US1890681A - Bake oven - Google Patents

Description

F. A. HOPPE Dec. 13, 1932.

BAKE OVEN Filed May '7, 1952 4 Sheets-Sheet 1 i N ww. @Wm NIT TM. mw. um. h

1,890,681 PE F. A. HOP

OVEN 2 BAKE '7 1932 4 Sheets-Sheet Filed May F. A. HoPPE Dec. 13, 1932.

BAKE OVEN Filed May v, 1952 4 sheets-sheet s Dec. 13, 1932. F, A HQPPE 1,890,681

BAKE OVEN Filed May 7, 1932 4 sheets-sheet 4 j J5 559 g J5 y Patented Dec. 13, 1932 AUNITED STATES PMPENTI OFFICE FRIEDRICH A. HOPPE, F CHICAGO, ILLINOIS, ASSIGNOB T0 SCHMIDT'SELUBITIES COM- PANY, 0F CHICAGO, `ILLINOIS,

a CORPORATION or ILLINQIS BAKE OVEN Application led lay 7,

This invention relates to bake ovens, and particularly to ovens in which the breadstuffs are carried through a circuitous path in which they are baked. y

In such ovens the'breadstus are normally conveyed by trays which form part of a conveyor, which\conveyor runs backwards and forwards through substantially horizontal superposed runs interconnected at their ends, to provide circuitous baking chambers.

My invention is particularly concerned with an'oven of the direct heating type, that is an oven in which the heating gases are admitted directly into lthe passages in which the breadstuffs are located, but it possesses this type is a matter of considerable 'diiliculty and it is the general object of this invention to improve this distribution. Thus, for example there is normally a tendency for one side of the oven to heat more strongly than the other and it has been practically unpossible to completely remedy the defect in ovens which have been constructed heretofore.'

One of the objects of theinvention is to improve the manner in which the hot gases are supplied to the various chambers within the oven.

A further object ofthe invention is to imprcve the manner in which the recirculated gases are withdrawn from the various chambers 'of the oven. l

.45 A )further vobject of the invention is to proissz. senin 11. 809,800,

vide means whereby the withdrawal from botll slides of the oven may be relatively contro e e A further object of the invention is to provide an improved interrelated control for the heating means and for the recirculation `of gases so that substahtially uniform conditions may be maintained in the oven irrespective of variation of load, that is variation of the rate of ysu ply of breadstufs tothe oven.

A fiirther object of the in'ventionis to pro-. vide an improved means for regulating the steam zone of the oven, whereby economy of ste'apl and more uniform results are obtained.

A further object of the Vinvention is toprovide improved means whereby the removed products of combustion may be exhausted at Ialcontrolled rate and at an advantageous position.

ther objects, advantages and capabilities of the invention will appear from the following description pf a preferred embodiment thereof taken in conjunction with the accompa ing drawings, in which igure 1 is a longitudinal section through 70 an oven embodying my invention;

Fig. 2 is a 'transverse sectional view thereof ta en on the line 2-2 of Fig. 1;

Fi 3 is a transverse sectional view therel of ta en on the lin'e 3-3 of Fig. 1;

Fig. 4 is a plan v iew of the oven;

Fig. 5 is a fragmentary sectional detail view taken on the line 5-5 of Fig. 1, and

Fig. 6 is a fragmentary side elevation, partly in section, showing a modified construction of recirculation control.

Referring to the drawings, the oven, which l is substantially rectangular in shape, comprises internal partitions which define horizontal runs 10, 11, 12 and 13 through which 85 extends a continuous conveyor shown by wa of example as a plurality of trays 14 whic depend froml trunnions 15 which are connected by chains 16 in series, which-chainsl ride upon guides in the upper part of eachwhich is the highest run, they run and pass over sprocket wheels or the` like 18 so as to mpve from one run to another. After the trays 14 pass inwardly through the run 10, outwardly through the ru'n 11 and inwardly through the run 12, descend through a vertical run or flight 19 and pass outwardly through the lower run 13 to the unloading and loading position 20, at the front of the oven.

