US3411219A - Dryness control - Google Patents

Description

Nov. 19, 1968 R. w. BARTHOLOMEW 3,411,219

DRYNESS CONTROL Filed Feb. 17, 1967 a Sheets-Sheet 1 ATTORNEY-7 Nov. 19, 1968 R. WFBARTHOLOMEW 3,411,219

DRYNESS CONTROL Filed Feb. 17, 1967 s Sheets-Sheet 2 INVENTOR. RUSSELL W BARTHOLOMEW FIGS ATTORNEY-S United States Patent 3,411,219 DRYNESS CONTROL Russell W. Bartholomew, Worthington, Ohio, assignor to Ranco Incorporated, Columbus, Ohio, a corporation of Ohio Filed Feb. 17, 1967, Ser. No. 616,882 Claims. (CI. 34-45) ABSTRACT OF THE DISCLOSURE A clothes dryer comprising a frame having a rotating drum therein through which heated air is passed to dry fabrics which are tumbled in the drum, the control of the heated air being effected by a moisture sensing circuit means including two electrodes adapted to be bridged by fabrics in the drum, the electrodes being disposed on a nonrotating part of the frame.

The present invention relates to fabric article drying apparatus and more particularly to fabric drying apparatus including dryness control circuitry for terminating a drying cycle of the apparatus in response to electrical resistance of fabrics being dried therein.

Fabric article drying apparatus having control circuitry for terminating a drying cycle of the apparatus have been constructed utilizing electrodes carried by an article tumbling drum, or the like. Such electrodes are engaged by articles in the drum to establish an electric current path through the articles having an electrical resistance which is dependent upon the moisture content of the articles. Such controls are generally constructed utilizing circuit elements which cooperate to perform a control function, such as energizing a relay to terminate operation of the apparatus, when the article resistance reaches a predetermined level. The use of electrodes mounted in the drum generally involves the use of slip rings to connect the electrodes into the control circuitry. .It has been found that slip rings generate undesirable electrical noise. Additionally, construction of slip ring assemblies involves the use of relatively large quantities of insulating materials and numerous conductive parts. The numerous parts used in slip ring assemblies tend to produce leakage and increase the possibility of short circuiting in the electrode circuits. Moreover, the parts of the assemblies are subject to wearing over a period of time. Leakage and wearing change the resistance of the slip ring assembly which produces corresponding false indications of article dryness to the function control circuitry and premature termination of drying cycles. The present invention provides a dryness control construction wherein slip ring assemblies and the problems associated therewith are eliminated.

A principal object of the present invention is th provision of a new and improved fabric article drying apparatus having a rotatable drum, or container, for agitating fabric articles to be dried and in which a forced flow,of heater air is circulated through the container so as to effect drying of the articles, and which includes circuitry for controlling functions performed by the apparatus in response to moisture content of the articles therein, which circuitry includes electrodes positioned for contact with articles in the container and connected to the control circuitry through a conductive path comprised of conducting members which are fixed against movement relative to each other during operation of the drying apparatus.

Another object of the present invention is the provision of new and improved drying apparatus as set forth ice ing a drying cycle of the apparatus, and wherein the electrodes are fixedly secured to the access door and extend therefrom into the container so that articles being agitated in the container wipe the electrodes to effect moisture sensing by the control circuitry.

Another object of the present invention is the provision of a new and improved article drying apparatus including a chassis rotatably supporting a drum-like container therein which is adapted to receive fabric articles to be dried, means for providing a forced flow of heated air through the container and into contact with the articles to effect drying thereof and circuitry for controlling operation of the apparatus in response to moisture content of articles in the container including electrodes fixed to an insulating member which extends from the chassis into the container for contact with articles, the electrodes being spaced a short distance from each other whereby articles bridging the electrodes provide a voltage drop thereacross which is a function of the dryness of the articles and wherein the electrodes are connected in the control circuitry by wire-like conductors and connections which are fixed against movement relative to each other.

