Abstract:
A control shaft and knob assembly includes a control knob having a slot defined therein. The assembly also includes a control shaft which (i) has a bore extending therethrough, (ii) includes a spring arm which is positionable within the slot of the control knob, and (iii) has an opening defined therein. The assembly further includes a locking pin having a first retention member secured thereto. The locking pin is positionable in the bore of the control shaft. When the locking pin is positioned in the bore of the control shaft (i) the locking pin is positioned to inhibit inward deflection of the spring arm, and (ii) the first retention member is received into the opening of the control shaft. A method of securing a control knob to a control shaft of an appliance timer is also disclosed.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to an appliance timer, and more particularly to an apparatus and method for securing a control knob to a control shaft an appliance timer. 
     BACKGROUND OF THE INVENTION 
     Appliance timers are commonly used in many household appliances, such as dishwashers, clothes washers, and clothes dryers. The appliance timer controls operation of the appliance by actuating and deactuating a number of switch assemblies which start and stop various work functions within the appliance such as a rinse function in the case of a clothes washer. The switch assemblies within the appliance timer are actuated and deactuated as a result of interaction between a number of a cam surfaces defined in a camstack of the appliance timer and a number of cam followers which are respectively associated with the switch assemblies. The camstack may be manually positioned to actuate and deactuate the switch assemblies associated with a particularly desired work function by rotating a control knob, which is typically located on the front of the appliance. 
     A control shaft couples the control knob to the camstack such that the camstack may be rotated in a direction corresponding to the rotation of the control knob by a user. As such, a locking mechanism is typically utilized to lock or otherwise secure the control knob to the control shaft. 
     One such locking mechanism for securing the control knob to the control shaft includes a locking pin which is friction fit into an axial bore defined in the control shaft. The locking pin forces the tips of the control shaft outwardly against the sides of a recess defined in the control knob. The force applied by the tips of the control shaft against the control knob effectively secure the control knob to the control shaft. 
     Such a design has a number of drawbacks associated therewith. For example, difficulties may arise during the assembly of an appliance timer which includes such a locking mechanism. In particular, due to manufacturing variations, the geometry of the locking pin may deviate from its intended design thereby rendering the locking pin difficult to install. Moreover, the force necessary to insert the locking pin into the control shaft may vary due to such a variation of the geometry of the locking pin thereby potentially preventing the locking pin from being fully “seating” in the control shaft. In either case, the control knob may not be properly secured to the control shaft thereby necessitating rework or repair during the manufacturing process. 
     What is needed therefore is an apparatus and method for securing a control knob to a control shaft which overcomes one or more of the aforementioned drawbacks. What is further needed is an apparatus and method for securing a control knob to a control shaft which allows for the reliable attachment of the knob to the shaft irrespective of typical manufacturing variations. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention, there is provided a control shaft and knob assembly. The assembly includes a control knob having a slot defined therein. The assembly also includes a control shaft which (i) has a bore extending therethrough, (ii) includes a spring arm which is positionable within the slot of the control knob, and (iii) has an opening defined therein. The assembly further includes a locking pin having a first retention member secured thereto. The locking pin is positionable in the bore of the control shaft. When the locking pin is positioned in the bore of the control shaft (i) the locking pin is positioned to inhibit inward deflection of the spring arm, and (ii) the first retention member is received into the opening of the control shaft. 
     In accordance with another embodiment of the present invention, there is provided a control shaft and knob assembly. The assembly includes a control knob having a slot defined therein. The assembly also includes a control shaft which (i) has a bore extending therethrough, (ii) includes a spring arm which is positionable within the slot of the control knob, and (iii) has a recess defined therein. The assembly further includes a locking pin having a first retention member secured thereto. The locking pin is positionable in the bore of the control shaft. When the locking pin is positioned in the bore of the control shaft (i) the locking pin is positioned to inhibit inward deflection of the spring arm, and (ii) the retention member is received into the recess of the control shaft. 
     In accordance with yet another embodiment of the present invention, there is provided a method of securing a control knob to a control shaft. The method includes the step of advancing a spring arm of the control shaft into a slot of the control knob. The method also includes the step of advancing a locking pin through a bore defined in the control shaft until (i) an end portion of the locking pin extends out of the bore and is located at a position in which the end portion of the locking pin inhibits inward deflection of the spring arm, and (ii) a first retention member which is secured to the locking pin extends into an opening defined in the control shaft. 
     It is therefore an object of the present invention to provide a new and useful apparatus for securing a control knob to a control shaft of an appliance timer. 
     It is a further object of the present invention to provide an improved apparatus for securing a control knob to a control shaft of an appliance timer. 
     It is moreover an object of the present invention to provide a new and useful method of securing a control knob to a control shaft of an appliance timer. 
     It is yet further an object of the present invention to provide an improved method of securing a control knob to a control shaft of an appliance timer. 
     It is moreover an object of the present invention to provide an apparatus for securing a control knob to a control shaft of an appliance timer that provides for ease of manufacture relative to heretofore designed appliance timers. 