The oven may be heated by any suitable fuel, for example gas, which is supplied through a pipe 21 and delivered to burners 22 through two pipes 23 and 24. The pipe 24 is provided with a valve 25 whereby the supply of gas may be manually controlled. The pipe 23 is provided with a valve 26 the actuation or control of which will be hereinafter descrf bed. The burners 22 deliver their products of combustion into an enlarged chamber 27 into which extends a downcomer 28 which returns the'gases to be recirculated. The mixture of recirculating gases and hightemperaturecombustion gases passes from the chamber 27 through an outlet 29 and is delivered to a fan or blower 30 which `discharges the stream into a main supply duct 31. The main supply duct 31 is located in the bottom of the oven and extends there- Ithrough for a substantial part of its length.

The runsV 10 and 13 are heated indirectly, that is they are heated through impervious partitions 32 and 33. Means are provided for circulating heated gases through the charnbers 34 and 35 provided on the underside of these partitions. The runs 11 and 12 are directly heated, that is the hot gases are de-v livered directlv into the chambers or spaces provided by these runs. The hot gases are discharged into the chambers 34 and 35 and the runs 11 and 12 from bxes'36 which extend transversely of the oven and are provided in their` upper face With dischargeslits which extend thewhole length of the boxes. The gasesare exhausted by means of boxes 37 which also extend transversely of the oven and are provided with longitudinal slots, preferably along one side. Thus it will be seen that the incoming gases are projected upwardly while the gases removed are col- ,lected from a point near the Hoor of the run or heating chamber, as the case mav be. Thus the heated gases, in the case of the runs 11 and 12 are projected vertically against the undersides of the pans 14 and between the pans up to the upper walls of the runs. After the gases have lgiven up a portion of their heat and have dropped to the floor of the runs they are removed by the boxes 37. The

i and 35 is similar.

The hot gas supply boxesy 36 receive their hot gases from the main lsupply duct 31 the other boxes receive their gases from the N other side This feature results in a much more uniform heating of the trays 14 and a much more satisfactory operation of the oven.

The exhaust boxes 37 communicate at one end with conduits 39, which are also located in the side walls and arranged alternately so that the alternate boxes 37 along one run discharge into conduits 39 in one wall and the other exhaust boxes 37 discharge into conduits 39 inthe other wall. This feature like- Y wise materially improves the uniform heating of the oven. The conduits 39 are connected by horizontal conduits 40, which are located inthe top of the oven, with main exhaust duct 41, which is located on top of the oven and extends substantially centrally thereof. I prefer to provide a longitudinal partition 42 down the center of the main ex-` haust duct 41 so as to separate the gases discharged thereinto by the conduits 40. I, provide at the end of the partition 42 means controlling the exhaust flow through each side of the oven. This means may suitably take the form of adainper 43 which can be located in any desired position so as to equalize the heating on one side of the oven with that on the other.v

, The main exhaustduct 41 gives into a conduit 44 which enters at right angles into the pipe 28. Adjacent thev pipe 28 the conduit 44 is provided with ayhorizontal partition 45, the outer end of which carries a damper 46 which is adapted to close the pipe 28, in, continuation with the partitionv 45. At the inner end of the partition 45 I provide a damper 47 which is provided with a horizontal axis about which it may be turned so as to divert a desired portion of the 'stream 'f gases passing through the conduit 44 above the partition 45. These gases possess considerable speed owing to the circulation setk up by the blower 30,and their momentum is suflicient to carry them out to the atmosphere through the upper part ofpipe 28,

notwithstanding the suction or low pressure created in the conduit 44 by the blower 30. This action isI assisted by the high temperature of the gases, the upper portion ofthe pipe 28 serving as a stack. The remainder ofthe gases, which preferably comprise about ninety percent of thetotal exhaust' lgases,

passes downwardly through the pipe 28 into the chamber A27 in the manner described above.

The damper 46 is preferably vemployed when oil is used asl fuel. It is opened When the through vertical conduits 38 located in the *il burner is started so .as to vent the soot side walls of the oven. *Asl will be noted, more and other products of incomplete combus- 13 .6,5 this instrument being capable of\`being lset 'objection to a considerable degree by locating within the run 1.0 and at a lowlevel therein a suitable number of boxes 49, which extend across the run 10 and are provided intheirA upper faces with slots 50.

