US3475829A - Clothes dryer with lint disposer - Google Patents

Description

N0v.l4, 1969 'r,J, BRlNKMAN ET AL 3,475,829

CLOTHES DRYER WITH LINT DISPOSER Filed Nov. 8, 1967 5 Sheets-Sheet 1 G BY cbffcjzzme ffy/M@ ATTORNB' v Nov. 4, 1969 T. J. BR'NKMAN ET AL 3,475,829

CLOTHES DRYER WITH LINT DISPOSER Filed Nov. 8, A1967 5 Sheets-Sheet 2 ATTORNEY Nov. 4,11969 T. J. BRINKMAN ET AL 3,475,829

CLOTHES DRYER WITH LINT DIsPosER Filed Nov. 8. 1967 5 Sheets-Sheet 5 INVENTORS iff-Wm@ ATTORNEY NOV. 4, 1969 T. J. BRINKMAN ETAL 3,475,829

CLOTHES DRYER WITH LINT DISPOSER Filed Nov. s, 1967 svsneets-sheet 4 Si DRYER CONTROL N L2 If/ZH /f// saga, ze

LIg/STARTn BUTTON f zal l f www @EEA-" i NO HEAT w Z THERMOSTAT w I 445 Ex /942 aff H W Swlymas 4e TWO Kfz CORI/K6 T Tamm/T091,

DRYER HEATER THERMOSTAT THERMOSTAT 660 B ong Nov. 4, 1969 T. J. BRlNKMAN ET AL 3,475,8(29

CLOTHES DRYER WITH LINT DISPOSER Filed Nov. 1967 5 Sheets-Sheet 5 .Tr/:omas JBrz'zzman, @lomas H. fcgi', Gear 5. Zang, 5 .BY Char es C Zwzzkzlec:

ATTORNEY United States Patent O U.S. Cl. 34-44 17 Claims ABSTRACT OF THE DISCLOSURE An automatic lint disposing or lint eliminating ryer in which the lint is collected on a screen in a chamber located between the clothes drum outlet and the fan used to flow the air through the drum. The collected lint is periodically burned in response to a timer control which interrupts the drying cycle. During burning, a positively controlled damper is positioned between the drum and the chamber to prevent back-dow to the drum of effluent resulting from the burning lint. The dryer fan and dryer motor are preferably maintained operable to provide a slight vacuum drawing the etiluent away from the drum and to eliminate restarting of the motor at the termination of the lint burning process. In a modification, the lint burning chamber has been incorporated into the dryer door and the chamber is completely sealed.

This invention relates generally to clothes dryers and more specifically to a clothes dryer in which lint is collected on a screen and periodically burned off during repeated short intervals throughout a normal operation of the clothes drying cycle.

No housewife need be told that the accumulation of lint in a dryer is a problem. Schemes for collecting and burning the lint as opposed to requiring the user to manually dispose of the lint have been proposed heretofore. For instance, see the U.S. Patents 3,081,554 (Long) granted Mar. 19, 1963, 3,085,348 (Adey et al.) granted Apr. 16, 1963 and 3,069,785 (Mitter et al.) granted Dec. 25, 1962. However, in these prior art systems, the problem either has been solved expensively or moved to a different location. F or instance, elaborate control systems or catalytic beds are required or the lint accumulation problem has been solved at the expense of introducing the problem of disposing of the efuent which is especially troublesome where the dryer is not vented to the outside. The effluent problem in addition to introducing objectionable odors and smoke into the room in which the dryer is located may cause a back-up of the eil-tuent into the clothes drum which is obviously undesirable. Accordingly, stated in its broadest aspect, the object of this invention is to provide an automatically controlled lint disposing system for a clothes dryer which circumvents the effluent problems associated with lint burning in a simple manner and with a structure simple in construction and capable of easily being incorporated into existing dryers.

In one of its aspects, the invention is directed to such a system in which the lint is periodically burned during the drying cycle for a short duration so that the quantities of efliuent at any given time is so small so as to be ordinarily imperceptible.

In another of its aspects, the invention is directed to such a system in which the lint burning is sealed from the clothes drum to prevent back-up of effluent into the clothes, such a problem being considered one of the more critical of the eluent problems to the user at least.

Another object of this invention is to provide a lint disposing clothes dryer in which the lint is collected and disposed of by burning in repeated shortintervals through- 3,475,829 Patented Nov. 4, 1969 out the drying cycle, the burning being controlled by a simple circuit easily adaptable to conventional dryer controls. 'l

Another object of this invention is to provide such a lint disposing clothes dryer in which the lint burning is sealed from the clothes drum.

Another object of our invention is to provide a lint disposing clothes dryer in which the lint burning chamber is sealed from the clothes drum during lint burning and whenever the clothes dryer is inoperative since the clothes dryer operation could be interrupted during the lint burning pro-cess when eluent is present.

