Dryer Appliance and Method for Dryer Cycle Control

The present subject matter relates to dryer appliances and apparatuses for dryer cycle control for dryer appliances.

Dryer appliances generally include a cabinet with a drum rotatably mounted therein. During operation, a motor rotates the drum, e.g., to tumble articles located within a chamber defined by the drum. Dryer appliances also generally include a system for passing dry, heated air through the chamber in order to dry moisture-laden articles positioned therein. Typically, an air handler or blower is used to urge the flow of heated air through the chamber to dry the clothes.

Dryer appliances may include an electronic controller having software configured to use a combination of timing, load moisture sensing, and temperature sensing to control cycle stages, heater pulsing, and cycle termination. However, for dryer appliances without such software, a temperature setpoint may not be variable.

Dryer appliances may generally be configured to operate using ambient inlet air ranging in temperature from 0 degrees Celsius to over 40 degrees Celsius. Such operating range can impact performance of the dryer appliance. For instance, at colder temperatures, dryer appliances may generally use more energy during the drying cycle to reach the temperature setpoint, which may result in increased energy consumption and over-drying the laundry load. At warmer temperatures, the dryer appliance may use less energy that results in under-drying the laundry load.

A dryer appliance addressing these issues would be beneficial and advantageous.

Advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

An aspect of the present disclosure is directed to a method for cycle control at a dryer appliance. The method includes positioning a first thermistor to receive a first temperature signal relative to an inlet flow of air to a heater assembly and positioning a second thermistor to receive a second temperature signal relative to a heated flow of air heated from the heater assembly. The first thermistor and the second thermistor have a substantially similar resistance-temperature curve as one another. The method includes determining an output voltage based on an input voltage, the first thermistor, and the second thermistor in a voltage divider circuit; comparing the output voltage to a reference voltage corresponding to a control pulsing, a timer adjustment, or a cycle termination; and adjusting a dryer cycle based on the output voltage relative to the reference voltage.

An aspect of the present disclosure is directed to a controller for a dryer appliance. The controller includes a voltage divider circuit having a first thermistor configured to receive a first temperature signal corresponding to an inlet flow of air to a heater assembly, and a second thermistor configured to receive a second temperature signal corresponding to a heated flow of air heated from the heater assembly. The first thermistor and the second thermistor have a substantially similar resistance-temperature curve as one another. A heater control relay is configured to compare an output voltage of the voltage divider circuit to a reference voltage.

An aspect of the present disclosure is directed to a dryer appliance. The dryer appliance includes a drum rotatably mounted within a cabinet. The drum defines a chamber for receipt of articles for drying. A heater assembly is configured to selectively generate, from an inlet flow of air, a heated flow of air for fluid communication with the chamber. A duct is positioned to flow the inlet flow of air into thermal communication with the heater assembly to generate the heated flow of air. A voltage divider circuit includes a first thermistor configured to receive a first temperature signal corresponding to the inlet flow of air to the heater assembly, and a second thermistor configured to receive a second temperature signal corresponding to the heated flow of air heated from the heater assembly. The first thermistor and the second thermistor have a substantially similar resistance-temperature curve as one another. A heater control relay is configured to compare an output voltage of the voltage divider circuit to a reference voltage.

These and other features, aspects and advantages of the present invention 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 invention and, together with the description, serve to explain the principles of the invention.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

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, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). In addition, here and throughout the specification and claims, range limitations may be combined and/or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. The terms “upstream” and “downstream” refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the flow direction from which the fluid flows, and “downstream” refers to the flow direction to which the fluid flows.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 10 percent margin, i.e., including values within ten percent greater or less than the stated value. In this regard, for example, 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, e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, e.g., clockwise or counterclockwise, with the vertical direction V.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” In addition, references to “an embodiment” or “one embodiment” does not necessarily refer to the same embodiment, although it may. Any implementation described herein as “exemplary” or “an embodiment” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, 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 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.

Referring now to the figures, an exemplary laundry appliance that may be used to implement aspects of the present subject matter will be described. Specifically,provide perspective views of a dryer applianceaccording to exemplary embodiments of the present disclosure. Particularly,provides a perspective view of dryer appliance.provides another perspective view of dryer appliancewith a portion of a housing or cabinetof dryer applianceremoved in order to show certain components of dryer appliance.

As depicted in, dryer appliancedefines a vertical direction V, a lateral direction L, and a transverse direction T, each of which is mutually perpendicular such that an orthogonal coordinate system is defined. While described in the context of a specific embodiment of dryer appliance, using the teachings disclosed herein it will be understood that dryer applianceis provided by way of example only. Other dryer appliances having different appearances and different features may also be utilized with the present subject matter as well. For instance, in some embodiments, dryer appliancecan be a combination washing machine/dryer appliance, a condenser dryer, or any other suitable laundry appliance.

