Tumble Dryer With Reduced Clothes Wear

Information

  • Patent Application
  • 20240376661
  • Publication Number
    20240376661
  • Date Filed
    May 12, 2023
    a year ago
  • Date Published
    November 14, 2024
    3 months ago
  • Inventors
    • Razzaghi; Mahmoud (Laguna Niguel, CA, US)
Abstract
In a tumble dryer, a horizontal drum rotates and separates wet clothes. Hot air is blown through the drum and between the clothes to evaporate their moisture. The drum is rotated intermittently to reduce the time that clothes are deformed and rubbed against each other, and thus, reduce the wear and tear to them. The hot air is continuously blown as in a regular dryer. In a repeating cycle, the drum rotates for a given first time period to separate the clothes and let the hot air remove moisture from them. Then, the drum stops for a given second time period to allow redistribution of moisture within and between the clothes and heating of them by the hot air for further drying. The hot air temperature or flow may be reduced in the stopping state compared to the rotating state of the drum to prevent overheating of the stationary clothes exposed to the hot air.
Description
FIELD OF THE INVENTION

This invention relates to clothes and fabrics dryers in general, and tumble dryers in particular.


BACKGROUND OF THE INVENTION

In a tumble dryer, a horizontal drum inside a cabinet rotates wet clothes to create air space between them. Heated air is circulated through the drum and between the clothes to evaporate and remove their moisture. The air leaves the drum through a lint screen or filter.


During this process, the clothes deform and rub consistently against each other, which causes compression, breaking, and separation of fibers from them. The wear and tear to the clothes is substantial and negatively affects their texture, color, softness, appearance, and useful life. Even the damage to new clothes is visible after the first drying. The amount of lint collected on the lint screen is evidence of the damage to the clothes.


Experiments have shown that heating of the clothes in tumble drying is not responsible for damages such as shrinking or discoloration. The mechanical agitation by tumbling and blowing air is the sole cause of all damage to the clothes including shrinkage, color change, wear, and tear. As an example, in a 30 min drying cycle, the clothing fibers are compressed and released a few thousand times.


In addition to damaging clothes, tumble drying also harms the environment. Microfibers from clothes pass through the dryer lint screens into the environment and pose a threat to human health. They have been found in ocean fish, beer, and even placentas of babies.


Worldwide, about one million ton of microfiber are blown into the air from tumble dryers annually. Besides households, tumble drying is used in businesses such as hospitality, healthcare, factories, and labs. The economic losses and environmental damages have global proportions.


OBJECTS OF THE INVENTION

The objects of this invention are:

    • 1. To improve tumble dryers so that they cause less wear and tear to the clothes in the drying process.
    • 2. To reduce environmental impact of tumble drying by at least 50%
    • 3. To allow continued use of clothing in their original quality for a longer time
    • 4. To save consumers on the cost of clothing







BRIEF DESCRIPTION OF THE INVENTION

In a tumble dryer, a horizontal drum inside a cabinet rotates and separates wet clothes to create air space between them. Hot air is blown through the drum and between the clothes to evaporate and remove their moisture.


The present invention uses intermittent rotation of the drum to reduce the time that clothes deform and rub against each other, and thus, reduce the wear to them. The hot air is continuously blown to essentially maintain the same drying time as in a regular dryer.


In a continuing cycle, The drum rotates for a given first time period to separate the clothes and let the moisture escape from them. Then, the drum stops and stays stationary for a given second time period to allow drying of clothes exposed to the hot air, outward transfer of moisture within the clothes, and heating of clothes by the hot air for further drying.


DESCRIPTION OF THE INVENTION

In a tumble dryer, a horizontal drum inside a cabinet rotates wet clothes to create air space between them. Hot air is blown through the drum and between the clothes to evaporate and remove their moisture.


In newer dryers, the drum has an open front end to receive wet clothes and a closed back end with a shaft for attachment and rotation via bearings to the cabinet. The cabinet has a door that covers the front end of the drum.


The drum has a few axial blades on its internal surface to lift the clothes during rotation. The clothes drop at the top of the drum by gravity and separate from each other.


The cylindrical surface of the drum is perforated. An enclosure around the drum creates a space around the drum. Hot air enters the space and flows through the perforations into the drum.


The air circulation system includes a blower, a heater, and ducts, having a first opening to receive air from outside the cabinet and blow it over the heater into the space between the drum and its enclosure. The air leaves the drum through a second opening at the open end of the drum, passes through a lint screen and leaves the cabinet through a third opening.


Some dryers use a heat pump as the heater in a closed loop air circulation system for energy efficiency. The air is heated by the heat pump condenser, enters the drum, and heats the cloths, and picks up their moisture. The moist air returning from the drum is then cooled down and dried by the heat pump evaporator and recirculated to the heat pump condenser.


