US3398459A

US3398459A - Clothes dryer control

Info

Publication number: US3398459A
Application number: US581379A
Authority: US
Inventors: Willie H Best; Jr Charley L Thompson; Jr Eugene C Woodward
Original assignee: Lear Siegler Inc
Current assignee: Lear Siegler Inc
Priority date: 1966-09-22
Filing date: 1966-09-22
Publication date: 1968-08-27
Anticipated expiration: 1985-08-27

Description

Aug. 27,1968 w. H. BEST ETAL CLOTHES DRYER CONTROL 5 Sheets-Sheet 1 Filed Sept. 22, 1966 lll'dillllll my/4 m// 7, 1968 w. H, BEST ETAL. 3,398,459

CLOTHES DRYER CONTROL Filed Sept. 22, 1966 s Sheets-$heet z 50/ E /Z w A /i 4 54 V 65 i 9 I E f a K L dd a m0 4 i W *5 t #3 I E 1968 w. H. BEST ETAL 3,398,459

CLOTHES DRYER CONTROL Filed Sept. 22, 1966 5 Sheets-Sheet u INVENTORS United States Patent 3,398,459 CLOTHES DRYER CONTROL Willie H. Best, Columbia, Charley L. Thompson, Jr., Cayce, and Eugene C. Woodward, Jr., Columbia, S.C., assignors to Lear Siegler, Inc., a corporation of Delaware Filed Sept. 22, 1966, Ser. No. 581,379 3 Claims. (Cl. 34-43) ABSTRACT OF THE DISCLOSURE Two gas-fired infrared generators are disposed to direct infrared radiation into the upper interior of the dryers drum. A first temperature sensor is coupled to one of the infrared generators to turn it off when a temperature increase resulting from the diminution of water vapor in the dryers exhaust is sensed. A second temperature sensor is coupled to the infrared generators to deenergize the generators upon the sensing of a higher temperature resulting from the substantial absence of water in the laundry. A cycle selector is operable to inactivate the drum and the dryers blower as well as the infrared generators after the completion of a cycle. A temperature selector functions to prevent the generation of infrared radiation from one of the infrared generators.

This invention relates to clothes dryers and in particular to clothes dryers utilizing infrared radiant energy as a drying medium.

Both electrical and gas clothes dryers are, of course, well known. High drying temperatures are often used in these dryers in order to produce a reasonably short drying time. However, high temperature drying has an adverse effect on many fabrics including the loss of fabric press and diminished fabric life. Elastic, for example, deteriorates with exposure to present day dryer temperatures.

The instant invention provides a new and improved clothes dryer which uses infrared radiation as a drying medium. The use of this drying medium avoids the requirement of high drying temperatures associated with prior art dryers without increasing drying time. The invention includes a dryer cabinet or housing. A dryer drum is mounted for rotation within the cabinet. At least a portion of the drums radial wall is pervious to infrared radiant energy in order to heat a load of laundry in the drum. Thus, the drums radial Wall can have a plurality of closely spaced openings to communicate its interior with its exterior. Suitable openings are readily provided by fabricating the drums radial wall of wire screen. At least one infrared generator is mounted within the cabinet in radiant communication, through the radial wall, with the interior of the drum. The generators are mounted within the housing to effect incident radiation on laundry in the upper portion of the drums interiod. Such incident radiation is produced by mounting the generators in the lower portion of the housing such that emanating radiation passes through the drums radial wall, across the interior of the drum, to laundry located in an upper quadrant of the drum. Means for rotating the drum and means for creating 'a draft through the interior of the drum are also provided.

In preferred form the dryer of the instant invention utilizes at least two gas fired infrared generators. In addition, means are provided for sensing two distinct temperature levels of the air and water vapor leaving the drum. The first temperature level is produced by the diminution in the concentration of water vapor leaving the drum. This temperature is used for de-energizing one in the infrared generators. The second temperature level,

"ice

which is higher than the first, indicates the substantial absence of water in a load of laundry and is used to deenergize the other infrared generator.

Each of the gas fired infrared generators preferably includes a gas pilot which is ignited by an electrical ignitor such as a glow coil, spark or the like. Flame sensors are used to indicate the presence of a pilot flame which indication is used to terminate current flow to the ignitors and to turn on gas flow to the main burners of the infrared generators. In the event that no pilot flame exists, the flame sensors are used to terminate gas flow to the pilots. Means for cycling and temperature control 'as well as safety devices are also included in a preferred form of the invention.

