Abstract:
A passive diverter is provided that does not require a dedicated motor to switch between multiple outlet ports. The diverter uses the forces provided by a flow of fluid from a pump to switch between different outlet ports and supply one or more spray assemblies or other fluid-using elements. A separate motor to power the diverter is not required, which allows a savings in costs and space. In addition, a secondary set of ramps may provide a manner in which to “zero” the angular position of the diverter, i.e., place the diverter in a known, home position. This can reduce the additional cost, weight, and complexity of including additional sensors to determine the angular position of the diverter.

Description:
FIELD OF THE INVENTION 
     The subject matter of the present disclosure relates generally to a diverter for an appliance. 
     BACKGROUND OF THE INVENTION 
     Dishwasher appliances generally include a tub that defines a wash compartment. Rack assemblies can be mounted within the wash compartment of the tub for receipt of articles for washing. Spray assemblies within the wash compartment can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. Multiple spray assemblies can be provided including e.g., a lower spray arm assembly mounted to the tub at a bottom of the wash compartment, a mid-level spray arm assembly mounted to one of the rack assemblies, and/or an upper spray assembly mounted to the tub at a top of the wash compartment. Other configurations may be used as well. 
     A dishwashing appliance is typically equipped with at least one pump for circulating fluid through the spray assemblies. However, due to e.g., government regulations related to energy and/or water usage, the pump may not be able to supply fluid to all spray assemblies at the same time. Accordingly, a dishwashing appliance that can be configured to selectively control the flow through different spray assemblies or other fluid elements would be useful. 
     Certain conventional dishwashing appliances use a device, referred to as a diverter, to control the flow of fluid in the dishwashing appliance. For example, the diverter can be used to selectively control which flow assemblies receive a flow of fluid. In one construction, the diverter uses an electrically powered motor to rotate an element between different ports for fluid control. The motor adds a significant expense to the overall manufacturing cost of the dishwashing appliance and must be separately controlled during cleaning operations so that the proper flow is occurring. 
     Additionally, the motor is typically positioned below the diverter, which is positioned below the sump portion of the appliance. As such, significant space is consumed which can reduce the space available in the dishwashing compartment for placement of dishes, glasses, silverware, and other items for cleaning. 
     In another construction, a diverter uses a hydraulically actuated rotation mechanism to rotate the diverter valve such that it rotates between flow assemblies without the need for a motor. Notably, however, this type of diverter requires additional means for determining its angular position at any given time. For example, one method used for determining the angular position of such a diverter is placing a magnet in a rotating portion of the diverter valve and using a stationary sensor, e.g., a Hall effect sensor, to determine the position of the magnet. However, such means for determining the angular position of the diverter valve require additional parts, resulting in additional cost and complexity. 
     Thus, a hydraulically actuated diverter that does not require a separate angular position sensor would be beneficial, resulting in a savings in both costs and space. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides a passive, hydraulically actuated diverter, i.e., a diverter that does not require a dedicated motor to switch between multiple outlet ports. The diverter uses the forces provided by a flow of fluid from a pump to switch between different outlet ports and supply one or more spray assemblies or other fluid-using elements. A separate motor to power the diverter is not required, which allows a savings in costs and space. Moreover, a secondary set of ramps may provide a manner in which to “zero” the angular position of the diverter, i.e., place the diverter in a known, home position. This can reduce the additional cost, weight, and complexity of including additional sensors to determine the angular position of the diverter. Additional aspects and advantages of the invention will be set forth in part in the following description, may be apparent from the description, or may be learned through practice of the invention. 
     In one exemplary embodiment, the present invention provides a dishwasher appliance. The dishwasher appliance includes a wash chamber for receipt of articles for washing and a pump for providing fluid flow for cleaning the articles. A diverter receives fluid flow from the pump and includes, a plurality of outlet ports for providing fluid to the wash chamber and a housing defining a chamber. The chamber fluidly connects a fluid inlet and a fluid outlet such that a fluid may flow into the chamber through the fluid inlet and out of the chamber through the fluid outlet to one or more of the outlet ports. The housing also defines a cylindrically-shaped well and a first ramped element is positioned within a distal end of the well. The diverter may further include a valve positioned within the fluid outlet that is rotatable about an axis and movable along an axial direction between a first position and a second position. The valve defines radial and circumferential directions, and includes a disk defining a plurality of apertures for selectively controlling fluid flow from the fluid outlet to one or more of the outlet ports, the apertures being spaced apart along a circumferential direction. A cylindrically-shaped shaft is connected to the disk, extends along the axial direction, and is slidably received within the well of the housing. The shaft defines an interior channel, and a plurality of cams is positioned on the cylindrical shaft near the disk and project radially inward from the cylindrical shaft into the interior channel. A second ramped element is positioned near a distal end of the shaft. A boss extends along the axial direction from the housing into the interior channel of the valve. A plurality of guide elements is positioned on the boss near the housing and extends radially outward from the boss. A biasing element extends between the boss and the valve and is configured to urge the valve towards the first position. The first ramped element and the second ramped element are configured to contact each other when the valve moves into the first position so as to cause the valve to rotate into a base angular position. The guide elements and the cams are configured to contact each other when the valve moves into the second position so as to cause the valve to rotate incrementally through a plurality of selected angular positions for fluid flow through one more outlet ports. 
