US 3696521 A
A dual-zone clothes dryer in which a smaller drum is disposable within the main rotatable drum, with the smaller drum in such driven engagement with the main drum that it is rotated at a speed higher than that of the main drum, and suitable to achieve tumbling of clothes within the smaller drum.
Claims available in
Description (OCR text may contain errors)
[451 Oct. 10, 1972 United States Patent Hubbard  References Cited UNITED STATES PATENTS  LAUNDRY DRYER  Inventor:
1,005,342 10/1911 Simpson ....................259/57 Philadelphia, Pa.
Primary Examiner-Carroll B. Dority, Jr. Attomey-Carl H. Synnestvedt  Filed: Dec. 24, 1970  ABSTRACT A dual-zone clothes dryer in which a smaller drum is  Appl. No.: 101,308
 Us. CL 34/128 34/133 259/57 disposable within the main rotatable drum, with the  Int Cl F26b 11/02 smaller drum in such driven engagement with the I main drum that is rotated ataspeed higher than that  Field of Search..................34/128, 68/4, 259/57 of the main drum and suitable to achieve tumbling of clothes within the smaller drum.
7 Claims, 5 Drawing Figures LAUNDRY DRYER BACKGROUND OF THE INVENTION This invention is concerned with household laundry apparatus and especially with improvements in laundry dryers of the kind having a clothes-containing drum rotatable about a horizontal axis. In the use of dryers of this kind a clothes load may contain a variety of fabrics which require different conditions for optimum drying. For example different drying times and temperatures are desirable for fabrics of different types, and a degree of tumble agitation which is optimum for one type of fabric may not be the best for others. Frequently this is the case with more delicate fabrics. The result has been impairment of drying efficiency, particularly if a small load of delicate fabrics is to be dried in a large drum.
SUMMARY OF THE INVENTION It is my objective to provide a dual-zone clothes dryer which is not subject to the mentioned deficiencies. Broadly, this objective is achieved by utilizing the available capacity of the machine in such a way as to facilitate simultaneous drying of different types of clothing in separate drying zones. In achievement of this objective I utilize a drying basket or drum of smaller size, which may be contained within the larger drum, and provide for subjecting clothes loads within each drum to the drying action of air circulating within the machine. Since the air is introduced first into the larger drum and thereafter flows through the smaller drum, the air in the smaller drum is cooler, ensuring more gentle drying action therein. Optimum drying time for special fabrics is readily achievable, since the smaller drum may be removed from the machine at any time in the cycle.
' It is also an object of the invention to provide a dualzone drying machine operable by a single, very simple, motor drive.
The apparatus of the invention is featured by the ease with which the smaller drum may be loaded and installed within the larger and by the fact that provision of the two drums requires no major changes in drive means, controls or heating circuits.
In summary, this invention provides a dryer construction having a small drum within which delicate fabrics may be dried, and which drum may readily be associated with or detached from the machine to meet various drying requirements. In the preferred embodiment, the invention is featured by the fact that, while each drum is driven at a speed suitable to promote tumbling of the clothes therein, the smaller drum derives its movement wholly from the larger drum.
BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawings:
FIG. 1 is a perspective illustration of a horizontalaxis laundry dryer embodying the invention;
FIG. 2 is a side sectional-elevational view showing portions of the dryer of FIG. 1 on a larger scale;
FIG. 3 is a perspective illustration of the smaller drying drum shown disassociated from the drying machine;
FIG. 4 is an exploded view illustrating features of construction of the smaller drum and showing the manner in which it may be removably associated with the door of the dryer cabinet; and
FIG. 5 is a front elevational view of the two drums used in the machine, showing the drums disassociated from the dryer and illustrating the preferred manner of driving the smaller drum.
DESCRIPTION OF THE PREFERRED EMBODIMENT Making initial reference to FIGS. 1 and 2, the illustrated laundry dryer 10 comprises a generally rectangular cabinet 11 provided with a first, larger, open-end receptacle or drum 12 which ismounted within the cabinet through the agency of suitable bearing means 13-14 (FIG. 2). The open end of this drum confronts an aperture 15 provided in the forward portion of the cabinet, as is seen in FIG. 1. Suitable door structure, for example the swinging door shown at 16, is mounted on the cabinet for movements between a closed position (FIG. 2), in which it confronts the open end of the drum 12, and an open position in which access may be had to said drum. It will be understood that a suitable latch (not shown) would be provided to hold the door 16 in closed position.