The advantages of the infrared dryer of th instant invention includes the ability to dry laundry without appreciably increasing its bulk temperature. It has been found that water is a preferential absorber of infrared radiation. Water in a load of wet laundry will, then, absorb infrared radiation more readily than the laundry itself resulting in low bulk temperatures, improved fabric life and fabric press. Bulk temperatures of from 20 to 40 degrees F. below those of prior art gas dryers can be expected for a given load of laundry dried for a given period of time. In addition, the use of more than one infrared generator allows efiicient drying of normal fabrics because one of the generators may be turned off after a period of time to utilize the ambient temperature within the drum and the other generator to complete the drying of the load of laundry. Moreover, for special requirements such as wool, the heat flux t0 th load may conveniently be reduced simply by turning off one of the generators. The -infrared generators are readily adapted with controls for safe and efficient operation.

These and other features, aspects and advantages of the instant invention will become more apparent in the following description, appended claims and drawings, in which:

FIGURE 1 is a front elevation, partly in section, of a preferred embodiment of the instant invention;

FIGURE 2 is a side elevation, partly in section, of the embodiment shown in FIGURE 1; and

FIGURES 3 and 4 are schematical depictions of the dryer of the instant invention together with its attendant electrical control circuitry.

Referring now to FIGURES l and 2 there is seen the clothes dryer 1 of the instant invention. Cabinet or housing 2 encloses the interior of dryer 1. An internal vertical wall 3 is mounted within this interior and cabinet 2. Clothes drum 4 is mounted for rotation within the dryer. This mounting is provided by an axle 5, which is secured to internal vertical wall 3 and coaxially jour naled in drum 4, and an external annular flange 6 formed in the face of drum 7 and engaged for rotation within annular ring 7. Annular ring 7 is disposed in the front wall of cabinet 2. If desired, frontal support for drum 4 can be provided through a sliding shoe arrangement in place of the mating flange 6 and ring 7. Radial cylindrical wall 8 of drum 4 is pervious to infrared radiant energy and is preferably comprised of a smooth porous metal material such as wire screen to avoid damage to clothes. Drum 4 has an interior 9 for the receipt of clothes to be dried. Electric motor 10 is mounted to internal vertical wall 3. Endless belts 11 and 12 are driven by motor 10. Belt 11 is disposed about a portion of the outer circumferential surface of drum 4 for rotating the drum when motor 10 is energized. Blower 13 is driven by endless belt 12 for creating a draft within drum 4. Each of the endless belts maybe provided with a device to insure their proper and continuous tension such as a spring and pulley. Blower 13 is mounted on exhaust duct which in tum is secured to vertical Wall 3. Duct 15 provides communication between the interior 9 of drum 4 and blower 13. Exhaust vent 16 passes through back wall 17 and provides the discharge for blower 13. Lint filter 18, formed of wire screen, is normally in position to gather lint within the exhaust duct 15 and can be removed for cleaning.

Infrared generators 20 and 22 are disposed within cabinet 2 in radiant communication with the interior 9 of drum 4. An insulation blanket 24, preferably of fiberglass, is disposed about the interior of cabinet 2. A reflective insulation sheet 25, such as aluminum foil, is secured to the inner surface of insulation blanket 24. Insulation blanket 24 provides heat insulation for the efficient operation of the dryer. Reflective insulation 25 serves to reflect infrared radiation back into the interior 9 of drum 4.

.A sliding transparent door is provided for frontal access to drum 4. This sliding door comprises a transparent window 26 bounded by frame 27. Lower frame element 28 and upper frame element 29 are retained by guides 30 and 31 in the form of angles mounted to the cabinet 2. The door translates in these guides.

Preferably, the infrared generators 20 and 22 are gas fired. Gas fired infrared generators are Well known and will not be described in detail. Each generator includes an orifice and a venturi to mix air with gas to provide a combustible mixture. This mixture passes into a burner plenum and out through slits in a ceramic flame anchor where it is ignited by a pilot flame. The burning gases heat the ceramic to incandescence. The incandescent ceramic produces infrared radiation. This radiation is di rected through the holes in the radial Wall 8 of drum 4 to a contained load of Wet laundry. Some of this radiant energy will strike insulation sheet 25 and be redirected into the load in drum 4. Reflectors 32 and 33 of infrared generators 20 and 22 serve as an aid for the direction of radiant energy from the generators to the load.