Other objects and features of the invention will become apparent to those skilled in the art as the disclosure is made in the following detailed description of preferred embodiments of the invention as illustrated in the accompanying sheet of drawing in which:

FIGURE l is a schematic representation of a clothes dryer with portions cut away to show the relationship of the lint burning chamber to the other parts of the dryer.

FIGURE la is a side section taken through the upper rear portion of the clothes dryer shown in FIGURE 1 showing the inlet and heater and its relation to the clothes drum.

FIGURE 2 is a section taken along the line 2-2 of FIGURE 1 showing a side section of the lint burning chamber and adjacent parts.

FIGURE 3 is an enlarged View showing the lint burning portion of FIGURE l.

FIGURE 4 is a section taken along the line 4-4 of FIGURE 3.

FIGURE 5 is a top view of the drive means for the lint chamber dampers.

FIGURE 6 is an elevation view of the drive means.

FIGURE 7 is a wiring diagram of a typical dryer control into which the lint burning control has been incorporated with the lint burning parts represented schematically.

FIGURE 8 is a horizontal section through the front panel of a dryer showing a modification ofthe invention in which the lint burning chamber has been incorporated into the dryer door.

FIGURE 9 is a section taken along the line 9--9 of FIGURE 8.

' Referring now more particularly to FIGURE 1, it shows a dryer indicated generally at 10 having a cabinet 12 in which is rotatably mounted a drum 14 having an access opening 16 aligned with an access opening in the cabinet which is closed by a door 15. An inlet 13 in the back of the cabinet 12 admits air to the drum 14 through a suitable inlet ducting in which is located a dual level dryer heater 42 and the perforate back wall of the drum 14. (See FIGURE la.) From the drum 14, the air exits out the access opening 16 of the drum 14 into an outlet duct 20 through holes in the port plate 18 as best shown in FIGURE 2. The port plate holes are preferably made as round as possible and extruded away from the air flow to prevent lint collecting at this point.

Returning to FIGURE l, the lint burning chamber 22 is located downstream of the outlet duct 20 being connected to a short tubular extension 24 of it. The bottom wall 25 of the duct 20 preferably slants away from the tubular extension, that is, slopes toward the left as viewed in FIGURES 1 and 3 so that foreign objects tend to collect in the left hand corner rather than to pass through the extension 24 and into the burning chamber 22. The chamber 22 has a lint burning screen indicated generally at 26 extending across it transverse to the direction of air ow. A pivotally mounted damper 28 is shown in its closed position blocking off the inlet to the chamber 22, while damper 48 is shown in its ow blocking position 3 adjacent the chamber outlet 30. The chamber outlet 30 is connected by a flexible conduit 32 to the suction side of a fan 34 which exhausts the air through a suitable conduit 36 to the outside of the cabinet. The drum 14 is belt driven from a dryer motor 80 which drives the fan 34 directly. The structural details of the belt drive, the dryer motor 80, the air inlet path with the heater 42 have been omitted for clarity. The heater 42 and motor 80 are shown schematically in FIGURE 7 and will be discussed in connection with the operation of the dryer.

THE LINT BURNING CHAMBER The structural details of the lint burning chamber 22 are best understood with reference to FIGURES 2, 3, and 4. More specifically, FIGURE 3 shows the chamber 22 as having an inlet 38 abutting the llanged end of the tubular extension 24 through an O-ring seal 40. A second seal 39 mounted on an inturned ilange adjacent the inlet 38 is slightly compressed by the damper 28, in its closed position. The damper 28 is mounted on a rod 41 journaled in the side walls of the chamber 22 on a horizontal axis. The rearward end of the rod 41 (right end as viewed in FIGURE 2) is drivingly connected to the output shaft 43 of a drive means 45 mounted on a sheet metal support 46 attached to the base of the cabinet 12 and the lint disposer housing 22. The drive means 45 will be described in detail in connection with FIGURES and 6. Suice it to say at this point that the drive means 45 is used to rotate rod 41 to control the position of damper 28.

The outlet 30 for the chamber 22 has a second damper 48 secured to a rod 50 which is journaled in the top and bottom walls of the chamber 22 for pivotal movement about a vertical axis. The rod 50 extends out of the top of the chamber 22. A rst crank arm S2, connecting link 54, and second crank arm 56 connects rod 50 with rod 41 so that dampers 28 and 48 move together from their solid line positions tothe phantom line positions indicated in FIGURES 3 and 4.

