Drying and gas or vapor contact with solids – Apparatus – Rotary drums or receptacles
Reexamination Certificate
2000-10-19
2002-01-01
Wilson, Pamela (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
Rotary drums or receptacles
C034S531000, C034S546000, C034S547000, C034S572000
Reexamination Certificate
active
06334267
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for drying clothes with heated air. Specifically, a controller is described which confirms the initial conditions of the dryer prior to the start of the drying cycle.
Conventional clothes dryers comprise a tumbling chamber into which a load of wet clothing is inserted. The chamber includes a tumbler which is rotated to effect tumbling of the clothes. A stream of hot air is forced through the tumbler which removes the moisture contained in the clothing to dry it. Conventional clothes dryers usually include a single motor which rotates the tumbling chamber as well as forces the air through the tumbler.
Reversing type clothes dryers have been in use for some time. A reversing type clothes dryer utilizes two separate motors. A first motor is attached to a fan or blower and is used for creating the air flow necessary in the drying process. A second motor is connected to the drive system which rotates the tumbler and enables the clothes tumbling action. Having separate motors for the fan and for the drive system allows the tumbling action of the clothes dryer to be reversed without affecting the fan and the air flow through the tumbling chamber.
In both the conventional and reversing type clothes dryers, damage may occur upon the failure of one of the dryer components. For example, if the blower or fan were to fail, it is possible that the burner would overheat causing damage to the burner system and potentially even a fire. In order to detect such unsafe situations resulting from insufficient air flow, a sail switch is utilized to measure the air flow in the combustion area as well as in the tumbler chamber. A sail switch is a mechanical switch that is switched on or off by the flow or non-flow of air. The sail switch is used to indicate that air is flowing to reduce the heat of combustion in the burner and thus prevent the destruction of heat exchanger components in the clothes dryer.
In a reversing machine, the presence of separate motors for the blower and the drive system make it possible to utilize the signal from the sail switch to provide additional safety features. The signal from the sail switch can be used to prevent any mechanical movement of the drive system when there is insufficient air flow in the drying chamber, thereby preventing personal injury in the event that the clothes dryer is used improperly.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for controlling the start of the drying cycle in a clothes drying machine. The present invention prevents the mechanical movement of the drive system to present personal injury in the event that the equipment is used improperly. The invention also detects an insufficient air flow in the drying chamber to prevent the drying machine from being damaged.
The clothes dryer of the present invention comprises a tumbler motor connected to a tumbler and a fan motor connected to a fan. The tumbler motor is controlled by a microprocessor controller and enables a tumbler motor contactor. Means such as a sail switch are arranged to measure the air flow in the clothes dryer. The microprocessor controller receives a signal from the sail switch and provides a control signal for the tumbler motor contactor. The microprocessor controller is programmed to send an enabling signal to the tumbler motor contactor to start the tumbler motor only when a predetermined air flow in the clothes dryer is measured.
In a method according to a preferred embodiment of the present invention, when a start cycle button is pressed, the microprocessor controller sends a start signal to the blower motor. The blower motor generates an air flow in the tumbler. A sail switch measures the air flow and sends a signal to the microprocessor controller when sufficient air flow is present in the clothes dryer. The microprocessor controller detects whether the sail switch has been activated within a predetermined period of time after the blower motor has started. If the sail switch has been activated within the predetermined period of time, the microprocessor controller sends a start signal to start the tumbler motor. Otherwise, the drying cycle is interrupted and an error message is displayed.
In another embodiment of the present invention, after the tumbler motor is started, it is disabled by the microprocessor controller whenever the sail switch indicates that the air flow has fallen below a predetermined level.
In another embodiment of the present invention, when the dryer door is opened and a door switch has failed, the sail switch acts as a backup to the door switch and indicates that the air flow has dropped below the predetermined level. Thus, the microprocessor no longer receives a signal from the sail switch and it therefore disables the tumbler motor.
The present invention utilizes the presence of two separate motors and as a result provides an additional level of safety to prevent personal injury in the event that the clothes dryer is misused.
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“Air Flow and Temperature Sensor” by S. Ghose, Apr. 1971, IBM Technical Disclosure Bulletin, vol. 13, No. 11.
“Air Flow Sensor for Fans” by G.M. Barthel, Aug. 1979, IBM Technical Disclosure Bulletin, vol. 22, No. 3. Cl.
American Dryer Corporation
Connolly Bove & Lodge & Hutz LLP
Wilson Pamela
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