US2268067A - Draft regulator for orchard heaters - Google Patents

Description

Dec. 30, 1941. J. R. CAMPBELL 2,268,067 DRAFT REGULATOR FOR vORCHARD HEATERS l IFiled 0G12. 17, 1938 :5V sheets-sheet i p 'j 1 W UA1/504' Janis 1. CAMpaELL Dc."30, 1941. 1 R CAMPBELL 2,268,067

DRAFT REGULATOR FOR ORCHARD HEATERS V v-Filgel oct. 17, 1938 s srheetsheet 2 I 3x1/UWM Juf/5.5 CAMPBELL Dec. 30, 1941. L4 R CAMPBELL 2,268,067

DRAFT REGULATOR FOR ORCHARD HEATERS Filed Oct. 1'7. 1938 3 Sheets-Sheet Patented Dec. 30, 1941 `DRAFT REGULATOR FOR ORCHARD HEATERs James Campbell, Ontario, Calif., `assigner to` William C. Scheu, Upland, Calif.

Application October 17,` 1938, Serial No. 235,299

8 Claims. (Cl. 158-91) This invention relates to `temperature-controlled draft regulators for liquid fuel orchard heaters and is concerned particularly with heatresponsive devices for automatically establishing a controlled influx ofcombustion air to the fuel vaporizing chamber of such a heater for` normal burning operation thereof following the starting or ignition period of such a heater.

`The heat-responsive draft-regulating device of this invention is primarily adapted for use with vaporizing type liquid fuel orchard heaters. In `heaters of this type a vaporizing name is maintained at'or near the surface of the body of fuel contained in the heater to cause vaporization from the surface of this fuel. The oil vapors pass upwardly into a stack where additional air is mixed with them to cause substantially complete combustion of the vapors in a main flame at a point removed from the vaporizing fiame. A heater of this general type provided with such a stack forming a main combustion chamber is shown in U. S. Patent No. 1,930,863, issued October 17, 1933, to William C. Scheu.`

Heaters of this type are provided with one or more air-admitting Openings in the body communicating with the vaporizing chamber to admit air to the vaporizing flame in the vaporizing chamber. With such Iarrangement it is preferablel to supply a relatively large quantity of air to the vaporizing chamber to support the vaporizing flame when the heater is first ignited and until the vaporizing chamber has been heated. After the vaporizing chamber has become heated and the main combustion flameis Wellestablished, a smaller amount of heat from the vaporizing flame is required to vaporize fuel; and if the `air supply is not reduced to diminish the flame, there will be a tendency to vaporize an excess quantity of fuel. These relations are all aiunction of the heat generated in the vaporizing chamber and are substantially independent of `the temperatures existing Where the main combustion takes place in the stack, or at any other place removed from the vaporizing iiame.

In order to obtain proper and satisfactory Op; eration `of such a liquid fuel heater it is desirable to restrict the flow of air admitted to the Vaporizing chamber after a sucient quantity of heat has been generated therein. In many cases this operation is performed manually or not `at all due to the labor involved. When this operation is not performed the heater consumes an excess quantity of` fuel and often smokes badly, thus wasting fuel. l

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

A further object of theinvention is to provvide a heat-responsive draft-regulating device for use in association with a vaporizing type liquid fuel orchard heater, Which is rugged, simple in operation and construction, and which may be readily removed for repair or for transfer to another heater where it may be readily installed.

Further objects and advantages of the invention, of which the above are typical, will become apparent as the description proceeds.

The `draft-regulating device of `my invention maycomprise a pivotally mounted regulating plate which is disposed adjacent an air-admitting opening communicating With the vaporizing chamber of a liquid fuel orchard heater in which a vaporizing flame is maintained Within the heater at a place removed from the main flame. 'I'he'draft-regulating plate is movable between a. first position which `provides the maximum access of air to the vaporizing chamber through the air-admitting opening and a second position restricting the passage of air through the airadmitting opening. The draft-regulating plate is biased toward the second position in which the-passage of air through the Opening is restricted. Thermostatic means, such as la bimetallic element, is disposed in heat-receiving relation to the 'vaporizing flame in the heater and is adapted to hold the plate in therst position andvis operable in response to the heat generated by the vaporizing` flame in the vaporizing chamber to release the plate and permit the plate to move into the second position.`

It is highly desirable `that the device operate in such manner as not toout off completely the air admitted to the vaporizing chamber. This may be accomplished by shaping the regulating plate so that it does not conform to and does not cover the entire air opening. Or it may be accomplished by providing limiting means, either fixed or movable for adjustment, that limits the movement of the plate toward the second position to a position at which the opening is not entirely closed-and the passage of air is restricted but not stopped, or both of the above means may be used to accomplish this object.