Other objects and advantages of the present invention will become apparent from the following detailed description thereof made with reference to the accompanying drawings and wherein:

FIG. 1 is a vertical sectional view of a clothes dryer embodying the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken approximately within the circular line 2 of FIG. 1 and on a scale which is larger than the scale of FIG. 1;

FIG. 3 is a schematic illustration of a control circuit forming a part of the dryer of FIG. 1:

FIG. 4 is a fragmentary vertical sectional view of a modification of the clothes dryer of FIG. 1;

FIG. 5 is a fragmentary sectional view taken approximately within the circular line 5 of FIG. 4 and shown on a scale which is larger than the scale in FIG. 4;

FIG. 6 is an elevational view of a modification of a clothes dryer embodying the invention;

FIG. 7 is a fragmentary sectional view taken approximately at line 77 of FIG. 6 on a scale which is larger than the scale of FIG. 6;

FIG. 8 is a fragmentary elevational view of an interior portion of another modification of a clothes dryer embodying the invention;

FIG. 9 is a sectional View taken approximately at line 99 of FIG. 8 and on a scale which is larger than the scale of FIG. 8;

FIG. 10 is a sectional view taken approximately at line 10-10 of FIG. 9 and on a scale which is larger than the scale of FIG. 9;

FIG. 11 is a sectional view of a further modified clothes dryer embodying the invention; and

FIG. 12 is a sectional view taken approximately at the line l212 of FIG. 11.

A domestic clothes dryer 10 is illustrated in the drawings and comprises a cabinet, or chassis, '11 having a frame member 12 therein which rotatably supports a perforated drum-like container 13 which may be loaded with clothes or similar fabric material to be dried through an access door 14 which is hinged at 15 to the cabinet 11. For this purpose, the drum 13 includes an access opening 13a at its right end, as viewed in FIG. 1, which opening lies in a plane extending transversely of the axis of rotation of the drum. The opening 13a is surrounded by aradially outwardly extending flange portion 13b of the container which cooperates with an annular felt gasket, or the like, 11a supported by the cabinet 11.

The drum 13 is rotated to agitate, or tumble, the articles therein by a drive motor 17 drivingly connected to the drum through suitable transmission means as a belt 18 and pulleys 19, 20 which are secured to the motor output shaft 21 and a drum shaft 22, respectively. The motor 17 additionally drives a suitably constructed blower 23 which induces a forced fiow of air through an intake opening 25 in the chassis 11, through the container 13 by way of the perforations therein, and through an exhaust duct 26 to the exterior of the cabinet.

Air which is drawn through the intake opening 25 is passed across an air heating means such as an electrical resistance type heater 27, or its equivalent, prior to passing through the container 13 and when the heater 27 is energized, air passing thereacross is heated to effect drying of the articles in the drum in a manner which is known. The motor 17 and heater 27 are energized from a conventional domestic three-wire power supply (see FIG. 3) which provides 220 volts AC across the lines L1, L2 and 110 volts AC across the lines L1, LN and L2, LN, respectively. The motor 17 is connectable across the lines L1, LN, while the heater is connectable across the lines L1, L2. The energization circuits for the motor and heater will be describe in detail presently.

The door 14 is associated with a suitable switch generally indicated at 16 which includes a movable contact 16a and fixed contacts 16b, 160, so that when the door 14 is opened to permit insertion or removal of articles from the container 13, or inspection of the articles therein, the contacts 16a .and 160 are closed to interrupt the energizing circuits for the motor 17 and air heating means 27, and which circuits will be described presently. When the door 14 has been closed, the contacts 16a and 16b are closed permitting the motor 17 and heater 27 to be energized. The provision of door switches, such as the switch 16, is standard practice and any suitably constructed switch may be utilized in conjunction with the door 14. Energization of the motor 17 and of the heater 27 is controlled by circuitry 30 (FIG. 3) which includes a function selector switch generally indicated at S in FIGS. 1 and 3. The function selector switch S is provided with a control knob K which may be manually rotated by the operator of the dryer to any one of a plurality of positions to select an operating mode for the dryer. Three such positions have been illustrated in the drawings which correspond to dry, damp dry, or air fluff but it should be appreciated that any reasonable number of such positions can be provided. When selection of a particular operating mode has been made by the operator, the knob K is pulled out to start operation of the dryer 10.

Assuming that the container 13 has been loaded with wet clothes, the door 14 has been closed, and the function selector switch has been rotated to its dry position and pulled out, as described, an energizing circuit for the motor 17 is completed from the line L1 through a junction 40, junction 41, closed contacts 39a, 39b, of the switch 39, junction 42, the contacts 16a, 16b of the door switch 16, a junction 43, a motor protector switch generally indicated at 44, the windings of the motor 17, and a junction at the common line LN. A suitable lamp 46, which may be of the germicidal type, is connected in parallel with the motor 17 between the junction 42, and a junction 47, at the neutral LN .and is lit when the motor 17 is energized.