The lint burning screen indicated generally at 26 extends across the chamber 22 transverse to the ow of air through it. Suice it to say that this element comprises a screen suitable for entrapping lint and .adapted to be electrically self-heating suilicient to bring the lint up to its combustion temperature. The screen is preferably heated to approximately 1400 at which temperature lint oxidizes. The electrical leads for periodically burning entrapped lint are shown at 58. Application Ser. No. F-7975 entitled Lint Collecting and Burning Screen filed in the names of Thomas J. Brinkman, Thomas H. Fogt and Charles C..Whistler, Jr. concurrently herewith and assigned to the assignee of the present invention shows a directly energized lint burning screen which is suitable for but not limited to use with this system. Briefly, the application shows a directly energized lint burning screen which is heated to approximately 1400 F. while drawing in the neighborhood of 1300 watts. For purposes of disclosure, it will be assumed that such a lint burning screen is utilized although other types of screens may be utilized, for instance, an ordinary screen with a separate heating element closely adjacent to it. The screen 26 is mounted on Ia removable panel 29 which also seals an access opening 27 in the chamber 22 so that the screen 26 is easily replaceable.

A thermostat 60 located on top of the chamber 22 provides a shut-off for the lint burning screen 26 should the temperature in chamber 22 rise above a predetermined value. A switch 310 located on the top of the chamber 22 is closed by ya plunger which extends through to the inside of the chamber where it is adapted to be moved to the switch closed position by damper 28.

THE DRIVE MEANS From FIGURES 5 and 6 it can be seen that the drive means 45 ccmprises a fram@ 62 having four bosses at which it is secured to the upper portion 68 of support 46. An electric drive motor 64 which receives its power through leads 66 is mounted on the frame 62. The motor 64 drives output shaft 43 through a gear train 70. The upper portion 68 of the support 46 is C-shaped and straddles the output shaft 43. A bent out flange 49 on the C-shaped portion 68 carries a rubber stop 51. A connector 72 on the output shaft 43 is provided with twor apertured ears 74 which receive a pin 76 on thedamper rod 41. The connector has Ian upper L-shaped ange 78Vand a lower Ifshaped flange 82. The axial leg of the L-shaped flange 78 cooperates with the stop 51 as more fully set forth below. A split sleeve 84 joumaled on the output shaft 43 is surrounded by a torsion spring 86 preloaded to have one end bear against one of the mounting bosses 67 on frame 62 and the opposite end bear against the axial leg of L-shaped flange 82 so that the spring 86 urges the connector 72 clockwise as viewed in FIGURE 6. This, in turn, urges the damper 28 to the closed position and the damper 48 to the llow restricting position. Note` the split sleeve 84 moves with the torsion spring 86 with the relative movement occurring between the split sleeve 84 and the output shaft 43. The sleeve 84 is split because as the torsion spring 86 acts, its end coils tend to tighten iirst. Thus one half of the sleeve moves with one end of the spring and the other half moves with the other end of the spring as it winds up. This action of the split sleeve 84 adds life to the torsion spring 86 by minimizing wear on its surface.

The .action of the motor 64 is such that when energized it opposes the spring 86 and opens the dampers 28 and 48. The energized motor rotates the output shaft 43 counterclockwise until the axial leg of the L-shaped ange 78 engages stop 51, at which time the motor stalls.

THE LINT BURNING CONTROL CIRCUIT A control circuit is illustrated in FIGURE 7. The control circuit comprises a dryer control circuit generally indicated at 88 into which has been incorporated the lint burning control circuit 90 schematically illustrated, parts of which have been mentioned heretofore. The dryer control circuit 88 as such need not be described in great detail since the lint `burning control circuit may be added to any number of dryer control circuits. An entire control circuit is disclosed to bring out desirable relationships between the dryer control circuit 88 and the lint burning control circuit 90. A more complete description of the dryer control circuit 88 is given in U.S. patent application Ser. No. 579,630 filed in the name of Melvin A. Menk on Sept. 15, 1966 for a Heat Control System for a Clothes Dryer, now Patent No. 3,409,994. The aforesaid application is assigned to the assignee of the present invention. For ease in incorporating the teachings of that application into this one, the corresponding elements have been referenced with the same numbers with the exception that the electronic control module is only shown schematically in FIGURE 7. Details of the function of the module 100 may be had by reference to the aforesaid Menk application and copending U.S. gglsication to Miller, Ser. No. 457,435 fledMay 10,

A broad general description of the lint burning control circuit 90 appears appropriate. For timing the lint burning operation, a timer motor 302 includes a timer switch 305 in circuit with the damper drive motor 64 and a timer switch 308 alternately in circuit with either the lint burning screen 26 or the dryer heater portion of the dryer control circuit 88. The timer motor 302 is directly connected to ground N through conductor 304 and connected to L1 through conductor 306, conductor 148, switch 108, conductor 144 of the start button and conductor 162.

The timer motor 302 is energized whenever the dryer is operating. In other words, the only parts of the dryer control circuit 88 that are utilized SQ far as the timer motor is concerned are initiation by start button 116, termination by module 100 (and cool down thermostat where applicable) or momentary termination by opening of the door switch 120. The drive motor 64 is energized through conductors 66, one of which includes the series connected timer switch 305 operated by the timer motor 302.

