Washing machine appliance and damper assembly for same

Washing machine appliances and damper assemblies are provided. A damper assembly includes a cylinder defining a central longitudinal axis, the cylinder including a sidewall that defines an interior, the sidewall defining a central bore and a pocket concentrically surrounding the central bore, the sidewall including an upper shoulder and a lower shoulder that each connect the pocket and the central bore. The damper assembly further includes a piston partially disposed in the central bore and movable along the longitudinal axis relative to the cylinder. The damper assembly further includes a tube assembly concentrically surrounding the piston and at least partially disposed in the pocket, the tube assembly having a length that is less than a length of the pocket. The piston is further movable along the longitudinal axis relative to the tube assembly.

FIELD OF THE INVENTION

The present subject matter relates generally to washing machine appliances, such as vertical axis washing machine appliances, and damper assemblies for washing machine appliances.

BACKGROUND OF THE INVENTION

Washing machine appliances generally include a cabinet which receives a tub for containing wash and rinse water. A wash basket is rotatably mounted within the wash tub. A drive assembly is coupled to the wash tub and configured to rotate the wash basket within the wash tub in order to cleanse articles within the wash basket. Upon completion of a wash cycle, a pump assembly can be used to rinse and drain soiled water to a draining system.

Washing machine appliances include vertical axis washing machine appliances and horizontal axis washing machine appliances, where “vertical axis” and “horizontal axis” refer to the axis of rotation of the wash basket within the wash tub. Vertical axis washing machine appliances typically have the wash tub suspended in the cabinet with damping devices. Vertical axis washing machine appliances exhibit vibration harmonics and work in a wide range of rotational speeds.

Many previously known damping devices are fixed friction damping devices which are tuned to one condition that requires the greatest amount of friction. Such fixed friction type damping devices, however, may poorly accommodate the wide range of mass, imbalance, and rotational speed seen in vertical axis washing machine appliances. More recently, various two-stage damping devices have been utilized. These devices provide minimal or no damping under certain conditions and substantial damping under other conditions. Such devices do not adequately address the wide range of mass, imbalance, and rotational speed seen in vertical axis washing machine appliances. Still further, the use of active dampers has been contemplated. However, such dampers are generally considered cost-prohibitive for washing machine appliance applications.

Accordingly, a need exists for improved damping devices for use in washing machine appliances. In particular, damping device which includes variable damping features for varying the damping force generated by the damping device would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one embodiment, a damper assembly is provided. The damper assembly includes a cylinder defining a central longitudinal axis, the cylinder including a sidewall that defines an interior, the sidewall defining a central bore and a pocket concentrically surrounding the central bore, the sidewall including an upper shoulder and a lower shoulder that each connect the pocket and the central bore. The damper assembly further includes a piston partially disposed in the central bore and movable along the longitudinal axis relative to the cylinder. The damper assembly further includes a tube assembly concentrically surrounding the piston and at least partially disposed in the pocket, the tube assembly having a length that is less than a length of the pocket. The piston is further movable along the longitudinal axis relative to the tube assembly.

In accordance with another embodiment, a washing machine appliance is provided. The washing machine appliance includes a cabinet, a tub disposed within the cabinet, and a damper assembly. The damper assembly includes a cylinder defining a central longitudinal axis, the cylinder including a sidewall that defines an interior, the sidewall defining a central bore and a pocket concentrically surrounding the central bore, the sidewall including an upper shoulder and a lower shoulder that each connect the pocket and the central bore. The damper assembly further includes a piston partially disposed in the central bore and movable along the longitudinal axis relative to the cylinder. The damper assembly further includes a tube assembly concentrically surrounding the piston and at least partially disposed in the pocket, the tube assembly having a length that is less than a length of the pocket. The piston is further movable along the longitudinal axis relative to the tube assembly.

DETAILED DESCRIPTION

FIG. 1provides a perspective view partially broken away of a washing machine appliance50according to an exemplary embodiment of the present subject matter. As may be seen inFIG. 1, washing machine appliance50includes a cabinet52and a cover54. A backsplash56extends from cover54, and a control panel58including a plurality of input selectors60is coupled to backsplash56. Control panel58and input selectors60collectively form a user interface input for operator selection of machine cycles and features, and in one embodiment a display61indicates selected features, a countdown timer, and other items of interest to machine users. A lid62is mounted to cover54and is rotatable about a hinge (not shown) between an open position (not shown) facilitating access to a wash tub64located within cabinet52, and a closed position (shown inFIG. 1) forming a sealed enclosure over wash tub64.

