dot-dash position shown allowing gravity to bias the plate 62 downwardly toward the position shown in dot da'sh lines in said figure. Dependent upon the position of the member 61, that is, the position to whichit is adjusted about the axis 68, the projecting portion thereof ill the upper end of the cap 64 and thus partially expose the opening 65. When the regulating plate 62 is lowered to the lowermost position as limited by the member 61, the air-supply to the vaporizing chamber will be gradually restricted until the correct volume for the desired burning rate is established. It will be apparent that this change in the air supply will be gradual and for this reason there is no danger of the vaporizing flame being snuffed out as might result from a quick operating device. The flat plate portion 69 of the limitingmember G'l' may be employed to cover or uncover certain index openings 18' in the regulating plate 62, providing a ready index to the operator as to the position of the tab 6'! with respect to the upper inclined portion H of the ramp 5%.

The form .of the device illustrated in Figs. 2 through 6 is further characterized by an advantageous flame stabilizing action due to the turbulence produced in the flow of air through the air-admitting opening. If the aim-admitting opening is such that the air admitted therethrough is subject to a smooth andsubstantially unobstructed path the air will enter the vaporizing chamber at high velocity-and will flow through said chamber and into the stack in amore or less. confined path. Such high velocity air flow will tend to restrict the vaporizing flame to the air path and produce an intermittent and feeble vaporizing flame. Furthermore, there will be a tendency for the vaporizing flame to jump into the stack when the heater is subjected to a disturbingfactor such as a gust of wind or the like.

These objectionable features are'overcome in my device by providing for turbulent air flow through the vaporizing chamber by admittingthe air thereto in a narrow stream, and prefer- .will be of little importance.

ably in a plurality of narrow streams and in different directions, whereby a turbulent air flow is produced in the vaporizing chamber which draft-regulating device is shown in the starting position with the plate 62 in the full open position providing a substantially unobstructed path for air through the opening 65. When the plate 62 is in this position and the heater is first lighted the air will flow through the opening 85 at a relatively low velocity due to the low temperature difference between the vaporizing chamber and the top of the stock and a flame stabilizing action However, as the vaporizing chamber becomes heated, the thermostat begins to operate and the plate 82 approaches and reaches the draft-regulating position shown particularly in Figs. 5 and 6, at which time the induced draft will be greatly increased and a flame stabilizing action will become desirable for proper operation of the heater.

Such flame stabilization action is provided by causing the air to flow through the narrow openings between the housing 84 and the plate 62 at each end of the ramp member 86 as .indicated by the arrows I05 in Figs. 5 and 6. This influx of air enters thelair inlet opening through narrow restrictions which tend to produce a throttling and turbulent action and also the air enters at substantially right angles to its normal direction of flow downwardly through the draft tube l3 so that it must change its direction of travel. This also tends to increase the turbulence.

In some instances, it may be advantageous to provide suflicient space between theedge of the plate 82 adjacent the ramp 68 and the inner edge of the ramp 68 so that an appreciable air inlet opening may be provided by said space. Air introduced through such a space, as indicated by arrows Hit in Fig. 5, will tend to flow downwardly along the vaporizing tube l3 and will mix with the air flowing in at a diiferent direction from the aforementioned openings provided at ends of the ramp and increase the turbulence and the flame stabilizing action.

The tab member 19 will also produce a definite flame stabilizing action by acting as a barrier and poducing turbulence when-the plate 82 is in the full-open or starting position. However, this action is not so pronounced due to the fact that the air velocity through the air inlet opening is not very high when the heater is first lighted and is cold. The tab member 19 is also useful for, shielding the thermostat tube 12 from the vaporizing flame, especially when the wick H has just been ignited and the vaporizing flame is confined largely to the upper portion of the draft tube l3.

Since the time required for the thermostat to operate after the heater is lighted depends to a certain extent upon the position of the thermostat with relation to the vaporizing flame it may be desirable to mount the thermostat so that it is in a less intimate heat receiving relation with the vaporizing flame, for example exteriorly of the vaporizing tube.- Referring to Fig. 7 the regulating plate 62 is shown hingedly connected to the cap member 64 disposed about the raised collar portion In of the cover 4 of the fuel receptacle of an orchard heater. A thermostatic element 8| is disposed within a tube member 82, which may be comparable to the tube member 62, and secured to the cover 4 in any suitable manner such as by screws 83 and positioned within the vaporizing chamber exteriorly of the vaporizing tube l3. A pin member 80, comparable to the pin member 60, is carried by the upper end of the thermostatic element 8| and may extend through a suitable slot or the like 84 in the upper end of the tube element 82 and through another slot or opening 85 in the flame stabilizing bailie or vaporizing tube l3. The pin 80 is suitably formed and positioned to extend through the opening 85 so as to engage a depending tab member 88, comparable to the tab member 19, secured to the plate 83. Before the heater is lighted, the thermostat will be cold and will assume a position shown in full lines in Fig. 7 forcing the regulating plate up to its full line position. After lighting the heater the action will be similar to that described in relation to Fig. 2. The thermostat will become heated and bend to a position such as shown in dot-dash lines in Fig. 7 and the plate 62 will be biased downwardly by gravity to a position such as shown by dot-dash lines, in which the projecting portion"!!! of the member 61 engages the upper edge H of the ramp 66, establishing a correct volume of air for the desired burning rate.

