US3616545A - Clothes dryer with means to vary centrifugal forces on the clothes - Google Patents

Abstract

A DOMESTIC CLOTHES DRYER HAS A TUMBLING DRUM, ROTATABLE ABOUT A HORIZONTAL AXIS, IN WHICH THE CENTER OF ROTATION FOR THE TUMBLING DRUM IS OFFSET FROM HE GEOMETRIC CENTER OF THE TUMBLING DRUM. AS THE TUMBLING DRUM ROTATES THE CLOTHES EXPERIENCE VARYING AMOUNTS OF CENTRIFUGAL FORCE DURING TUMBLING THEREOF TO VARY THEIR TUMBLING PATTERN WITH RESPECT TO A FIXED AIR STREAM.

Description

J W. JACOBS CLOTHES DRYER WITH MEANS TO VARY CENTRIFUGA Nov. 2, 1971 FORCES ON THE CLOTHES Filed NOV. 28, 1969 ATTORNEY United States Patent Oflice 3,616,545 Patented Nov. 2., 1971 3,616,545 CLOTHES DRYER WITH MEANS TO VARY CENTRIFUGAL FORCES ON THE CLOTHES James W. Jacobs, Dayton, Ohio, assignor to General Electric Corporation, Detroit, Mich. Filed Nov. 28, 1969, Ser. No. 880,609 Int. Cl. F26b 11/02 US. Cl. 34-433 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a domestic appliance and more particularly to an improved clothes dryer.

Conventional domestic clothes dryers have a fixed air stream through the tumbling drum. As clothes are tumbled during a clothes drying cycle, they are lifted b the baflles or vanes of the tumbling drum and dropped through the air stream toward the bottom of the tumbling drum. This action continues throughout the clothes drying cycle as the clothes give up their moisture. However, clothes during the cycle give up their moisture gradually and as they do the adhesion of the clothes to the tumbling drum lessens. This advances the point at which the clothes are dropped by the vanes. An early drop point tends to shift the clothes out of the air stream.

Accordingly, it is an object of this invention, during any one segment of a clothes tumbling cycle, to vary the point at which clothes are dropped through a fixed air stream.

Another object of the invention in a domestic clothes dryer is the provision of a cylindrical tumbling drum rotatably mounted offset from the geometric center of the tumbling drum whereby a major portion of the tumbling drum orbits about the axis of rotation.

Another object of this invention in a domestic clothes dryer is the provision of a tumbling drum configuration which varies the centrifugal forces experienced by the clothes during a tumbling operation.

A still further object of this invention in a domestic clothes dryer is the provision of a tumbling drum configuration which, during any given rotation thereof, varies the tendency of the clothes to cling to the wall of the tumbling drum.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIG. 1 is a front sectional view of a clothes dryer, partly in elevation, showing the mounting arrangement of the tumbling drum with respect to its enclosing cabinet; and

FIG. 2 is a top sectional view of the clothes dryer, partly in elevation.

BACKGROUND The prior domestic clothes dryer art has recognized the value of dropping clothes uniformly through a fixed air stream. In this way the clothes are exposed to the maximum drying effect of the air stream. However, this is not so easily done. The clothes tend to cling to the inside of the tumbling drum with a varying tenacity as they give up their moisture. The prior art has attempted to compensate for this variable by providing multiple speed drives for the tumbling drum. Thus the tumbling drum can be rotated more slowly when the clothes are wet and speeded up as the clothes dry. The attempt is to cause the clothes to follow the same drop path through the drying air stream throughout the clothes drying cycle. However, these prior art attempts to solve the problem have the disadvantage of multiple speed motors and complicated control systems. My invention solves the problem with a constant speed tumbling drum and can best be understood by briefly reviewing some theory relating to centrifugal forces.

To practice my invention it is well to understand the forces which act on a clothes load in a conventional concentrically rotating tumbling drum. For this purpose, I use the equation where F=force of the clothes load directed outwardly against the drum wall w weight of the clothes load in pounds g=the gravitational acceleration constant of 32.2 feet per second per second D=diameter of drum in feet R=radius of drum in feet N =revolutions of drum per second Using the formula and solving for N one finds that a one pound clothes load (w) in a two foot diameter drum (D) rotating at 54.6 revolutions per minute (r.p.m.) will just barely ride clear around the drum without tumbling. In practice, however, it has been found that the clothes do not perform as theoretical bodies in a clothes dryer.

They are not positively fastened to the drum and are influenced by air flow. Also, their ability to ride with the drum has been found to be influenced by their moisture content. In such a concentrically rotating 24" diameter drum, for example, it has been found that the range of clothes normally dried will properly tumble at speeds between 46 and 51 r.p.m. But to provide a 46 r.p.m. to 51 r.p.m. range of speeds to a dryer clothes tumbling drum is difficult using a fixed or 2-speed AC motor. In ad dition, any way of varying the speed of a motor of the usual type is expensive and often inefficient, for it usually means a variable speed mechanical drive system, such as variable diameter pulleys, speed changers, or some type of electronic control system to pulse the drive motor. Most of such systems would also usually complicate the design, because the fan needs to be operated near its design speed to provide a proper air stream in the dryer.