     In another exemplary embodiment, the present invention provides a passive diverter for selectively controlling fluid flow in an appliance. A diverter receives fluid flow from the pump and includes, a plurality of outlet ports for providing fluid to a wash chamber and a housing defining a chamber. The chamber fluidly connects a fluid inlet and a fluid outlet such that a fluid may flow into the chamber through the fluid inlet and out of the chamber through the fluid outlet to one or more of the outlet ports. The housing also defines a cylindrically-shaped well and a first ramped element is positioned within a distal end of the well. The diverter may further include a valve positioned within the fluid outlet that is rotatable about an axis and movable along an axial direction between a first position and a second position. The valve defines radial and circumferential directions, and includes a disk defining a plurality of apertures for selectively controlling fluid flow from the fluid outlet to one or more of the outlet ports, the apertures being spaced apart along a circumferential direction. A cylindrically-shaped shaft is connected to the disk, extends along the axial direction, and is slidably received within the well of the housing. The shaft defines an interior channel, and a plurality of cams is positioned on the cylindrical shaft near the disk and project radially inward from the cylindrical shaft into the interior channel. A second ramped element positioned near a distal end of the shaft. A boss extends along the axial direction from the housing into the interior channel of the valve. A plurality of guide elements is positioned on the boss near the housing and extend radially outward from the boss. A biasing element extends between the boss and the valve and is configured to urge the valve towards the first position. The first ramped element and the second ramped element are configured to contact each other when the valve moves into the first position so as to cause the valve to rotate into a base angular position. The guide elements and the cams are configured to contact each other when the valve moves into the second position so as to cause the valve to rotate incrementally through a plurality of selected angular positions for fluid flow through one more outlet ports. The disk is positioned within a path of fluid flow through the chamber such that valve is moved toward the second position by a predetermined rate of fluid flow through the fluid outlet of the chamber. 
     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 front view of an exemplary embodiment of a dishwashing appliance of the present invention. 
         FIG. 2  provides a side, cross-sectional view of the exemplary dishwashing appliance of  FIG. 1 . 
         FIG. 3  is a perspective view of an exemplary embodiment of a passive diverter of the present invention. 
         FIG. 4  is a side view of an exemplary embodiment of the exemplary passive diverter of  FIG. 3 . 
         FIG. 5  is a cross-sectional view of the exemplary passive diverter of  FIG. 3  with a diverter valve shown in a first position. 
         FIG. 6  is also a cross-sectional view of the exemplary passive diverter of  FIG. 3  with the diverter valve shown in an intermediate position between the first position and a second position. 
         FIG. 7  is also a cross-sectional view of the exemplary passive diverter of  FIG. 3  with the diverter valve shown in the second position. 
         FIG. 8  is an exploded view of the exemplary passive diverter of  FIG. 3 . 
         FIG. 9  is a bottom, perspective view of the diverter valve of the exemplary passive diverter of  FIG. 3 . 
         FIG. 10  is a top view of the diverter valve of the exemplary passive diverter of  FIG. 3 . 
         FIG. 11  is an exploded, cross-sectional view of the exemplary passive diverter of  FIG. 3 . 
         FIG. 12  is a top, perspective view of the diverter valve of the exemplary passive diverter of  FIG. 3 . 
         FIG. 13  is a bottom, perspective view of a first portion of the housing of the exemplary passive diverter of  FIG. 3 . 
         FIG. 14  is a schematic, bottom view of a diverter valve inside the first portion of the housing of an exemplary diverter valve as the diverter valve is rotated between selected angular positions. 
         FIG. 15  is a schematic side view of a boss and a valve channel of the passive diverter of  FIG. 3 , showing the rotation of the valve channel as it moves from the second position to the first position. 