How the-above, as Well as other objects and advantages of my invention are attained will be more readily understood by reference to the following description, and the annexed drawings, in which:

Fig. 1 is a fragmentary vertical section through the base of a vaporizing type orchard'heater provided with the draft-regulating device of my invention, the draft-regulating plate being shown y in an open or substantially non-restricting position;`

Fig..2 is a fragmentary plan view of the draftregulating device taken from above on line 2 2 ofii'g. 1;V n

n VFig". 3 is an enlarged fragmentary vertical section through the draft-regulating devicein the aspect of Fig. 1, showing the draft-regulating plate in Va closed or Aair-restricting position;

n Fig. 4 is an inverted plan View of the draftregulating device taken on line 4-4 of Fig. 3, with the insulating cover over the bimetallic element removed;

Fig. 5 `is a view similar to Fig. 4 of the draftregulating device alone, except that the insulating cover of the bimetallic strip is in vplace and the draft-regulating plate is shown in an open position;

Fig. 6 is a vertical section through the draftregula'ting device on line 6-6 of Fig. 3;

l Fig; 'l is a plan view of a draft-regulating device'showing a variational form of draft-regulating plate;

Fig. 8 is a vertical section through Fig. 7, partially in elevation, showingthe variational form of lplate in cross-section; and

y Figs. 9 and 10 are views similar respectively to Figs. Vv'l vand 8, showing another variational form of draft-regulating plate.`

There is shown in Figs. 1. to 3 of the drawings a portion'of a standard type of vaporizing liquid fuelorcha'rd heater, indicated generally at I0. The orchard heater -comprises a bowlA II which not onlyA provides a base for supporting the upper structure but also forms a reservoir that contains a body'offliquid fuel I2 which is vaporized in bowl "I I and burned in the heater stack. Bowl` II is provided with a cover I4 which has a centrally disposed collar portion Ida/around which the lower end of stack 4I5 lits snugly. The stack may be of .any type suitable for orchard heaters, the exact kind being immaterial as far as the present invention is concerned.

. rLIT-he space I 6 above the fuel body I2 and enclosed by the walls of bowl II and cover I4 constitutes a vaporizing chamber.- A suitable opening defined by the raised collar portion II of cover .Ill` is provided in order to admit air to the vaporizing chamber for maintenance of the vaporizing'ilame therein. The collar portion II also forms a mounting means for the draft-regulating device described later. A draft tube or flame-stabilizing rbaille I8`is preferably provided to facilitate the maintenance of a vaporizing flame within chamberV IG. The upper end of draft tube I8 is preferablynprovided with an outwardly extending flange which engages the inwardly turned flange on raised collar Il as shown to support the draft tube, which extends downwardly from the wall of cover I4 into the oil body I2 as illustrated in Fig. l. The upper end of draft tube I8 is open for the admission of air which enters the vaporizing chamber through the draft tube. A suitable wick I9 is preferably provided adjacent the upper end of tube I8, the wick member taking any suitable form, such as the body indicated, and is preferably of fibrous asbestos or other porous material. The wick is preferably wrapped or'enclosed in a foraminous metal envelope 2i! which holds the wick in place and yet permits `access of oil to the lower portion of the wick.

As may be seen best from Fig. 3, draft tube I8 is provided with an opening 22 just beneath the top flange at the lower or left-hand side as viewed in Fig. 3. A short lug 23 projects inwardly through opening 22 from the rim of `collar il. This construction not only assures that the draft tube will be inserted through collar II and maintained in the proper position, but the lug also locks the dra-ft tube to cover I4 against accidental removal.

