Patent Application
20190161907
Not applicable.
The present invention relates to clothes dryers, and more specifically, a system to prevent fire by reducing the buildup of static electricity during the drying cycle and by reducing the potential for spontaneous combustion.
A clothes dryer generally comprises a cabinet, a drum, motor, mechanism for spinning the drum, a heating element, and electronic controls. The user inserts damp clothes into the dryer drum. The clothes dryer is then powered on, and the drum rotates causing the clothes to tumble while a stream of heated air is blown into the drum and contacts the clothes. The heated air removes water from the clothes over time.
The tumbling of the clothes creates friction between pieces of drying fabric by causing different pieces of clothing and different layers of the same piece of clothing to rub against each other. The coulomb friction caused by the clothes rubbing together causes electrical charges to be built up and stored within the fabric of the clothes. Some fabrics receive electrons causing them to have a negative charge whereas other fabrics donate electrons causing them to have a positive charge.
The buildup of static electric charges in the drying fabric causes the clothes to clump together based on the attraction between a positively charged clothing item to a negatively charged clothing item. The clumping together impedes circulation of the heated air throughout the drum making it more difficult and time consuming for the heated air to effectively dry the clothes. As a result, the user must increase the temperature of the heated air or increase the length of the drying cycle in order to dry the clothes. These options increase the risk of fire and are not energy efficient.
In addition, it is not uncommon for clothes to be left overnight (or even longer) undisturbed in a clothes dryer after the drying cycle is completed. Even after the dryer shuts off, the undisturbed mass of hot clothes, or portions thereof, may continue to self-heat depending on the presence of certain fats/oils that were not removed during the washing process. This heat can continue to build up on the clothes which can promote spontaneous combustion and a resultant fire.
One product design intended to reduce clothes clumping during the drying cycle was the introduction of metal fins in the drum. See U.S. Pat. No. 4,190,874. However, the metal fins create inefficiencies by absorbing the heat that should be delivered to the damp clothes. U.S. Pat. No. 5,416,983 teaches the use of conductive material in order to reduce static electricity build-up in the drum but this is inefficient as it relies on necessary contact with the clothes in order to dissipate the static electricity. During a cycle in the dryer, the clothes do not all touch the drum continuously resulting in inefficient static reduction. Another solution is to use anti-clump fabric sheets that are separately purchased by the consumer and put into the drum with the clothes. However, this solution generates extra expense for the user and requires the user to remember to purchase and insert the sheets.
The aforementioned solutions are imperfect and there remains a need to develop a clothes dryer with the ability to efficiently eliminate static electricity build up during the drying cycle.
The present invention is a dryer with the capability to monitor electrical charge within the drum and turn off the flow of heated air when the electrical charge reaches a designated threshold. Once the threshold is reached, ion rich air is introduced into the drum through an ion generator. The ion rich air interacts with and neutralizes the built-up static electric charge within the drum and the clothes. The ion rich air stream penetrates the fabric layers allowing contact with the interior fabric layers. This increases the amount of contact between the ion rich air and static electricity resulting in increased neutralization of the static electricity and more effective de-clumping of the clothes which increases surface area of the clothing to allow for more efficient moisture removal.
The present invention further reduces the potential for an internal fire by decreasing the conditions necessary for spontaneous combustion. A controller measures the time between the completion of the drying cycle and when the dryer door is opened as detected by the door sensor. If a sufficient time has passed without the door opening, the controller turns on the drum to permit it to rotate for a designated period of time without introduction of heat. The tumbling of clothes permits exposure to the air within the drum allowing any entrapped heat to dissipate. At the same time, a light radiation source (UV light or LED) is turned on during the additional tumbling cycle. Any moisture remaining within the clothes creates an environment for microbes to grow which generates heat. The visible and invisible optical radiation generated by the light helps destroy microbes. Thus, the tumbling after drying aerates the clothes, dissipates entrapped heat, and destroys microbes reducing the potential for spontaneous combustion.