         FIG. 16  top, perspective view of a ramped feature in the second portion of the housing well of the exemplary passive diverter of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE 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 term “article” may refer to, but need not be limited to, dishes, pots, pans, silverware, and other cooking utensils and items that can be cleaned in a dishwashing appliance. The term “wash cycle” is intended to refer to one or more periods of time during the cleaning process where a dishwashing appliance operates while containing articles to be washed and uses a detergent and water, preferably with agitation, to e.g., remove soil particles including food and other undesirable elements from the articles. The term “rinse cycle” is intended to refer to one or more periods of time during the cleaning process in which the dishwashing appliance operates to remove residual soil, detergents, and other undesirable elements that were retained by the articles after completion of the wash cycle. The term “drying cycle” is intended to refer to one or more periods of time in which the dishwashing appliance is operated to dry the articles by removing fluids from the wash chamber. The term “fluid” refers to a liquid used for washing and/or rinsing the articles and is typically made up of water that may include additives such as e.g., detergent or other treatments. The use of the terms “top” and “bottom,” or “upper” and “lower” herein are used for reference only as example embodiments disclosed herein are not limited to the vertical orientation shown nor to any particular configuration shown; other constructions and orientations may also be used. 
       FIGS. 1 and 2  depict an exemplary domestic dishwasher  100  that may be configured in accordance with aspects of the present disclosure. For the particular embodiment of  FIGS. 1 and 2 , the dishwasher  100  includes a cabinet  102  having a tub or inner liner  104  therein that defines a wash chamber  106 . The tub  104  includes a front opening (not shown) and a door  110  hinged at its bottom  112  for movement between a normally closed vertical position (shown in  FIGS. 1 and 2 ), wherein the wash chamber  106  is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from the dishwasher  100 . Latch  116  is used to lock and unlock door  110  for access to chamber  106 . 
     Upper and lower guide rails  120 ,  122  are mounted on tub side walls  124  and accommodate roller-equipped rack assemblies  126  and  128 . Each of the rack assemblies  126 ,  128  is fabricated into lattice structures including a plurality of elongated members  130  (for clarity of illustration, not all elongated members making up assemblies  126  and  128  are shown in  FIG. 2 ). Each rack  126 ,  128  is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber  106 , and a retracted position (shown in  FIGS. 1 and 2 ) in which the rack is located inside the wash chamber  106 . This is facilitated by rollers  134  and  136 , for example, mounted onto racks  126  and  128 , respectively. A silverware basket (not shown) may be removably attached to rack assembly  128  for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by the racks  126 ,  128 . 
     The dishwasher  100  further includes a lower spray-arm assembly  140  that is rotatably mounted within a lower region  142  of the wash chamber  106  and above a tub sump portion  144  so as to rotate in relatively close proximity to rack assembly  128 . A mid-level spray-arm assembly  146  is located in an upper region of the wash chamber  106  and may be located in close proximity to upper rack  126 . Additionally, an upper spray assembly  148  may be located above the upper rack  126 . 
     The lower and mid-level spray-arm assemblies  142 ,  146  and the upper spray assembly  148  are part of a fluid circulation assembly  150  for circulating water and dishwasher fluid in the tub  104 . The fluid circulation assembly  150  also includes a pump  152  positioned in a machinery compartment  154  located below the tub sump portion  144  (i.e., bottom wall) of the tub  104 , as generally recognized in the art. Pump  152  receives fluid from sump  144  and provides a flow to the inlet  202  of a passive diverter  200  as more fully described below. 
     Each spray-arm assembly  140 ,  146  includes an arrangement of discharge ports or orifices for directing washing liquid received from diverter  200  onto dishes or other articles located in rack assemblies  126  and  128 . The arrangement of the discharge ports in spray-arm assemblies  140 ,  146  provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the spray-arm assemblies  140 ,  146  and the operation of spray assembly  148  using fluid from diverter  200  provides coverage of dishes and other dishwasher contents with a washing spray. Other configurations of spray assemblies may be used as well. 
     The dishwasher  100  is further equipped with a controller  156  to regulate operation of the dishwasher  100 . The controller  156  may include one or more memory devices and one or more microprocessors, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. 
     The controller  156  may be positioned in a variety of locations throughout dishwasher  100 . In the illustrated embodiment, the controller  156  may be located within a control panel area  158  of door  110  as shown in  FIGS. 1 and 2 . In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of dishwasher  100  along wiring harnesses that may be routed through the bottom  112  of door  110 . Typically, the controller  156  includes a user interface panel/controls  160  through which a user may select various operational features and modes and monitor progress of the dishwasher  100 . In one embodiment, the user interface  160  may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the user interface  160  may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface  160  may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface  160  may be in communication with the controller  156  via one or more signal lines or shared communication busses. 
     It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher  100 . The exemplary embodiment depicted in  FIGS. 1 and 2  is for illustrative purposes only. For example, different locations may be provided for user interface  160 , different configurations may be provided for racks  126 ,  128 , and other differences may be applied as well. 
