The present subject matter relates generally to dryer appliances, and more particularly to dryer appliances configured for detecting when a heating system of the dryer appliance is not operating, such as due to a nuisance trip or heater failure, and related methods.
A conventional appliance for drying articles such as a clothes dryer (or laundry dryer) for drying clothing articles typically includes a cabinet having a rotating drum for tumbling clothes and laundry articles therein. One or more heating elements, for example electric heating elements, heat air prior to the air entering the drum, and the warm air is circulated through the drum as the clothes are tumbled to remove moisture from laundry articles in the drum.
In order to avoid excessive heating of articles within the drum, dryer appliances include one or more heat control systems which measure or monitor temperatures within the dryer appliance and deactivate the one or more heating elements in response to the temperatures exceeding predetermined thresholds. For example, the one or more heat control systems may include one or more thermostats which trip, or open a circuit to interrupt a supply of electrical power, at one or more respective temperature thresholds.
When one or more such thermostats trip, it or they must reset before the dryer appliance can resume operation. The time for the reset increases the overall time duration of the drying operation. Thus, it is desirable to minimize or avoid tripping the thermostats. In particular, it is desirable to minimize or avoid tripping of the thermostats due to a false positive or other nuisance tripping of the thermostats.
Accordingly, a dryer appliance having improved heat control systems and improved methods of determining status of the heating systems would be advantageous.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one exemplary aspect of the present disclosure, a dryer appliance is provided. The dryer appliance includes a cabinet with a drum rotatably mounted within the cabinet. The drum defines a chamber for the receipt of articles for drying. The dryer appliance also includes a heating system fluidly coupled to the drum whereby heated air flows from the heating system to the chamber of the drum for drying of articles within the chamber. The dryer appliance further includes a primary heat control system comprising a thermistor and a secondary heat control system comprising a thermostat. The dryer appliance also includes a controller in operative communication with the thermistor of the primary heat control system. The controller is configured to monitor a temperature with the thermistor of the primary heat control system. The controller is also configured to determine a temperature gradient of the monitored temperature based on a rate of change in the monitored temperature over time. When the temperature gradient changes from positive to negative, the controller is configured to store a current value of the monitored temperature as a peak temperature. After a first wait period has elapsed, the controller is further configured to verify the temperature gradient is still negative. After verifying the temperature gradient is still negative after the first wait period, the controller is configured to verify there is a call for heating. The controller is also configured to allow a second wait period to elapse after verifying the call for heating. After the second wait period, the controller is configured to verify the temperature gradient is still negative. After verifying the temperature gradient is still negative after the second wait period, the controller is configured to store a present value of the monitored temperature. The controller is further configured to determine that a difference between the peak value of the monitored temperature and the present value of the monitored temperature is greater than a predetermined threshold. The controller is also configured to detect a nuisance trip because the difference between the peak value of the monitored temperature and the present value of the monitored temperature is greater than the predetermined threshold.
In another exemplary aspect of the present disclosure, a method of operating a dryer appliance is provided. The method includes monitoring a temperature with a thermistor of a primary heat control system of the dryer appliance and determining a temperature gradient of the monitored temperature based on a rate of change in the monitored temperature over time. When the temperature gradient changes from positive to negative, the method includes storing a peak value of the monitored temperature. After a first wait period, the method includes verifying the temperature gradient is still negative. After verifying the temperature gradient is still negative, the method includes verifying there is a call for heating. After verifying the call for heating, the method includes allowing a second wait period to elapse. After the second wait period, the method includes verifying the temperature gradient is still negative. After verifying the temperature gradient is still negative, the method includes storing a present value of the monitored temperature. The method also includes determining that a difference between the peak value of the monitored temperature and the present value of the monitored temperature is greater than a predetermined threshold. The method further includes detecting a nuisance trip because the difference between the peak value of the monitored temperature and the present value of the monitored temperature is greater than the predetermined threshold.