Preferably the drum 12 is of cylindrical shape and its periphery is formed of imperforate sheet steel. Baffles 17 provide for tumbling of the clothes within the drum l2. Resistive heater means, shown diagrammatically at 18 in FIG. 2, is provided to heat the air which dries the clothes and it will be understood that the apparatus would further include motor means (not shown) for rotating the drum, for example, through the agency of a belt 19 which surrounds the drum. Air propelling means, shown diagrammatically as a fan identified at F, is provided for moving the air upwardly past the heater l8, thence through the perforated rear wall 20 of the drum and into contact with clothes contained therein. As thus far described the main drum and drive apparatus is conventional.
As shown by arrows designating air flow in FIG. 2, the circulating air flows toward the forward part of the drum l2 and, when the smaller drum to which detailed reference will be madehereinafter is not in place, exits directly through the open end of drum 12 and through perforations provided in the rear wall 21 of cabinet door 16. As shown by the arrows, the air completes its circulatory flow by passing downwardly through lint collecting means shown at 22 and thence to a suitable exit (not shown).
In particular accordance with this invention, the dryer is provided with a second receptacle or drum 23, smaller than the first drum. This second drum, which may conveniently be fabricated of molded plastic material to minimize the weight thereof, is provided with a fixed end wall 24 which is perforated, and with a removable perforated cap or wall 25 which is flanged, as shown at 26, (see particularly FIG. 4) releasably to retain the cap on the drum. The removable cap 25 provides access to drum 23, in the manner shown in FIG. 4, and serves also to retain a lint filter 27. This filter is supported between the removable cap wall 25 and a flanged portion 28 of smaller drum 23. The smaller drum is provided with baffles 29 which may be conventional in nature.
Drum 23 is removably and rotatably supported upon the door 16 and, for this purpose, the end wall 24 of drum 23 is provided with an extemalIy-splined shaft 30 which is receivable within an internally splined hollow shaft or socket structure 31 mounted in the door 16 through the agency of a journal 32 and a set of bearings 33. The end wall 24 of the smaller drum is provided with a flange 240 which seats against the front of the cabinet, as shown at 24b in FIG. 1, to prevent inadvertent dislodgement of the drum 23 when it is in use. To provide for driving the smaller drum at a desired speed, different than that of the larger drum, the journal 32 is so located and secured within the door that the socket structure 31 defines a rotational axis A for the smaller drum which is eccentric with respect to the axis B of the larger drum (FIG. 2).
As will now be understood, smaller drum 23 may readily be associated with and disassociated from the door and access may be had to its interior through the cap structure 25, 26. If desired, means (not shown) may be provided to cover the internally splined socket structure 31 when the smaller drum is not in use.
When the smaller drum is in use, circulating air flows first through the larger drum and thereafter through the smaller drum, exiting through perforated drum wall 24 into and through the door, as shown by the arrows in FIG. 2. As noted above it is of advantage, in drying certain fabrics, that the air is at a lower temperature by the time it reaches the smaller drum.
Preferably the wall 21 of the door is also perforated, as shown at 21a in FIG. 1, in a lower region which is not covered by the smaller drum when the latter is in place. This permits some outflow of air directly from the larger drum, even if the smaller drum is in use.
While the invention is not limited to use of drums of any particular size, the larger drum 12 may, for example, have a diameter of about 29 inches and its forward access opening 15a may have a diameter of about 18 inches. As shown below, when a larger drum having these dimensions is used, the smaller drum 23 will have a diameter of about 12 inches. A drum of this size is readily insertable within the larger drum when the door 16 is swung from the position shown in FIG. 1 to the position shown in FIG. 2.
As will be understood, the larger drum is driven through the belt 19 and drive motor (not shown) at a speed suitable to cause tumbling of fabrics contained therein, for example about 48 rpm, for a 29 inch drum. This speed, and use of appropriate baffles, provides a satisfactory tumble pattern.
In the broader aspect of the invention, any convenient means may be employed for driving the smaller drum at the proper tumble speeds. However, it is a feature of the preferred embodiment of my invention that a drive connection between the drums is established automatically when the second drum is positioned within the first, and it is highly advantageous that the smaller drum be driven by the larger drum. By use of such an arrangement it is possible to achieve speeds which are optimum for the achievement of tumbling in the two drums, without imposing any unusual requirements as to power or drive mechanism for the larger drum.
Frictional drive means may be interposed between the two drums, with the resultant advantage of low noise, but I prefer to use an internal gear secured to the larger drum l2 and extending around its opening 15a. This gear may comprise an internally toothed belt of suitable material, for example plastic material. An external gear is provided also preferably as a belt and extends about the periphery of the smaller drum, adjacent the region in which it is supported by the door.