The draft-regulating device indicated generally at 25 comprises body 26` having an air-admitting opening 2l, a draft-regulating plate 28 pivotally mounted adjacent opening 2'I and adapted to control the flow o f air through the opening, and a bimetallic thermostatic elementl 3,9 enclosed within an insulating housing 3| and adapted to effect closure of the draft-regulating plate. Body 26 is of circular outline and has a depressed central portion which is of proper diameter to tsnugly Within the open upper end of draft tube i8. The vertical wall portion ofv the body formedl by the` central depression is indented at 32 to receive lug 23 (see Figs. 4 and 5); A similar indentation 33, is made in the body opposite indentation 3 2, the indentation 3-3 receiving the folded seam in draft tube I 8. The twoV indentations 32 and 33 being of a different size l and shape, `itis possible to insert body 26 into the upper end of draft tube I-in only one position.y This construction has the advantage Vthat the draft-regulatingdevice isalways held in the proper position, and the devices in all the heaters are in the same position, the uniformity of position malringlfor simplicity and certainty in operation by unskilled labor of the large number of heaters required in an orchard.

The air-admitting opening 21 is placed in the generally horizontal central plate-like portion 26a. of body 2t, and is preferably semi-circular in shape as shown in Figs. 2 and 4. The flow of air through Aopening 21 into the upper end of draft tube I8 and thence into chamber I6 is regulated-by draft-regulating plate 28 which is also generally semi-circular in outline and is shown as `having a recess or notch 41 located.V

28 swings, lasV may be seen from a comparison of Figs. 1 and 3.

The thermostatic Vcontrol means comprises` a coiled` bimetallic element -3which is attached in any suitable manner at one end to bracket-,31.

Bracket 3'I-is attached to plate-26a by any suit-` able means, as by rivets andisfpreferably heatk lWhile.` it` is not necessary that shank 43 insulated from direct engagement with` theplate.

`by a layer of insulation 38, asseen best in Fig. 6,

to retard the rate `of heat'transfer tothe thermostat. Bimetal strip 38 `curves through almost one complete turn or circle when it iscold, and` 1 roccupies a position shown in Fig. 5. In this po- `sition,1it is engaged by a holding member in the form `of curved arm 4I)` which is attached to the `underside of plate 28 and projects downwardly therefrom `in such a manner that the` end `of arm 48 bearsagainst the side of bimetallic element138. Engagement of arm 48, which constitutesa downwardly projecting portion of lplate 28, with `the bimetallic element holds plate L28 `raised in the upwardly tilted position illustrated in Fig. l. 1

ingflame within vaporizing chamber I6, .bimetallic` element 38 straightens out somewhat and reaches a position similar to that illustrated in `material 49, such as asbestos or the like,

in chamber IIS.` For this reason, the interior walls of housing 3ll are lined with a layer of insulating It is preferable to extend the top layer of insulation 38 entirely across the interior of housing 3l, as

` shown in Fig. 6. To facilitate this, plate 26a is j a In` response to heat generated by the vaporiz` i preferably` provided with a pair of elongated bosses 48 which space thelayer of insulation 38 from the under side of plate 26a sufciently `that it clears cam 42 andpasses just above bimetallic element 38. I a I The operation of my improved draft-regulating device `will now be described briefly. Assuming the reservoir to have been filled with a body of `liquid fuel I2 to the proper level, the

heater is now ready `to be` lighted. To accomplish this, an attendant first raises Vthe outer` edgerof draft-regulator plate 28 and swings the Fig. 4 in which the arm 48 no longer engages l the bimetallic element. When arm 48 disengages e `the bimetallic elementnplate` `28 drops suddenlyg a e under the influence of 'gravity to a lowered posi- -tion such as shown in Figs. 3 and 4. In the extreme lowered position, the edge` of plate 28 lies against the portion lof body plate 26a which forms a margin around opening 21, because the dimensions of plate 28 are slightly larger than those of opening` 21. However, under some circumstances it may beidesired that` plate 28be not allowed to r-eachthis extreme lowered position, but that its downward movement be limited toa position such as is shown `in Fig. 3 in which the plate is not entirely closed. For this purpose, some `typeof I shank so that the cam can be rotated about the ,shank axis into adjusted positions` by` turning plate clockwise about its hinge until the plate passes top dead centerand rests against the top ofshaft 43, which acts as a stop to hold the :plate in this open position, `as shown by dotted lines in Fig.` l. The attendant then inserts theetip of hislighting torch in opening 21 and discharges a suitable quantity of a burning ignition fluid,

lwhich may comprise a mixture `of gasoline and kerosene or the like, through opening 2 1` onto wick` I8. A portion of this burning uid falls do-wn upon the` surface` of` fuel body I2. The