To overcome these disadvantages in design, and yet achieve an apparent or effective change in acceleration of the clothes toward the axis of rotation of the drum, I propose to place a circular drum offset from or eccentric to its axis of rotation. This in effect makes various points on the drum wall, because of their different radii from the axis of rotation, operate at different linear speeds.

As an example in my new concept, assume that the 24" diameter clothes drum is offset eccentrically by one inch and that the drum operates at 49 r.p.m. Now the farthest point on the drum from the axis of rotation will be 12 inches plus 1 inch or 13 inches and the effective diameter of this point is 26 inches.

Now, using the foregoing equation, the 'Force (F) is found to be essentially equivalent to that exerted in a concentrically rotating drum (24" diameter) operating at 51 r.p.m. The clothes Will tumble.

Consider now another point on the offset drum. In my new concept, assume clothes are at the nearest point on the drum from the axis of rotation. Thus this point will be 12 inches minus 1 inch, or 11 inches from the axis, and the effective diameter will be 22 inches. Again assume the drum operates at a fixed speed of 49 r.p.m. Then using the foregoing equation the force (F) is found to be essentially equivalent to that exerted in a concentrically rotating drum (24 inches in diameter) operating at approximately 46 r.p.m.

The preceding analysis shows that the concentrically rotating drum speed requirements of 46 r.p.m. to 5l r.p.m. can be met by a single speed drum of the same diameter (24 inches) mounted 1 inch eccentric to its axis of rotation and operated at a fixed speed of 49 r.p.m. Such an arrangement is easily achieved in design, adds no basic complication to the design, and enables a wide variety of types of clothes, from delicate to heavy to be properly tumbled and dried in a single-speed drum.

In accordance with this invention a preferred embodiment is described with reference to FIGS. 1 and 2. A vented type clothes dryer is shown generally at 10. The dryer includes a control housing 12 having suitable controls for temperature 8 and cycle termination 9. A cabinet 14 encloses a rotatably mounted clothes or fabric tumbling drum 16 having a diameter of 24 inches. The cabinet 14 is comprised of a rear wall 18 having air inlet openings 20 and a front wall 22. For supporting the tumbling drum 16 and forming an air inlet passageway 17, a rear bulkhead 24 extends from bottom to top in spaced parallel relationship to the rear wall 18. A drum drive shaft 26 is journaled on the rear wall 18 and carries a pulley 28. The tumbling drum 16 is formed along its peripheral wall 21 into a cylindrical shape and includes a rear mounting wall 30 ported or perforated, as at 32, for facilitating ingress of drying air to the tumbling drum. The shaft 26 mounts on the drum wall 30. The interior of the drum 16 forms a drying cham ber for containing clothes during a clothes drying cycle. Clothes lifting vanes or bafiles 19 may be added to the peripheral wall 21 as an assist in the tumbling operation.

At the opposite end of the drum an axially directed collar 34 defines the air outlet and access opening for the tumbling drum. The opening formed by the collar 34 axially aligns With an opening in collar 36 in the casing front wall 22 and nests therewithin for support. Suitable felt sealing material 44 is interposed between the opening collar 36 and the drum access collar 34 to minimize leakage at this point from the tumbling drum.

For additional details on a suitable support and seal arrangement reference may be had to U.S. Pat. 2,886,901, granted May 19, 1959. A front bulkhead 38 forms with the front wall 22 a front duct or air passage 48 leading to a blower 50. Exhaust outlets 46 place the tumbling drum 16 in air flow communication with the front duct 48.

Circulation of heated air through the dryer is initiated by the blower 50. This blower is driven by a single speed motor or drive means 52 which is, in turn, connected through a pulley 54 and belt 56 with the drum pulley 28. Thus, the motor 52 is utilized to initiate air flow through the tumbling drum and, at the same time, to rotate the tumbling drum at a constant speed. The blower 50 shown in FIG. 2, includes an outlet duct 58 which may be connected to the side or rear walls of the dryer for connection therefrom with the atmosphere in accordance with conventional practice.

In the rear wall 30 of the tumbling drum, an annular shoulder 64 is formed to support an annular flexible, noncombustible seal 66. The seal 66 nests between the drum shoulder 64 and an annular shoulder 68 on the inside of the bulkhead wall 24-. A heater chamber 69 is thus defined between the bulkhead 24 and the rear wall of the tumbling drum which is in communication with 4 the air inlet passageway 17. It is in the chamber 69 that a clothes drying heater 70 is disposed. To the rear of the heater 70 is a juxtaposed support panel 72 including a series of air inlet ports 74 positioned so that air drawn through the ports 74 is directed evenly over the heater 76 before it enters the tumbling drum.

The air flow system defined by the construction outlined hereinabove for a vented clothes dryer is as follows. With the energization of the motor 52, both the blower and the tumbling drum 16 are actuated. Air is drawn through the openings 20 in the casing rear wall and enters the heater chamber 69 by way of the inlet ports 74. After being heated by the heater 70, the air then enters the tumbling drum as a fixed air stream through the perforations 32 in the drum rear Wall.