The gearing arrangement appears to best advantage in FIGS. 1 and 5. The external belt gear 34 is secured in any suitable fashion, about the periphery of smaller drum 23, while the internal belt gear 35 extends and is secured by any convenient means around the access opening 15a of the larger drum and lies generally in the plane of said access opening, which is in registry with the opening in the forward wall of the cabinet. Although the gear teeth provided on the two belts need not be precisely formed, preferably they are of approximately involute shape. As the door 16, carrying the smaller drum, is swung toward theclosed position the external teeth of gear ring 34 are brought into engagement with the internal teeth of ring 35. The two drums are shown in FIG. 5 disassociated from the cabinet, and a portion of the forward wall of drum 12, which wall defines the drum opening 15a, is shown broken away to illustrate the engagement between the gears 34 and 35. If necessary the ends of the teeth may be bevelled to accommodate engagement and disengagement thereof.
As mentioned above, a drum 29 inches in diameter must be rotated at about 48 rpm to achieve a value of centrifugal force within the drum which is slightly less than the force of gravity. As is known in this art, a value for centrifugal force slightly less than gravity is required for proper tumbling in a horizontal axis clothes dryer. In any particular design the smaller drum must be of a diameter such that it will pass freely into the larger drum. Further, if it is to carry an external gear or friction means, the diameter of the smaller drum also must be so chosen that it rotates at a speed which results in a value of centrifugal force within said smaller drum which is slightly less than the force of gravity. As shown below, a smaller drum 12 inches in diameter meets these conditions.
The speed of rotation of the larger drum, multiplied by the ratio of the diameters of the two gears, equals the speed of rotation of the smaller drum. For simplicity in calculating the rotational speeds of the drums, the value given above for the diameter of the smaller drum (12 inches) should be understood as comprising the diameter of the pitch circle of its external gear. Similarly, the diameter of the opening 15a 18 inches) should be understood as being the diameter of the pitch circle of the internal gear carried by the larger drum.
Since, in the particular apparatus under consideration, the larger drum carries an internal gear which is concentric therewith and is 18 inches in diameter, and since the diameter of the external gear is approximately equal to that of the smaller drum, the speed of rotation of the smaller drum is 48 X 18/ l 2 72 rpm. This can be shown to yield a value for centrifugal force which is in the region of 0.9 G, and proper tumbling is achieved.
1. In apparatus for drying fabrics: a first open-end receptacle; means supporting said receptacle for rotation about a generally horizontal axis; door structure movable between a closed position in which it confronts the open end of said receptacle and an open position in which access may be had to said receptacle; a second receptacle smaller than said first receptacle;
means removably and rotatably supporting said second receptacle upon said door structure in a position such that closing of said door structure causes said second receptacle to be moved into said first receptacle and to occupy a position therein in which it may be rotated about a generally horizontal axis; means for driving said first receptacle at a speed suitable to cause tumbling of fabrics contained therein; and means for establishing a driving connection between said receptacles when said second receptacle is positioned within said first receptacle, the driving connection being such that said first receptacle drives said second receptacle at a speed higher than that of said first receptacle and suitable to cause tumbling of fabrics contained in said smaller second receptacle.
2. Apparatus in accordance with claim 1, in which said receptacles are perforated and there is included means for passing drying air into said first receptacle and for thereafter passing said air into and through said second receptacle.
3. Apparatus in accordance with claim 1, and further characterized in that said door structure is provided with journal means for rotatably and removably supporting said second receptacle.
4. A clothes dryer comprising: a cabinet; an openend drum rotatably supported by said cabinet, said cabinet having an opening in registry with the open end of said drum; a door normally closing said opening in said cabinet and movable to a position in which access may be had to the interior of said drum; and a second smaller drum carried by said door and normally disposed within the larger drum; the construction and arrangement being such that clothes contained within each of said drums are subjected to drying air circulating through the cabinet, and provision is made to rotate said drums simultaneously each at a speed suitable to produce tumbling of clothes therein.
5. In a dual-zone laundry dryer: a main drum rotatable about a substantially horizontal axis; means for driving said main drum at a speed suitable to tumble fabrics therein; a smaller drum disposed within the main drum and rotatable about a substantially horizontal axis eccentric with respect to the axis about which said main drum is rotatable; and means establishing a driving connection between said main drum and said smaller drum, said driving connection being such that said smaller drum is driven by said main drum at a speed higher than that of said main drum and suitable to tumble fabrics in said smaller drum.
6. Apparatus in accordance with claim 5, and further characterized in that said driving connection comprises: an internal gear carried by and concentric with the axis of rotation of said main drum; and an external gear carried by and concentric with the axis of rotation of said smaller drum and in driven engagement with said internal gear.
7. Apparatus in accordance with claim 6, and in which said main drum has a forward access opening, said internal gear surrounds said opening, and said external gear surrounds and is carried by the peripheral wall of said smaller drum.