The motor 17 is mechanically linked to a switch in an energizing circuit for the air heater means 27 so that upon operation of the motor 17, an energization circuit for the heater means can be traced from the line L1 through the junctions 40, 41, the contacts of a normally closed switch 51, the heater 27, a thermostat generally designated 52, the contacts of the switch 50, and to a junction 53 at the line L2.

In the preferred embodiment, the dryer 10 is adapted to perform a series of functions, or operations, during the course of a drying cycle. While other functions can be performed, the illustrated dryer is operative to complete its dry portion of the cycle as will be described, and

subsequently go through a fluff dry portion of the cycle wherein the articles in the drum are tumbled with air at ambient, or room, temperature circulated therethrough to permit handling of the dried articles after completion of the dry cycle without discomfort to the operator which might otherwise result from the relatively high temperature of the articles.

The dryer 10 includes circuitry for controlling the functions performed thereby in response to the moisture content in the articles being dried. The control circuitry includes an input, or signal, circuit 55 which produces a signal voltage level at a point 56 in the circuitry which depends on the moisture content of the articles being dried, and voltage responsive function control means 57 operable to initiate performance of a control function of the dryer in response to a predetermined voltage level at the point 56. The signal circuit for the control means 57 can be traced from the line L1, through the junctions 40, 41, the contacts of the switch 39, junction 42, the switch 16, junction 43, a junction 60, a capacitor C1, a junction 61, the anode and cathode electrodes of a diode D1, junction 62, a resistor R1, contacts 63b, 63a of a switch 63, contacts of a switch 64 at the point 56, a resistor R2, contacts 65b, 65a, of a switch 65, article dryness sensing means generally designated at 66 and to a junction 67 at the line LN. The junctions 60, 62 in the signal circuit are coupled by a regulated voltage doubler comprising the capacitor C1 and diode D1, and is generally indicated .at C. The voltage doubler C is described in detail in US. patent application Ser. No. 548,771, now Patent No. 3,364,586, issued Jan. 23, 1968, assigned to Ranco Incorporated.

The switch 63 is connected to the knob K such that the moving contact 63a thereof can be selectively engaged with the contacts 63b, 630, or 63d which are associated with resistors R1, R3, R4, respectively, by rotation of the knob to provide different degrees of dryness of the articles in the container 13 as mentioned previously. With the switch 63 positioned as illustrated, the resistor R1 and the articles in the container 13, which are in contact with the sensing means 66, form a voltage divider which provides the aforemetnioned signal voltage level at the point 56 which depends upon the conductivity of the articles contacting the sensor 66. As is known, the conductivity of the articles is dependent upon the moisture content thereof. As the articles dry, the voltage level at the point 56 increases and when the voltage level reaches a predetermined value, the function control means 57 is triggered to initiate a subsequent function of the dryer. The triggering circuitry of the function control means may be of any suitable construction and one such construction is described and illustrated in US. patent application Ser. No. 373,947, now Patent No. 3,330,047, issued July 11, 1967, assigned to the assignee of this invention.

In the illustrated dryer, when the function control means 57 is triggered, contacts 70a, 70b of a switch 70 are momentarily closed to complete an energization circuit for a stepping solenoid 71 which circuit may be traced from the line L1 through switches 39, 16, to the junction 43, through the junction 60, the solenoid 71, the contacts of the switch 70 and to a junction 72 at the line LN. The stepping solenoid 71 is associated with a suitable linkage for closing the contacts 64a, 64b of the switch 64 and opening the switch 51 to de-energize the heating means 27. Closing of the contacts 64a, 64b of the switch 64 connects the resistor R4 and the function control means 57 in series whereby the function control means is responsive to the voltage at the contacts 64a, 64b of the switch 64.

After a period of time which is determined by the construction of the function control means 57, the contacts 70a, 70b of the switch 70 are again momentarily reclosed in response to operation of the function control means 57, resulting in opening of the contacts 39a, 39b of the switch 39 by operation of the solenoid 71 and its associated linkage, to terminate operation of the dryer. A suitably constructed linkage usable in conjunction with the stepping solenoid 71 for performing the noted functions, is disclosed in the aforementioned US. patent application Ser. No. 373,947.

