DRYER APPLIANCE AND METHOD FOR DRYER CYCLE CONTROL

Description

FIELD OF THE INVENTION

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

BACKGROUND OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

FIG. 1 provides a perspective view of a dryer appliance in accordance with exemplary embodiments of the present disclosure.

FIG. 2 provides a perspective view of the example dryer appliance of FIG. 1 with portions of a cabinet of the dryer appliance removed to reveal certain components of the dryer appliance.

FIG. 3 provides a schematic diagram of an exemplary dryer appliance in accordance with exemplary embodiments of the present disclosure.

FIG. 4 provides an exemplary controller for a dryer appliance in accordance with exemplary embodiments of the present disclosure.

FIG. 5 provides an exemplary resistance-temperature curve in accordance with exemplary embodiments of the present disclosure.

FIG. 6 provides a flowchart outlining steps of a method for dryer cycle control in accordance with exemplary embodiments of the present disclosure.

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.

DETAILED DESCRIPTION

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, FIGS. 1 and 2 provide perspective views of a dryer appliance 10 according to exemplary embodiments of the present disclosure. Particularly, FIG. 1 provides a perspective view of dryer appliance 10. FIG. 2 provides another perspective view of dryer appliance 10 with a portion of a housing or cabinet 12 of dryer appliance 10 removed in order to show certain components of dryer appliance 10.

As depicted in FIG. 1, dryer appliance 10 defines 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 10, using the teachings disclosed herein it will be understood that dryer appliance 10 is 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 appliance 10 can be a combination washing machine/dryer appliance, a condenser dryer, or any other suitable laundry appliance.

Cabinet 12 includes a plurality of panels including a front panel 14, a rear panel 16, a pair of side panels 18 and 20 (e.g., a first side panel 18 and a second side panel 20) spaced apart from each other by front panel 14 and rear panel 16 along the lateral direction L, a bottom panel 22, and a top cover 24. Cabinet 12 defines an interior volume 29. A container or drum 26 is mounted for rotation about a substantially horizontal axis within the interior volume 29 of cabinet 12. Drum 26 defines a chamber 25 for 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. Drum 26 extends between a front portion 37 and a back portion 38, e.g., along the transverse direction T. Drum 26 also includes a back or rear wall 34, e.g., at back portion 38 of drum 26. For example, dryer appliance 10 may 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 motor 31 is provided 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. Drum 26 has 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. Drum 26 includes a plurality of lifters or baffles 27 that extend into chamber 25 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.

Rear wall 34 of drum 26 is rotatably supported within cabinet 12 by a suitable bearing. Rear wall 34 can be fixed or can be rotatable. Rear wall 34 may include, for instance, a plurality of holes 39 that receive hot air that has been heated by a heater assembly 40. The heater assembly 40 may include a heat pump or refrigerant-based heater assembly. Moisture laden, heated air is drawn from drum 26 by an air handler 42 that draws air through chamber 25 of drum 26 when motor 31 rotates a fan assembly 48. In particular, ambient air, shown schematically via arrow 51, enters heater assembly 40 due to air handler 42 urging relatively cool ambient air 51 into the heater assembly 40. Such cool air 51 is selectively heated through the heater assembly 40 and is provided as heated air, shown schematically via arrow 52 to chamber 25. In various embodiments, heater assembly 40 may be non-activated or deactivated such that air 52, 53 provided to the chamber 25 is substantially similar to ambient air 51 (i.e., unheated). Air handler 42 draws heated air 52 through a duct 41, such as a back duct or first duct, to drum 26. Heated air 52 enters through the plurality of holes 39 and flows through chamber 25, such as depicted schematically via arrow 53. Within chamber 25, heated air 53 can accumulate moisture (e.g., from damp articles disposed within chamber 25). In turn, air handler 42 draws the moisture laden heated air, depicted schematically via arrow 54. Air 54 enters through an outlet duct 44. Duct 44 may form a front duct or second duct including a lint filter 46 (e.g., a screen filter) configured to collect lint during drying. Heated air 54 passes through duct 44 enclosing filter 46, which traps lint particles. More specifically, filter 46 may include a screen, mesh, or other material to capture lint in the air flow. The location of lint filters in appliance 10 as shown in FIG. 2 is provided by way of example only, and other locations may be used as well. As shown, lint filter 46 is readily accessible by a user of the appliance. Air then passes through air handler 42 to an exhaust duct 50, such as depicted schematically via arrows 55.

A door 33 provides for closing or accessing drum 26 through opening 32. According to exemplary embodiments, a window (not shown) in door 33 permits viewing of chamber 25 when door 33 is in the closed position, e.g., during operation of dryer appliance 10. Door 33 also includes a handle that, e.g., a user may pull when opening and closing door 33. Further, although door 33 is illustrated as mounted to front panel 14, it should be appreciated that door 33 may be mounted to another side of cabinet 12 or any other suitable support according to alternative embodiments. Dryer appliance 10 may further include a latch assembly 36 (see FIG. 1) that is mounted to cabinet 12 and/or door 33 for selectively locking door 33 in the closed position. Latch assembly 36 may be desirable, for example, to ensure only secured access to chamber 25 or to otherwise ensure and verify that door 33 is closed during certain operating cycles or events.

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 user interface panel 71) and are communicatively coupled with an appliance controller 56. Controller 56 may also be communicatively coupled with various operational components of dryer appliance 10, such as motor 31, fan assembly 48, and/or components of heater assembly 40. In turn, signals generated in controller 56 direct operation of motor 31, fan assembly 48, or heater assembly 40 in response user inputs to selector inputs 70.