As illustrated inFIG. 1, washing machine appliance50is a vertical axis washing machine appliance. While the present disclosure is discussed with reference to a vertical axis washing machine appliance, those of ordinary skill in the art, using the disclosures provided herein, should understand that the subject matter of the present disclosure is equally applicable to other washing machine appliances, such as horizontal axis washing machine appliances.

Tub64includes a bottom wall66and a sidewall68, and a basket70is rotatably mounted within wash tub64. A pump assembly72is located beneath tub64and basket70for gravity assisted flow when draining tub64. Pump assembly72includes a pump74and a motor76. A pump inlet hose80extends from a wash tub outlet82in tub bottom wall66to a pump inlet84, and a pump outlet hose86extends from a pump outlet88to an appliance washing machine water outlet90and ultimately to a building plumbing system discharge line (not shown) in flow communication with outlet90.

FIG. 2provides a front elevation schematic view of certain components washing machine appliance50including wash basket70movably disposed and rotatably mounted in wash tub64in a spaced apart relationship from tub side wall68and tub bottom66. Basket70includes a plurality of perforations therein to facilitate fluid communication between an interior of basket70and wash tub64.

A hot liquid valve102and a cold liquid valve104deliver fluid, such as water, to basket70and wash tub64through a respective hot liquid hose106and a cold liquid hose108. Liquid valves102,104and liquid hoses106,108together form a liquid supply connection for washing machine appliance50and, when connected to a building plumbing system (not shown), provide a fresh water supply for use in washing machine appliance50. Liquid valves102,104and liquid hoses106,108are connected to a basket inlet tube110, and fluid is dispersed from inlet tube110through a nozzle assembly112having a number of openings therein to direct washing liquid into basket70at a given trajectory and velocity. A dispenser (not shown inFIG. 2), may also be provided to produce a wash solution by mixing fresh water with a known detergent or other composition for cleansing of articles in basket70.

An agitation element116, such as a vane agitator, impeller, auger, or oscillatory basket mechanism, or some combination thereof is disposed in basket70to impart an oscillatory motion to articles and liquid in basket70. In various exemplary embodiments, agitation element116may be a single action element (oscillatory only), double action (oscillatory movement at one end, single direction rotation at the other end) or triple action (oscillatory movement plus single direction rotation at one end, single direction rotation at the other end). As illustrated inFIG. 2, agitation element116is oriented to rotate about a vertical axis118.

Basket70and agitator116are driven by a motor120through a transmission and clutch system122. The motor120drives shaft126to rotate basket70within wash tub64. Clutch system122facilitates driving engagement of basket70and agitation element116for rotatable movement within wash tub64, and clutch system122facilitates relative rotation of basket70and agitation element116for selected portions of wash cycles. Motor120and transmission and clutch system122collectively are referred herein as a motor assembly148.

Basket70, tub64, and machine drive system148are supported by a vibration dampening suspension system. The dampening suspension system can include one or more damping assemblies92, such as piston-cylinder damping assemblies as discussed herein, coupled between and to the wash tub64and the basket70. The dampening suspension system can include other elements, such as a balance ring94disposed around the upper circumferential surface of the wash basket70. The balance ring94can be used to counterbalance an out of balance condition for the wash machine as the basket70rotates within the wash tub64. The wash basket70could also include a balance ring96located at a lower circumferential surface of the wash basket70.

A dampening suspension system generally operates to dampen dynamic motion as the wash basket70rotates within the wash basket64. The dampening suspension system has various natural operating frequencies of the dynamic system. These natural operating frequencies are referred to as the modes of suspension for the washing machine. For instance, the first mode of suspension for the washing machine occurs when the dynamic system including the wash basket70, tub64, and dampening suspension system are operating at the first resonant or natural frequency of the dynamic system.

Operation of washing machine appliance50is controlled by a controller150which is operatively coupled to the user interface input located on washing machine backsplash56(shown inFIG. 1) for user manipulation to select washing machine cycles and features. In response to user manipulation of the user interface input, controller150operates the various components of washing machine appliance50to execute selected machine cycles and features.