The position of infrared generators 20 and 22 with respect to laundry within drum 4 is very important. Infrared energy has low penetration properties. For eflicient drying, therefore, the infrared energy emanating from the generators should directly strike as much laundry surface as possible. When laundry is in the upper portion of the drum, it will have a tendency to fall, unfold and separate. The separation and unfolding presents a large surface area which is available for incident radiant energy. The generators are, therefore, mounted in the lower portion of the cabinet in order to produce direct impingement of infrared radiation on the unfolding and expanding laundry. In short, mounting position is important to maximize the surface area of laundry directly contacted by infrared radiation. In addition, the products of combustion from the generators should, for eflicient operation, be used in the drying process. These hot gases have a natural tendency to rise. In order to employ this natural tendency to aid in drying, the generators should be placed in the bottom of the cabinet. The draft created by blower 13 aids in the circulation of the products of combustion through the drum and thus augments the drying process.

Referring to FIGURE 3, dryer 1 is shown schematically with its attendant control circuitry and gas supply for its infrared generators. In general, the circuitry and gas supply consists of z a gas distribution system; a control unit 34, consisting of a cycle selector 35 and a temperature selector 36; thermally responsive switching elements in exhaust duct 15; and a gas control circuit 37.

As previously described, drum 4 is driven in rotation by belt 11. Belt 11 in turn is driven by motor 10. Motor 10 also drives belt 12 which drives blower 13. Blower 13 is in communication with the interior of drum 4 through exhaust duct 15. Exhaust in the form of air and water vapor is vented by exhaust vent 16 to atmosphere. Infrared generators 20 and 22 are mounted within the dryer in radiant communication with interior 9 of .drum.4. In.- frared generator 20 has a main burner 50 which transforms chemical energy of a gas-air mixture into infrared radiation by means of combustion upon a ceramic surface. In like manner, infrared generator 22 has a main burner 52 to generate infrared radiant energy. 7 p

The gas distribution system includes gas line 54, from a source of combustible gas, which is in gas communication with gas line 56 and pilot gas line 58. Normally closed solenoid valve 60, connected in gas line 56, prevents gas flow to

lines

62 and 64 unless actuated.

Gas lines

62 and 64 are in gas communication with gas line 56 through a standard T connection. Normally closed solenoid actuated valve 66 is disposed in line 62 to selectively supply gas to burner 52 of infrared generator 22. Burners 50 and 52 are in gas communication with

lines

64 and 62, respectively. Normally closed solenoid actuated valve 68, in pilot gas supply line 58, prevents the flow of gas to gas line 70 unless actuated. Gas line 70 is in gas communication with gas line 58. Pilotnozzle 72 is disposed at one end of gas line 70 to supply a pilot flame for infrared generator 20. Similarly, pilot nozzle 73 is in the other end of gas line 70 to provide a pilot flame for infrared generator 22.

Alternating current source 74 is connected through normally open door switch 76 to cycle selector 35 of control unit 34. The door switch, when open, prevents cur rent from reaching the remaining portions of the dryers circuitry. Door switch 76 is closed when the dryers door is closed. Magnetic switch 78 is in circuit with cycle selector 35 and circuit breaker 80. The magnetic switch is the dryers on-off control and it remains closed, once depressed, until the dryer completes a cycle. The circuit breaker prevents current flow to motor 10 when the latter has a malfunction. Friction-driven, spring-loaded, centrifugal switch 82 is in circuit with circuit breaker 80 and safety thermostat 84. Switch 82 is closed by the rotation of drum 4. When open, switch 82 prevents the operation of generators 20 and 22. Thermostat 84 is a normally closed, thermally actuated switch disposed in exhaust duct 15 to terminate gas flow to generators 20 and 22 in the event that the temperature within the exhaust duct reached a prescribed level, for example 160 degrees F. For this purpose, thermostat 84 is connected in circuit with temperature selector 36 of control unit 34. Modulating thermostat 86 is located in exhaust duct 15 and is in circuit with temperature selector 36 and cycle selector 35 to de-energize the solenoid of valve 66 at a selected temperature, for example degrees F. Variable setting thermostat 88, also disposed in exhaust duct 15, is connected to temperature selector 36 and cycle selector 35. The setting of thermostat 88 is controlled by temperature selector 36 through a flexible shaft (not shown) to produce drying conditions within drum 4 to suit the particular requirements of a given load of laundry. Suitable settings for thermostat 88 are: degrees F. for a normal laundry load; degrees F. for a high temperature timed cycle; and 120 degrees F. for a special load. Upon reaching the appropriate one of these temperatures, thermostat 88 de-energizes the infrared generators.