In accordance with the present invention, the sensing means 66 includes electrodes which are engageable with the articles in the container during tumbling thereof and which are connected into the signal circuit 55 through conductive paths comprised of electrically conductive parts which are fixed against relative movement during operation of the dryer 10. As illustrated in FIGS. 1 and 2, the sensing means 66 includes electrodes 80, 81, which are each constructed of a conductive, noncorrosive material, such as stainless steel, and attached to a generally cone-shaped member 82 composed of a nonconducting plastic material which is fixedly secured to the internal surface 14a of the door 14. The base portion 84 of the member 82 is secured to the surface 14a of the door 14 and the apex portion 85 thereof projects into the container 13 beyond the plane of the access opening therein. In the embodiment illustrated in FIG. 1 and FIG. 2, the body 82 is constructed to provide a generally conical cavity 83 therein.

The electrodes 80, 81 are suitably embedded in the material of the member 82 adjacent its apex and encircle the member at closely spaced locations so that articles being tumbled in the container at its right hand end, as viewed in the drawings, fall onto the member 82 and slide across the electrodes 80, 81 before falling to the bottom of the container. The electrodes 80, 81 are connected to suitable fasteners 86, 87 which extend through the wall of the member 82 and into the cavity 83 and which fasteners are electrically connected to conductors 90, 91 connected into the signal circuit 55 at the junction 67 and the switch 65. The conductors 90, 91 are insulated Wires which are of sufficient length to permit opening and closing of the door 14 without undue bending or stressing thereof. It should also be apparent that a suitably constructed switch could be associated with the door 14 so as to connect the electrodes 80, 81 into the input circuit 55 when the door is closed and open the signal circuit when the door is open.

The apex 85 of the member 82 extends from the door and into the container 13 as described, and the sliding action of the articles, or clothing across the electrodes produces a relatively low resistance electrical contact between the eletrodes and the articles being dried to establish a voltage drop across the articles which provides the aforementioned voltage level at the point 56 in the signal circuit 55. In addition to the low resistance contact between the articles being dried and the electrodes 80, 81, the signal circuit 55 is devoid of any relatively movable parts forming electrical connections, such as slip rings, thus eliminating the problems of electrical noise, potential leakage and short circuits, and wearing associated with such connections.

FIGS. 4 and 5 illustrate a modified portion of a dryer embodying the invention wherein parts which are similar to parts previously described are illustarted by corresponding primed reference characters. As illustrated in FIGS. 4 and 5, the door 14 includes a metallic dish-like member 81 which provides the inner surface 14a of the door 14 and projects into the container 13 beyond the plane of the access opening therein. The dish-like member 81' is composed of a conductive noncorrosive material so as to form one electrode of the sensor 66' and for this reason is electrically insulated from the door 14' by a suitably constructed insulator 93.

The electrode 81' supports an electrode 80' adjacent its lower edge, as viewed in the drawings, and which electrode 80' is composed of a conductive, noncorrosive material, such as stainless steel, in the form of a button, or knob, which projects into the container 13 from the member 81. The electrode 80' is separated from the electrode 81' by a washer-like member constructed of insulating material which is interposed therebetween.

The electrode 80 includes a threaded shaft, or rod, 96 composed of a conductive material which extends through a suitable opening in the electrode 81' and into a space 97 between the electrode 81 and the door 14'. The shaft 96 is surrounded by a suitable bushing 100 composed of an insulating material which provides an electrically nonconductive support between the shaft 96 and the electrode 81. The threaded end of the shaft 96 receives a nut or similar fastener member 101, which is advanced on the threads to compress a conductor 90' into electrical contact therewith and to maintain the electrode 80' in a fixed position on the door 14. A conductor 91' is suitably fastened to the electrode 81 by a solder joint, or similar connection, to assure good electrical contact therebetween.

It is apparent from the description above that the articles being tumbled in the container 13 impinge on the electrodes 80, 81' and slide across the electrodes while falling toward the lower portions of the container. The sliding action thus obtained produces the aforementioned low contact resistance connection of such articles into the signal circuit 55.