In an illustrative embodiment, laundry items are loaded into basket70, and washing operation is initiated through operator manipulation of control input selectors60(shown inFIG. 1). Tub64is filled with water and mixed with detergent to form a wash fluid, and basket70is agitated with agitation element116for cleansing of laundry items in basket70. That is, agitation element is moved back and forth in an oscillatory back and forth motion. In the illustrated embodiment, agitation element116is rotated clockwise a specified amount about the vertical axis of the machine, and then rotated counterclockwise by a specified amount. The clockwise/counterclockwise reciprocating motion is sometimes referred to as a stroke, and the agitation phase of the wash cycle constitutes a number of strokes in sequence. Acceleration and deceleration of agitation element116during the strokes imparts mechanical energy to articles in basket70for cleansing action. The strokes may be obtained in different embodiments with a reversing motor, a reversible clutch, or other known reciprocating mechanism. After the agitation phase of the wash cycle is completed, tub64is drained with pump assembly72. Laundry items are then rinsed and portions of the cycle may be repeated, including the agitation phase, depending on the particulars of the wash cycle selected by a user.

Referring now toFIGS. 3 through 7, damping assemblies92for use in washing machine appliances50are provided. Such damping assemblies are advantageously passive damping assemblies which provide variable damping during operation. Accordingly, improved damping of the washing machine appliance50generally in a variety of modes of suspension, etc., is facilitated through use of such damping assemblies. Further, such damping assemblies are relatively inexpensive due to their passive nature, thus allowing for use in both high and low end washing machine appliances50.

As illustrated, a damping assembly92may include a cylinder200. The cylinder200defines a central longitudinal axis202, and includes a sidewall204that defines an interior206. The interior206includes a central bore208and one or more pockets that concentrically surround the central bore208. The central bore208and the one or more pockets are further defined by the sidewall204, as shown.

For example, a first pocket210may concentrically surround the central bore208. The sidewall204may include an upper shoulder212and a lower shoulder214(the term upper shoulder may be defined as the shoulder closer to the portion of the piston, discussed herein, that is external to the cylinder relative to the other associated shoulder, while the term lower shoulder may be defined as the shoulder further from the portion of the piston that is external to the cylinder relative to the other associated shoulder). Each shoulder212,214may connect the pocket210and the bore208. The shoulders212,214may, for example, be transverse portions of the sidewall204.

Central bore208may have a length209, and first pocket210may have a length211. The lengths209,211may be defined along the central longitudinal axis. As shown, the length211of the first pocket210may be less than the length209of the central bore208. Further, in some embodiments as shown, the first pocket210may be generally centered along the length209of the central bore208.

Further, in some embodiments, a second pocket220may concentrically surround the first pocket210and the central bore208. The sidewall204may thus further include an upper shoulder222and a lower shoulder224. Each shoulder222,224may connect the second pocket220and the first pocket210. The shoulders222,224may, for example, be transverse portions of the sidewall204.

Second pocket220may have a length221. The length221may be defined along the central longitudinal axis202. As shown, the length221of the second pocket220may be less than the length211of the first pocket210. Further, in some embodiments as shown, the second pocket220may be generally centered along the length211of the first pocket210.

Still further, in some embodiments, a third pocket230may concentrically surround the second pocket220, first pocket210and the central bore208. The sidewall204may thus further include an upper shoulder232and a lower shoulder234. Each shoulder232,234may connect the third pocket230and the second pocket220. The shoulders232,234may, for example, be transverse portions of the sidewall204.

Third pocket230may have a length231. The length231may be defined along the central longitudinal axis202. As shown, the length231of the third pocket230may be less than the length221of the second pocket220. Further, in some embodiments as shown, the third pocket230may be generally centered along the length221of the second pocket220.

Additionally, it should be noted that a maximum width or diameter of the first pocket210may be greater than a maximum width or diameter of the central bore208, a maximum width or diameter of the second pocket220may be greater than a maximum width or diameter of the first pocket210, and a maximum width or diameter of the third pocket230may be greater than a maximum width or diameter of the second pocket220.