Each of the infrared generators 20 and 22 has a pilot ignitor and pilot flame sensor. Infrared generator 20 .is equipped with a pilot flame ignition coil 90 .which is wired in parallel with pilot flame ignition coil 92 of generator 22. When energized, these ignitors establish pilot flames from pilot nozzles 72 and 73. Flame sensor 94 is positioned with respect to pilot nozzle 72 to sense the presence of a flame. Similarly, flame sensor 96 is disposed to sense a pilot flame from nozzle 73. The flame sensors are preferably series connected thermocouples, but capillary actuated bellows switches may be used. The solenoids of

valves

60 and 68,

flame sensors

94 and 96, and

pilot ignitors

90 and 92 are coupled to gas control circuit 37.

The dryers circuitry and controls just described with reference to FIGURE 3. are shown in greater detail in FIGURE 4 Alternating current source 74 is connected through normally open door switch 76 and on switch 78 to cycle selector 35. Normally open magnetic switch 78 is used to maintain cycle selector 35 de-energized unless actuated. Circuit breaker 80 is a protective device for motor 10.

Cycle selector 35 consists of two cam actuated switches and a'timing motor. Timing motor 100

drives cams

102 and 104 through a shaft 106. Cam 104 has a plurality of lugs which represent different dryer functions. Lug 108 is an air cycle lug, lug 110 a timed cycle lug and stepped lug 112 is used for automatic and automatic extra dry cycles. Switch 114 is actuated by the lugs of cam 104 and comprises switching

elements

116 and 118 as well as contact or pole 120. When air cycle lug 108, timed cycle lug 110 and the raised portion of lug 112 contact switching element 116, switch 114 is fully closed, that is, switching

elements

116 and 118 are in contact with each other and contact 120. ,The depressed portions of lug 112 actuate only

contacts

116 and 118 leaving contact 120 out of circuit. Switching element 116 is in series with alternating current source 74. Contact 120 is in circuit with thermostat 88 and switching element 118 is in series with motor to supply the latter with current.

Cam 102 has a time cycle lug 122 and an automatic extra dry lug 124. The lugs actuate switch 126. Switch 126 consists of a switching element 128 and contact or pole 130. Switching element 128 is in circuit with thermostat 86 and thermostat 88, and contact 130 is in circuit with thermostat 84. Timer 100 is in circuit with contact or pole 120 and thermostat 88.

Thermostat 88 has a pole 132 which is in circuit with pole 120 and timer 100. The thermostat also has a bimetallic switching element 134 which is in circuit with thermostat 86 and switching element 128. Pole 136 completes thermostat 88 and is in circuit with temperature selector 36.

Thermostats

84 and 86 both include bimetallic elements. Thermostat 86 is connected to switching

elements

128 and 134 as well as temperature selector 36. Thermostat 84 is connected in series with normally open :drum switch 82 and pole 130. Temperature selector 36 includes switch 138 which is connected to pole 136and terminal 140 of gas control circuit 37. Switch 142 is also connected to pole 136 as well as through the solenoid of valve 66 to ground. Switch 144 is serially connected to thermostat 86 and the solenoid of valve 66.-

Terminal 140 of gas control circuit 37 is connected to alternating current source 74 through switch 138 of temperature selector 36. Gas control circuit 37 includes pilot flame sensing relay 146 together with its normally open contacts 148 and normallyclosed contacts 150. The coil of relay 146 is in series circuit with

flame sensors

94 and 96. Normally open contacts 148 are serially connected to terminal 140 and through the coil of solenoid valve 60 to ground. Normally closed contacts 150 are connected in series with terminal 140, heater coil 152, transformer 154 and bimetallic switch 156. Upon the sensing of pilot flames in both generators, current will flow through the coil of relay 146 to close contacts 148 and open contacts 150. The coil of solenoid valve 68 is connected to terminal 140 and between the primary winding of transformer 154 and bimetallic switch 156. Bimetallic switch 156 is normally closed, but opens when heater coil 152 is on for a suflicient period of time. The secondary winding of transformer 154 energizes parallel

connected pilot ignitors

90 and 92.