The boxes 49 are connected at one end by a suitable duct 51, suitably loated -in o'ne side wall. The duct 51 communicates with a duct 52, also located in said side wall, which duct feeds into a. duct 53 located at the top of to any desired temperature by means of a handle 65. The instrument 64 is energized by leads 66. When this desired temperature is attained crcuits are completed through leads 67 which throw switches within a relay 68 so as to divert'power from lead 69 to suitable motors 70, 71- and 72 through a pair of conductors 73. When the temperature falls a certain amount, for example three degrees, the reverse action takes place and the switches of the relay 68 are thrown in the opposite direction so as to send the current through another pair of the conductors 73. The motors 70, 71 and 72 are of known type, being reversible motors equipped w'th limit switches so that at the end of the predetermihed operation in either direction they stop, making the circuit for the other pair of con.- ductors 73 to operate them in the opposite direction, when said conductors are energized in response to change of temperature. u It will b e understood that the instruments 64, 68, 70', 71 and 72 are of known type and are the oven. Means adapted to produce sucti0n^ not claimed broadly, the present invention are associated with the conduit 53 so as to withdraw relatively cold gas from a lower level of the run 10.,.thereby avoiding" the expulsion of the steam laden gases through the `feed opening. Above the feed opening 20 `is provided a' hood 54 which extends upwardly' into a duct 55. AThe hood 54 preferably contains a transverse partition 5,6l which terminates at the lower end of the duct 55 and is provided there -with a damper 57 which may be adjusted so as to regulate the withdrawal of 'the hot gases discharged through the opening 20, away from the operator whois normally stationed at the feed opening. The duct 55 is providedwith an exhaust blower 58, drivenin any suitable manner, and its upper end is reduced` slightly as shown at 59; The upper endof the duct 55 extends through a chamber' 60into which 45. communicates the' duct 53. 'A gate 'valve or the like 61 controls-the supply of exhaust gases from the codut 53 to the chamber 60.

Yco

The upper' end of the chamberGOtapers intopropinquity with the tapered-end 59 of' the duct and extends upwardly therebeyond in the form of a stack 62.L The tapered portion of the chamber '60 and the tapered end 59 of the duct 55 'cooperate to provide a Venturi e'iect so that the flowof gases through the duct 55 creates a suction within the lchamber 60,v which suction effects the removal of ,gases fromthe lower levelof the run 10, through the boxes 49? In accordance with my invention I provideautomatic mechanism whereby 'both the recirculation and the `supply of highly heated' gases are correlated and adjusted. At 63I show diagrammatically a thermo-electric device, such asa'thermo-couplewhich is connected toan instrument 64 ofknown type,

Jthe blower 30.

being concerned onlyv with their application to a bake oven. The motor 70 is connected by suitable linkage 74 with the valve 26 vso that this valve is completely closed in one extreme position of the motor and is fully open .in the other extremev positon. The

motor 71 is connected through asuitable linkage 75 with a damper 76 located in the downcpmer 28.

. The motor 72 is connected through a 'suitable linkage 77 with a damper 78 located 'atthe outlet of the blower 30. The damper 78, is adapted to limit `the low of gasesand ynot completely stop same. For example, it may be adapted to permit half the normal flow of gases to take place when in its closed tion. lThedamper 76 is adapted to partially close downcomer\28 so as to increase some-,

osi-

what the suction in chamber 27, with the result that suiicient airis drawn in to supply the burners notwithstanding the restriction provided by ther damper` 7 8 in the outlet of- It will be undestood that when'the motor '70 is actuated to Aclose the valve 26, the motors 71 and 72 are simultaneously actuatedthe recirculating gases in the chamber 27.