As seen in
The drum 30 is positioned inside the cabinet 3 between the front panel 4 and the interior panel 10. The drum 30 is cylindrically shaped with a front circular edge 31 defining an open front end 32 and a rear circular edge 33 defining an open rear end 34. The drum 30 rests on a wheel assembly (not shown) which is well known in the art. The front circular edge 31 seals against the drum receptacle 12 such that the drum 30 may rotate while the drum receptacle 12 remains stationary. A portion of the open front end 32 corresponds with opening 14. The door 13, when closed, covers the open front end 32. The rear circular edge 33 of the drum 30 seals against the front surface 11 of the interior panel 10 such that the drum 30 may rotate while the interior panel 10 remains stationary. Connections of the drum to the interior panel 10 and the drum receptacle 12 are well known in the art. A portion 19 of the front surface 11 of the interior panel 10 is exposed to the interior of the drum 30 through the open rear end 34.
In the disclosed embodiment, a motor 50 having a drive shaft 51 is mounted to the bottom panel 7 of the cabinet 3. A drive belt 52 wraps around the outer surface 37 of the drum 30 and is rotatably attached to the drive shaft 51. In operation, the motor 50 spins the drive shaft 51 ultimately causing the drive belt 52 (and drum 30) to spin. Such operation is well known in the art and may include idler pulleys and other mechanisms that control revolution of the drum 30.
The drum 30 has baffles 35 protruding from the interior surface 36 of the drum 30. In an embodiment of the clothes dryer static electricity reduction system, the baffles 35 are constructed from a plastic material impregnated with carbon fiber or aluminum shards. A typical dryer has three baffles 35 that run longitudinally (extending from the front circular edge 31 to the rear circular edge 33) and are generally spaced one hundred and twenty degrees relative to another.
An ultraviolet light 40 is mounted to the interior panel 10 such that it emanates light into the interior of the drum 30. The ultraviolet light 40 may be an LED light, non-visible laser, or other ultraviolet source. The ultraviolet light 40 may be of sufficient strength to kill, sterilize, and/or limit growth of mold and mildew within the drum 30 and/or clothes within the drum 30.
The heater and blower system of a typical dryer are well known in the art. The air supply intake 61 is fluidly connected to the heater housing 62. A heating element 76 is positioned within heater housing 62 and is controlled by a thermostat 77. The first end 63 of the drum inlet conduit 64 is fluidly connected to the heater housing 62 and the second end 65 of the drum inlet conduit 64 is fluidly connected to the drum inlet 66 of the interior panel 10. The drum inlet 66 is in fluid communication with the interior of the drum 30. A drum outlet 67 is in fluid communication with the interior of the drum 30 and positioned within the drum receptacle 12. A lint catcher 68 may be placed within the drum outlet 67. The first end 69 of the drum outlet conduit 70 is fluidly connected to the drum outlet 67 and the second end 71 of the drum outlet conduit 70 is fluidly connected to the blower housing 72. A blower wheel is positioned within the blower housing 72 and connected to the drive shaft 51. The first end 73 of the exhaust conduit 74 is fluidly connected to the blower housing 72. The exhaust conduit 74 extends through the rear panel 9 of the cabinet 3 and terminates in an outlet 75. The outlet 75 may be fluidly connected to an additional conduit that routes exhaust outside a room. One skilled in the art understands that the location and design of the heat and exhaust system components varies between different styles and brands of dryers.
As seen in
A controller 100 (identified in
It should be readily appreciated the circuitry may be configured in a multitude of ways to require certain precursors such that the motor 50 must be on before the ion generator 81, air compressor 82, ultraviolet light 40, and/or voltmeter 89 may operate. Conversely, the circuitry may be configured such that the air compressor 82 is always operating when the drum 30 to provide a continued flow of air to cool the ion generator 81 even when the ion generator 81 is not generating ions.