`ignition iiuid,` burningon the surface of `fuel body I2. and around wick I9, establishes Ya vaporizing flame which heats the liquid fuel sufficiently `to effect generation ofL fuel vapor therefrom, and

, this vaporiscarried into the stack I by the draft element 38 in the manner shown in Fig. 5.

thegshank, but the shape of the shank makes it possible to turn it by means of` a detachable key or wrench of the proper size. Theoutline of cam 42 may be aspiral or eccentric curve or other outline of `varying radius about the axis of cam rotation. Lever `45, having one end flatthrough shank 43 and bears against the flat end `of leverr45to hold shaft 43 `against dropping downwardly through plate 26a. l a

be square, it is preferred that 1it be some shape other `than round, in` order `that the cam and hand lever 45 may be non-rotatably affixed to the shankand that the` lattermay `be turned "bya detachable key. If akey or the like is not used, lever45 may be usedito rotate shank 43 in adjusting the positionof cam 42; and if a key` is used, lever 45 serves as visual means to indicate the position of ca1n42.`

Bimetallic element 38 and cam 42 are prefername `andlthus properly delay the responsey of the thermostat to heat receivedl from" the flame through the vaporizing chamber.` When the rate of `evolutionof fuel vaporsis adequate, the main combustion flame of the heater is established within or above the stack assembly I5, and

it will beV understood` that some ignition fluid mayibe poured into the stack to facilitate ignition of the fuel vapors withinthe stack.

After the tip o-f` the lighting torch is removed from opening` 21,., plate 28 is` manually rotated counter-clockwiseto the fullline position of Fig.

1 in `which arm 48 engages the side of bimetallic In this first or initial operating position, regulating plate 28 is raised above body plate 26a and allows maximum passage` of air through opening 21 Draft-regulating plate 28 is gravity biased in the rst positiontoward a closed position and is held in this first position, `by engagement of arm 48 with bimetallic element 38, `against gravity which tends to move the plate counter-clockwise into alsecond or closed position in which thepassage of air through opening 211 is more or less restricted. All the time that the regulating plate is held in this first position, a relatively large amount of air is admitted to vaporizing chamber I6` and the vaporizing flame maintained therein burns at a relatively highrate. The heat from thisvaporizingflame is transmitted to bimetallic element 38 by conduction and radiation from the `metal parts ofthe draft tube and regulating device, and in response to this heatreceived thermostat 38 tends to straighten out. The curvature of the thermostat is preferably such that all movement of thefree end of the thermostat is substantially at right angles to the path of movement of plate 28 and arm 48 and consequently the straightening movement of the A* thermostat, while engaging arm 48, causes'substantially no movement of arm 40 that raises or heat `received. by .bimetallic element 30 is such that the free end of the thermostat element movespast and disengages the end of arm 40, reaching some such position as shown in Fig. 4. As the free end of bimetal 'strip 30 moves past the end of arm 40 out of engagement with the arm, plate 28 drops under the influence ofv grav- -ityy toits second operating position in which the flow of air through opening 21 is restricted to a greater or lesser extent accordingto the amount of closure permitted plate 28.`

The position of draft'plate 28 rin its second or air-restricting position is' determined in general bythe position of cam 42. If'carn 42 is turned in av-counter-clockwise direction as viewed in Figs. 4 and 5 for approximately one-fourth revolution, then'a portion of the involute cam of relaplate r28 is allowed to. drop until it comes into contact with plate 26a, which limits further movement of the plate. point of maximum closure; Abut even then the Plate 28 is now at itsv draft plate has been released by thermostat 30 inresponse to heat received from the Vaporizing flame.