Supposing the temperaturincreased unduly. for example owingto fa decrease -in the amount of breadstuffs supplied in the feed opening 20, the temperature reachingthat valve 26 to be open, the

predeterminediby the instrument 64. Then circuits are made through a pair of conduc tors 73 so as to actuate the motors 7 0, 71 and 7 2, with the result that the fuel suppliedI is cut down and the amount of gases recirculated is likewise cut down. The devices are preferably adjusted so that the ratio of gases recirculated to hot gases supplied is mainel() Su tained substantially the same in both cases. In thisway substantially uniformity of temperature is maintained throughout every part of the oven irrespective of whether the hal fire.

ln the modified construction shown in Fig.. 6, a by-pass 79 connects the outlet of the blower 30 with the exhaust vconduit 44. The

damper 78 is replaced by a damper 80 Which is adaptedl toclose either the by-pass 7 9 or the entrance to the main supply duct 31. The damper`80 is controlled by the motor 72. ln

V this modification the motors 71 and 72 are 29 actuated simultaneously so as to close `the valve 26, move the` damper 7 6 to closed po-` sition and move the damper 80 so as to close the inlet to the main supply duct 31. Thus (it will be seen that the fuel supply is reduced to aminimum and the supply of gases to the oven is shut ofi', the blower 3() serving to circulate gases throughAby-pass 79, eX-

haust conduit 44, downcomer 28 and cham-` ber 27. The closing or partial closing of `the damper 76 increases the suction within the chamber 27 so that an adequatev supply of air is drawn in, to supply the burners. During this operation, which continues until the temperature of the oven falls to the de- Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A bake oven comprising a plurality of superposed zones, horizontal partitions separatingsajd zones, said zones communicating at theirends in series to form a continuous chamber, means for injecting steam into the initlal baking zone, and means for withdrawing gases at the level of the lower partition of ff said zone.

back flow of gases through said run .and feed opening.

3. A bake oven comprising a plurality of .superposed runs connected at their ends in ly of gas or other fuel is at full lire oriA series to form a continuous chamber, horizontal partitions between 'said runs,kmean s for injecting steam into the initial baking run, conduits/communicating with the initlal baking run at the bottom partition thereof, and mechanical means for creating suction in said conduits.

4. A bake oven comprising a. plurality of substantially horizontal vruns connected at theirvends to provide a circuitous baking chamber, said oven being provided with a feed opening, pipes for injecting steam into the initial baking run, conduits opening into said run at a low level thereof, and a blower adapted to remove gases discharged through said feed opening and adapted to create suction within said conduits.

5. A bake oven comprising a plurality of exhaust pipe, and Venturi means whereby the j 2. A bake oven comprising a pluralityof f substantially horizontal runs connected at n their mends to provide a circuitous baking chamber. horizontal partitions between said runs, said 'oven being providedv withfa feed opening, pipes for injecting-.steamfinto'thev i 'initial baking run,l conduits opening into said run between the trays therein and the hori`` `zontal partition therebeneath` and means for .relation connected at their en s to formn a exhaust flow creates a suction in said conduits..

6. A bake oven comprising a plurality of substantially horizbntal runs in superposed relation connected at their ends to form a circuitous baking chamber, a main for supplying hot gases. a main for'exhausting cooler gases, a plurality of supply conduits 1n each run open across the oven, andvertical conduits in the side walls communicating bei tween the supply main and supply conduits,

run openy across the o ven, and vertical con saidvertical.conduits/being staggered one on rection thereof.

8. A bake ovenrcomprising a. plurality of y substantially horizontal runs 1n superposed circuitousbakingchamberya main for supleach side ofthe oven in the longitudinal diplying hot gasesa main `for exhausting cooler gases, afplurality of supply conduits in each run open across the oven, vertical conduits in f abstracting gases therethrough to reduce the the side Iwalls communicating between the gases from the runs, a plurality of vertic vrelation conne lets from the conduits on one si supply main and supply conduits, said yertical conduits being staggered one on each side of the oven in the longitudinal direction thereof, a pluralityof exhaust conduits in each run open across the oven, and vertical conduits in the side walls communicating between the exhaust main and exhaust conduits, said vertical conduits being staggered one on each side of the oyen in the longitudin direction thereof.