The drum is rotated by a pulley-belt drive system with a first pulley fixed at the end of the drum shaft coupled to an electric motor through a second pulley and a belt.


A control system allows drying option setting by the user via an interface and controls the running time and air temperature accordingly. In advanced dryers, the control system monitors and controls the dryness of the cloths through humidity or temperature sensors.


If the difference in air temperature entering and leaving the drum is small, it indicates that either the clothes are dry, or the entering air temperature is too high. In this condition, the control system reduces the air heating level or ends the drying process.


In older versions of tumble dryers, the wall of the drum is not perforated. The back end of the drum is also open and is covered by a vertical wall. Hot air enters the drum through a perforated portion of the vertical wall. The drive system uses the drum as a pulley with a belt around it coupled to a pulley on the motor shaft.


For complete elimination of the wear to the clothes in a tumble dryer, they should be kept stationary, but the hot air cannot go through the bulk of clothes for convective heating, and clothes have low conductivity and cannot efficiently conduct the heat through them. Even if heated in any way, the vaporized moisture cannot escape easily through the layers of clothes. The rotation is also needed to prevent creasing of the clothes.


Also, the drum cannot be rotated below a certain speed to reduce the duration and severity of clothes deforming and rubbing because it cannot lift the clothes from its bottom side and drop them at the top side for separation.


The present invention uses intermittent rotation of the drum in any tumble dryer, such as those described above, to reduce the time that clothes deform and rub against each other, and thus, reduce the wear and tear to them. The hot air blows continuously so the total drying time remains essentially the same as in a regular dryer.


According to the present invention, in a repeating cycle, the control system rotates the drum for a given first time period to separate the clothes and remove moisture from them. The control system then stops and keeps the drum stationary for a given second time period to allow outward transfer of moisture within the body of the clothes, convective heating and drying of clothes exposed to the hot air, and some conductive heating of the bulk of the clothes in contact with the drum. The drying air is heated, enters into the drum, heats the clothes, removes moisture from the cloths, and leaves through the lint screen as in a standard tumble dryer.


The principle of the invention applies to all types of tumble dryers. The control system of the dryer of the invention has additional features to automatically control the intermittent rotation of the drum and the corresponding temperature or flow of the circulating air as required.


During each rotating state, the clothes are shuffled and reoriented. This helps redistribution of temperature and moisture inside and between the clothes. As a result, in the next stationary state, heat transfer and moisture removal will be more uniform and efficient.


A dryer with perforated drum is preferred for the present invention as it allows more distributed heating of the exposed clothes, higher rate of heating to the bulk of clothes in contact with drum wall through convection and conduction, and additional moisture removal at the perforations. This is especially helpful for optimized heating and drying during the stationary state of the drum.


The duty cycle of the dryer is defined as the duration of rotation of the drum to the total drying cycle time. The smaller the duty cycle, the less the deformation, rubbing and wearing of the clothes. The amount of wear and tear to the clothes as well as separated lint are proportional to the duty cycle. Therefore, if the dryer runs at a duty cycle of 25%, the wear and tear resulting from the process of the invention would be 25% that of a standard tumble dryer.


As an example, rotate the drum for 3 seconds and keep it stationary for 9 seconds for a duty cycle of 3/12 or 25%. The drum speed is about 60 rpm. So, in 3 sec the drum rotates 3 times which is quite sufficient for tumbling, shuffling, aerating, and smoothing the clothes.


The rotation duration could be as little as the time for a few turns. The goal is to minimize the stationary state duration to the extent that the drive system capabilities and the minimum required rotation allow. To the purpose of the present invention, a direct drive system is recommended for higher efficiency, lower noise and inertia, and faster response.


A higher duty cycle places less stringent conditions on the dryer and clothes but also with less reduction in wear and tear. For example, the dryer can be easily run with the drum turning for 5 sec and stopping for 5 sec resulting in a duty cycle of 5/10 or 50% which is still considerable.


During the stationary state, the amount of air flow or temperature may be reduced by the control system for optimized and distributed heating of the clothes.


During the drum rotation, higher air flow or temperature may be set by the control system to maximize heat input to the clothes. This allows maximum removal or moisture during the drum rotation and continued evaporation of moisture during the stationary state.


Cloth balls or towels have been added to the wet cloths to reduce the drying time. The present invention can even take further advantage of these tools for humidity transfer during the stationary state.