The rate of heat transferred to thermostat 30, r Adepends upon the quantity and efficiency `of theV insulating means '38 and46 within housing 3l; and-the period of time required for the thermo- 'stat to release plate 28 maybe increased or `decreased,respectively byr increasing or decreas- Atively small radius is turned opposite arm 40 and opening 2T is notentirely 'closed because therel cess or indentation 41 in the edge lof plate '218 con- Atinues'topermit a certain amount of 'air to pass through opening 21 and reach the vaporizing flame. V,The vaporizing flame is reduced in size and ability to vaporize fuel as a consequence of its reduced air supply, and under-these condiv `tions the main vaporizing flame in stack l5 is y also reduced to a minimum.

When cam 42 is in the position of Fig. 4, the

i edge of yarm 4ll engages the edge of cam 42 when draft plate 28 has dropped to the position of Fig. 3, and before the point of maximum closure of the 4plate has been reached. In this position, less` restriction is afforded on the amount of i air passing through opening 21 vthan under the conditions previously described, because there is space between plates 28 and 26a through which air may pass to reach, opening `2l. This opening is in additionl to the opening afforded by the recess 41 inthe edge of plate 28. As a consequence ofthe somewhat increased air supply to thevaporizing flame, more fuel will be Vaporized 'and the *mainv combustion :flame will burn higher.

A still higher fire in sta-ck l5 may be secured by rotating cam 42 in a clockwise direction as viewed in Fig. 4, any desired amount up to apby extinguishing' the vaporizing name, thermostat 30 cools and tends to return toits initial po `ing ,31 to permit .cam 42 and arm ing the amount of insulation within the housing. The insulation preferably entirely surrounds the bimetal strip, or substantially so. For any particular type of heater, the correct amount of insulationmay be determined by experiment, land should be made such that the maximum amount of air is admitted to the vaporizing name for a sufficient time to insure an adequate heating of the fuel body and the generation of an "adequatel amount of fuel vapor within chamber I6..V LT-shaped slot is cut in oneside of hous- `49 to operate through the housing wall.

Afterv the re in the heater has been put out sition as shown in Fig. 5. However, as will be seen from Fig. 4, the bimetallic element cannot proximate-ly a quarter revolution. In its new po- Y sition, the portion of cam 42 opposite arm 4.0 'l

isof greater radius and engages the edge of arm 40 -when plate 28 is in a higher position than in Fig.` 3. Consequently, the gap between plates Y28 and 26a is increased and a still greater amount of airis allowed to enter through .opening 121,

the increased amount of air causing the Vaporizing flame to burn higher than under the vconditions previously described.

From this .discussion it will be seen thatthe secondr operating position into which the draftregulating platefalls under the influence of `gravity after arm 40 has become disengaged from bimetallic element 30, may be varied somewhat with respect 'to plate 26a by a limiting means,

' such as cam 42. VIn this second position of draftregulating plate 28, the quantity of air liowing throughl opening 2l is restricted to a greater or lesser extent accordingly as plate'ZB is'nearer or n farther from plate 26a, and the burning rate of the vaporizing flame isfcontrolled by the quantity of air admitted. But in any event, the air admitted through opening 21 is less than that admitted whenthe draftplate is in vits original position'for admission of the maximum amount kof `air tothe newly lighted flame and 'before the do this since its free end now comes into contact with the side of arm 40. gagement, continued cooling of thebimetallic element does not change .its position but merely causes it to press lightly against the side of arm 48; and because of the circular shape of the'ther- .mostat no damage is done to it since the pressureV vis not sufficient to cause any permanent deforma- `tion of the bimetallic element. Thev parts remain inthis position until itY is desiredto lagain light the heater, at which time draftplate 28 is lifted as previously described; and-the act of lifting Ythe draft plate removes arm 4! from engagement l with thermostat 30 which latter can then spring .back to its normal position when cold, that is,`

the position shown in Fig. 5. When the draft- .regulating plate is again lowered to its initial operating position, arm 4El'comes into contact with the/side of .thermostat 30, and the draft-regulat- `ing device is reset to repeat the cycle of operations` previously described. Recess 4,7 serves as a finger hole to grip the plate and lift it.

`The coiled shape of thermostat 2li is of definite advantage in preventing injury to this element.Y

nent deformation ofthe thermostat which would K impair its operation. V Additional safeguard against injury of the rparts is provided by Wire hinge 35. If draft plate 28, when in a lowered' or air-restricting position and in` engagement Iwith cam 42, as shown inFig. 3, is forced down- `wardly, hinge 35 simple bows slightly and permits the draft plate to rock about its point of engagement with the limiting cam until the plate comes in contact with body plate 26a. As soon` as pressure on theplate is released, the hinge springs the plate black to its proper position.