It should be understood that the present disclosure is not limited to three pockets. Damping assemblies92with only one or two pockets may be utilized, and damping assemblies92with more than three pockets are further within the scope and spirit of the present disclosure.

Damping assembly92may further include a piston240. The piston240may extend between a first end242and a second end244, and may have a length246defined between the first end242and second end244. The piston240may be partially disposed in the central bore208, such that for example the first end242is disposed in the interior206and the second end244is external to the cylinder200. The piston240may further be movable along the longitudinal axis202relative to the cylinder200.

Still further, damping assembly92may include one or more tube assemblies that concentrically surround the piston240. The tube assemblies may each provide frictional force and resulting damping for the damping assembly92. Further, due to differential sizing of the tube assemblies relative to the piston240and each other, variable damping may be provided by the damping assembly92.

For example, a first tube assembly250may concentrically surround the piston240. The first tube assembly250may be movable along the longitudinal axis202, and the piston240may be movable along the longitudinal axis202relative to the first tube assembly250, as discussed herein. The first tube assembly250may be at least partially disposed in the first pocket210, such that the first tube assembly250may contact the respective shoulders212,214when the first tube assembly250has moved along the longitudinal axis202to the respective ends of the pocket210. The first tube assembly250may further have a length252, which may be less than the length211of the first pocket210such that the first tube assembly250can move along the longitudinal axis202within the pocket210.

In some embodiments, the length252of the first tube assembly250may be greater than the length221of the second pocket220. The length252of the first tube assembly250may further be less than the length246of the piston240.

Further, a second tube assembly260may concentrically surround the first tube assembly250and piston240. The second tube assembly260may be movable along the longitudinal axis202, and the first tube assembly250may be movable along the longitudinal axis202relative to the second tube assembly260, as discussed herein. The second tube assembly260may be at least partially disposed in the second pocket220, such that the second tube assembly260may contact the respective shoulders222,224when the second tube assembly260has moved along the longitudinal axis202to the respective ends of the pocket220. The second tube assembly260may further have a length262, which may be less than the length221of the second pocket220such that the second tube assembly260can move along the longitudinal axis202within the pocket220.

In some embodiments, a difference between the length211of the first pocket210and the length252of the first tube assembly250may be greater than a difference between the length221of the second pocket220and the length262of the second tube assembly260. Further, in some embodiments, the length of the second tube assembly260may be greater than the length231of the second pocket230. The length262of the second tube assembly260may further be less than the length252of the first tube assembly250.

Still further, a third tube assembly270may concentrically surround the second tube assembly250, first tube assembly250and piston240. The third tube assembly270may be movable along the longitudinal axis202, and the second tube assembly260may be movable along the longitudinal axis202relative to the third tube assembly270, as discussed herein. The third tube assembly270may be at least partially disposed in the third pocket230, such that the third tube assembly270may contact the respective shoulders232,234when the third tube assembly270has moved along the longitudinal axis202to the respective ends of the pocket220. The third tube assembly270may further have a length272, which may be less than the length231of the second pocket230such that the third tube assembly270can move along the longitudinal axis202within the pocket230.

In some embodiments, a difference between the length221of the second pocket220and the length262of the second tube assembly260may be greater than a difference between the length231of the third pocket230and the length272of the third tube assembly270. The length272of the third tube assembly270may further be less than the length262of the second tube assembly260.

It should be understood that the present disclosure is not limited to three tube assemblies. Damping assemblies92with only one or two tube assemblies may be utilized, and damping assemblies92with more than three tube assemblies are further within the scope and spirit of the present disclosure. Typically, the total number of tube assemblies is equal to the total number of pockets.

In some embodiments, the tube assemblies may each be formed from a single material and may thus be single components. In other embodiments, multiple components may be included in each tube assembly. For example, a tube assembly may include a rigid layer and a flexible layer. The first tube assembly250is illustrated for example as having a rigid layer254and a flexible layer256, while the second tube assembly260is illustrated for example as having a rigid layer264and a flexible layer266and the third tube assembly270is illustrated for example as having a rigid layer274and a flexible layer276. A rigid layer254,264,275may, for example, be a metal cylinder as shown. A flexible layer256,266,276may, for example, be formed from an elastomeric tube. In particular, compressible elastomers, such as foams, are desirable. Alternatively, rubbers, including unsaturated and saturated rubbers, along with other non-compressible elastomers may be utilized. The elastomeric tube may be adhered or otherwise fastened to the metal cylinder. Alternatively, a rigid layer and flexible layer may each be formed from any suitable material. In some embodiments, a flexible layer may for example include one or more o-rings, which may for example be mounted in grooves defined in the rigid layer.