       FIGS. 3 and 4  provide a top, perspective view and a side view, respectively, of an exemplary embodiment of a passive diverter  200  of the present invention. Passive diverter  200  has a fluid inlet  202  for receiving a flow of fluid from pump  152  that is to be supplied to spray assemblies  140 ,  146 , and/or  148  as well as other fluid-using components during cleaning operations. As stated, pump  152  receives fluid from e.g., sump  144  and provides a fluid flow to diverter  200 . 
     For this exemplary embodiment, diverter  200  includes a plurality of outlet ports—shown in  FIG. 3  and  FIG. 4  as first outlet port  204  and a second outlet port  206 . However, in other embodiments of the invention, three, four, or more than four outlet ports may be used with diverter  200  depending upon e.g., the number of switchable ports desired for selectively placing pump  152  in fluid communication with different fluid-using elements of appliance  100 . Diverter  200  includes a valve  210  (see, e.g.,  FIG. 9 ), more fully described below, that can be selectively switched between ports  204  and  206  without using a separate motor for such purpose. 
     By way of example, first outlet port  204  can be fluidly connected with upper spray assembly  148  and lower spray arm assembly  140  and second outlet port can be fluidly connected with mid-level spray arm assembly  146 . Other connection configurations may be used as well. As such, the rotation of valve  210  in passive diverter  200  can be used to selectively place pump  152  in fluid communication with spray assemblies  140 ,  146 , or  148  by way of outlet ports  204  and  206 , as described in an exemplary embodiment below. Diverter  200  includes multiple apertures  212  that allow for fastening diverter  200  to the sump  142  of wash tub  104  ( FIG. 2 ). 
     Referring now to  FIGS. 3 through 8 , diverter  200  is constructed from a housing  214  that includes a first portion  218  and a second portion  220 . An O-ring  222  provides a fluid seal therebetween. Housing  214  defines a chamber  224  into which fluid flows through its fluid inlet  226 . Chamber  224  also defines a fluid outlet  228 , which is formed by the circular edge  230  at the top of second portion  220  ( FIGS. 5 through 7 ). In this manner, the chamber may provide fluid communication into the chamber  224  through the fluid inlet  226  and out of the chamber through the fluid outlet  228  to one or more of the outlet ports  204 ,  206 . 
     Valve  210  is positioned within fluid outlet  228  of chamber  224  and defines a radial direction R and a circumferential direction C (see, e.g.,  FIG. 9 ). More particularly, valve  210  includes a cylindrically-shaped shaft  240  that extends along the axial direction and is received into a cylindrically-shaped well  242  formed by second portion  220  of housing  214 . This cylindrically-shaped shaft  240  is slidably received within the well  242  of the housing  214 , such that valve  210  is rotatable about axis A-A relative to housing  214  and movable back and forth along axial direction A. 
     For this exemplary embodiment, a first ramped element  244  is positioned within a distal end  246  of well  242 . A second ramped element  248  is positioned near a distal end  250  of valve shaft  240 . As will be described below, the first ramped element  244  and the second ramped element  248  are used to selectively position the diverter valve  210  in a known angular position. 
     As can be seen by comparing  FIGS. 5 through 7 , valve  210  is movable along the axial direction A (or along axis A-A, which is parallel to the axial direction A) between a first position shown in  FIG. 5  and a second position shown in  FIG. 7 . An intermediate position of the valve  210  is shown in  FIG. 6 . In the first position shown in  FIG. 5 , valve  210  rests on second portion  220  of housing  214 . More particularly, valve  210  may include a frustoconical surface  252  positioned on the distal end of a flange  254 . In turn, flange  254  projects along axial direction A from the circular main body, or disk  256 , of valve  210  towards second portion  220  of housing  214 . In the first position, frustoconical surface  252  rests in a complementary manner on an interior surface  258  of second portion  220  that is also frustoconical in shape. In the second position shown in  FIG. 7 , valve  210  is pressed against first portion  218  of housing  214 . For this exemplary embodiment, a top surface  260  ( FIG. 10 ) of valve  210  contacts an interior surface  262  of first portion  218 . 
     Movement of valve  210  back and forth between the first position shown in  FIG. 5  and the second position shown in  FIG. 7  is provided by two opposing forces: i) a flow of water passing through diverter  200  that is counteracted by ii) a biasing element  270 . More particularly, when pump  152  is off, biasing element  270  pushes along axial direction A against valve  210  and forces it downward along axis A-A (arrows D) to the position shown in  FIG. 5 . Conversely, when there is a sufficient flow of fluid F through diverter housing  200 , the momentum of fluid exiting chamber  224  through the fluid outlet  228  of housing  214  will impact valve  210 . As the fluid passes through apertures  272 ,  274 ,  276 ,  278  to exit diverter  200  through one of the outlet ports  204 ,  206 , this momentum overcomes the force provided by biasing element  270  so as to shift valve  210  along axial direction A (arrows U) away from diverter bottom  220  towards diverter top  218  to a second position shown in  FIG. 7 . 