A bake oven comprising a plurality of substantially horizontal runs in superposed cted at their endsto form a circuitous baking chamber, means for supplying hot gases, a main for exhausting cooler gases from the runs, a plurality of vertical conduits communicating with the exhaust main and adapted to supply exhaust gases thereto, said Vertical conduits being located on both sides of the. oven, and a partition within said exhaust main separating the inde from those on the other side. i

l10. A bake oven comprising a plurality of substantially horizontal runs in superposed relation connected at their ends to form a circuitous baking chamber, means for supplying hot gases, a 4main for exhausting cooler gases from the runs, a plurality of vertical con)- duits communicating with the exhaust main and adaptedto supply exhaust gases thereto, said vertical conduits being located on both sides of the oven, a partition within said exs haust main. separating the inlets from the conduits on`\ one side from those on lthe other side, and means at the end of said partition operable to'equalize the iiow on each side thereof. A Q

11. A' bake oven comprising a plurality of substantiallyhorizontal runs in superposed relation connected at theiriends to form a circuitous baking chamber, means for supplying hot gases, a main for exhausting cooleil` a conduits communicating with the exhaust main and adapted to supply exhaust gases thereto, said vertical conduits being located on bothsides of the oven, a partition within said exhaust main separating the inletsfrom the conduits on yone sideyfrom those on the other side, and a damper pivotally mounted heated outlet blower gases c gases to the recirculating gases, an. for gases on the suctionv side of the located so that the momentum of the arries them out of the system, and a damper ada ted to control thev flow of gases through said) outlet.

14. A. bake oven comprising la baking chamber gases through the oven in heating relation to the breadstu-ffs, means- `for supplying highly heated gases to the recirculating gases, an outlet forgases on the suction side of the blower located so that the momentum of the gases carries them out of the system, and an adjustable damper pivotally mounted adjacent said outlet and presented against the stream.

15. A bake oven comprising a. baking chamber, a blower adapted to circulate hot gases through the oven into direct contact with the breadstufs, means for supplying highly heated gases to the recirculating gases, an outlet for gases on the suction side of said blower so located that the momentum of the gases carries them out of the system,- and a stack into which said outlet leads.

16. A bake oven comprising a baking chamber, a blower adapted to circulate hot gases through the oyen into direct contact with the breadstuffs, means for supplying blower adapted to circulate hot l highly heated gases to the recirculating ros circulation .of gases, means for` supplying highly heated gases to the recirculating gases, meahs for controlling the said heat supply `means, and means 1n said conduit on each side of said; heat supply means for controlling the flow of gases through theN conduit, and means responsive to oventemperature for actuating said controlling '115 18. In a recirculating bake oyen, in combimeans in unison.

at the'end 0f the partition adapted@ equalze'nation, a conduit for removing exhaust gases gases carries them out of the system.

13. A bake o ven comprising a baking chamber, a blower adapted to circulate hot gases through theoven in heating relation to '55 the breadstuffs, means for supplying highly 1 9. In a recirculating bake er, a blower bination, a conduit for removing exhaust gases from said oven, means for removing a portion thereof from the system, a mixing chamber into which said conduit dischar es, a fluid fuel burnerfor supplying higly heatedgases into' such chamber, a blower adapted to withdraw mixed gases from said chamber, a conduit adapted to receive said gases and supply same to the oven, 'a by-pass connecting' last said conduit to first saidconduit, a damper in the first said conduit between said by'pass and said mixing chamber,

a'damper in last said conduit adapted to close said conduit and to close said by-pass, a valve controlling said fuel supply, and temperature actuated electrical means for controlling'said dampers and Valve in corelation. .y i

20. A bake oven comprising a baking chamber, a conduit connecting one point of the chamber .to another point thereof, a blower in said conduit adapted to pass gases A therethrough, and an exhaust conduit having an' open mouth in the first said conduit on the suction side of the blower and. directed against the How of the stream whereby the momentum ofthe gases tends to exhaust a part thereof through said mouth.

In witness whereof, l hereunto subscribel my name this 28th day of April, 1932.

y aambeien A. Horen,

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