In exemplary embodiments as shown, the flexible layer of a tube assembly may be disposed within the rigid layer. Alternatively, however, the rigid layer may be disposed within the flexible layer.

In some embodiments, as shown, the thickness of the tube assemblies, such as of the layers thereof, may be constant throughout the lengths of the tube assemblies. In other embodiments, however, the thickness of the tube assemblies may change. For example, the thickness of one or more tube assemblies may taper throughout the length or a portion thereof in either direction along the central longitudinal axis202. For example, in some exemplary embodiments wherein a rigid layer and a flexible layer are utilized to form a tube assembly, the rigid layer, the flexible layer, or both may taper in thickness throughout the length or a portion thereof in either direction along the central longitudinal axis202.

Interaction between the tube assemblies themselves and between the tube assemblies and the piston advantageously provide variable damping. For example,FIGS. 3 through 7illustrate the variable damping that occurs during a movement of the piston240within the cylinder200in one direction along the central longitudinal axis202. In exemplary embodiments, such variable damping may occur in both directions of movement along the central longitudinal axis202as shown.

FIG. 4illustrates initial movement. During this movement, the piston240and the first, second and third tube assemblies250,260,270all move together in a direction along the central longitudinal axis202. A minimal frictional force is provided by the outside surface of the third tube assembly270(in this case the rigid layer274) against the sidewall204in the third pocket230.

Once the third tube assembly270contacts a sidewall of the third pocket230, however, such as sidewall234(or232), the third tube assembly270can no longer move in that direction along the central longitudinal axis202. When such contact occurs, movement of the third tube assembly270stops, but the piston240and the first and second tube assemblies250,260all continue to move together in a direction along the central longitudinal axis202, as shown inFIG. 5. An increased frictional force, such as a low intermediate frictional force, is provided by the inside surface of the third tube assembly270(in this case the flexible layer276) against the second tube assembly270. Such increase in frictional force may, for example, be due to the pliant and compressible nature of the flexible layer276.

Once the second tube assembly260contacts a sidewall of the second pocket220, however, such as sidewall224(or222), the second tube assembly260can no longer move in that direction along the central longitudinal axis202. When such contact occurs, movement of the second tube assembly260stops, but the piston240and the first assembly250all continue to move together in a direction along the central longitudinal axis202, as shown inFIG. 6. An increased frictional force, such as a high intermediate frictional force, is provided by the inside surface of the second tube assembly260(in this case the flexible layer266) against the first tube assembly250. Such increase in frictional force may, for example, be due to the length of the second tube assembly260and resulting increased friction-providing surface area relative to the length of the third tube assembly270.

Once the first tube assembly250contacts a sidewall of the first pocket210, however, such as sidewall214(or212), the first tube assembly250can no longer move in that direction along the central longitudinal axis202. When such contact occurs, movement of the first tube assembly250stops, but the piston240continues to move in a direction along the central longitudinal axis202, as shown inFIG. 7. An increased frictional force, such as a maximum frictional force, is provided by the inside surface of the first tube assembly250(in this case the flexible layer256) against the piston240. Such increase in frictional force may, for example, be due to the length of the first tube assembly250and resulting increased friction-providing surface area relative to the length of the second tube assembly260.

Accordingly, the present disclosure provides improved damping assemblies92which facilitate variable damping during operation. Such damping assemblies92may be connected within washing machine appliances50. For example, it should be noted that a damping assembly92may additionally include one or more coupling features for coupling the damping assembly92to, for example, the basket70and tub64. For example a coupling feature300may be provided on an exterior end of the cylinder200, such as the end distal from the exterior portion of the piston240, and a coupling feature302may be provided on the second end244of the piston240. One of the coupling features300,302may be connected to the basket70, and the other may be connected to the tub64. A coupling feature may, for example, be a protrusion defining an aperture through which a mating fastener may be provided to connect the coupling feature. Alternatively, any suitable coupling features are within the scope and spirit of the present disclosure.