Moisture is entrained in the air from the tumbling moist clothes within the tumbling drum and this moisture laden air is withdrawn from the tumbling drum by way of the front duct 48 and the blower 50 for subsequent disposal to the atmosphere by way of outlet 58.

In accordance with my invention the shaft 26, and thus the axis of rotation 80, is connected to the back wall of the drum 16 1 inch offset from the geometric center 82 of the drum. The clothes will first be lifted by vane 19'. This vane is on one portion of the drums peripheral wall most remote (13 inches) from the horizontal axis of rotation 80. As the drum continues to rotate the clothes will be lifted near the top of the drum and dropped from vane 19' and the adjacent peripheral wall portion of drum 16 through the air stream to land, for example, on vane 19". Now the vane 19 is least remote (11 inches) from the axis of rotation. Thus the centrifugal forces acting on the clothes (for any given dryness condition) will be greater when the clothes are being lifted and tumbled at the peripheral wall position of vane 19 than at the peripheral wail position of vane 19".

The centrifugal force and thus the acceleration of the clothes toward the axis is a measure of the clothes ability to adhere to the drum wall at any given dryness condition. 50 the clothes will tend to adhere and cling to the drum wall more at the drum position of vane 19 than at the position of vane 19". The result is that clothes lifted by vane 19' will tend to drop more to the left side of the air stream (as viewed in FIG. 1); and when lifted by vane 19 these same clothes will tend to drop more to the right side of the air stream. This variation of drop paths, repeated over and over throughout a clothes drying cycle, will insure the optimum heat transfer exposure of all the clothes to the fixed air stream. This same variation of drop paths will compensate for the lessening tendency of the clothes to cling to the drum wall as they become progressively drier. The clothes will constantly be subjected to a variable drop path transversely through the fixed air stream throughout the clothes drying cycle.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is:

1. A domestic clothes dryer comprising an exterior cabinet, casing means within said cabinet having a mounting wall and a generally cylindrical peripheral wall defining a drying chamber for containing clothes during a clothes drying cycle and rotatable about a fixed generally horizontal axis, means operable for circulating heated air in a fixed air stream through said drying chamber in the direction of said horizontal axis for vaporating moisture from said clothes, means connected to said mounting wall and rotatable for driving said casing means for rotation about said horizontal axis within said cabinet, one portion of said peripheral wall having a radial dimension from said horizontal axis which is greater than another portion of said peripheral wall, the greater radial dimension being less than a dimension from said horizontal axis to said cabinet, and motor means for operating said means for circulating heated air and for rotating said driving means at a constant speed throughout said clothes drying cycle whereby clothes in lifting contact with said one portion of said peripheral wall experience a different amount of centrifugal force and a different tendency to cling to said one portion than when said clothes are on said other portion of said peripheral wall with said casing means rotating at a constant speed thereby to vary the tumbling drop point for said clothes transversely through said fixed air stream throughout said clothes drying cycle in accordance with the portion of said peripheral wall which is in lifting contact with said clothes.

2. The domestic clothes dryer of claim 1 wherein the driving means is a shaft connected to said mounting wall and offset from the geometric center of said casing means.

3. The domestic clothes dryer of claim 1 wherein the peripheral wall includes vanes for aiding the lifting contact between said clothes and said portions of said peripheral wall.

4. The domestic clothes dryer of claim 1 wherein the means for circulating heated air includes perforations in said mounting wall, a heater on the upstream side of the mounting wall and a blower on the downstream side thereof.

5. The domestic clothes dryer of claim 2 wherein said casing means is a tumbling drum twenty-four inches in diameter and said offset is one inch.

6. In a domestic clothes dryer, means forming a chamber having generally cylindrical peripheral wall portions adapted to contain clothes to be dried and rotatable about a fixed generally horizontal axis, means for providing a fixed stream of air through said chamber in the direction of said horizontal axis, means for moving said chamber forming means at a constant speed about said axis to tumble said clothes relative to said chamber forming means in said fixed stream of air, said chamber forming means including one peripheral wall portion offset with respect to said axis a greater distance than another peripheral wall portion for accelerating clothes in contact with said one peripheral wall portion toward said axis at a different rate than clothes in contact with said another peripheral wall portion while said chamber forming means is moving about said axis at said constant speed thereby to vary the tumbling drop point of said clothes transversely through said fixed stream of air.

References Cited UNITED STATES PATENTS 2,037,523 4/193'6 MacDonald 68-141 2,843,945 7/1958 Whyte 34133 X 2,878,662 3/1959 Brucken 34-133 X 2,994,216 8/1961 Morton 3'4l33 CARROLL B. DORITY, JR., Primary Examiner 732 5 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N9, Dated 2 Inventorbs) James W. Jacobs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 4-5,

delete "assignor to General Electric Corporation" and insert assignor to General Motors Corporation Column 2, line 20,

that portion of the equation reading F 1 should read F 3 q 9 Signed and sealed this 8th day of August 1972.

SEAL) Attes t: l.

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

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