The timer motor 302 operates in addition to timer switch 305 and simultaneously therewith the timer switch 308. The timer switch 308 is movable between the position shown in FIGURE 7 where it engages contact 303 and forms a closed switch series connected into line 184 of the dryer control circuit 88. In this position, the lint burning screen 26 is not energized and the dryer control circuit operates as if the lint burner control circuit were not there except for the series connected thermostat 60 physically located on the lint burning chamber 22 which opens the line 184 above a predetermined temperature to de-energize the dryer heater 42. When timer switch 308 is moved to engage contact 307, conductor 184 is opencircuited and consequently, the dryer heater 42 is prevented from being energized. With the timer switch 308 on contact 307, lint burning screen 26 and an indicator light 312 are connected in parallel across Lz-N through conductors 184, and 304, respectively. The simultaneous opening of the switch 305 by the timer motor 302 when timer switch 308 engages contact 307 de-energizes the drive motor 64 by opening switch 305. De-energization of drive motor 64 closes damper 28 and moves damper 48 to its flow restricting position. Closing of the damper 28 closes switch 310 which completes the circuit through the lint burning screen 26 via conductors 58. The pres ence of switch 310 insures that screen 26 is not energized unless the damper 28 is closed. The indicator light 312 is mounted on the console panel to advise the user that collected lint is being burned. Disposal by lint burning, however, will not proceed unless the damper 28 is closed sealing the screen 26 from the drum 14 to prevent the back-up of effluent into the drum 14.

OPERATION Briefly, the operation of the lint eliminating dryer is as follows. Wet clothes are placed in the drum 14 and the access door is closed, closing a safety switch at 120 and 138 which prevent dryer operation while the door is open. The starter button 116 is actuated, initiating the drying cycle. This particular dryer is electronically controlled in response to the moisture in the clothes. Simultaneously, with initiation of the dryer cycle, the independent lint burning timer motor 302 is energized. This timer is independent of the drying cycle except that it initiates and terminates with it. So long as the dryer is operating, the timer motor 302 will operate. The drive motor 64 is also energized opening dampers 28 and 48. Periodically, for instance, every ten minutes, the timer motor calls for lint burning for thirty seconds. When lint burning is called for, switch 308 is moved to contact 307 de-energizing the dryer heater 42, and energizing indicator light 312; however, the dryer motor 80 (connected across Ll-N) continues to drive the drum 14 and the fan 34. Switch 305 is opened, de-energizing the damper drive motor 64 which closes damper 28 and moves damper 48 to a ow restricting position. In this partially closed position, the damper 48 performs two functions, namely, it prevents direct flow from the screen 26 to the outlet 30 (see FIGURE 4) and thus reduces the possibility of burning lint particles from flowing through the fan 34 and out the dryer. Secondly, the partial opening provides evacuation of the chamber 22 by the fan 34 which aids in preventing even back leakage of effluent into the drum 14. The dryer is now conditioned to burn lint for thirty seconds. The lint screen 26, however, is only energized if a second switch 310 is closed by the damper 28 in its closed position. After the thirty seconds, the timer motor 30.2 Ymoves switch 308 to contact 303, de-energizing the screen 26 and the indicator light 312 and again placing the dryer heater 42 in circuit. Switch 305 is closed, energizing the motor 64 to open the dampers 28 and 48.

More specically, in connection with FIGURE 7, the control circuit operates as follows. Assuming the door switches and 138 are closed, the dryer operation is initiated by depressing the start button to complete a circuit from L1 to N of the power supply through conductor 162, starter button 116, conductor 118, switch 120, conductors 122 and 124, terminal 126, module 100, coil 102, terminal 136, conductor 134, and switch 138. Energization of the coil 102 closes switches 108, 110, and 112 to complete, respectively, a motor energization circuit for motor 80, a holding circuit for module 100, an energization circuit for heater 42 yand the lint control circuit for timer motor 302 and drive motor 64.

More particularly, the module holding circuit is completed from L1 through conductor 140, the holding relay controlled switch 110 which is positioned against a contact 142, conductor 124 to terminal 126 of the module 100 whereby the coil 102 is energized through circuit previously described.

The motor energization circuit runs from L1 through conductor 162, closed contact 144 of the momentary switch 116, conductor 146, the closed relay controlled motor energization switch 108, conductor 148 to one side of the run winding 150 of the motor 80. The opposite end of the run winding 150 is connected by a conductor 152 through the door switch 138 to N of the three-wire power source.

During initial energization of the motor 80, a centrifugal switch 154 of the motor 80 is positioned to include a start winding 156 in circuit with the running winding 150 until the motor reaches a predetermined percentage of its operating speed at which time the centrifugal switch 154 is moved to drop the start winding 156 and electrically engage a contact of 158 concurrently with closing a motor speed responsive switch 160 in the heater energization circuit.