     The above and other objects, features, and advantages of the present invention will become apparent from the following description and the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an appliance which includes an appliance timer which incorporates the features of the present invention therein; 
     FIG. 2 is a perspective view of the appliance timer of FIG. 1; 
     FIG. 3 is an exploded perspective view which shows the control knob, the control shaft, and the locking pin of the appliance timer of FIG. 2; 
     FIG. 4 is an enlarged perspective view of the control shaft of FIG.  3 . 
     FIG. 5 is a perspective view which shows the locking pin of FIG. 3 positioned within the elongated bore of the control shaft of FIG. 3; 
     FIG. 6 is a view similar to FIG. 5, but showing (i) the assembly of the control shaft and the locking pin rotated 90°, and (ii) the control knob secured to the control shaft; and 
     FIG. 7 is a cross sectional view taken along the line  7 — 7  of FIG. 6, as viewed in the direction of the arrows. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     Referring now to FIG. 1, there is shown an appliance  10  which is a clothes washing machine. The appliance  10  includes an appliance timer  12  shown in FIG. 2. A control knob  14  is secured to a control shaft  16  extending from the appliance timer  12 . The control shaft  16  allows the appliance timer  12  to be positioned inside the appliance  10  while the control knob  14  is positioned outside the appliance  10 . Therefore, an operator may rotate the appliance timer  12  into a desired position by rotating the control knob  14 . 
     Referring now to FIGS. 3-6, there is shown a control knob  14 , a control shaft  16 , and a locking pin  18 . The control knob  14  has a backside  22  and a front side  24 . A slot  20  is defined in the control knob  14  and extends from the backside  22  through the control knob  14  to the frontside  24 . Additionally, the slot  20  is rectangular shaped. Control knob seats  60  are located at the two ends of the slot  20  to receive the spring arms  26  of the control shaft  16 . 
     The control shaft  16  includes a control shaft base end  28 , a shaft bore  30 , and spring arms  26 . The control shaft  16  locates the control shaft base end  28  at one end and the spring arms  26  at the opposite end. Three cylindrical shaped sections extend from the control shaft base end  28  to the spring arms  26 . 
     The first cylindrical shaped section  40  is located adjacent to the control shaft base end  28 . The diameter of the first cylindrical shaped section  40  is smaller than the diameter of the control shaft base end  28 , thus creating a first edge  42 . 
     A second cylindrical shaped section  44  is adjacent to the first cylindrical shaped section  40  and has a slightly smaller diameter than the first cylindrical shaped section, thus creating a second edge  46 . The second cylindrical shaped section  44  has an opening  36  defined in the side thereof which extends from the surface of the second cylindrical shaped section  44  to the bore  30  of the control shaft  16 . This opening  36  receives a first spring member  76  of the locking pin  18 . Although this first embodiment of the present invention has one opening  36  defined in the second cylindrical shaped section  44 , another embodiment could include a second hole (shown in phantom in FIG. 5) defined in the second cylindrical section  44  to receive the second spring member  78 . Moreover, although the opening  36  is herein described as extending all the way through the side of the control shaft  16  (i.e. so as to extend from the outer surface of the second cylindrical shaped section  44  to the bore  30  of the control shaft  16 ), and has significant advantages thereby in the present invention, certain of such advantages may be achieved by other configurations of the opening  36 . For example, the opening  36  may extend into the inner sidewall of the control shaft  16  (i.e. the surface into which the shaft bore  30  is defined) by a depth which does not cause the opening  36  to extend all the way through the sidewall to the outer surface of the control shaft  16  (i.e. the opening  36  would not be visible from the “outside” of the control shaft  16 ). Such a configuration of the opening  36  is contemplated for use in the present invention and is therefore intended to be within the meaning of the term “opening” as utilized herein. 
     The third cylindrical shaped section  48  is located adjacent to the second cylindrical shaped section  44  and has a slightly smaller diameter than the second cylindrical shaped section  44 , thus creating a third edge  50 . The third edge  50  limits the distance the control shaft  16  will travel in the axial direction  52  when the control knob  14  is pulled outward in order to start the appliance timer  12 . Two spring arms  26  extend from the end of the third cylindrical shaped section  48  opposite to the second cylindrical shaped section  44 . The spring arms  26  extend axially outward from the third cylindrical shaped section  48 . Spring arm barbs  54  are secured to the ends of both spring arms  26  such that the space  56  defined between the spring arm barbs  54  is rectangular shaped. Additionally, a v-shaped notch  58  is defined in the spring arm barbs  54 . The v-shaped notch  58  creates a surface area that will overlap the seats  60  of the control knob  14 . 