In yet another exemplary aspect of the present disclosure, a method of operating a dryer appliance is provided. The method includes monitoring a temperature with a thermistor of a primary heat control system of the dryer appliance. The method also includes determining a relay signal is calling to close a relay and thereby activate a heating system of the dryer appliance and verifying that the relay is closed. The method further includes allowing a minimum relay on time to elapse after verifying that the relay is closed. The method also includes determining a temperature gradient of the monitored temperature based on a change in the monitored temperature over the minimum relay on time. The method further includes detecting a nuisance trip because the determined temperature gradient is negative.
These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
As used herein, terms of approximation, such as “generally,” or “about” include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, “generally vertical” includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.
Turning now to the figures,
Cabinet 12 includes a front panel 14, a rear panel 16, a pair of side panels 18 and 20 spaced apart from each other by front and rear panels 14 and 16, a bottom panel 22, and a top cover 24. Within cabinet 12, an interior volume 29 is defined. A drum or container 26 is mounted for rotation about a substantially horizontal axis within the interior volume 29. Drum 26 defines a chamber 25 for receipt of articles of clothing for tumbling and/or drying. Drum 26 extends between a front portion 37 and a back portion 38. Drum 26 also includes a back or rear wall 34, e.g., at back portion 38 of drum 26. A supply duct 41 may be mounted to rear wall 34 and receives heated air that has been heated by a heating assembly or system 40.
As used herein, the terms “clothing” or “articles” includes but need not be limited to fabrics, textiles, garments, linens, papers, or other items from which the extraction of moisture is desirable. Furthermore, the term “load” or “laundry load” refers to the combination of clothing that may be washed together in a washing machine or dried together in a dryer appliance 10 (e.g., clothes dryer) and may include a mixture of different or similar articles of clothing of different or similar types and kinds of fabrics, textiles, garments and linens within a particular laundering process.
A motor 31 is provided in some embodiments to rotate drum 26 about the horizontal axis, e.g., via a pulley and a belt (not pictured). Drum 26 is generally cylindrical in shape, having an outer cylindrical wall 28 and a front flange or wall 30 that defines an opening 32 of drum 26, e.g., at front portion 37 of drum 26, for loading and unloading of articles into and out of chamber 25 of drum 26. A plurality of lifters or baffles 27 are provided within chamber 25 of drum 26 to lift articles therein and then allow such articles to tumble back to a bottom of drum 26 as drum 26 rotates. Baffles 27 may be mounted to drum 26 such that baffles 27 rotate with drum 26 during operation of dryer appliance 10.
Drum 26 includes a rear wall 34 rotatably supported within main housing 12 by a suitable fixed bearing. Rear wall 34 can be fixed or can be rotatable. Rear wall 34 may include, for instance, a plurality of holes that receive hot air that has been heated by a heating assembly or system 40, as will be described further below. Motor 31 is also in mechanical communication with an air handler 48 such that motor 31 rotates a fan 49, e.g., a centrifugal fan, of air handler 48. Air handler 48 is configured for drawing air through chamber 25 of drum 26, e.g., in order to dry articles located therein. In alternative example embodiments, dryer appliance 10 may include an additional motor (not shown) for rotating fan 49 of air handler 48 independently of drum 26.
Drum 26 is configured to receive heated air that has been heated by a heating assembly 40, e.g., via holes in the rear wall 34 as mentioned above, in order to dry damp articles disposed within chamber 25 of drum 26. For example, heating assembly 40 may include a heating element (not shown), such as a gas burner, an electrical resistance heating element, or heat pump, for heating air. In particular embodiments, the heating assembly 40 may be or include an electric heater comprising a plurality of electric resistance heating elements with a plurality of relays for selectively providing or obstructing electrical power to the heating elements, such as two relays which permit operation of the heating assembly 40 at various power levels, such as 50% power when only one of two relays is closed. As discussed above, during operation of dryer appliance 10, motor 31 rotates drum 26 and fan 49 of air handler 48 such that air handler 48 draws air through chamber 25 of drum 26 when motor 31 rotates fan 49. In particular, ambient air enters heating assembly 40 via an inlet 51 due to air handler 48 urging such ambient air into inlet 51. Such ambient air is heated within heating assembly 40 and exits heating assembly 40 as heated air. Air handler 48 draws such heated air through supply duct 41 to drum 26. The heated air enters drum 26 through a plurality of outlets of supply duct 41 positioned at rear wall 34 of drum 26.
