US3882613A - Clothes dryer - Google Patents

Abstract

This invention relates to a clothes dryer having a drying system which includes a heat generating chamber through which a hot gaseous drying medium is supplied to a clothes tumbling and drying chamber under thermostatic control without substantial recirculation until a predetermined maximum temperature is attained in the tumbling and drying chamber. The generation of heat and the furnishing of fresh drying medium are then automatically suspended by thermostatic control means for a coasting period. During the coasting period, the drying medium present in the system is recirculated, first through a reheating chamber which surrounds the heat generating chamber and which is in intimate heat exchanging relation therewith, and then through the idle heat generating chamber, itself, until the temperature in the tumbling and drying chamber has fallen to a predetermined minimum. At that point the generation of heat and the furnishing of fresh drying medium are automatically caused to be resumed by the thermostatic control means.

Description

United States Patent [191 Wilson [451 May 13,1975

1 1 CLOTHES DRYER [76] Inventor: Joseph M. Wilson, 133 Cornwall St.,

Salinas, Calif. 93901 [22] Filed: May 20, 1974 [21] Appl. No.: 471,503

[52] US. Cl. 34/48; 34/133; 432/105 [51] Int. Cl. F23b 19/00 [58] Field of Search 34/133, 132, 48, 131, 140,

[56] References Cited UNITED STATES PATENTS 2,236,711 4/1941 Kilbury 34/44 3,604,824 9/1971 Hardison 34/155 3,624,919 12/1971 Miller 34/133 Primary Examiner-Carroll B. Dority, Jr. Assistant ExaminerLarry l. Schwartz Attorney, Agent, or FirmClarence M. Crews [57] ABSTRACT This invention relates to a clothes dryer having a dry ing system which includes a heat generating chamber through which a hot gaseous drying medium is supplied to a clothes tumbling and drying chamber under thermostatic control without substantial recirculation until a predetermined maximum temperature is attained in the tumbling and drying chamber. The generation of heat and the furnishing of fresh drying medium are then automatically suspended by thermostatic control means for a coasting period. During the coasting period, the drying medium present in the system is recirculated, first through a reheating chamber which surrounds the heat generating chamber and which is in intimate heat exchanging relation therewith, and then through the idle heat generating chamber, itself, until the temperature in the tumbling and drying chamber has fallen to a predetermined minimum. At that point the generation of heat and the furnishing of fresh drying medium are automatically caused to be resumed by the thermostatic control means.

4 Claims, 4 Drawing Figures CLOTHES DRYER This invention relates to clothes dryers of thetype in which the clothes are put into a rotary tumbling and drying drum, and in which the maximum temperature to which the clothes are exposed in the drum is pre-set for automatic limitation to a relatively low predetermined maximum temperature if the clothes are of the drip-dry variety, but may be pre-set for automatic limitation to a higher maximum temperature if the clothes are of a character to withstand such higher temperature without detriment.

In conventional clothes dryers, it is usual for the gaseous drying medium passed through the tumbling and drying chamber, limited to a predetermined temperature according to the character of the materials to be dried, to be consistently passed once through the drying chamber and then discharged to the atmosphere.

This is a wasteful procedure. The gaseous drying medium, passed once through the tumbling and drying chamber, has its capacity for picking up moisture reduced by a single pass through the drying chamber, but certainly not exhausted thereby.

At a first pass through the drying chamber the temperature of the gaseous drying medium is lowered somewhat and the relative humidity isincreased both by the lowering of the temperature and the absorption of moisture. If the drying medium is recirculated around and then through the heat generating chamber, in which the generation of heat has been thermostatically suspended, the temperature of the drying medium will be materially raised, and the relative humidity will, in consequence, be reduced.

When the gaseous drying medium passed through the tumbling and drying chamber has attained the assigned upper limiting temperature in my novel dryer, the generation of heat and the admission of drying medium components from outside are substantially interrupted for a coasting period of substantial duration. During the coasting period the drying medium present in the system is caused to pass through the system repeatedly. As this recirculation proceeds, the drying medium will be cooled and will become more moisture-laden progressively. This deterioration is retarded materially, however, by causing the recirculating drying medium to pass successively through a reheating chamber which surrounds, and is in intimate heat exchanging relation with, the heat generating chamber, and then through i the heat generating chamber itself.