     Flange  254  assists in capturing the momentum provided by fluid flow through fluid outlet  220 . In addition, as shown in  FIG. 9 , a bottom surface  280  of disk  256  of valve  210  may further include a plurality of arcuate ribs  282 . These arcuate ribs  282  capture the momentum and of the fluid flow and tend to cause the valve  210  to rotate in only one direction. The arcuate ribs  282  cause the valve  210  to rotate in a clockwise manner about axis A when viewed from bottom of valve  210 . As shown in  FIG. 9 , the disk  256  may include three arcuate ribs  282 . However, one skilled in the art will appreciate that any number of arcuate ribs may be used. Similarly, the ribs may be different size, shape, or orientation depending on the needs of the application. 
     Valve  210  will remain in the second position until the fluid flow ends or drops below a certain flow rate. Then, biasing element  270  urges valve  210  along axial direction A away from diverter top  218  towards diverter bottom  220  and back into the first position shown in  FIG. 5 . As shown in the exemplary embodiment of  FIGS. 5 through 7 and 11 , the biasing element  270  extends between a boss  284  of first portion  218  and the valve shaft  240  and is configured to urge the valve  210  toward the first position. In this regard, boss  284  may define a recess  286  into which a top end  288  of the biasing element  270  may be slidably received, and a bottom end  290  of the biasing element  270  may be received in a conically-shaped seat  292  defined, for example, at the bottom of an interior channel  294  of valve shaft  240 . In the illustrated embodiment, conically-shaped seat  292  is disposed opposite the second ramped element  248  that may be used to return the valve  210  to a known angular position, as described in detail below. The conically-shaped seat  292  and second ramped element  248  may be formed as an integral piece within the interior channel  294 , or may be constructed of separate pieces. 
     As best shown in  FIG. 11 , the biasing element  270  may be, for example, a plunger  302  including a plunger shaft  304  connected with a plunger head  306 . The plunger head  306  may have a larger diameter than the plunger shaft  304  and a compression spring  308  may be received onto the plunger shaft  304  and compressed against the plunger head  306 . In the exemplary embodiment, the plunger head  306  has a conically-shaped tip  310  that is received in the conically-shaped seat  292  disposed opposite the second ramped element  248 . One skilled in the art will appreciate that the above-described biasing element  270  is only an example, and other types of biasing elements are possible. For example, in some embodiments, the biasing element may be a simple compression spring. 
     The movement of valve  210  back and forth along axis A-A between the first and second positions shown in  FIGS. 5 and 7  also causes valve  210  to rotate about axis A-A so that apertures  272 ,  274 ,  276 ,  278  are switched between outlet ports  204  and  206 . For this exemplary embodiment, a single movement in either direction (arrow U or arrow D) causes valve  210  to rotate 60 degrees. Accordingly, valve  210  rotates about axis A-A a full 120 degrees each time it is moved out of, and then returned to, the second position ( FIG. 7 ). This is true as long as the valve  210  does not reach the first position ( FIG. 5 ), which resets the value to a “home” position as described below. 
     As noted above, disk  256  of valve  210  may include a plurality of apertures  272 ,  274 ,  276 ,  278  which may be selectively placed in fluid communication with one or more outlet ports  204 ,  206  to provide fluid flow to spray assemblies  140 ,  146 , and  148 . For example, as shown in the illustrated embodiment of  FIGS. 9 and 10 , disk  256  may include a first aperture  272 , a second aperture  274 , a third aperture  276 , and a fourth aperture  278 . The disk  256  can be rotated so as to place one or more of its apertures  272 ,  274 ,  276 ,  278  in fluid communication with one or more of outlet ports  204 ,  206 . As shown in  FIG. 13 , the fluid outlet ports  204 ,  206  are spaced apart circumferentially on the first portion  218  of the housing  214  by 180 degrees. Apertures  272 ,  274 ,  276 ,  278  are spaced circumferentially around disk  256  such that apertures  272  and  278  are spaced apart by 180 degrees and apertures  274  and  276  are placed circumferentially between apertures  272  and  278  on one half of disk  256  with 60 degree spacing between the centers of apertures  272 ,  274 ,  276 ,  278 . 
