Abstract:
A control knob for controlling the operation of a component of a household appliance is disclosed. The control knob includes a body configured to be attached to a rotatable rod extending from the appliance. A locking element reversibly secures the body in at least one rotational position. The locking element is movable between a first position and a second position. The locking element is configured to engage with a notch to rotatably secure the body in the at least one rotational position when the locking element is in the first position, and to disengage from the notch to permit the body to be rotated when the locking element is in the second position.

Description:
FIELD OF THE INVENTION 
       [0001]    The following description relates generally to a safety control lockout knob and, more specifically, to a cooking appliance with a safety control lockout knob for preventing accidental operation of the appliance. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cooktops or other appliances can include a plurality of control knobs for allowing a user to actuate a function of the cooktop or appliance, e.g., to set the temperature in an oven, to control a gas burner, electric heating element, or infrared heating element, etc. The control knobs usually are placed at a location whereby a user can easily access the control knobs during operation of the appliance. However, this convenient placement of the control knobs can allow children easy access to the control knobs. Moreover, if left unattended, individuals with dementia or Alzheimer&#39;s may access the control knobs and create an unsafe condition. 
         [0003]    It is desirable to have a control knob with a lockout feature that is designed to prevent accidental actuation of various functions of the cooktop or other appliance. 
       SUMMARY OF THE INVENTION 
       [0004]    A control knob for controlling the operation of a component of a household appliance is disclosed. The control knob comprising a body configured to be attached to a rotatable rod extending from the appliance. A locking element reversibly secures the body in at least one rotational position. The locking element is movable between a first position and a second position. The locking element is configured to engage with a notch to rotatably secure the body in the at least one rotational position when the locking element is in the first position, and to disengage from the notch to permit the body to be rotated when the locking element is in the second position. 
         [0005]    A further control knob is disclosed. The control knob comprising a rotatable knob body having a longitudinal axis. A locking element comprises a pin portion extending therefrom. The pin portion extends through the knob body. A spring biases the locking element into a first position wherein a distal end of the pin portion extends to a forward position relative to a front end of the knob body. The pin portion is slidable against a biasing force of the spring into a second position wherein the distal end thereof is withdrawn from the forward position. 
         [0006]    Yet another control knob is disclosed. The cooktop comprising a rotatable knob body having a longitudinal axis, and a locking element comprising at least one leg extending in a generally longitudinal direction. The at least one leg is in a first, relaxed position wherein a distal end of the at least one leg is spaced from the longitudinal axis. The at least one leg is resiliently deflectable into a second position wherein the distal end is deflected toward said longitudinal axis. 
         [0007]    Still another control knob is disclosed. The control knob comprising a rotatable knob body having a longitudinal axis. A locking element comprises a lever portion extending therefrom. The lever portion extends in a generally longitudinal direction and is pivotable about an axis extending in a direction generally perpendicular to the longitudinal axis of the knob body. A spring biases the locking element into a first position wherein a distal end of the lever portion extends to a forward position relative to a front end of the knob body. The lever portion is pivotable against a biasing force of the spring into a second position wherein the distal end of the lever portion is withdrawn from the forward position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Preferred embodiments are disclosed and described in detail herein with reference to the accompanying drawings which form a part hereof, and wherein: 
           [0009]      FIG. 1  is a perspective view showing a control knob in an OFF position and a locking element of the control knob in a first position, according to a first embodiment; 
           [0010]      FIG. 2  is a perspective view of the first embodiment shown in  FIG. 1 , showing the locking element in a second position; 
           [0011]      FIG. 3  is a sectional view of the first embodiment shown in  FIG. 1  taken along line  3 - 3 ; 
           [0012]      FIG. 4  is a sectional view of the first embodiment shown in  FIG. 2  taken along line  4 - 4 ; 
           [0013]      FIG. 5  is an exploded view of the first embodiment shown in  FIG. 1 ; 
           [0014]      FIG. 6  is a perspective view showing a control knob in an OFF position and a locking element of the control knob in a first position, according to a second embodiment; 
           [0015]      FIG. 7  is a perspective view of the second embodiment shown in  FIG. 6 , showing the locking element in a second position; 
           [0016]      FIG. 8  is a sectional view of the second embodiment shown in  FIG. 6  taken along line  8 - 8 ; 
           [0017]      FIG. 9  is a sectional view of the second embodiment shown in  FIG. 7  taken along line  9 - 9 ; 
           [0018]      FIG. 10  is an exploded view of the second embodiment shown in  FIG. 6 ; 
           [0019]      FIG. 11  is a perspective view showing a control knob in an OFF position and a locking element of the control knob in a first position, according to a third embodiment; 
           [0020]      FIG. 12  is a perspective view of the third embodiment shown in  FIG. 11 , showing the locking element in a second position; 
           [0021]      FIG. 13  is a sectional view of the third embodiment shown in  FIG. 11  taken along line  13 - 13 ; 
           [0022]      FIG. 14  is a sectional view of the third embodiment shown in  FIG. 12  taken along line  14 - 14 ; and 
           [0023]      FIG. 15  is an exploded view of the third embodiment shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0024]      FIG. 1  shows a control knob  50  of a household appliance (not shown), e.g., a cooktop. The household appliance may include a plurality of control knobs  50 . For the purposes of the present application, only one control knob  50  will be described in detail. 