As illustrated in FIGS. 6 and 7, the interior of the door 14' is provided with a panel-like disc composed of insulating material which supports conductive metallic strips 106, 107 forming the electrodes of the moisture sensing means. The member 105 is secured to a panel-like member 108 which is fixed to the door 14 and which member is dished so as to project into the article receiving container beyond the plane of its access opening to thereby support the member 105 and electrodes 106, 107 within the container as described above.

In the form of the invention illustrated in FIGS. 6 and 7, the strips 106, 107 are embedded in the member 105 so as to be flush wit-h the surface 105a thereof which is exposed to the tumbling articles in the article receiving container. The electrodes 106, 107 are electrically connected to rod-like conductors 110, 111, respectively, which are threaded at their ends and extend through the insulator member 105 and panel 108 to a chamber formed between the door 14 and the panel 108. The threaded ends of the rods 110, 111 receive suitable nut-type fasteners which are advanced thereon to provide electrical contact between the rods 110, 111 and conductors 112, 113, as described above in reference to the electrode 80' of FIG. 5, and which conductors are connected into the signal circuit as described above in reference to the conductors 90, 91. The rods 110, 111 are surrounded by bushings 117, 118 constructed of insulating material as described above in reference to the bushing 100 of FIG. 5 and which prevents conduction between the rods 110, 111, and the panel 108 of the door 14.

FIGS. 8-10 are illustrative of a further embodiment of the invention in a modified clothes dryer 10', only a part of which is shown. FIG. 8 is a view of the interior of a drum 13' of the dryer 10, looking toward the access opening 14a and door 14'. The access opening 140 is a generally D-shaped aperture in the front of the dryer and is tightly closed by the door 14' which includes a generally rectangular body 14b having a D-shaped raised area 14c on its interior side which projects into the opening 14a when the door is closed.

The chassis 11' of the dryer 10' includes a generally circular bezel having an inner periphery 126 surrounding the access opening 14a and an outer periphery 127 adjacent a radially inwardly projecting flange portion 130 of the drum 13'. A suitable seal 131 is disposed between the bezel 125 and the flange 130 (see FIG. 9) to prevent leakage of air therebetween.

A generally semicircular exhaust opening 134 is located between the inner periphery of the bezel 125 and the lower portion 135 of the door sill as viewed in FIG. 8. The opening 134 is covered by a metallic screen-like member 136 which is suitably connected to the bezel and door sill as illustrated in FIG. 9. The exhaust opening 134 communicates with an exhaust duct, only a part of which is shown at 137, which in turn communicates with a suitable fan which induces a flow of air through the drum and exhausts the air from the rear of the machine. A lint filter 138, shown in broken lines in FIG. 9, is positioned in the duct portion 137 behind the screen 136 so that lint from fabrics in the drum may be removed from the air before it is exhausted from the dryer. The lint filter is supported by the door sill portion 135 and can be lifted out of the duct by the operator of the dryer when the door is open, for disposal of accumulated lint therein. Except for the above noted differences, the dryer 10 is constructed similarly to the dryer 10 of FIG. 1.

As best illustrated in FIG. 10, the screen 136 supports a sensor, or electrode, 140 which is connected into the function control circuitry by the conductor 91. The electrode 140 is preferably constructed of a section of stainless steel tubing which is flattened at its ends 141, 142 and which flattened ends are clamped to the screen member 136 by suitable fasteners, such as bolts 143 which are received in apertures in the ends 141, 142 and the screen member 136 for reception of nuts at the opposite side of the screen member. A plate-like insulator 145 is disposed between the ends 141, 142 of the sensor and the screen to prevent conduction therebetween and, as illustrated, the bolts 143 extend through apertures in the insulator. The threaded ends of the bolts and their associated nuts are electrically isolated from the screen by annular shouldered insulator members 145 which are disposed between the nuts and the screen with the shoulder of the insulator 145 extending into the aperture in the screen member to insure against electrical leakage between the bolts and the screen. As illustrated in FIG. 10 the conductor 91 is secured between the bolt 143 and its associated nut at the end 141 of the electrode 140.

The electrode 140 is suitably bent adjacent its ends to provide a substantially cylindrical section 146 intermediate the ends and which cylindrical section is spaced away from the screen 136 into the drum 13' for engagement with fabrics being tumbled in the drum. The screen 136 and bezel 125 are grounded to provide a second electrode spaced electrically from the electrode 140. Clothing which is tumbled in the drum engages the electrode 140 and the screen member 136 and bezel 125 to provide the aforementioned conductive path between the electrodes. Due to positioning of the electrodes at the exhaust opening 134, fabrics being tumbled in the drum tend to be moved toward the electrodes by the air fiow in the drum to insure substantially continuous sensing of the moisture content thereof.