Claims
  • 1. An improved tumble dryer for drying clothes or fabric with reduced wear and tear to the clothes, the dryer rotates the clothes inside a drum to separate them and blows heated air through the drum to heat the clothes and remove moisture from them,according to the improvement, in a repeating cycle, the dryer rotates the drum for a given first time period to separate the clothes, so the heated air removes moisture from them,then, the dryer stops and keeps the drum stationary for a given second time period to allow outward transfer of moisture within the clothes and heating them by the heated air for further moisture removal.
  • 2. The improved tumble dryer of claim 1 wherein the temperature or flow rate of the heated air during the rotation of the drum is higher than that during its stationary period.
  • 3. The improved tumble dryer of claim 1 wherein the repeating cycle time is less than one minute.
  • 4. A tumble dryer for drying clothes, the dryer is comprised of a rotatable drum with an open end installed horizontally inside an enclosure,a plurality of blades attached axially to the inside surface of the drum,a door attached to the enclosure to close the open end of the drum,a drive system including an electric motor to rotate the drum,an air blower,a heater,a lint screen,a duct and enclosure system communicating with the blower, the heater, the inside of the drum, and the filter,a control system to control the drive system, heater, and blower and provide human interface for operating the dryer,when the dryer is turned on through the control interface,the drum rotates and separates wet clothes inside of it with the help of its blades,air enters the blower, passes over the heater, enters the drum, heats the clothes,removes moisture from them, exits the drum, and leaves fiber or lint separated from the clothes at the lint screen,the rotation of the drum is intermittent to reduce the time that clothes are deformed and rubbed against each other during drying, and thus, reduce the wear and tear to them,in a repeating cycle, the drum rotates for a given first time period to separate the clothes, so the heated air removes moisture from them,then, the drum stops and stays stationary for a given second time period to allow outward transfer of moisture within the clothes and heating of them by the heated air for further moisture removal.
  • 5. The tumble dryer of claim 4 wherein the repeating cycle time is less than one minute.
  • 6. The tumble dryer of claim 4 wherein the heated air temperature or flow rate is higher during the rotation of the drum than when the drum is stationary.
  • 7. A clothes drying process to reduce wear and tear to the clothes wherein wet clothes are tumbled inside a horizontal rotating drum to get separated,heated air is blown continuously through the drum to heat the clothes and remove moisture from them,the drum is rotated for a given first time period,then, the drum is stopped and kept stationary for a given second time period,the cycle of rotating and stopping the drum is repeated until the clothes are dried.
  • 8. The clothes drying process of claim 7 wherein the first and second time periods are fractions of a minute.
  • 9. The clothes drying process of claim 7 wherein the heated air temperature or flow rate is higher during the rotation of the drum than when the drum is stationary.
  • 10. An improved tumble dryer for drying clothes or fabric with reduced wear and tear to the clothes, the dryer rotates the clothes inside a drum to separate them and blows heated air through the drum to heat the clothes and remove moisture from them, A control system allows drying option setting by the user via an interface and controls the running time, air temperature, or air flow,according to the improvement, in a repeating cycle, the dryer rotates the drum for a given first time period to separate and redistribute the clothes, and allow the heated air to remove moisture from them,then, the dryer stops the drum and keeps it stationary for a given second time period to allow redistribution of moisture within and between the clothes and heating of them by the hot air for further drying.
  • 11. The improved tumble dryer of claim 10 wherein the temperature or flow rate of the heated air during the rotation of the drum is higher than that during its stationary period.
  • 12. The improved tumble dryer of claim 10 wherein the repeating cycle time is less than one minute.
  • 13. A tumble dryer for drying clothes, the dryer is comprised of a rotatable drum with an open end installed horizontally inside an enclosure,a plurality of blades attached axially to the inside surface of the drum,a door attached to the enclosure to close the open end of the drum,a drive system including an electric motor to rotate the drum,an air blower,a heater,a lint screen,a duct and enclosure system communicating with the blower, the heater, the inside of the drum, and the filter,a control system to control the drive system, heater, and blower and provide human interface for operating the dryer,
  • 14. The tumble dryer of claim 13 wherein the repeating cycle time is less than one minute.
  • 15. The tumble dryer of claim 13 wherein the heated air temperature or flow rate is higher during the rotation of the drum than when the drum is stationary.
  • 16. A clothes drying process to reduce wear and tear to the clothes wherein wet clothes are tumbled inside a horizontal rotating drum to get separated,heated air is blown continuously through the drum to heat the clothes and remove moisture from them,the drum is rotated for a given first time period,then, the drum is stopped and kept stationary for a given second time period,the cycle of rotating and stopping the drum is repeated until the clothes are dried.
  • 17. The clothes drying process of claim 16 wherein the first and second time periods are fractions of a minute.
  • 18. The clothes drying process of claim 16 wherein the heated air temperature or flow rate is higher during the rotation of the drum than when the drum is stationary.
Parent Case Info

This application has priority date of provisional patent application 63/463,281 filed 1, May 2023.