Thus, once the motor is up to speed causing air to be circulated through the tumbling drum 56, the heater 42 is energized from L1 through conductor 162, heater energization motor controlled switch 160, conductors 164 and 166 to one end of element 44 constituting one portion of the dryer heater 42. The electrical resistance element 44 is connected in series with a second resistance element 46 which in turn is connected to a conductor 172. The conductor 172 includes a limit thermostat 174 to terminate heater energization upon the occurrence of an undesirable temperature increase in the air inlet chamber of the dryer and a thermally responsive bimetallic switching element 176 of a control thermostat 178 located in the outlet duct 20 of the dryer 10 to sense the temperature of the air being circulated through the drum 14 as it leaves the drum 14.

Conductor 180 connects thermostat 178 through a no-heat switch 182 which in turn is connected by conductor 184 and the relay controlled heater energization switch 112 through a conductor 186 to wire L2. Conductor 184 has switch 308 and thermostat 60 of the lint burning control circuit interposed between the no-heat switch 182 and the relay switch 112.

Additionally, the heater energization circuit includes ya high-energy circuit from wire L1 through conductor 162, switch 160, conductor 164, conductor 188 through a movable thermally responsive bimetallic arm 190 of an energy level control switch 192 that assumes the position illustrated in FIGURE 7 when cold to engage a contact 194 which through conductor 196 shunts the element 44 and maintains only the resistance element 46 across the power source.

The lint burning control circuit and more specifically, the circuit for timer motor 302 i-s completed from L1 to N through conductor 162, switch 144, conductor 146,

switch 108, and conductors 148, 306, and 304. The drive motor 64 is likewise connected in circuit through conductors 66, one of which includes timer switch 305. Thus, by virtue of the above-described arrangement, when wet articles are placed in the tumbling drurn and the start switch 116 is depressed, the control module 100 completes la motor energization circuit, a dryer heater circuit, and lint burning timer and damper drive motor circuits. Once completed, the lint burning timer circuit operates independently of the clothes drying cycle controlled by the module 100 except that the lint burning timer circuit is opened simultaneously with the shut down of the dryer by the module 100. In other words, once energized, the timer motor is the sole control for the lint burning process and will continue to control it until the dryer is shut down by the control module opening switches 108, 110, and 112. This is what is meant by independent control, that is, the lint burning process is called for irrespective of the dryer cycle except, of course, the lint burner timer circuit is energized and de-energized with the dryer control circuit. However, lint burning will not occur if the chamber 22 is above a predetermined temperature or the dryer is in a cool down period as more fully explained below.

The dryer has now been drying clothes under a cycle controlled by the module 100 and sensor 92-94. After a predetermined time interval, for instance, ten minutes of dryer operation time, the timer motor 302 interrupts the drying cycle by moving timer switch 308 from contact 303 to contact 307. The opening of switch 305 de-energizes the dryer heater 42 and energizes the lint burning screen 26. This burns the lint in chamber 22 which is sealed from the drum 14 by damper 28. Since the fan 34 is still operating and since the damper 48 is moved to a flow restrictive position, the chamber 22 is at a slight vacuum pressure during the lint burning which also aids in preventing back-up of the effluent into the drum 14. The thermostat 60 de-energizes the lint screen 26 should the temperature in chamber 22 rise above a predetermined level. After thirty seconds, the lint burning screen is deenergized, the dampers are opened, and the clothes drying cycle is resumed.

COOL DOWN Most dryer cycles include a cool-down period, that is, the drum is rotated a short period at the end of the drying cycle with the dryer heater 42 de-energized.

The control circuit illustrated provides such a cooldown period initiated by the control module 100 opening switches 108 and 112. This de-energizes the heater 42; however, the motor 80, timer motor 302 and drive motor 64 remain energized through thermostat 192. More specically, the circuit for motor 80 is from N to L1 through line 152, the motor winding (150 or 242), speed switch 238, motor start switch 154 which has been moved to its running position where it contacts contact 158 which continues through the thermostat 192. The switch 190 of the thermostat 192 is in the position when it contacts 198 and connects line 158 to line 162 through line 164 and switch 160. The open switch 108 effectively has been bypassed. The line 306 is also in circuit to maintain timer motor 302 and drive motor 64 energized. The screen heater 26, however, cannot -be energized when lint burning is called for since switch 112 is open. Consequently, lint burning will not take place during a cool down period. Dryer operation is then terminated by the cool down thermostat which moves switch 190 to contact 194 at a predetermined temperature.

FIGURE 8 In the embodiment shown in FIGURE 8, the lint burning chamber has been incorporated in the dryer access door. More specifically, the dryer generally indicated at 410 includes a cabinet 412 in which is rotatably mounted a clothes drum 414. A port plate 418 extends a short distance into the access opening 416 of the drum 414.