     Notably, this geometry of outlet ports  204 ,  206  and apertures  272 ,  274 ,  276 ,  278  provides three modes of operation when disk  256  is configured to rotate in 120 degree increments. As described below, this rotation is achieved by using three cams along with three upper and three lower guide elements to provide 120 degrees of rotation. This operation is shown schematically in  FIG. 14 , which shows the disk  256  of valve  210  rotating clockwise (as viewed looking up on first portion  218 ) within the first portion  218  of the housing  214  in 120 degree increments. A first angular position  320  corresponds with a dual-spray configuration because apertures  272  and  278  are each in fluid communication with one of outlet ports  204  and  206  while apertures  274  and  276  are blocked. Therefore, when valve  210  is rotated to place disk  256  in a first angular position  320 , a flow of fluid from pump  152  is supplied to spray assemblies  140 ,  146 , and  148 . Similarly, when the disk  256  is rotated within housing  14  to a second angular position  322 , which is 120 degrees from the first angular position  320 , aperture  276  is in fluid communication with fluid outlet port  204 , but apertures  272 ,  274 , and  278  are blocked, as is fluid outlet port  206 . In this manner, a flow of fluid from pump  152  is supplied only to spray assemblies  140  and  148 . When the disk  256  is rotated another 120 degrees to a third angular position  324 , aperture  274  is in fluid communication with fluid outlet port  206 , but apertures  272 ,  276 , and  278  are blocked, as is fluid outlet port  204 . In this manner, a flow of fluid from pump  152  is supplied only to spray assembly  148 . Finally, when the disk  256  is rotated another 120 degrees, the disk  256  has returned to its first angular position  320 , and dual-spray operation is resumed. As such, passive diverter  200  can be used to selectively provide fluid flow from pump  152  through outlet ports  204  and  206  in three operation modes. The manner in which disk  256  of valve  210  is rotated in 120 degree increments, thus indexing between the three modes of operation, is described in more detail below. 
     Although the illustrated embodiment shows a valve  210  and disk  256  having four apertures  272 ,  274 ,  276 ,  278  and rotating in 120 degree increments, one skilled in the art will appreciate that this configuration is provided only as an example. The disk  256  may have more or fewer apertures and may be indexed at different increments. In addition, the increments may not be constant, but may instead vary according to the needs of the application. Similarly, the housing  214  may have more than two outlet ports, and the scheduling of fluid communication between disk  256  and the outlet ports may be manipulated as desired. 
     Referring now to  FIG. 13 , a cylindrically-shaped boss  284  extends along axis A-A from first portion  218  of housing  214  into an interior channel  294  ( FIGS. 10 through 12 ) defined by valve  210 . As mentioned above, boss  284  defines recess  286  into which a first end  288  of biasing element  270  is received. Boss  284  also includes a plurality of guide elements  330  and  332  that are spaced apart from each other along circumferential direction C and extend radially outward from the boss  284 . A first plurality of lower guide elements  330 , are located near a midpoint  334  of boss  284  while a second plurality of upper guide elements  332  are located near diverter top  218 . Upper and lower guide elements  330 ,  332  are spaced apart along axial direction A and are also offset from each other along circumferential direction C. More particularly, as best seen in  FIG. 15 , along axial direction A, each of the upper guide elements  332  is aligned with a gap  336  positioned between a respective pair of the lower guide elements  330 . Conversely, each of the lower guide elements  330  is aligned with a gap  338  between a respective pair of the upper guide elements  332 . 
     Referring now to  FIGS. 13 and 15 , each of the lower guide elements  330  may be a projection having a straight side  340  that is parallel to the axial direction. In addition, lower guide elements  330  may include an upper contact face  342  extending from straight side  340  and forming a non-zero, acute angle from the axial direction and a lower contact face  344  extending from upper contact face  342  and forming a non-zero, acute angle from the axial direction. Each of the upper guide elements  332  may be a projection having a pair of straight sides  346 ,  348  that are parallel to the axial direction. In addition, upper guide elements  332  may include a contact face  350  extending between the pair of straight sides  346 ,  348  and forming a non-zero, acute angle from the axial direction. The upper and lower guide elements  330 ,  332  may thus define contact faces at non-zero angles between zero and 90 degrees from the axial direction A. For the exemplary embodiment shown, this angle is about 45 degrees. In another embodiment, this angle is about 42 degrees. In still another embodiment, this angle is about 40 degrees to about 50 degrees from the axial direction. However, other angles may be used as well. 