The operation of the dryer will be described with reference to FIGURES 3 and 4 and in terms of various dryer cycles.

When it is desired to rotate drum 4 without a radiant heat input from infrared generators 20 and 22, the dryer is air cycled. Air cycling is accomplished by adjusting the cycle selector 35 to bring air cycle lug 108 of cam 104 into position to close switch 114. In this position, switching

elements

116 and 118 are brought into contact with pole 120. Switch 126 remains open during an air cycle because there is no lug of cam 102 in contact with switching element 128. Switching element 134 is out of contact with pole 132. Thus, gas control circuit 37 is de-energized and infrared generators 20 and 22 cannot operate during an air cycle. With the door of the dryer closed, switch 76 is closed. When switch 78 is closed, a circuit is established between alternating current source 7 4, through switching

elements

116 and 118, and motor 10. If the circuit through circuit breaker is closed, motor 10 is energized, drum 4 rotates, and blower 13 circulates air through the drum. Timer is in circuit with alternating current source 74 through pole 120 and begins to rotate cam 104 and air cycling lug 108. Air cycling continues until air cycling lug 108 passes out of contact with switching element 116 thus opening switch 114 and terminating current flow to motor 10.

If an operator desires a timed cycle, cam 104 is rotated until timed cycle lug is in position to close switch 114. With door switch 76 and on switch 78 closed, a circuit is established to motor 10 through switching

elements

116 and 118. For a timed cycle, time cycle lug 122 of cam 102 is in position to close switch 126. Timer 100 is in circuit with current source 74 through pole 120. When motor 10 is energized, drum 4 will rotate resulting in switch 82 being closed. Switching element 134 of thennostat 88 is in contact with pole 136. Thus, a circuit is completed to temperature selector 36 through

switches

82 and 126, and

thermostats

84 and 88. For a timed cycle, temperature selector 36 may be set for either a high temperature timed cycle of, for example, 150 degrees F. or for a timed cycle at a low temperature of, for example, degrees F. for special laundry loads. If a high temperature cycle is desired, both switches 138 and switch 142 are closed establishing a circuit to the solenoid of valve 66 and terminal of gas control circuit 37. Thermostat 86 is eflectively out of circuit for a high temperature timed cycle.

In a high temperature timed cycle, current .will flow through the solenoid-s of valve 66 and pilot gas valve 68 opening these valves to gas flow. Simultaneously, current will pass through normally closed contacts of relay 146 to heater coil 152, transformer 154 and bimetallic switch 156 to ground. From the secondary of transformer 154, current will flow through

pilot flame ignitors

90 and 92. The pilot flame ignitors will initiate pilot flames from pilot nozzles 72 and 73.

Flame sensors

94 and 96 will sense the pilot flames and energize the coil of relay 146. When the coil of relay 146 is energized, contacts 148 close and contacts 150 open. The closing of contacts 148 establishes a circuit through the solenoid of valve 60 which opens the valve to admit gas to burners 50 and 52. The pilot flames will ignite this gas and the infrared generators will be activated. With contacts 150 open,

ignitors

90 and 92 are taken out of circuit. In the event that

flame sensors

94 and 96 do not sense the presence of pilot flames, contact 148 will remain open and contacts 150 will remain closed. After a period of time, heater coil 152 will open bimetallic switch 156. The opening of this switch terminates current flow through the solenoid of valve 68 preventing gas from reaching the pilot nozzles. Because the gas supply to the burners is determined by the presence of pilot flames from both pilot nozzles, valve 60 remains closed.