         [0025]    The control knob  50  is mounted to a panel  12  of the appliance. The control knob  50  is provided for allowing a user to control a component or a function of the household appliance, e.g., adjust the temperature in an oven, control a gas burner, electric element, infrared heater, etc. 
         [0026]    As best seen in  FIG. 5 , a rotatable rod  14  extends through an opening  16  formed in the panel  12 . The rod  14  is connected to a component of the appliance wherein rotation of the rod  14  controls the operation of the component. For example, the rod  14  can be a valve stem (as for a gas burner) or the stem of a potentiometer (as for controlling an electric burner or heating element). In a further alternative it can be linked to a cam element to actuate a conventional bimetal switch (not shown). In the illustrated embodiment a distal portion  14   a  of the rod  14  is notched to define a flat surface  14   b . In the embodiment shown, the distal portion  14   a  has a generally “D-shaped” cross section but other cross sectional shapes are contemplated as also being acceptable. As understood by those skilled in the art, the rod  14  is made of a conventional material, including but not limited to, steel and aluminum. 
         [0027]    In the embodiment shown, the opening  16  is generally circular in shape. A portion of the panel  12  is contoured to define a notch  16   a . The notch  16   a  is positioned and dimensioned as described in detail below. 
         [0028]    Referring now to  FIGS. 1-5 , the control knob  50  is shown. The control knob  50  has a front end oriented toward a user and a rear end oriented toward the appliance. In general, the control knob  50  includes a body  52  and a locking element  72 . The body  52  is generally cylindrical in shape with a longitudinal axis “A” and includes a contoured grip  52   a , a front face  52   b  and a rear face  52   c . Grip  52   a  is contoured in a customary manner (having opposing side flats  53 ) to allow for easy gripping by a user. The body  52  is made of a conventional material, including but not limited to, plastic and aluminum. 
         [0029]    A boss  56  extends from the rear face  52   c  of the body  52 . An opening  54 , best seen in  FIG. 5 , extends through the boss  56  and into the body  52 . Both the opening  54  and the boss  56  are axially aligned with the longitudinal axis “A.” The opening  54  extends a predetermined distance into the body  52 . In the embodiment shown, the opening  54  is “D-shaped” to correspond to the cross sectional shape of the distal portion  14   a  of the rod  14 , which is received within the opening  54  and retained therein via an interference fit. 
         [0030]    A counter-bored, through hole  62  extends from the rear face  52   c  to the front face  52   b  of the body  52 . The hole  62  includes a counter-bored portion  62   a  that communicates with the rear face  52   c . The hole  62  is offset from the longitudinal axis “A” and extends in a direction generally parallel to the longitudinal axis “A.” 
         [0031]    An L-shaped recess  64  is formed in the body  52  when viewed in side cross-section as in  FIGS. 3-4 . A first portion  64   a  of the recess  64  is formed in the front face  52   b  and a second portion  64   b  of the recess  64  is formed in an outer cylindrical surface of grip  52   a ; preferably in an upper portion of that surface disposed between the opposing side flats  53  where a user would typically grasp the knob  50 . The first portion  64   a  of the recess  64  is positioned such that the hole  62  exits the body  52  at the first portion  64   a . The recess  64  is dimensioned to receive a portion of the locking element  72 . 