     As stated and shown, boss  284  is received into an interior channel  294  defined by the shaft of valve  210 . Referring to  FIGS. 10 through 12 , a plurality of cams  352  are positioned on the interior channel  294  of the cylindrical valve shaft  240  and project radially inward (i.e., along radial direction R) from the cylindrical shaft  240  into the interior channel  294 . As best shown in  FIG. 15 , each cam  352  includes an upper contact face  354  and a lower contact face  356 . Each cam  352  is spaced apart from adjacent cams  352  along the circumferential direction, and each cam  352  is at the same axial position along the axial direction. In addition, each cam  352  is shown as a triangular shaped projection. However, one skilled in the art will appreciate that this is only an exemplary embodiment of the plurality of cams, and that different cam shapes, configurations, and spacing are contemplated as within the scope of the present invention. 
     Still referring to  FIG. 15 , as a flow of fluid overcomes biasing element  270  and valve  210  moves from the first position ( FIG. 5 ) towards the second position ( FIG. 7 ), upper contact face  354  of each cam  352  contacts upper guide element  332  at contact face  350 . In this manner, valve  210  is caused to rotate 60 degrees so that each cam  352  moves into gap  338  between a pair of the upper guide elements  332 . This movement is guided by contact face  350 . In this second position ( FIG. 7 ), apertures  272 ,  274 ,  276 ,  278  may be aligned with one of the outlet ports  204  and  206 . As the flow of fluid is turned off, biasing element  270  causes valve  210  to move towards the first position ( FIG. 5 ). During this movement, lower contact face  356  of each cam  352  contacts upper contact face  342  of guide element  330  and causes valve  210  to rotate another 60 degrees so that each cam  352  moves into a gap  336  between a pair of the lower guide elements  330 . This movement is guided by contact face  342 . Upon returning to the second position, valve  210  is again caused to rotate by 60 degrees as previously described so that apertures  272 ,  274 ,  276 ,  278  are switched to the next mode of operation, as discussed above. The process can be repeated to switch between modes of operation. In this manner, the guide elements  330 ,  332  and cams  352  are configured to contact each other when the valve  210  moves into the second position so as to cause the valve  210  to rotate incrementally through a plurality of selected angular positions to provide fluid flow through one or more outlet ports  204 ,  206 . 
     As stated, the passive diverter  200  of the present invention may be used with more than two outlet ports and the disk  256  may have less than or more than four apertures. In such case, as will be understood by one of skill in the art using the teachings disclosed herein, the configuration of cams  352  and guide elements  336 ,  338  described above can be modified to provide the desired amount of rotation between the selected number of outlet ports. For example four cams along with four upper and four lower guide elements are used to provide 90 degrees of rotation between four outlet ports in another exemplary embodiment. 
     Accordingly, during operation of appliance  100 , controller  156  can be programmed to operate pump  152  and control the position of valve  210 . More specifically, when valve  210  is oscillating between the first position ( FIG. 5 ) and the intermediate position ( FIG. 6 ), such that first ramped element  244  and second ramped element  248  do not contact each other, the controller  156  can determine the current angular position of the valve  210  by counting the number of times the pump  152  has been cycled on and off. Notably, however, the controller  156  must know the initial angular position of the valve  210 . For example, knowing the last outlet port through which fluid flow occurred, controller  156  can activate pump  152  to rotate valve  210  to the next outlet port in the direction of rotation of valve  210  so as to control the flow of fluid. Each time pump  152  is cycled off and back on to provide a flow of fluid through passive diverter  200  (e.g., during or between wash and rinse cycles), the controller  156  will “know” that valve  210  has been rotated to the next outlet port. 
     However, a variety of factors may affect the angular position of the valve  210 , so the controller  156  may not always be able to accurately track the angular position of the valve  210 . In addition, at certain times during operation of the washing machine appliance  100 , it may be desirable to reset the angular position of the diverter valve  210  to a known position. This may be desirable when, for example, the controller  156  does not know the angular position, or when it is desirable to skip the next incremental angular position. To achieve this reset, first ramped element  244  and second ramped element  248  are configured to contact each other when the valve  210  moves into the first position so as to cause the valve  210  to rotate to a base angular position. The region in which the first and second ramped elements  244 ,  248  interact (e.g., between the intermediate position and the first position) may be referred to as the first region of axial movement. Similarly, the region in which the first and second ramped elements  244 ,  248  do not interact (e.g., between the intermediate position and the second position) may be referred to as the second axial region. 
     Referring now to  FIGS. 9, 15, and 16 , first ramped element  244  and second ramped element  248  are configured to interact such that they cause rotation of the valve  210  when it travels through the first axial region and reaches the first position. In this manner, first ramped element  244  is disposed in the second portion  220  of the housing  214  at a distal end  246  of the well  242  and defines an upwardly oriented first contact surface  360 . The second ramped element  248  is disposed at a distal end  250  of the valve shaft  240  and defines a downwardly oriented second contact surface  362 . The first ramped element  244  and the second ramped element  248  are in axial alignment, such that movement of the valve shaft  240  within the first axial region into the first position causes the first contact surface  360  and the second contact surface  362  to contact each other. 