The access door 415 is hinged on the cabinet 412 and interrupts the iiow from the drum 414 to the outlet duct 420.

More specifically, the door 415 comprises a first sheet metal panel 421 which includes a central dome 422 having inlets 424. A baffle plate 423 is secured in spaced relation to the panel 421 with inner and outer annular screen heaters 440 and 442 mounted therebetween s0 that lint laden air entering through the inlets,424 will flow radially through the screen heaters. The inner screen 440 acts as a -lint collector and burner while the second screen acts as an oxidizer for the efiiuent from the first screen and a iiame suppressor. Each screen is shown as having individual electric leads and the outer screen 442 may be advantageously energized first to assure that its temperature is elevated suicient to oxdize efiiuent from the iirst screen 440. If the second screen is maintained above approximately 1200 F., it should completely oxidize the efliuent; however, either or both screens may be coated with an oxidation catalyst such as platinum or palladium to enhance oxidation of the etiiuent. The inner screen should be heated to approximately 1400 F., which is a suitable range for burning the lint. Outlets 426 in the panel 421 align with apertures 428 in the port plate 418 to continue the air ow path to the dryer outlet duct 420 which communicates with a fan and suitable ducting (not shown) to the outside of the cabinet. A pair of spaced dampers 430 and 432 are mounted on a rod 434 and are biased into the solid line position shown in FIGURE 8 by a spring 436. In this position, the iiow from the inlets to the screens 440 and 442 is blocked by damper 430 and flow from the screens to the outlets 426 is blocked by damper 432. A closed lint burning chamber 438 is formed between dampers 430 and 432 and portions of the panel 421. The damper 432 carries a switch 433 which is series-connected with each of the screen heaters 440 and 442. The switch is closed by closure of the dampers, thus preventing energization of either of the screens without the closed chamber being formed. Note that in the lint burning position of the dampers 430 and 432 as illustrated in the solid line positions, the chamber 438 is positively sealed both from the drum 414 and from the exhaust duct 420. The lint burning chamber is thus sealed and should the door 415 be opened during lint burning, the etiiuent will be maintained in a sealed chamber. The dampers 430 and 432 may be operated by any suitable means, time controlled as in the previous system. The particular means illustrated in FIGURE 8 is a vacuum motor. More specifically, a flexible annular diaphragm 444 is secured to the damper 432 at its inner end and sandwiched at its outer end between a vacuum manifold 446 secured to the panel 421 to form a chamber 448. The manifold 446 which is connected by a conduit 450 to a suitable point in the outlet duct 420 is in uid communication with the chamber 448 via aperture 449. The connection of the conduit 450 to the outlet duct 420 must be sufficiently near the -dryer fan (not shown) to evacuate chamber 448 and move the dampers 430 and 432 to their dotted line positions against the action of spring 436. The conduit 450 includes a pilot valve 452 which is closed during lint burning so that chamber 448 is at or near atmospheric pressure and the dampers are in their solid line positions forming the closed lint burning chamber 438. When the lint burning is completed, valve 452 is opened, evacuating chamber 448, and the dampers 430 and 432 are moved to the phantom line position against the action of spring 436.

The lint laden air from the drum 414 will iiow through inlets 424 through the screens 440 and 442 past the outer edge of the damper 432 through the outlets 426 for-port plate 418 and into the exhaust 420 until lint burning again is called for. An outer panel 456 completes the door 415.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A lint burner for a clothes dryer having a clothes drum, conduit means and a fan in a series flow relationship comprising, a chamber having an inlet and an outlet interposed in `said conduit means between said drum and said fan,a lint collecting screen in said chamber, damper means at said chamber inlet, means to periodically burn lint collected on said screen in repeated short intervals while said fan is operating, and means to close said damper during lint burning to seal said chamber from said drum to prevent the back-flow of eiuent into said clothes drum.I

2. A lint burner for a clothes dryer having a drum, conduit means and a fan in a series ow relationship comprising, a chamber having an inlet and an outlet interposed in said conduit means between said drum and said fan, a lint collecting screen in said chamber, damper means at said chamber inlet, spring means biasing said damper means to close said chamber inlet, actuation means to open said damper means against spring means, means to periodically burn 'lint collected on said screen in repeated short intervals while said fan is operating and means to ldeactivate said actuating means during lint burningwhereby said damper means is closed by said spring means to seal said chamber from said drum to prevent the back-flow of eiiluent into said clothes drum.

3. The combination as defined in claim 2 wherein said actuating means includes an electric motor which is deenergized during lint burning and wherein a second damper is provided at the outlet of said chamber, said second damper being drivingly connected to said iirst damper whereby said second damper is moved to a ilow restricting position as said rst damper is closed.