FIGS. 11 and 12 illustrate a further modified dryer embodying the present invention and which includes a chassis supporting a drum 161 for rotation therein by an electric drive motor 162. The drum 161 is a generally cyindrical member having openings at its opposite ends and supported for rotation about its axis by roller assemblies 163, 164.

Each roller assembly includes a rotatable shaft 165 which extends parallel to the axis of the rotation of the drum 161 and is supported at its ends by suitable bearings, not shown, in the front and rear walls of the chassis 160. Rollers 166, 167 are fixed to the shaft 165 for rotation therewith. The peripheries of the rollers 166, 167 engage the outer periphery of the drum member 161 and are constructed of a suitable frictional material, such as hard rubber, to establish a frictional driving connection between the peripheries of the rollers and the drum. The shaft 165 of the roller assembly 164 is driven from the motor 162 through a suitable endless belt and pulley arrangement including a pulley 170 fixedly connected to the shaft 165. The belt is trained around the drive pulley 171 associated with the drive shaft of the motor 162, the pulley 170 and an idler pulley 172. The rollers 166, 167

of the roller assembly 164 are driven from the motor to effect rotation of the drum member 161, while the rollers of the roller assembly 163 are undriven and provide a bearing against which the drum periphery runs.

The motor 162 additionally drives a fan 23 which draws air into the chassis through a duct 175, across a heater coil 176 and into the drum 161 through a generally rectangular opening 177 at its rear end, as viewed in FIG. 11. In the illustrated embodiment the opening 177 is formed in a generally circular end plate or panel 180 connected to the chassis and which includes a frustoconical wall portion 181 adjacent a radially inwardly projecting flange 182 of the drum 161. The frusto-conical wall portion 181 is fixed against rotation relative to the chassis and a suitable seal is disposed between the flange 182 of the drum 161 and the frusto-conical portion of the panel 180 to minimize leakage of air therebetween. Air which has passed through the drum 161 is directed therefrom through an exhaust opening 185 at the front of the drum, as viewed in the drawings, and located at the lower side of the access door. The exhaust opening is covered by a suitable screen 186 and may be associated with a lint trap 187 in the exhaust air duct as described above in reference to FIGS. 8 and 9.

The panel 180 supports an electrode 190 which is connected into the function control circuitry by the conductor 91, as described above. The electrode 190 is preferably constructed in the same manner as described in reference to FIG. 10. The panel 180 is grounded to the chassis 160 to form the second electrode so that fabric tumbling in the drum bridges the electrodes to control operation of the function control circuitry in the manner which has been described.

Although a number of dryer constructions embodying the present invention have been illustrated and described herein in considerable detail, the invention is not to be considered limited to the precise constructions disclosed.

It is my intention to cover hereby all adaptations, modifications, and uses of the present invention which come within the scope of the appended claims.

Having described my invention, I claim:

1. A fabric dryer comprising a frame, a container supported for rotation about an axis by said frame, said container including an access opening for receiving fabric to be dried with said opening lying in a pane generally transverse to said axis, motor means for rotating said container to effect tumbling of said fabric, air circulating means for producing a flow of air for impinging on said fabric in said container and exhausting said air from said container, means for heating said air prior to contact with said fabric, and circuit means for controlling operation of said heating means in response to moisture content of said fabric comprising a signal circuit for providing a control signal to said circuit means, said signal circuit including moisture sensing means supported by said frame and stationary relative to said container during movement thereof by said motor means, said sensing means including a first electrode projecting into said container for engagement with said fabric during tumbling thereof and means providing a second electrode spaced from said first electrode and engageable with said tumbling fabric, said first and second electrodes connected to said signal circuit through conductive paths comprised of electrically conductive parts which are fixed against relative movement during operation of said motor means to provide a voltage level at a point in said signal circuit which corresponds to the moisture content of fabric across said electrodes, said frame supporting an access door member adjacent said axis opening in said container and which door is movable to permit fabric to be inserted into and removed from said container, one of said electrodes attached to said door member by insulating means located on a surface of said door facing said container when said door is closed.