In the event that an operator selects a timed cycle for a special load, it is desired that the maximum temperature felt by a load of laundry be reduced below that for a high temperature timed cycle. Thermostat 88 is adjusted such that the circuit through switching element 134 and pole 136 opens at a low temperature, for example, 120 degrees F. Switch 138 is closed while switch 142 remains open. Switch 144 also remains open. The cycle is then the same as that just described for a high temperature timed cycle except that the solenoid of valve 66 remains out'of circuit and valve 60 closes when thermostat 88 senses 120 degrees F. because switching element 134 opens the circuit to pole 136. With valve 66 closed, only infrared generator 20 is capable of actuation.

For both the high temperature timed cycle and the special load timed cycle, timed cycle lug 122 of am 102 opens switch 126 before the cycle is complete. The opening of switch 126 de-energizes gas control circuit 37. However, timed cycle lug 110 of cam 104 remains in contact with switching element 116 maintaining the circuit through pole 120 to timer 100. Timer 100 remains in circuit for a time sufiicient to cool laundry within drum 7. Ample time is usually about five minutes.

For an automatic cycle, lug 112 of cam 104 is brought into position to control switch 114 and lug 124 into position to control switch 126. An operator may desire that the automatic cycle be extended for a period of time, for example when drying a large load of laundry. Provision for this exigency is present as will become subsequently apparent. The automatic cycle will also afiord a choice between normal and special laundry requirements.

To initiate a standard automatic cycle the indented portion between the two raised segments of lug 112 of cam 104 is positioned to close switching

members

116 and 118 which leaves pole 120 out of circuit. A circuit is then established between alternating current source 74 and motor through circuit breaker 80. Automatic cycle lug 124 of c-am 102 is positioned to close switch 126. The timer 100, during this portion of the cycle, is not in circuit with alternating current source 74. Switching element 134 of thermostat 88 will be in contact with pole 136. In the event that a normal load is being dried, switch 138 is closed to establish a circuit to terminal 140 of gas control circuit 37. Switch 144 is closed to establish the circuit to the solenoid of valve 66 through modulating thermostat 86. Thermostat 88 is set such that the circuit through switching element 134 and pole 136 opens when a temperature of, for example 140 degrees F. is reached. Modulating thermostat 86 opens at a lower temperature of, for example, 130 degrees F. When the temperature in exhaust duct reaches 130 degrees F., thermostat 86 opens, closing valve 66 and inactivating generator 22. When the temperature reaches 140 degrees F., the entire gas control circuit 37 is de-energized because switching element 134 opens the circuit to pole 136. For a special load, switches 142 and 144 are open and switch 138 is closed thus taking the solenoid of valve 66 out of circuit. In addition, switching element 134 is set to open the circuit to pole 136 at 120 degrees F. The dryer will operate until the temperature in exhaust duct 15 reaches a level sufficient to cause bimetallic switching element 134 to move out of contact with pole 136 and into contact with pole 132. When switching element 134 is in contact with pole 132, the timer 100 is in circuit through pole 120. The timer will then rotate shaft 106 and cam 102 moving lug 124 out of contact with switch 126. When switch 126 opens, gas control circuit 37 is de-energized. However, the last raised portion of lug 112 is brought into contact with switching element 116 which closes the circuit between switching element 118 and pole 120 to maintain the timer 100 in circuit. The motor will continue to drive blower 13 for a prescribed time, for example, four minues, to cool the laundry within drum 4.

In the event that an extra dry automatic cycle is desired, the first depression of lug 112 of cam 104 will be brought into contact with switch 114. The timer 100 will then be out of circuit until switching element 134 establishes a connection with pole 132 whereupon the initial raised portion of lug 112 will connect switching element 118 to pole 120. Timer 100 will then be in circuit despite the cooling of switching element 134 which would otherwise take the timer out of circuit. Cam 104 will continue to rotate until the second depression of lug 112 engages switch element 116. The remaining portion of the extra dry automatic cycle is'merely a repetition of that described with reference to a standard automatic cycle.