' The'plate is preferably attached to Wire 35 near the mid-point of the latter to obtain the full After this ent be given tothe draft-regulating plate;

benefit of the resilient character of the hinge.` Spring hinge 35 is preferably made of some material that will not lose its resilient characteristicsfafter being repeatedly subjected to relatively high temperatures.

It is preferable, though not necessary, that draftplate 28 be so shaped asto never fully cut off the flow of air through opening 21 but be capable only of imposing restriction upon the air flow up to some predetermined maximumextent. In the form of the invention previously described, this lwas accomplished by providing notch 41 at the edge of plate 28 which left a portion of the opening `21 permanently uncovered. variational forms of the draft-regulating plate which accomplisn lthis same object, are shown in Figs. 7 to 10 inclusive, from which it will be seen that Stillother shapes of the draft plate may be employed within the scope of my invention. f In Figs, '7 and 8 there is shown a draft-regulating plate 28al of whichthe curved margin has beenturned upwardlywat right angles to the main portion of the plate to form an upturned flange 50. The flange ishighest` at `its center opposite indentation 32 and tapers away in either direction from that point tothe face` of the plate. -The upturned fiange 50 not only provides a projection .by which the draft plate may bellifted after it has dropped into lowered posil.

tion, but it also leaves a `crescent-shaped portion 5| "of opening 21 which is not covered by the draft plate and so remainsopen to admit air even when the draft-regulating plate is` in its position of maximum restriction of air flow.

Draft plate 28h in Figs. 9 and l0 ,illustrates another modification of the forms which may In this form, a sector of the plate is turned upwardly along a line representing a chord parallel to hinge 35. `Flange 53 formedinthis manner provides a convenient projection for graspingthe plate when it is desired to lift it from the closed position and manually reset the device for further operation. The turned-up portion of plate 28h forming flange 53 leaves a sector-shaped opening 54 when the draft plate is fully` closed as shown in Figs. 9 and l0, andthis sector-shaped opening 54, which is a` portion of air-admitting opening 21, remains permanently uncovered by thedraft plate to admit air even when the draft plate is in its position of maximum air restriction. l

In all other features of construction and operation the modifications of my invention illus` trated in Figs. 1 to 10 inclusive `are the same as have been `previously disclosed in connection with the description of Figs. 1 to 6.

Having described a preferred embodiment of than limitative upon, the invention set forth in l the appended claims.

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 heater at a place removed from the main flame, a heat-responsive draft-regulating device which comprises: a pivotally mounted regulating plate a said thermostatic means comprising a bimetallic element engaging the projecting arm to hold the -plate in the first position, and operable in response to `heat generated by said vaporizing ame "to release the plate and permit the plate to move into said second position; and a rotatably adjustable cam member engaged by the projecting arm as a result ofsaid movement of the plate to limit the restriction imposed by the plate on passage of air through `the opening.`

" 2. A heat-responsive draft-regulating device for an orchard heater,` Whichlcomprises: a body member having an air opening; a draft-regulating plate pivotally mounted on the body adjacent said opening jand movable between a first position` affording relatively free passage of air` through the opening and a second `position restrictingpassage of air through the opening, said plate being biased toward the second position; and thermostatic means engaging the plate, said `thermostatic meanscomprising a coiled bimetallic elementcurved in a plane at right angle to the plane of movement ofthe plate that is adapted to hold the plate in the first position and is operable `in response to heat generated within the heater to release the plate andpermit the no movement of the plate while engaging the*v latter. Y

i 3. A heat-responsive draft-regulating device l for an orchard heaterLwliich comprises: a body member having an air opening; a draft-regulating vplate pivotally mounted onV the body adjacent said opening and movable betweenl a first position affording relatively free `passage `of air through the opening and a second position re` jlsttricting passage of air through the opening,

said plate being biased toward the second position; thermostatic means engaging the plate, said thermostatic means comprising a coiled bimetallic element curved ina planeperpendicular toA i. the planeof movement ofthe plate that is adapted` to hold the plate inthe first position and isA operable in responseto heat generated within the heater to release `the plate and permit the plate tov move into the second position; andheat insulating meansl substantially entirely `surrounding the bimetallic element toretard the transfer of heat to andfrom the bimetallic element.