     The shaft bore  30  extends through the control shaft  16  from the control shaft base end  28  through the spring barbs arms  26 . As shown in FIG. 7, a first portion  32  of the shaft bore  30  is cylindrically shaped, whereas a second portion  34  of the shaft bore  30  is rectangularly shaped. The diameter of the cylindrically-shaped portion  32  of the shaft bore  30  changes at the intersection between the second cylindrical shaped section  44  of the control shaft  16  and the third cylindrical shaped section  48  of the control shaft  16 . Specifically, the diameter of the cylindrically-shaped portion  32  of the shaft bore  30  which extends through the control shaft base end  28 , the first cylindrical shaped section  40 , and the second cylindrical shaped section  44  is larger than the diameter of the cylindrically-shaped portion  32  of the shaft bore  30  which extends into the third cylindrical shaped section  48  of the control shaft  16 , thus creating an interior ridge  62 . The interior ridge  62  prevents the over-insertion of the locking pin  18  in the axial direction  52 . 
     The rectangularly-shaped portion  34  of the shaft bore  30  is provided to ensure proper alignment of the locking pin  18  when the pin  18  is inserted into the shaft bore  30 . In particular, the locking pin  18  is rectangularly shaped with a rectangularly shaped cross-sectional area. As such, the locking pin  18  is only positionable in the rectangularly-shaped portion  34  of the shaft bore  30  in one of two orientations which are 180 degrees apart from one another (as opposed to four orientations if the pin  18  and bore portion  34  were configured square in shape or a unlimited number of orientations if the pin  18  and the bore portion  34  were configured cylindrical in shape). As shall be discussed below in greater detail, the locking pin  18  is symmetrical in shape and therefore may be inserted into the shaft bore  30  in either one of two orientations and still remain desirably locked within the bore  30 . 
     The locking pin  18  includes a locking pin shaft  82 , a first retention member  64 , a second retention member  66 , a first locking pin stop  68 , a second locking pin stop  70 , a locking pin base end  72 , and a tapered end  74 . The first retention member  64  and the second retention member  66  are secured to the locking pin shaft  82  and are positioned 180 degrees apart. Such positioning of the retention members  64 ,  66  (i.e. 180 degrees apart from one another) provides for the aforedescribed symmetrical design of the locking pin  18  thereby allowing the locking pin  18  to be inserted into the shaft bore  30  in either one of two orientations. 
     The first retention member  64  includes a first spring member  76 . The first spring member  76  is secured to the first retention member  64  and extends in a direction parallel to the locking pin shaft  82 . The tip  90  of the first spring member  76  extends outwardly away from the locking pin shaft  82 . Additionally, the tip of the first spring member  76  is slanted such that the top  92  of the tip is longer than the bottom  94  of the tip. The first spring member  76  is received into the opening  36  of the control shaft  16  when the locking pin  18  is inserted into the bore  30  of the control shaft  16 . 
     The second retention member  66  includes a second spring member  78 . The second spring member  78  is secured to the second retention member  66  and extends in a direction parallel to the locking pin shaft  82 . The tip  96  of the second spring member  78  extends outwardly away from the locking pin shaft  82 . Additionally, the tip of the second spring member  78  is slanted such that the top  98  of the tip is longer than the bottom  100  of the tip. The second spring member  78  is biased against the inner surface of the control shaft  16  when the locking pin  18  is inserted into the bore  30  of the control shaft  16 . 
     The first locking pin stop  68  is located on the locking pin shaft  82  between the first retention member  64  and the tapered end  74 . The second locking pin stop  70  is located on the locking pin shaft  82  between the second retention member  66  and the tapered end  74 . The first locking pin stop  68  and second locking pin stop  70  are 180 degrees apart. During insertion of the locking pin  18  the first locking pin stop  68  and the second locking pin stop  70  contact the interior ridge  62  of the control shaft  16  thus preventing over-insertion of the locking pin  18 . 
     The locking pin  18  has a tapered end  74  which facilitates insertion of the locking pin  18  between the spring arm barbs  54  of the control shaft  16 . When inserted, the tapered end  74  of the locking pin  18  forces the spring arms  26  outward such that the surfaces defined by the v-shaped notch  58  defined in the spring arm barbs  54  are urged outwardly against the control knob seats  60 . 
     The control knob  14  is secured to the control shaft  16  by first inserting the spring arms  26  of the control shaft  16  into the slot  20  of the control knob  14 . The tapered end  74  of the locking pin  18  is then inserted into the shaft bore  30  of the control shaft  16  at the control shaft base end  28 . The locking pin  18  is advanced in the axial direction  52  until the tapered end  74  forces the spring arm barbs  54  against the control knob seat  60 . For the locking pin  18  to be fully inserted into the control shaft  16  the rectangular shaped tapered end  74  must be aligned with the rectangular shaped gap defined between the spring arm barbs  54 . When the locking pin is so aligned, the first spring member  76  will be aligned with and received by the opening  36  of the control shaft  16 . Additionally, the first locking pin stop  68  and the second locking pin stop  70  will contact the interior ridge  62  of the control shaft bore  30 . 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 
     There are a plurality of advantages of the present invention arising from the various features of the appliance timer described herein. It will be noted that alternative embodiments of the appliance timer of the present invention may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of an appliance timer that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present invention as defined by the appended claims.