Referring to FIG. 4, a schematic voltage divider circuit 80 is provided. The voltage divider circuit 80 forms a passive linear circuit configured to generate an output voltage as a fraction of an input voltage. The voltage divider circuit 80 includes two or more thermistors, such as a first thermistor 81 and a second thermistor 82, in serial arrangement. The input voltage is applied across the thermistors 81, 82. The output voltage is generated from the connection between the thermistors 81, 82. The voltage divider circuit 80 may be configured based on a voltage divider equation such as:

V out = R 2 R 1 + R 2 × V i ⁢ n

in which R₂ corresponds to second thermistor 82 and R₁ corresponds to first thermistor 81.

Thermistors 81, 82 include any appropriate type of semiconductor resistor having a resistance substantially dependent on temperature. In various embodiments, the resistance at thermistors 81, 82 is substantially similar to one another. First thermistor 81 is configured to receive a first temperature signal corresponding to an inlet flow of air, such as ambient air 51 to the heater assembly 40. Second thermistor 82 is configured to receive a second temperature signal corresponding to a heated flow of air, such as heated air 52, 54 generated from the heater assembly 40.

Embodiments of the controller 56 may include the voltage divider circuit 80. For instance, referring to the schematic embodiment of the dryer appliance 10 depicted in FIG. 3, controller 56 is configured to receive the first temperature signal and the second temperature signal. In some embodiments, the first thermistor 81 is positioned in thermal communication with the ambient air 51, such as at duct 41 upstream of the heater assembly 40. In still some embodiments, the second thermistor 82 is positioned in thermal communication with the heated air, such as at duct 41 or outlet duct 44 downstream of heater assembly 40.

The controller 56 may include a heater control relay 84 configured to compare an output voltage of the voltage divider circuit 80 to 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 relay 84 is 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 FIG. 5, an exemplary resistance-temperature curve 500 is provided, including a first axis 501 corresponding to resistance in Ohms and a second axis 502 corresponding to temperature in Celsius. In various embodiments, the thermistors 81, 82 are configured with substantially identical curves 500. The thermistors 81, 82 having substantially similar curves facilitates comparison between the first thermistor 81 and the second thermistor 82. Thermistors 81, 82 include a substantially linear thermistor curve 511 relative to a linear relationship 512 between a first resistance at a lower end of a temperature range, depicted at point 503, and a second resistance at a higher end of the temperature range, depicted at point 504. 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 difference 505 between the resistance-temperature curve 511 and the linear relationship 512 is compared to an operating threshold to determine the thermistors 81, 82 included at the voltage divider circuit 80. The operating threshold includes an operational error from the linear relationship 512, such as a margin of error. The thermistor 81, 82 is substantially linear (e.g., relative to linear relationship 512) when the difference 505 is at or below (e.g., within) the operating threshold, such that differences between the curves 511, 512 are substantially negligible. Linearity of the curve 511 facilitates comparison of the thermistors 81, 82 using the voltage divider circuit. The substantially linear resistance-temperature curve 511 between thermistors 81, 82 decreases the effect that received temperature from air flows 51, 52 will have on thermistor response. As such, the voltage divider circuit 80 may measure approximately the same difference in temperature without regard to the ambient temperature of inlet air 51.

The voltage divider circuit 80 including two or more thermistors 81, 82 having substantially similar resistances relative to first and second temperatures (e.g., corresponding to flows 51, 52) such as described herein may provide a structure and method for ambient temperature compensation at the dryer appliance 10. First thermistor 81 is in thermal communication with substantially ambient air flow 51 and second thermistor 82 is in thermal communication with the desired sensing environment, such as heated air flow 52 downstream of heater assembly 40, or heated air 54 at dryer outlet duct 44.

In some embodiments, heater control relay 84 is configured to receive the output voltage. Controller 56 may 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 relay 84 may compare the output voltage generated from the voltage divider circuit 80 to 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 81, 82.

Referring now to FIG. 6, a flowchart outlining steps of a method for cycle control at a dryer appliance is provided (hereinafter, “method 1000”). Method 1000 may be implemented in any appropriate dryer appliance, such as embodiments of dryer appliance 10 depicted and described herein. However, it should be appreciated that embodiments of the method 1000 may be included at other embodiments of dryer appliances not depicted herein.

Method 1000 includes at 1010 positioning a first thermistor (e.g., thermistor 81) to receive a first temperature signal relative to an inlet flow of air (e.g., air 51) to a heater assembly (e.g., heater assembly 40). Method 1000 includes positioning a second thermistor (e.g., thermistor 82) to receive a second temperature signal relative to a heated flow of air (e.g., air 52, air 54) heated from the heater assembly. The first thermistor and the second thermistor include a substantially similar resistance as one another, such as described herein.

Method 1000 includes at 1020 determining 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 80. Method 1000 includes at 1030 comparing the output voltage to a reference voltage corresponding to a control pulsing, a timer adjustment, or a cycle termination. Method 1000 includes at 1040 adjusting a dryer cycle based on the output voltage relative to the reference voltage.

In some embodiments, method 1000 includes at 1050 comparing 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 appliance 10 and method 1000 provided 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 controller 56 may avoid configurations including, or requiring, processors and memory devices, while facilitating dryer cycle control and adjustment. For instance, embodiments of the controller 56 may 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.