- I'claim:

1. In association with a vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having 'an air-admitting opening for maintaining a vaporizing flame within said chamber removed from the main heating flame, a heat-responsive draft-regulating device which comprises: a pivotally mounted regulating plate disposed adjacent said opening and biased toward a lowered position partially closing said opening, and movable to a tilted position to provide substantially free access of air to said opening, said regulating plate being provided with an air-admitting opening for admission of a restricted volume of air to said chamber when said plate is in said lowered closing position; and a bi-metallic thermostatic detent means mounted in heat-receiving relation to said vaporizing flame and positioned to engage said regulating plate and hold the same in said tilted position, said detent means being heat-operable to permit said regulating plate to move to said lowered position in response to heat generated by said vaporizing flame, and to return the regulating plate to said tilted position when the detent means has cooled.

2. In association with a vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having an air-admitting opening for maintaining a vaporizing flame within said heater at a place removed from the main heating flame, a heat-responsive draft-regulating device which comprises: a hingedly mounted draft-regu-' lating plate disposed adajcent said opening in position to restrict the passage of air therethrough and biased toward a lowered position partially closing said opening, and movable to a raised tilted position to provide substantially free access of air to said vaporizing chamber through said opening, thermostatic means disposed within said heater in heat-receiving relation to said vaporizing flame and having a portion bearing against said plate to hold the same in said raised tilted position, and heat operable in response to heat generated by said vaporizing flame to release said plate and permit the plate to move to said lowered position; cooperating limiting means mounted on said plate and on said heater adjacent said plate, said cooperating limiting means being adapted for engagement with one another during a lowering movement of said plate toward said lowered position to limit such downward movement of said plate.

3. In association with a vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having an air-admitting opening for maintaining a vaporizing flame within said heater at a place removed from the main heating flame, a heat-responsive draft regulating device which comprises: a hingedly, mounted draft-regulating plate disposed adjacent said opening in position to restrict the passage of air therethrough and biased toward a lowered position partially closing said opening, and movable to a tilted position to provide substantially free access of air to said vaporizing chamber through said opening, thermostatic means disposed within said heater and provided with a portion engaging said plate to hold the same in tilted position, and heat operable in response to heat generated by said vaporizing flame to release said plate and permit the plate to move to said lowered position; a movable limiting member mounted on said plate, and a ramp member adjacent said opening in position to be engaged by said limiting member when said plate is lowered.

4. In association with a vaporizing type liquid fuel orchard heater provided with an air-admitting opening for maintaining a vaporizing flame within said heater at a place removed from the main heating flame, a heat-responsive draftregulating device which comprises: a housing member disposed over said opening; a draft regulating plate hingedly mounted on said housing member and disposed adjacent said opening, said plate being positioned to restrict the passage of air through said opening, and biased toward a lowered position partially closing said opening, and movable to a raised tilted position to provide substantially free access of air to said vaporizing chamber through said opening; thermostatic means associated with said plate for holding the same in tilted position and heat operable in response to heat generated by said vaporizing flame within said heater to release said plate and permit the plate to move to said lowered position; a movable limiting member mount-- ed on said plate; and an inclined ramp member mounted on said housing member in position to engage said limiting member when said plate is lowered.

5. In association with a vaporizing type liquid fuel orchard heater provided with an air-admitting opening for maintaining a vaporizing flame within said heater at a place removed from the main heating flame, a heat-responsive draft-regulating device which comprises: a hingedly mounted draft-regulating plate disposed adjacent said opening in a position to restrict the passage of air therethrough and biased-toward a position partially closing said opening and movable to a tilted position to provide substantially free access of air to said vaporizing chamher through said opening; a ramp positioned adjacent the outer edge of said opening and extending along a portion of said opening, a limiting member pivotally mounted on said draftregulating plate and having 'a portion projecting outwardly of said draft-regulating plate in position to engage said ramp; and thermostatically controlled means associated with said plate for holding the same in tilted position and heat operable to release said plate and permit the plate to move toward a partially closing position determined by the setting of said limiting member with relation to said ramp, in response to heat generated by said vaporizing flame within said heater.