Within chamber 25, the heated air may accumulate moisture, e.g., from damp clothing disposed within chamber 25. In turn, air handler 48 draws moisture-saturated air through a screen filter (not shown) which traps lint particles. Such moisture-statured air then enters an exit duct 46 and is passed through air handler 48 to an exhaust duct 52. From exhaust duct 52, such moisture-statured air passes out of dryer appliance 10 through a vent 53 defined by cabinet 12. After the clothing articles have been dried, they are removed from the drum 26 via opening 32. A door 33 (
In some embodiments, one or more selector inputs 70, such as knobs, buttons, touchscreen interfaces, etc., may be provided or mounted on a cabinet 12 (e.g., on a backsplash 71 of the cabinet 12) and are in operable communication (e.g., electrically coupled or coupled through a wireless network band) with a processing device or controller 100. A display 56 may also be provided on the backsplash 71 and may also be in operable communication with the controller 100. Controller 100 may also be provided in operable communication with motor 31, air handler 48, and/or heating assembly 40. In turn, signals generated in controller 100 direct operation of motor 31, air handler 48, and/or heating assembly 40 in response to the position of inputs 70. In the example illustrated in
Controller 100 is a “processing device” or “controller” and may be embodied as described herein. As used herein, “processing device” or “controller” may refer to one or more microprocessors, microcontrollers, application-specific integrated circuits (ASICS), or semiconductor devices and is not restricted necessarily to a single element. The controller 100 may be programmed to operate dryer appliance 10 by executing instructions stored in memory (e.g., non-transitory media). The controller 100 may include, or be associated with, one or more memory elements such as RAM, ROM, or electrically erasable, programmable read only memory (EEPROM). For example, the instructions may be software or any set of instructions that when executed by the processing device, cause the processing device to perform operations. Controller 100 may include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions and/or instructions (e.g. performing the methods, steps, calculations and the like and storing relevant data as disclosed herein). It should be noted that controllers as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein. For example, in some embodiments, methods disclosed herein may be embodied in programming instructions stored in the memory and executed by the controller.
In some exemplary embodiments, the dryer appliance 10 may include one or more temperature sensors, such as inlet temperature sensor 43 and/or outlet temperature sensor 47. The temperature sensor(s) may be in operative communication with the controller 100. For example, in various embodiments, the controller 100 may be operable to detect, measure, and/or monitor one or more temperatures within the dryer appliance 10. Such temperatures which may be detected, measured, and/or monitored include, for example, an inlet temperature measured with the inlet temperature sensor 43 and/or an outlet temperature measured with the outlet temperature sensor 47. The temperature sensors 43 and 47 may be, in some embodiments, thermistors.
The temperature sensors 43 and 47 may be part of a primary heat control system of the dryer appliance 10. The dryer appliance 10 may also include a secondary or backup heat control system including one or more thermostats. When either the primary heat control system or the second heat control system (or both) detects excessive heat, e.g., a temperature above a threshold or limit value, which may be an instantaneous temperature or a temperature exceeding the limit for a minimum period of time, the heating assembly 40 may be deactivated until the respective heat control system resets. As will be recognized by those of ordinary skill in the dryer art, the thermostats of the secondary heat control system generally take longer to reset after detecting excessive heat. Thus, the secondary heat control system may be set to a higher temperature threshold value or temperature limit in order to reduce or avoid tripping the secondary heat control system and thus reduce or avoid the relatively longer (as compared to the thermistors of the primary heat control system) reset time of the thermostat(s) in the secondary heat control system.