My system, which involves the reheating and recirculating of the hot drying medium already present in the system at the interruption of heat generation, prolongs the coasting period materially as compared with conventional systems in which the unrestricted introduction of atmospheric air at atmospheric temperature is maintained throughout the coasting period. The recirculation achieves an important economy of heating energy.

I have found, however, that because the recirculation of all the heating medium throughout the coasting period causes the heating medium to become more and more moistureladen, with a consequent progressive loss of heat absorbing efficiency, that a compromise is desirable.

It is a feature, therefore, that provision is made for restricted aspiration of atmospheric airinto the system at all times. Since the air thus introduced is relatively cool and relatively dry, it has the disadvantage, because of its coolness, of shortening thecoasting period, but it has the compensating advantage, because of its dryness, of promoting the efficiency of moisture absorption during that period. It also has the advantage in a system employing heat generation by combustion and the utilization of the combustion product as the drying medium, of assuring a surplus of oxygen supply during combustion in the heat generating, combustion chamber.

When the temperature in the tumbling and drying chamber has been reduced to a predetermined minimum, fresh drying medium is caused thermostatically to be admitted to the heat generating chamber, and the generation of heat is resumed. The freshly introduced drying medium will cause the cooled, moisture-laden drying medium to be forced out of the system and to be progressively replaced by drier and warmer drying medium supplied from the heat generating chamber.

Under my system the intended drying of a load of clothes may take a little longer than when the heating medium is passed once through the clothes tumbling and drying chamber and then discharged, but the expenditure of energy for achieving that result will be very materially reduced. A significant saving of cost will be realized.

Other objects and advantages will hereinafter appear.

In the drawing forming part of this specification,

FIG. 1 is a perspective view of the essential operating parts of a novel dryer embodying my invention in which combustion is relied on for the generation of heat;

FIG. 2 is a fragmentary view in side elevation of a portion of the structure of FIG. 1, showing a heat generating chamber and a neutral chamber, open at both ends, which may serve for recirculation of drying medium or discharge thereof to the atmosphere, depending on whether or not fresh drying medium at any given moment is being supplied to the system;

FIG. 3 is a fragmentary view, partially broken away, of a portion ofa modified embodiment in which electrical heating is employed; and

FIG. 4 is an electrical diagram showing in full lines 7 the electrical set-up when a burner is employed, and in broken lines an electrical heating unit which may be used with air alone admitted to the heat generating chamber, instead of fuel.

An external framework 10 of the dryer is indicated in broken lines in FIG. 1. This framework is without patentable significance, being purely conventional. Within the framework there is provided a solid, stationary cylinder 12, and within the cylinder 12, but spaced therefrom and in coaxial relation therewith, is a motor driven, rotary, perforated cylinder 14, desirably equipped with clothes tumbling fins 15. The cylinder 12 is closed at its rear end by a fixed rear wall (not shown), and at its forward end by a hinged, circular door (not shown). The rotary perforated cylinder 14, together with the rear wall and the hinged door, defines a tumbling and drying chamber.

In the form of the invention shown in FIGS. 1 and 2, a pilot light 16, located in a heat generating chamber 16a, burns continuously. The pilot light 16 is furnished with a mixture of gas and air from a supply line 17. When the tumbling and drying chamber, bounded in part by the cylinder 14, has been loaded with clothes, a drying cycle is initiated by manual closing of a master control switch 18 to drive the cylinder 14 continuously and to initiate. through energization ofa solenoid 19,.

drying medium, travel through a conduit 21 to the interior of cylinder 14 for intermingling with the clothes to.

be dried. The drying medium takes up moisture from the clothes and, in a more humid condition, is sucked out of the drying chamber through a conduit 22 and a removable lint filter 2211 by a fan 24. i

The output of fan 24 is delivered through a conduit 26, and then through a reheating chamber 25 which surrounds the heat generating chamber a in intimate heat exchanging relation therewith. The drying medium then passes from the reheating chamber to a conduit 28 through an aspirator which sucks in dry atmospheric air. The aspirator comprises a discharge pipe a of very small diameter, through which all the dry ing medium travels at comparatively high velocity, and hence at considerably reduced pressure, being delivered at that reduced pressure into the introductory end of conduit 28. The introductory end of conduit 28 is supported in the mouth of pipe 2512 by means of pins 250, being maintained out of contact with the pipes 25a and 25b.