Cabinetincludes a plurality of panels including a front panel, a rear panel, a pair of side panelsand(e.g., a first side paneland a second side panel) spaced apart from each other by front paneland rear panelalong the lateral direction L, a bottom panel, and a top cover. Cabinetdefines an interior volume. A container or drumis mounted for rotation about a substantially horizontal axis within the interior volumeof cabinet. Drumdefines a chamberfor receipt of articles for tumbling and/or drying. 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. Drumextends between a front portionand a back portion, e.g., along the transverse direction T. Drumalso includes a back or rear wall, e.g., at back portionof drum. For example, dryer appliancemay be configured as an electric dryer appliance with electrical heating elements or as a gas dryer appliance with gas heating elements (e.g., gas burners) for heating air.

In some embodiments, a motoris provided to rotate drumabout the horizontal axis, e.g., via a pulley and a belt (not pictured). Drumis generally cylindrical in shape. Drumhas an outer cylindrical walland a front flange or wallthat defines an openingof drum, e.g., at front portionof drum, for loading and unloading of articles into and out of chamberof drum. Drumincludes a plurality of lifters or bafflesthat extend into chamberto lift articles therein and then allow such articles to tumble back to a bottom of drumas drumrotates. Bafflesmay be mounted to drumsuch that bafflesrotate with drumduring operation of dryer appliance.

Rear wallof drumis rotatably supported within cabinetby a suitable bearing. Rear wallcan be fixed or can be rotatable. Rear wallmay include, for instance, a plurality of holesthat receive hot air that has been heated by a heater assembly. The heater assemblymay include a heat pump or refrigerant-based heater assembly. Moisture laden, heated air is drawn from drumby an air handlerthat draws air through chamberof drumwhen motorrotates a fan assembly. In particular, ambient air, shown schematically via arrow, enters heater assemblydue to air handlerurging relatively cool ambient airinto the heater assembly. Such cool airis selectively heated through the heater assemblyand is provided as heated air, shown schematically via arrowto chamber. In various embodiments, heater assemblymay be non-activated or deactivated such that air,provided to the chamberis substantially similar to ambient air(i.e., unheated). Air handlerdraws heated airthrough a duct, such as a back duct or first duct, to drum. Heated airenters through the plurality of holesand flows through chamber, such as depicted schematically via arrow. Within chamber, heated aircan accumulate moisture (e.g., from damp articles disposed within chamber). In turn, air handlerdraws the moisture laden heated air, depicted schematically via arrow. Airenters through an outlet duct. Ductmay form a front duct or second duct including a lint filter(e.g., a screen filter) configured to collect lint during drying. Heated airpasses through ductenclosing filter, which traps lint particles. More specifically, filtermay include a screen, mesh, or other material to capture lint in the air flow. The location of lint filters in applianceas shown inis provided by way of example only, and other locations may be used as well. As shown, lint filteris readily accessible by a user of the appliance. Air then passes through air handlerto an exhaust duct, such as depicted schematically via arrows.

A doorprovides for closing or accessing drumthrough opening. According to exemplary embodiments, a window (not shown) in doorpermits viewing of chamberwhen dooris in the closed position, e.g., during operation of dryer appliance. Dooralso includes a handle that, e.g., a user may pull when opening and closing door. Further, although dooris illustrated as mounted to front panel, it should be appreciated that doormay be mounted to another side of cabinetor any other suitable support according to alternative embodiments. Dryer appliancemay further include a latch assembly(see) that is mounted to cabinetand/or doorfor selectively locking doorin the closed position. Latch assemblymay be desirable, for example, to ensure only secured access to chamberor to otherwise ensure and verify that dooris closed during certain operating cycles or events.

In some embodiments, one or more selector inputs, such as knobs, buttons, touchscreen interfaces, etc., may be provided or mounted on a cabinet(e.g., on a user interface panel) and are communicatively coupled with an appliance controller. Controllermay also be communicatively coupled with various operational components of dryer appliance, such as motor, fan assembly, and/or components of heater assembly. In turn, signals generated in controllerdirect operation of motor, fan assembly, or heater assemblyin response user inputs to selector inputs.

Referring to, a schematic voltage divider circuitis provided. The voltage divider circuitforms a passive linear circuit configured to generate an output voltage as a fraction of an input voltage. The voltage divider circuitincludes two or more thermistors, such as a first thermistorand a second thermistor, in serial arrangement. The input voltage is applied across the thermistors,. The output voltage is generated from the connection between the thermistors,. The voltage divider circuitmay be configured based on a voltage divider equation such as:

in which Rcorresponds to second thermistorand Rcorresponds to first thermistor.

Thermistors,include any appropriate type of semiconductor resistor having a resistance substantially dependent on temperature. In various embodiments, the resistance at thermistors,is substantially similar to one another. First thermistoris configured to receive a first temperature signal corresponding to an inlet flow of air, such as ambient airto the heater assembly. Second thermistoris configured to receive a second temperature signal corresponding to a heated flow of air, such as heated air,generated from the heater assembly.

Embodiments of the controllermay include the voltage divider circuit. For instance, referring to the schematic embodiment of the dryer appliancedepicted in, controlleris configured to receive the first temperature signal and the second temperature signal. In some embodiments, the first thermistoris positioned in thermal communication with the ambient air, such as at ductupstream of the heater assembly. In still some embodiments, the second thermistoris positioned in thermal communication with the heated air, such as at ductor outlet ductdownstream of heater assembly.