4. The combination as dened in claim 2 wherein said actuating means includes a vacuum chamber which is pressurized during lint burning and wherein a second damper is provided at the outlet of said chamber, said second damper being drivingly connected to and movable with said first ydamper whereby said chamber is closed during lint burning.

5. In a dryer comprising a cabinet, a drum rotatably mounted in said cabinet, inlet means for said drum, heating means in said inlet means, outlet means for said drum, fan means in said outlet means, a dryer control circuit including means to rotate said drum, drive said fan, and energize said heating means in a predetermined cycle, the improvement comprising,` a chamber uidly connected in said outlet means between said drum and said fan, a lint screen in said chamber, lint burning means to dispose of lint entrapped onA said screen, a lint burning control circuit including a timer motor energized from said dryer control circuit whereby said timer motor is energized only when said dryer control circuit is energized, said timer motor periodically energizing said lint burning means and deenergizing said heating means in said dryer control circuit without otherwise effecting the dryer control circuit and the operation of said drum and said fan.

V6. In a dryer as dened in claim 5 the improvement further including a damper at said chamber inlet movable between yan open and a closed position, spring means urging said damper to a closed position, and motor means to open said damper, and wherein said timer motor deenergizes said motor means as it energizes said lint burning means.

7. In a dryer comprising a cabinet, a drum rotatably mounted in said cabinet, inlet means for said drum, heating means in said inlet means, outlet means for said drum, fan means in said outlet means, and means to rotate said drum, drive said fan, and energize said heating means in a predetermined cycle, the improvement comprising, a chamber uidly connected in said outlet means between said drum and said fan, a lint screen in said chamber, lint burning means to disposed of lint entrapped on said screen and a damper at said chamber inlet movable between an open and a closed position, spring means urging said damper to la closed position, electric motor means to open said damper, timer means to periodically energize said lint burning means and deenergize said heating means and said electric motor means without effecting the operation of said drum and said fan, and a second damper at the outlet of Said chamber, said second damper being drivingly connected to said first damper whereby said second damper is moved to a -flow restricting position as said iirst damper is closed.

8. A dryer comprising in combination, a cabinet, a drum rotatably mounted in said cabinet, means to drive said drum, inlet means for said drum, heating means in said inlet means, an outlet conduit for said drum, a chamber having an inlet connected to said outlet, a damper mounted adjacent said inlet movable between an open and a closed position, a lint collecting, electrically resistance heatable screen transversely mounted in said chamber, means to energize said screen, said chamber having an outlet, a second damper mounted adjacent said outlet movable" between open and flow restricting positions, means to connect said dampers for concurrent movement from said open positions to be closed and said ow restricting positions, respectively, spring means to bias said dampers in said closed and ow restricting positions, respectively, drive means to open said dampers against said spring means including an electric motor, fan means downstream of said chamber, control means to operate said fan, said drum and said heating means according to a predetermined cycle, and timer control means to periodically deenergize said electric motor and energize said screen while said fan is operating whereby lint is burned in a chamber sealed from said drum, said chamber being evacuated by said fan when said lint is being burned.

9. A dryer comprising in combination, a cabinet, a drum rotatably mounted in said cabinet, means to drive said drum, inlet means for said drum, heating means in said inlet means, an outlet conduit for said drum, a chamber having an inlet connected to said outlet, a dampe'r mounted adjacent said inlet movable between an open and a closed position, a lint collecting, electrically resistance heatable screen transversely mounted in said chamber, means to energize said screen, said chamber having an outlet, a second damper mounted adjacent said outlet movable' between open and ow restricting positions, means to connect said dampers for concurrent movement from said open postions to said closed and said iiow restricting positions, respectively, spring means to bias said dampers in said closed and flow restricting positions, respectively, drive means including an electric motor to open said dampers against said spring means, fan means downstream of said chamber, control means to operate said fan continuously and said drum and said heating means according to a predetermined cycle, and timer control means to periodically deenergize said heating means and said electric motor to condition said dryer for lint burning, the deenergization of said electric motor allowingsaid spring means to close said first damper means to energize said screen whereby lint is burned in a chamber sealed from said drum.

10. A dryer comprising in combination, a cabinet having an access opening closed by'a door, a drum rotatably mounted in said cabinet, air inlet means for said drum, heating means in said inlet means, said drum having an access opening in alignmentv in said cabinet access opening, an outlet conduit in said cabinet in iluid communication with said cabinet access opening, said door being hollow to provide a ow path from said drum to said outlet conduit in its closed position, a pair of spaced dampers mounted in said hollow door for movement -between a iirst and a second position, said dampers in said first position forming a closed chamber interrupting the air ow from said drum to said outlet conduit, spring means to bias said dampers into said rst position, motor means to move said dampers to said second position against said spring means, a lint collecting, electrically resistance heatable screen mounted in said chamber, and timer control means to periodically deenergize said motor means and energize said screen whereby lint is burned in a sealed chamber.