2. A fabric dryer as defined in claim 1 wherein said first and second electrodes include strips of conductive material supported by a body of insulating material which is fixed to said surface on said door member.

3. A fabric dryer as defined in claim 2 wherein said body of insulating material includes a generally coneshaped member having a base portion attached to said door member and an apex portion extending into said container when said door member is closed, said electrodes being integral with an external surface of said insulating member adjacent said apex.

4. A fabric dryer as defined in claim 3 wherein said electrodes are generaly frusto-conical strips which encircle said cone-shaped member and with adjacent edges of said strips separated by said insulating material.

5. A fabric dryer as defined in claim 2 wherein said body of insulating material includes an insulating member fixed to said door member, said insulating member including a generally planar surface exposed to said fabric when said door member is closed, and said electrodes attached to said planar surface at closely spaced locations thereon.

6. A fabric dryer as defined in claim 2 wherein said body of insulating material includes an insulating member fixed to said door member, said one of said electrodes attached to said insulating member at a location thereon Within said container and said other electrode forming a part of said door member.

7. A fabric dryer as defined in claim 6 wherein said other electrode includes a panel-like member providing a surface of said door member facing said container when said door member is closed and with said insulating member and said one electrode attached thereto and projecting toward said container beyond said plane of said access opening.

8. A fabric dryer comprising a frame, a container supported for rotation about an axis by said frame, said container including an access opening for receiving fabric to be dried with said opening lying in a plane generally transverse to said axis, motor means for rotating said container to effect tumbling of said fabric, air circulating means for producing a flow of air for impinging on said fabric in said container and exhausting said air from said container, means for heating said air prior to contact with said fabric, and circuit means for controlling operation of said heating means in response to moisture content of said fabric comprising a signal circuit for providing a control signal to said circuit means, said signal circuit including moisture sensing means supported by said frame and stationary relative to said container during movement thereof by said motor means, said sensing means including a first electrode projecting into said container for engagement with said fabric during tumbling thereof and means providing a second electrode spaced from said first electrode and engageable with said tumbling fabric, said first and second electrodes connected to said signal circuit through conductive paths comprised of electrically conductive parts which are fixed against relative movement during operation of said motor means to provide a voltage level at a point in said signal circuit which corresponds to the moisture content of fabric across said electrodes, and further including an exhaust duct for said air flow, said duct being fixed to said frame and opening into said container, said first electrode positioned adjacent said exhaust opening and said means providing said second electrode including a metallic member surrounding said exhaust opening.

9. A fabric dryer comprising a frame, a container supported for rotation about an axis by said frame, said container including an access opening for receiving fabric to be dried with said opening lying in a plane generally transverse to said axis, motor means for rotating said container to effect tumbing of said fabric, air circulating means for producing a How of air for impinging on said fabric in said container and exhausting said air from said container, means for heating said air prior to contact with said fabric, and circuit means for controlling operation of said heating means in response to moisture content of said fabric comprising a signal circuit for providing a control signal to said circuit means, said signal circuit including moisture sensing means supported by said frame and stationary relative to said container during movement thereof by said motor means, said sensing means including a first electrode projecting into said container for engagement with said fabric during tumbling thereof and means providing a second electrode spaced from said first electrode and engageable with said tumbling fabric said first and second electrodes connected to said signal circuit through conductive paths comprised of electrically conductive parts which are fixed against relative movement during operation of said motor means to provide a voltage level at a point in said signal circuit which corresponds to the moisture content of fabric across said electrodes, said first electrode including a generally tubular member composed of conducting material having an end portion fixed relative to said frame and electrically connected into said signal circuit, said end portion of said tubular member being flattened and said member being bent adjacent said flattened end to provide a cylindrical section of said tubular member extending into said container.

10. A fabric dryer as defined in claim 9 wherein said air circulating means is associated with a first duct for directing air into said container and a second duct for exhausting air from said container with one of said first and second ducts opening into said container, said means providing said second electrode including panel means adjacent said duct opening and fixed against rotation with respect to said frame, said tubular member supported by said panel means and insulated therefrom.

References Cited UNITED STATES PATENTS 2,991,641 7/1961 Woodling 3445 XR 3,300,869 1/1967 Bergeson et al. 34-45 FREDERICK L. MATTESON, IR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner.

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