The operation of the clothes dryer static electricity reduction system is described in reference to
The controller 100 operates the thermostat 77 which controls the heating element 76. If the heating element 76 is on, the air passing over the heating element 77 is heated prior to entering the drum inlet conduit 64 and ultimately the drum 30. The heated air passes over and through the damp clothes causing the moisture in the clothes to evaporate in the heated air. Clothes that are not clumped together dry faster as the clothes have more surface area for the heated air to contact. The moisture content of the air passing thorough the exhaust conduit 74 may be measured for dryer performance and may alter the cycle time based on predetermined settings from the control panel 18 and/or logic within the controller 100. Alternatively, the heating element may be off and then unheated air is drawn into the drum 30.
As the drum 30 spins, friction is created as the clothes rub against each other, and/or as layers of one piece of clothing rub against other layers. This friction creates a buildup of static electrical charge which is stored in the fabric of the clothes. Some portions of the clothes gain electrons and other lose electrons resulting in the clothes, or layers of a clothing article, to cling together due to the positive and negative charges attracting to each other. In the disclosed embodiment, the baffles 35 are impregnated with conductive material in order to cancel some of the static electrical charge. More specifically, the conducive polymer composition of the baffles 35 serves as a “short” circuiting member so as to cause charge cancellation on the portions of the drying clothing that make contact with the electrically conductive baffles 35. However, baffles 35 cannot generally absorb electric charge at the rate it is being generated as the static electric charge in the clothes increases over time.
As seen in
Referring back to
In a modification to the above, the controller 100 may not turn off the ion generator 81 and air compressor 82 until the predetermined threshold cutoff voltage A2 is reached and the ion generator 81 and air compressor 82 have run for a predetermined amount of time.
The activation and run cycle of the ion generator 81 and air compressor 82 may be modified by settings on the control panel 18 and/or preprogrammed in the controller 100. In an alternative embodiment as disclosed in
In alternative embodiments, the heating element may be turned off while the ion generator 81 and ion compressor 82 are in operation.
As seen in
An exemplar source of ions is the ion generator made by Keyence, including the SJ series. Some ion generators have internal static sensing circuits, which would negate the need for voltage measuring circuit which would permit the voltage sensor assembly 87 to be integral with the ion generator 81, 110. In accordance with standard dryer fire safety, the last ten minutes or so of clothes drying makes use of tumbling only to help dissipate trapped/entrained heat flux within the fabric layers. This “cooling off” cycle remains subject to static electrical build up. By injecting the neutralizing ions during the cooling off period, the layers of fabric can better cool off in that they do not stick together as much.
While use of a controller or processor to control the operation of the ion generator 81, 100 is preferred, other circuit mechanisms may be employed such as causing an SPDT relay to energize, based on a preset voltage reading, that transfers power from the heating element to the ion generator based on the movement of the coil.
As seen in
It should be readily appreciated the heat dissipation cycle 300 may operate in a multitude of matters including linking the heat dissipation cycle 300 with a wrinkle resistant cycle, limiting the number of heat dissipation cycles 300, utilizing only the motor 50 and not utilizing the ultraviolet light 40, utilizing only the ultraviolet light 40 and not the motor 50, or utilizing the ultraviolet light 40 separate from motor 50. Furthermore, the preset amount of time T2 and preset amount of time T3 may be variable and/or dependent upon the number of heat dissipation cycles 300 executed. For example, the preset amount of time T2 may be shorter for the first heat dissipation cycle 300 and increase in length as more heat dissipation cycles 300 are executed. Moreover, the preset amount of time T3 may be longer the first heat dissipation cycle 300 and decrease in length as more heat dissipation cycles 300 are executed.
The embodiment has been described with reference to a standard dryer cabinet. Those skilled in the art understand that the static electricity reduction system disclosed can be modified to be used in any dryer. The components can be arranged differently and mounted in different places within the interior of the dryer. Additionally, the source of heat could be a fueled gas burner, as opposed to a resistance heater. The conductive polymer fins can also be made from a conductive metal. It is also anticipated that some clothes/fibers may dry better if both heated air and injection of ions by way of compressed air are carried out simultaneously.
This application claims the benefit of U.S. Provisional Application Ser. No. 62/591,544 filed Nov. 28, 2017 entitled Improved Clothes Dryer. The contents of said application are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62591544 | Nov 2017 | US |