4. A heat-responsive draft-regulating device for an orchard heater, which comp-rises: a body member having an air opening; a draft-regulating plate pivotally mounted on the body adjacent said opening and movable between a first position affording relatively free passage of air through the opening and a second position restricting passage of air through the opening, said plate being biased toward the second position and having a. downwardly projecting arm;` and thermostatic means engaging the plate, said thermostatic means comprising a coiled 4bimetal- 75 lic element curved in a plane at right angles to through the opening the planeof movement ofthe plate that is'radapt'- ed to hold'the' plate inthe rstposition and is operable iny response to heat generated within the yheater to releasethe Vplate and permit the plateA to move into the second position; and a l plate-like member adjustably mounted on and beneath thebody in a position to engage the projecting arm as a result of downward movement of the plate to limitthe restriction imposed bythe plate onthepassage of 'air through the-opening. v v y f 5. Av y heat-responsive draft-regulating .device foran orchard heater, which comprises: a body member shaving anr air opening; a draft-regulating plate pivotally mounted on the body adjacent said opening and movable between a first position affording relatively free passage of air throughvthe opening and-a second position restricting passage of yair `through the opening,

said plate vbeing biased to-wardthe second position; thermostatic means engaging theplate, said thermostaticxmeans comprising a bimetallio element adapted to hold the plate, in thefirst position and operable in response tov heat generatedr within the heater to release theplate and permit vthe plate tomove into the secondposition, the

ing platepivotally vmounted on the body ladjacent said opening and movable between a rst position affording relatively free passage of air through the opening and a second position restricting passage of kair through the opening, said plate being biased toward the second position; aV holding member;

` and thermostatic means holding the plate in the rsvt.l position byengagement with the holding memberfand operable in response to heat generated within the'heater to move out of engagement "with the holding member and release the platerto permit the plate rto move freely into the secondgposition, said vthermostatic' means comprising'a Acoiled bimetallic element curved in a planeet right angles kto the plane of movement of the plate, themovement of the bimetallic elementtat thev point of said engagement in response'v -tokheatV1 .being substantially atyrightjangles to the Qpath ofmovement of the plate and causing when the plate is moved to f f i v2,268,067

substantially no movement of the plate during engagement of lthe bimetallic element and said holding member. f

7. A heat-responsive draft-regulating device for an orchard heater, which comprises: a body member having an air opening; a draft-regulating plate pivotally mounted on theV body adjacent said open-ing land movable between a first position aifording relatively free passage of air through the opening and a second position restricting passage of air through the opening, said plate being biased toward the second position; and fixed thermostatic means mounted on the body member lto engage a portion of the movable plate and hold the plate in the first position, said thermostatic means comprising a, coiled bimetallic element having a free end that engages said plate and is movable in response to heat generated by the heater to disengage the plate and 4permit the plate to fall freely into the second position,` the bimetallic element being so positioned that movement of the free end of the element at the point of said engagementis substantially at right angles to the path vof movement of the plate at that point and causes substantially no movement of the plate during yen-v gagement therewith.

SQA heat-responsive draft-regulating device for an orchard heater having a vaporizing llame within the heater, which comprises: a body member having an opening admitting air to maintain the vaporizing llame; a draft-regulating plate 'pivotally mounted on'. the body adjacent said openingy and movable between a first position affording relatively free passage of air through the opening Yand a second position restricting passage of*v air through the opening, said plate being biased toward the second position; a holding member; and thermostatic means disposed in'heat-receiving lrelation to the vaporizing flame and `holding the plate in the rst position by engagement with the holding member and heat operable to move in engagement with the holding member-before reaching a position out of engagement with the holding-member, said thermostatic means comprising a bimetallic element 'having a free end that engages said holding Y member and is movable in response to heat generated by the vaporizing flame to disengage the holding member and permit the plate to move Vfreely into the lsecond position, the bimetallic element being so positioned that movement of the free endof the element at the point of said engagement is in a direction that causes substantially' no movement of the plate during said 7engagen'rent. 1 i

' JAMES R. CAMPBELL.

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