The drying medium is drawn into the conduit 28 by a second fan 29. The fan 29 discharges into a conduit 30 which delivers into a neutral chamber 31 through progressively larger pipe segments 32 and 33, each of these segments being open at both ends. The chamber 31 can discharge to the atmosphere through a pipe 41 if the pressure in the system exceeds atmospheric pressure, or it can return the circulated drying medium, or any unexpelled portion of it, to and through the heat generating chamber for recirculation.

When heat is being supplied by the burning of gas in the main burner 20 of the heat generating chamber, the requisite air and gas are supplied to the burner from outside so that spent drying medium in the system is displaced and caused to be discharged by the freshly introduced. hot products of combustion. but when the principal burner is shut off and only a pilot burner remains lighted, the combustion products freshly introduced are reduced to a substantially negligible quantity, and virtually no drying medium is discharged. In these circumstances the drying medium present in the system at shut-off of the main burner will travel around and then through the tumbling and drying chamber again and again. taking up moisture each time until the lower limiting temperature of the tumbling and drying chamber has been reached. Each time round the drying medium is caused to pass through the reheating chamber and through the heat generating chamber.

This heats the drying medium. causing its absorptivity to be increased.

The same principle is applicable when electrical heating is employed as illustrated in FIG. 3. Conversion of the dryer of FIGS. I and 2 for electric heating involves very little changing. The main burner 20 is replaced by an electric heater 48 in the heat generating chamber, and air rather than a mixture of gas and air is supplied in response to energization of solenoid 19.

to the heat generating chamber. The other structure. with the exception of a slight modification of the electrical supply system may be the same as in FIGS. I and 2, and consequently the same reference characters as in FIGS. 1 and 2 havebeen applied to corresponding .7 parts of FIG. 3. with the postscript x added in each in stance. and no further description of the duplicated parts will be given.

FIG. 4 shows the requisite wiring for the dryer FIGS. 1 and 2 in full lines, and the only modification of j the full line arrangement for electrical heating is shown a I in broken lines.

Referringfirst to the full line sh0wing.a source 42*of electrical energy may be connected to a conductive active. Either switch,.throughout its assigned temperature range, will energize solenoid l9to bring about the feeding of an appropriate gas and airmixture to'the main burner, the conduct0r 49 serving as a'return conv ductorfor the solenoid 19.

The only change in the described circuitry required for electrical heating involves the addition of conductor 50 and the electrical heating unit 48 in the heat generating chamber 20a.

I have described what I believe to be the best embodiment of my invention. What I desire to coverby letters I patent is set forth in the appended claims.

I claim: I v

1. A clothes dryer having a drying system that 'includes, in combination,

. a. aheat generating chamber having been generating 1 means therein; H

b. a clothes tumbling and drying chamber;

c. a first conduit running from the heat generating chamber to the tumbling and drying chamber and communicating exclusively with said chamber so that essentially all gaseous drying medium introduced through the heat generating chamber is 'required to pass to and through the'turnbling and dry- I i ing chamber;

d. asecondconduit rneansconnected to gaseous drying medium from the tumbling and dry,-'

ing chamber to a reheating chamber which surrounds the heat generating chamber .in intimate heat exchanging relation therewith;

e. a third conduit means connected to deliver thedryj ing medium from the reheating chamber to a new tral chamber having discharge openings'one from which it maybe discharged to the atmosphere. and the other connected to said heat generating chaniber sothat part ofsaid drying medium may befref turned for recirculation through the heat generating chamber:

f. drying medium impelling means in certain. of said conduits for causing the drying medium to progress as described:

g. thermostatic switch means associated with the tumbling and drying chamber and responsiyeto the f temperature thereof; and V I h. means responsive to. said thermostatic. switch means for activating the heat generating means and causing drying medium to be freshly introduced from the heat generating chamber for transmittal in its entirety to and through the tumblingand drying chamber so long as the temperature in the tumbling v conduct the and drying chamber has not attained a predetermined maximum value, but effective upon the attainment of such maximum value to cut off the furnishing of fresh drying medium through the heat generating chamber and to suspend the generation of heat in said chamber, with the consequence that drying medium already in the system at such cutoff is caused to recirculate through said chambers, including particularly the heat generating chamber, until the temperature in the tumbling and drying chamber has fallen to a predetermined minimum, at which point the thermostatic means reinstitutes the generation of heat in the heat generating chamber and the delivery of fresh drying medium therefrom. 2. A clothes dryer as set forth in claim 1 in which an aspirator is provided between the reheating chamber and the neutral chamber through which fresh dry air is drawn into the system for replacing a like quantity of damper drying medium.

3. A clothes dryer as set forth in claim 1 in which the heat generating chamber includes a constantly lit pilot burner and a principal burner of the Bunsen type, so that heating medium supplied to the principal burner in the heat generating chamber under thermostatic control takes the form of gaseous fuel admixed with air in correct proportion for clean, non-luminous combustion.

4. A clothes dryer as set forth in claim 1 in which the heat generating chamber includes electrical means and air intake valve means controlled in common from the thermostatic switch means.

Claims (4)

1. A clothes dryer having a drying system that includes, in combination, a. a heat generating chamber having heat generating means therein; b. a clothes tumbling and drying chamber; c. a first conduit running from the heat generating chamber to the tumbling and drying chamber and communicating exclusively with said chamber so that essentially all gaseous drying medium introduced through the heat generating chamber is required to pass to and through the tumbling and drying chamber; d. a second conduit means connected to conduct the gaseous drying medium from the tumbling and drying chamber to a reheating chamber which surrounds the heat generating chamber in intimate heat exchanging relation therewith; e. a third conduit means connected to deliver the drying medium from the reheating chamber to a neutral chamber having discharge openings, one from which it may be discharged to the atmosphere, and the other connected to said heat generating chamber so that part of said drying medium may be returned for recirculation through the heat generating chamber; f. drying medium impelling means in certain of said conduits for causing the drying medium to progress as described; g. thermostatic switch means associated with the tumbling and drying chamber and responsive to the temperature thereof; and h. means responsive to said thermostatic switch means for activating the heat generating means and causing drying medium to be freshly introduced from the heat generating chamber for transmittal in its entirety to and through the tumbling and drying chamber so long as the temperature in the tumbling and drying chamber has not attained a predetermined maximum value, but effective upon the attainment of such maximum value to cut off the furnishing of fresh drying medium through the heat generating chamber and to suspend the generation of heat in said chamber, with the consequence that drying medium already in the system at such cut-off is caused to recirculate through said chambers, including particularly the heat generating chamber, until the temperature in the tumbling and drying chamber has fallen to a predetermined minimum, at which point the thermostatic means reinstitutes the generation of heat in the heat generating chamber and the delivery of fresh drying medium therefrom.

2. A clothes dryer as set forth in claim 1 in which an aspirator is provided between the reheating chamber and the neutral chamber through which fresh dry air is drawn into the system for replacing a like quantity of damper drying medium.

3. A clothes dryer as set forth in claim 1 in which the heat generating chamber includes a constantly lit pilot burner and a principal burner of the Bunsen type, so that heating medium supplied to the principal burner in the heat Generating chamber under thermostatic control takes the form of gaseous fuel admixed with air in correct proportion for clean, non-luminous combustion.

4. A clothes dryer as set forth in claim 1 in which the heat generating chamber includes electrical means and air intake valve means controlled in common from the thermostatic switch means.

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