The controllermay include a heater control relayconfigured to compare an output voltage of the voltage divider circuitto a reference voltage. In still various embodiments, the reference voltage corresponds to a control pulsing, a timer adjustment, or a cycle termination. The heater control relayis configured to adjust one or more of the control pulsing, the timer adjustment, or the cycle termination based on comparing the reference voltage to output voltage.

Referring to, an exemplary resistance-temperature curveis provided, including a first axiscorresponding to resistance in Ohms and a second axiscorresponding to temperature in Celsius. In various embodiments, the thermistors,are configured with substantially identical curves. The thermistors,having substantially similar curves facilitates comparison between the first thermistorand the second thermistor. Thermistors,include a substantially linear thermistor curverelative to a linear relationshipbetween a first resistance at a lower end of a temperature range, depicted at point, and a second resistance at a higher end of the temperature range, depicted at point. For instance, the first resistance may correspond to a low or first temperature limit (e.g., approximately zero degrees Celsius) and the second resistance may correspond to a high or second temperature limit (e.g., approximately 40 degrees Celsius).

A differencebetween the resistance-temperature curveand the linear relationshipis compared to an operating threshold to determine the thermistors,included at the voltage divider circuit. The operating threshold includes an operational error from the linear relationship, such as a margin of error. The thermistor,is substantially linear (e.g., relative to linear relationship) when the differenceis at or below (e.g., within) the operating threshold, such that differences between the curves,are substantially negligible. Linearity of the curvefacilitates comparison of the thermistors,using the voltage divider circuit. The substantially linear resistance-temperature curvebetween thermistors,decreases the effect that received temperature from air flows,will have on thermistor response. As such, the voltage divider circuitmay measure approximately the same difference in temperature without regard to the ambient temperature of inlet air.

The voltage divider circuitincluding two or more thermistors,having substantially similar resistances relative to first and second temperatures (e.g., corresponding to flows,) such as described herein may provide a structure and method for ambient temperature compensation at the dryer appliance. First thermistoris in thermal communication with substantially ambient air flowand second thermistoris in thermal communication with the desired sensing environment, such as heated air flowdownstream of heater assembly, or heated airat dryer outlet duct.

In some embodiments, heater control relayis configured to receive the output voltage. Controllermay be configured to compare a predetermined reference voltage corresponding to a control pulsing (e.g., ON/OFF operation of the heater assembly or generation of heat), a timer advance (e.g., adjustment to dryer cycle time), or a cycle termination (e.g., commanding an end to the dryer cycle). For instance, the heater control relaymay compare the output voltage generated from the voltage divider circuitto one or more reference voltages to determine whether one or more thresholds are triggered, such as to adjust or terminate the dryer cycle based on responses from the thermistors,.

Referring now to, a flowchart outlining steps of a method for cycle control at a dryer appliance is provided (hereinafter, “method”). Methodmay be implemented in any appropriate dryer appliance, such as embodiments of dryer appliancedepicted and described herein. However, it should be appreciated that embodiments of the methodmay be included at other embodiments of dryer appliances not depicted herein.

Methodincludes atpositioning a first thermistor (e.g., thermistor) to receive a first temperature signal relative to an inlet flow of air (e.g., air) to a heater assembly (e.g., heater assembly). Methodincludes positioning a second thermistor (e.g., thermistor) to receive a second temperature signal relative to a heated flow of air (e.g., air, air) heated from the heater assembly. The first thermistor and the second thermistor include a substantially similar resistance as one another, such as described herein.

Methodincludes atdetermining an output voltage based on an input voltage, the first thermistor, and the second thermistor in a voltage divider circuit, such as described in regard to voltage divider circuit. Methodincludes atcomparing the output voltage to a reference voltage corresponding to a control pulsing, a timer adjustment, or a cycle termination. Methodincludes atadjusting a dryer cycle based on the output voltage relative to the reference voltage.

In some embodiments, methodincludes atcomparing an operating threshold to a difference between a resistance-temperature curve and a linear relationship between a first resistance and a second resistance. Positioning the first thermistor and the second thermistor is based on the difference being at or below the operating threshold. For instance, the thermistor positioned at the appliance may be based on the difference between the resistance-temperature curve and the linear relationship between the temperatures being at or below the operating threshold.

It should be appreciated that thresholds, margins, comparisons, or discrete values provided herein may include a range of 10% greater than or less than a stated value or relative curve or reference. Ranges provided herein may additionally, or alternatively, include values 10% greater than or less than of a full range scale of a nominal range.

Embodiments of the dryer applianceand methodprovided herein may provide temperature compensation and dryer cycle control without requiring electronic controller software. Embodiments provided herein may mitigate or eliminate over-drying and under-drying of laundry articles, reduce energy consumption, and improve overall dryer cycle performance. Embodiments of the controllermay avoid configurations including, or requiring, processors and memory devices, while facilitating dryer cycle control and adjustment. For instance, embodiments of the controllermay be configured as an analog controller.

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.