Drying and gas or vapor contact with solids – Process – Gas or vapor contact with treated material
Reexamination Certificate
2000-03-01
2001-03-13
Gravini, Stephen (Department: 3749)
Drying and gas or vapor contact with solids
Process
Gas or vapor contact with treated material
C034S486000, C034S496000, C034S499000
Reexamination Certificate
active
06199300
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
The present invention relates to a method and apparatus for controlling the heat input to a dryer and, more specifically, to controlling the heat input in an energy efficient manner.
Typically in dryers known in the art, full heating energy is applied to a clothes treatment chamber throughout a drying cycle up to a point in time when the moisture content of the clothes is reduced below a threshold level. At this point or a predetermined time period thereafter, the drying energy is terminated and the drum of the dryer continues to rotate for a predetermined amount of time to allow cooling of the clothes treatment chamber. When a sufficient time to allow cooling or after a cool down temperature has been reached, the dryer is then shut-off. Alternatively, it is also known in the art to simply maintain an exhaust temperature of the dryer at a set temperature level after an initial period of heating from the start of the drying cycle for a predetermined time period.
However, it has been discovered by the Applicants that efficient drying of clothes (i.e., moisture reduction) does not necessarily require that the power level of the heating element or the exhaust temperature of the dryer be maintained at a set level. Rather, the Applicants have found through testing that moisture retention of clothing within the dryer declines at a relatively constant rate even when the applied heating energy or the exhaust temperature is reduced after an initial full energy heating period of approximately 5 to 30 minutes at the start of the cycle. Accordingly, dryers known in the art that maintain a set power level or exhaust temperature are not energy efficient since full energy or exhaust temperature is not necessary to reduce moisture at a constant rate.
Thus, there is a need for an energy efficient control of drying energy that benefits from the discovery of effective moisture reduction at a constant rate with less than maximum drying energy or exhaust temperature.
SUMMARY OF THE PRESENT INVENTION
The above need and other needs are met by the present invention that provides a method and apparatus for controlling the level of drying energy applied to the clothes treatment chamber in a dryer at varying levels during different periods in the drying cycle in order to reduce total energy consumption.
According to one aspect of the invention, a methodology is provided for controlling heat input to a dryer including setting the heat input to a first prescribed level at a start of the drying cycle. Next, the dryer temperature and load moisture level are monitored and the heat input is reduced to a second prescribed level when is the dryer temperature reaches a substantially non-varying temperature level. The heat input is increased to a third prescribed level when the dryer load moisture level is detected as falling below a predetermined dryer load moisture level. The heat input to the dryer is terminated according to one of a number of predetermined termination conditions. These termination conditions may include one or more of monitoring the dryer temperature and terminating drying when the temperature exceeds a prescribed level, determining when a rate of increase of temperature with respect to time exceeds a prescribed level, monitoring the total time of the drying cycle and terminating heat input when a maximum time limit is exceeded or determining when an arbitrary temperature set by an operator has been exceeded and terminating drying when the temperature is exceeded. This method is advantageous in that it reduces power consumption from the time of initial heating to the point at which the load moisture level of the clothes falls below a predetermined level. This is also advantageous in that the clothes load is not overheated.
According to another aspect of the present invention, an apparatus for controlling a dryer is provided for a dryer having a heating element for delivering heat input to the dryer. The control apparatus includes at least one heat sensor for sensing the exhaust temperature of the dryer and at least one load moisture sensor to sense the load moisture level of the dryer. A controller receives inputs of exhaust temperature from the heat sensor and moisture level from the load moisture sensor and outputs a first control signal to set a power level of the heating element to a first prescribed level at the start of a drying cycle. The controller also monitors the dryer temperature and dryer load moisture level and outputs a second control signal to reduce the power level of the heating element to a second prescribed level when the dryer temperature reaches a substantially non-varying temperature level. A third control signal is output from the controller to increase the power level of the heating element to a third prescribed level when the dryer load moisture level falls below a predetermined level. Finally, the controller terminates power input to the heating element or gas burner according to at least one of a plurality of predetermined termination conditions.
Additional advantages and novel features of the invention will be set forth, in part, in the description that follows and, in part, will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
REFERENCES:
patent: 3621202 (1971-11-01), Gemert
patent: 3942265 (1976-03-01), Sisler et al.
patent: 4019259 (1977-04-01), Veraart
patent: 4231166 (1980-11-01), McMillan
patent: 4397101 (1983-08-01), Rickard
patent: 4622759 (1986-11-01), Abe et al.
patent: 4827627 (1989-05-01), Cardoso
patent: 4991313 (1991-02-01), Joslin
patent: 5245764 (1993-09-01), Sung
patent: 5291667 (1994-03-01), Joslin et al.
patent: 5347727 (1994-09-01), Kim
patent: 5443541 (1995-08-01), St. Louis
patent: 5444924 (1995-08-01), Joslin et al.
patent: 6047486 (2000-04-01), Reck et al.
patent: 106646 (1984-04-01), None
patent: 481561 (1991-10-01), None
patent: 436374 (1996-08-01), None
Heater Timothy E.
Kendall Mark F.
Markert Gregory J.
Oltz Shawn Richard
Gravini Stephen
Rice Robert O.
Roth Thomas J.
Van Winkle Joel M.
Whirlpool Corporation
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