     As shown in the illustrated embodiment, the first and second contact surfaces  360 ,  362  may be mirror images of each other. The first contact surface  360  may be defined between a peak  364  at a distal end of the first ramped element  244  and a valley  366  proximate to second portion  220  of housing  214 . Similarly, the second contact surface  362  may be defined between a peak  364  at a distal end of the second ramped element  244  and a valley  366  at a proximate end. The first and second contact surfaces  360 ,  362  may be curved or straight, and are configured to ensure that when the first ramped element  244  and the second ramped element  248  come into axial contact, the first and second contact surfaces  360 ,  362  may slide relative to each other so as to rotate the valve shaft  240  to a base angular position. As shown in  FIG. 15 , when the valve shaft  240  reaches the first position, the peak  364  of the first ramped element  244  is adjacent the valley  370  of the second ramped element  248 , and the valve  210  and valve shaft  240  have rotated to the base angular position. One skilled in the art will appreciate that mating ramped elements are only one way to ensure that valve returns to a base angular position, and other suitable mechanisms for achieving angular rotation are within the scope of the invention. 
     As described above, the first and second ramps  244 ,  248  are configured to interact when the valve  210  is moving axially within a first axial region and the cams  352  and guide elements  330 ,  332  are configured to interact as the valve  210  moves within a second axial region. Because biasing element  270  begins driving valve  210  toward the first position (i.e., downward) as soon as the flow of fluid is stopped, the duration of time that the pump  152  is turned off determines whether the valve  210  moves within the second axial region only, or whether the valve  210  reaches the first axial region. Therefore, by stopping the fluid flow through the diverter  200  for a short time period before restarting the flow, the valve  210  remains in the second axial region, thus making one incremental rotation for each time the fluid flow is temporarily stopped and started. In this manner, the dishwasher appliance  100  may iterate through various wash cycles by cycling the pump  152  off momentarily before switching it back on to deliver wash water to selected spray assemblies  140 ,  146 ,  148 . However, by leaving the pump  152  off for a longer time period, the biasing element  270  causes the valve  210  to enter into the first axial region where, as discussed above, the valve  210  is rotated to its base angular position. In this manner, the “home” position of the diverter valve  210  may always be achieved by stopping the pump  152  for a predetermined amount of time longer than the short period of time used to cycle through the plurality of angular positions. 
     In order to ensure that the pump  152  may accurately control the rotation of the valve, it may be desirable to increase the difference between the short time period and the long time period. For example, if the off time required to cycle through the different angular positions is 0.5 seconds and the off time required to “home” the diverter valve  210  is 1 second, it may not be feasible for the controller  156  and pump  152  to consistently cycle through the plurality of positions without unintentionally entering the first axial region and setting the valve  210  to the base angular position. By slowing the descent speed of the valve  210 , the controller  156  and pump  152  may be able to more accurately control the rotation of the valve  210 . 
     Therefore, in some embodiments, the valve shaft  240  may form a tight fit within the well  242  of the second portion  218  of the housing  214 . Alternatively, a seal may be used to restrict the flow of fluid between the well  242  and the chamber  224  of the housing  214 . In this manner, fluid flow into and out of the well portion  242  of the housing  214  may be restricted, e.g., by forcing wash water to travel through an orifice in the center of the valve shaft  240  or within the restricted interface between the well  242  of the housing  214  and the outside of valve shaft  240 . In this manner, for example, the valve shaft  240  and well  242  act as a damper to slow the axial speed of the valve  210 , and the time it takes for the valve  210  to travel from the first axial region to the second axial region may be extended. By increasing this travel time, the controller  156  will be able to more accurately control the on/off time of the pump  152 . In this manner, the controller  156  can ensure that the diverter  210  is set to the base angular position only when desired and is incrementally rotated only when desired. 
     One skilled in the art will appreciate that many factors determine how quickly the valve  210  travels between the first and second position, and there are many other ways in which the travel time of the valve may be adjusted. For example, the spring constant of biasing element  210 , wash fluid viscosity, valve shaft  240  and well  242  dimensions, and the axial length of the valve shaft  240 , among other factors, all may be relevant in determining the travel time of the valve  210  between the first and the second position. Therefore, configuring the geometry of the valve shaft  240  and well  242  to act as a damper is only one exemplary way of affecting the travel time, and other methods are contemplated as within the scope of the present invention. 
     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 language of the claims.