6. In association with a'vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having an air-admitting opening for maintaining a vaporizing flame within said heatuiating plate disposed adjacent to said opening in position to restrict the passage of air thereer at a place removed from the main heating 1 flame, aheat-responsive draft-regulating device' which comprises: a hingedly mounted draft-regagainst said plate to hold the same in said raised tilted position, and heat operable in response to heat generated by said vaporizing flame to release said plate and permit theplate to move to said lowered position; and a baflle member secured to said plate and disposed within said opening at a. position adjacent said thermostatic means and in a shielding relation thereto with respect to said vaporizing flame.

7. In association with a vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having an air-admitting opening for maintaining a vaporizing flame within said heater at a place removed from the main heating flame, a. heat-responsive draft-regulating device which comprises: a hingedly mounted draft-regulating plate disposed adjacent to said opening 7 in position to restrict the passage of'air therethrough and biased toward a lowered position partially closing said opening, and movable to a raised tilted position to provide substantially free access 0 air to said vaporizing chamber through said ope ing; thermostatic meansdisposed within said heater. in heat-receiving relation to said vaporizing flame and having a portion bearing against said plate to hold the same in said raised tilted position, and heat operable in response to heat generated by said vaporizing flame to release said plate and permit the plate to move to said lowered position; a wick member disposed within said air-admitting opening adjacent said thermostatic means; and a baflle member secured to said draft-regulating plate and positioned to shield said thermostatic means from direct contact of a vaporizing flame located adjacent said wick member when saidvdraft-regulating plate is in said raised tilted position.

8. In association with a vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having an air-admitting opening for maintaining a vaporizing flame within said heater'at a place removed from the main heating flame, a heat-responsive draft-regulating device which comprises: a hlngedly mounted draft-regulating plate disposed adjacentto said opening in position to restrict the passage of air therethrough and biased toward a lowered position partially closing said opening, and movable to Y.

a raised tilted position to provide substantially free access of air to said vaporizing chamber through said opening; thermostatic means disposed within said heater in heat-receiving rela-- in response to heat generated by said vaporiz-H ing flame to release said plate and permit the plate to move to said lowered position; said draftregulating plate being of such shape with respect to said air-admitting opening as to define therewith a narrow elongated air-admitting slot when said plate is in said lowered position.

9. In association with a vaporizing type liquid fuel orchard heater provided with a vaporizing chamber having an air-admitting opening for maintaining a vaporizing flame within said heater at a. place removed from the main heating flame, a heat-responsive draft-regulating device which comprises: a hingedly mounted draft-regulating plate disposed adjacent to said opening in position to restrict the passage of air therethrough and biased toward a lowered position partially closing said opening, and movable to a raised tilted position to provide substantially free access of air to said vaporizing chamber through said opening; thermostatic means disposed within said heater in heat-receiving relation to said vaporizing flame and having a portion bearing against said plate to hold the same in said raised tilted position, and heat operable in response to heat generated by said vaporizing flame. to release said plate and permit the plate to move to said lowered position; said draftregulating plate being of such shape with respect to saidair-admitting opening as to define therewith a plurality of narrow elongated air-admitting slots extending in different directions when said plate is in said lowered position,- whereby air admitted to said vaporizing chamber when said plate is in said lowered position is caused toenter said air-admitting opening in a plurality of narrow streams in different directions.

10. In association with a vaporizing type liquid fuel orchard'heater provided with a vaporizing chamber having 'an air-admitting opening for maintaining a vaporizing flame within said heater at a place removed from the main heating flame, a, heat-responsive draft-regulating device which comprises: a pivotally mounted regulating plate disposed adjacent said opening and movable between a first position providing substantially free access of air to said vaporizing chamber through said opening and a second position restricting the passage of air through said opening, said regulating plate being biased toward said second position, and bi-metallic thermostatiomeans disposed in heat-receiving relation to the vaporizing flame maintained within said-heater, said thermostatic means normally holding said regulating plate in said first position and being operable in response to heat generated by said vaporizing flame gradually to release said regulating plate and permit the plate to move slowly into said second position, and

operable to return said plate to said first posi- 7 tion when the bi-metallic thermostatic means has cooled.

WILLIAM C. SCHEU.

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