11. A dryer comprising in combination, a cabinet having. an access opening closed by a door, a drum rotatably mounted in said cabinet, means to drive said drum, air inlet means for said drum, heating means in said inlet means, said drum having an access opening in alignment in said cabinet access opening, an outlet conduit in said cabinet in uid communication with said cabinet access opening, a fan drawing air through said drum and said outlet conduit, an electric motor to drive said fan and said drum, said door being hollow to provide a flow path from said drum to said outlet conduit in its closed position, a pair of spaced dampers in said hollow door for movement between a first and a second position, said dampers in said first position forming a closed chamber interrupting ow from said drum to said outlet conduit, spring means to bias said dampers into said first position, motor means to move said dampers to said second position against said spring means, an annular lint collecting, electrically resistance heatable screen mounted in said hollow door in said ow path, said screen being enclosed in said chamber when said dampers are in said first position and timer control means to periodically deenergize said motor means and said heater means and energize said screen while maintaining said electric motor operable whereby an excess load is not required to restart the electric motor at the termination of the lint burning thereby enabling the dryer heating means to be energized.

12. A dryer comprising a cabinet, a drum rotatably mounted in said cabinet, inlet means for said drum, heating means in said inlet means, outlet means for said drum, fan means in said outlet means, electric motor means to drive said fan and drum, control means to energize said electric motor and said heating means in a predetermined cycle, said control means including a starting circuit for said motor, and switch means to maintain said heating means deenergized while said starting circuit is energized, a chamber uidly connected in said outlet means between said drum and said fan, a lint screen in said chamber, lint burning means to dispose of lint entrapped on said screen and timer means to periodically energize said lint burning means and deenergize said heating means and maintain said electric motor means energized whereby said heating means is adapted to be energized at the termination of the lint burning.

13. A fabric dryer comprising a casing dening a drying chamber and having an air inlet opening and an air outlet opening therein, lint collecting means communicating with said air outlet opening, an air exhaust duct for receiving air from said drying chamber and said lint collecting means, means for circulating air sequentially through said drying chamber, said lint collecting means and said exhaust duct throughout a fabric drying cycle, means for burning the lint collected on said lint collector means in repeated short intervals throughout said drying cycle, means for reducing the volume of air circulated past said lint collecting means, and means for concurrently actuating said burning means and said air circulation reducing means, said air circulation reducing means including damper means between said drying chamber and said lint collecting means and operable to completely interrupt communication between said drying chamber and said lint collecting means whereby to establish a slight vacuum downstream of said lint collecting means for withdrawing as they are produced the products of combustion from burning the lint.

14. The fabric dryer of claim 13 wherein said air circulation reducing means includes another damper means between said lint collecting means and said means for circulating air and operable to partially interrupt communication between said lint collecting means and said means for circulating air, both of said damper means interrupting communication while said lint burning means is actuated during said clothesdrying cycle and whenever said fabric dryer is inoperative for providing a clothes drying cycle.

15. In a fabric dryer, having a drying chamber, an air inlet opening and an air outlet opening, lint collecting means communicating with said air outlet opening, means for circulating air sequentially through said dry` ing chamber and said lint collecting means, means for burning the lint collected on said lint collector means, the improvement comprising, damper means between said drying chamber and said lint collecting means to completely interrupt communication therebetween, and means for concurrently actuating said burning means and said damper means including an interlock means to insure that said damper means completely interrupts communication between said drying chamber and said lint collecting means as said burning means is actuated.

16. A lint burner for a clothes dryer having a drum, conduit means and a fan in a series ow relationship comprising, a chamber having an inlet and an outlet interposed in said conduit means between said drum and said fan, a lint collecting screen in said chamber, damper means at said chamber outlet, spring means biasing said damper means to close said chamber outlet, actuation means to open said damper means against spring means, means to periodically burn lint collected on said screen in repeated short intervals while said fan is-operating, means to deactivate said actuating means during lint burning whereby said damper means is closed by said spring means, and second damper means at the inlet of said chamber, said second damper means being movable to a closed position in response to movement of said first damper means to a closed position whereby said chamber is closed during lint burning.

17. The combination as defined in claim 16 wherein said actuating means includes a vacuum chamber which is pressurized during lint burning and wherein said second damper means is drivingly connected to said first damper means.

References Cited UNITED STATES PATENTS 696,914 4/ 1902 Swanson. 3,061,942 11/ 1962 Scofield 34-82 3,069,785 12/ 1962 Mitter et al. 34-53 3,081,554 3/1963 Long 34-79 XR 3,085,348 4/1963 Adey et al 34-82 3,263,343 8/ 1966 Loos 3,4-,82

FREDERICK L. MATTEsoN, JR., Primary Examiner H. B. RAMEY, Assistant Examiner Us. c1. xn. 34-82

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