In some instances, the secondary heat control system may experience a nuisance trip, when one or more, e.g., both, thermostats in the secondary heat control system trip and deactivate, e.g., cut off electric power from, the heating assembly 40.
As shown in
After storing the peak value of the temperature, the method 200 may then allow a first wait period to elapse. For example, as illustrated at step 206 in
When the temperature has continued to decrease after the first wait period, the method 200 may also include verifying that there is a call for heating, e.g., as illustrated at step 208 in
In some embodiments, the method 200, e.g., the step 210 of verifying the call for heating, may also include verifying that no relays were opened within a predetermined period of time, such as within the last about fifteen seconds. The predetermined period of time may, in various embodiments, be between about five seconds and about thirty-five seconds, such as between about ten seconds and about thirty seconds, such as between about fifteen seconds and about twenty-five seconds, such as about fifteen seconds, or about twenty seconds, or about twenty-five seconds.
When the temperature gradient is still negative at step 208 and there is a call for heating, e.g., no relays were opened within the predetermined period of time and/or at least one relay is closed, at step 210, the method 200 may then include a second wait period. In various embodiments, the second wait period may be between about five seconds and about twenty-five seconds, such as between about ten seconds and about twenty seconds, such as about fifteen seconds.
In some embodiments, for example as illustrated at step 212 in
In some embodiments, the monitored temperature may be an inlet temperature which is monitored with an inlet thermistor, e.g., a thermistor which is positioned upstream of the drum 26 and the chamber 25 defined therein with respect to the flow of heated air from the heating system 40. For example, the inlet thermistor may be inlet temperature sensor 43 positioned in the supply duct 41, e.g., as illustrated in
In some embodiments, the method 200 may include allowing a third wait period to elapse. In various embodiments, the third wait period may be between about five seconds and about twenty-five seconds, such as between about ten seconds and about twenty seconds, such as about fifteen seconds. Allowing the third wait period to elapse may be performed after verifying that the temperature gradient is still negative following the second wait period and/or after comparing the outlet temperature to the one or more outlet temperature setpoints (e.g., determining whether the outlet temperature is less than both the upper outlet setpoint and the lower outlet setpoint, as described above). In embodiments which include the third wait period, the method 200 may also include a third slope check, e.g., verifying that the temperature gradient is still negative after the third wait period.
As illustrated at step 214 in
Still with reference to
In at least some embodiments, e.g., as illustrated at step 218 in
In at least some embodiments, after detecting the nuisance trip, the primary heat control system temperature setpoints may be lowered in order to reduce the chance of another nuisance trip. For example, with lower primary heat control system setpoints, it is more likely that the heating system will be controlled by or in response to the primary heat control system before reaching a temperature at which the thermostat(s) of the secondary heat control system will trip. In some embodiments, a count may be increased, e.g., by one, after detecting the nuisance trip. In such embodiments, lowering the setpoints of the primary heat control system may be performed after the count reaches a limit value.
Turning now to
The method 300 may then include determining that at least one relay configured for providing electrical power to the heating system is on. For example, as illustrated at step 304 in
After verifying that the relay is closed, the method 300 may include a step 308 of allowing a minimum on time to elapse. In various embodiments, the minimum on time may be between about five seconds and about ten seconds, such as about seven and a half seconds.
In some embodiments, e.g., as illustrated at step 310 in
The method 300 may then include determining whether the temperature gradient is negative, e.g., as illustrated at step 312 in
Embodiments of the present disclosure include dryer appliances and related methods with indirect detection of the status of the thermostat(s) in the secondary heat control system. For example, the dryer appliances and methods disclosed herein may detect a nuisance trip of the thermostat without a direct physical connection to the thermostat. As another example, the dryer appliances and methods disclosed herein may also be useful for detecting a malfunction or fault in the heating system.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.