, It' has been found that a typical load of laundry dried with the infrared dryer of the instant invention will experience an initial temperature increase until the temperature within exhaust duct 15 reaches from about to ll5 degrees F. The exhaust temperature will remain in this range'until the moisture content of the laundry is lowered to less than fifty percent of initial load weight. At this point, the exhaust temperature climbs slowly to about 130 degrees F. which indicates a moisture content of from fifteen to twenty percent of load"weiglit; When the energy fiux from the generators is'r educedby deactivating one of the generators after the load temperature] reaches approximately 130 degrees'F., the exhaust temperature will drop to about to degrees F. The load temperature will remain in the 120 to 125 degree range until the moisture content becomes small whereupon the temperature again rises slowly. When the exhaust temperature reaches about 140 degrees F., most of the moisture will have been removed. The moisture content at this time will be so small that the load will be sensibly dry. The setting for modulating thermostat 86' is set at about degrees F. to reflect the relative constancy of temperature of a laundry load during this portion of its drying cycle. Thermostat 86 controls infrared generator 22 through its connection to the solenoid of valve 66. The modulation of heat flux by thermostat 86 increases the dryers efliciency by lowering the total heat input into drum 4 during a portion of'the drying cycle when "a high heat flux is notreq'uired to produce a reasonable drying time. Adjustable thermostat 88 has three settings. During normal drying cycles, the' temperature at which switching element 134 opens the circuit between it and pole 136 is about degrees F. to reflect the substantial absence of moisture in the dryers load. For delicate fabrics, thermostat 88 will de-energ'ize gas control circuit 37 at about 120 degrees F. to protect the fabrics. On the high temperature timed cycle, both generators are in operation until the exhaust ducts temperature reaches degrees F. Because this cycle is time determined, a higher generator deactivation temperature is selected. Safety thermostat 84 is in circuit Whenever the generatorsare in operation. Thermostat 84 opens the circuit to the gas control circuit 37 and the solenoid of valve 66 when it senses a temperature of about degrees F. to avoid damage to laundry within drum 7 and hazardous conditions.

The subject invention has been described with reference tolcertain specific embodiments. The scope and spirit "of the appended claims should not, however, be limited to this description.

What is claimed is:

1. A dryer comprising:

(a) a housing;

(b) a drum mounted for rotation in the housing havingan interior for the receipt of articles of laundry to be dried and an outer radial, infrared-radiationpervious wall; 1

(c) at.-least two gas-fired infrared generators within the housing in infrared-radiant communication with the interior of the drum through the radial wall, each generator being disposed to direct emanating radiant energy to the upper portion of the drums interior;

(d) means for supplying gas to the generators;

(e) means for igniting the gas in the generators;

(f) means for rotating the drum;v

(g) means for introducing air into and for exhausting air and water vapor from the drums interior, such means including a dryer exhaust;

'(h) first temperature sensitive means for sensing a temperature in the dryers exhaust corresponding to a diminution in the water vapor content of the water vapor and air in the dryers exhaust, the temperature sensitive means being operable to prevent the generation of infrared radiation by one of the infrared generators upon the sensing of such temperature;

(1) second temperature sensitive means for sensing temperature in the dryers exhaust, such means being adjustable to sense a selected one of a plurality of temperatures in the exhaust and operable upon the sensing of the selected temperature to prevent the generation of infrared radiation by both of the infrared generators;

(j) cycle selector means coupled to the infrared generators, the drum rotating means and the air introduction and exhaust means, the cycle selector means being operable to inactivate the drum rotating means and air introduction and exhaust means after any selected one of a plurality of cycles and to inactivate both of the infrared generators at one portion of such selected cycle; and

(k) temperature selector means selectively operable to prevent the generation of infrared radiation from one of the infrared generators.

2. The dryer claimed in claim 1 wherein the cycle selector means includes a timer operable to advance a given cycle, the selector means being operable to inactivate the timer during a portion of a selected one of the cycles, and the second temperature sensing means being operable to activate the timer during such cycle upon the sensing of one of a plurality of temperatures in the exhaust.

3. The dryer claimed in claim 2 including:

(a) means for sensing rotation of the drum coupled to the infrared generators and operable to prevent the generation of infrared radiation from both infrared generators unless the drum is rotating; and

(b) third temperature sensing means coupled to the infrared generators and operable to prevent the generation of infrared radiation from both infrared generators upon the sensing of a relatively high temperature in the dryers exhaust.

References Cited UNITED STATES PATENTS 8/1946 Ferris 344 X 2,991,990 7/1961 Mitter 263-33 3,021,605 2/1962 Anderson 26333 JOHN J. CAMBY, Acting Primary Examiner.