         [0032]    Referring now to  FIG. 5 , locking element  72  is best seen. Locking element  72  includes a gripper portion  74  and a pin portion  76 . Gripper portion  74  is a generally L-shaped element that includes a base  74   a  and a leg  74   b . The base  74   a  is attached to one distal end of the pin portion  76 . The leg  74   b  extends from an end of the base  74   a  in a direction generally aligned with a longitudinal axis of the pin portion  76 . The base  74   a  and the leg  74   b  are dimensioned to be received and normally seated into the first portion  64   a  and the second portion  64   b  of recess  64 , respectively, when the locking element  72  is engaged to prevent rotation of the knob  50  (explained below). 
         [0033]    The pin portion  76  of the locking element  72  is rod-shaped element having a distal end  76   b . The pin portion  76  is dimensioned to slide within the counter-bored, through hole  62 . An annular groove  76   a  ( FIG. 4 ) is formed near the distal end  76   b  of the pin portion  76 . The annular groove  76   a  is dimensioned to receive and retain a locking washer  82 , therein. 
         [0034]    A biasing element  84  is provided for biasing the locking element  72  in a predetermined, locked position. In the embodiment shown, the biasing element  84  is a conventional compression spring having a predetermined spring constant. 
         [0035]    As best seen in  FIG. 5 , the control knob  50  is assembled by inserting the pin portion  76  of the locking element  72  into the countered-bored through hole  62 . In particular, the pin portion  76  is inserted through the hole  62  from the front face  52   b  of the body  52 . When fully inserted into the hole  62 , the gripper portion  74  of the locking element  72  is seated within the recess  64  of the body  52 , with its distal end  76   b  extending past the rear face  52   c  of the body  52 . 
         [0036]    The biasing element  84  is placed into the counter-bored portion  62   a  of the hole  62  from the rear face  52   c  of the body  52 . Thereafter, the locking washer  82  is positioned in the annular groove  76   a  of the locking element  72  to retain the biasing element  84  between the locking washer  82  and a bottom of the counter-bored portion  62   a . In particular, the biasing element  84  applies a force to the locking washer  82  to bias the gripper portion  74  of the locking element  72  into the L-shaped recess  64  and to bias the distal end  76   b  of the pin portion  76  a predetermined distance past the rear face  52   c  of the body  52 , as shown in  FIG. 1  and  FIG. 3 . It is also contemplated that the biasing element  84  may bias the distal end  76   b  of the pin portion  76  a predetermined distance from the front end of the control knob  50  such that the distal end  76   b  may or may not extend past the rear face  52   c  of the body  52 . 
         [0037]    The locking element  72  is moveable between a first, forward position, shown in  FIGS. 1 and 3  and a second, retracted position, shown in  FIGS. 2 and 4 . When the locking element  72  is in the first position, the base  74   a  and the leg  74   b  of the gripper portion  74  are disposed in the first portion  64   a  and the second portion  64   b  of recess  64 , respectively, and the distal end  76   b  of the pin portion  76  of the locking element  72  extends past the rear face  52   c  of body  52 . When the locking element  72  is in the second position, the base  74   a  of the gripper portion  74  is spaced from the first portion  64   a  of the recess  64  and the distance between the distal end  76   b  and the rear face  52   c  is reduced as compared to when the locking element  72  is in the first position. Alternatively, the distal end  76   b  of the pin portion  76  can be withdrawn within the counter-bored portion  62   a  of the hole  62  in the second position. 
         [0038]    Referring again to  FIG. 5 , the attachment of the control knob  50  to the distal portion  14   a  of the rod  14  on the panel  12  is shown. As noted above, the front end of the control knob  50  is oriented toward a user and the rear end of control knob  50  is oriented toward the appliance. In particular, the opening  54  of the body  52  is dimensioned to receive the distal portion  14   a  of the rod  14 . It is contemplated that other attachment means, such as, but not limited to, screws, set screws, threads, interference fits, knurled surfaces, etc., may be used alone or in combination to secure the control knob  50  to the rod  14 . It is also contemplated that the rear end of the control knob  50  may extend into or through the opening  16  in the panel  12 . 
         [0039]    The control knob  50  will now be described with reference to the operation of the control knob  50 . Referring to now  FIGS. 1 and 3 , the control knob  50  is shown in a first rotational position, hereinafter referred to as an OFF position. In this position, the distal end  76   b  of the pin portion  76  aligns with and extends into a hole, recess or notch  16   a  in the panel  12 . (In this application the term “notch” shall refer collectively to any such hole, recess, notch or other opening in a panel or surface on an appliance with which a locking element or portion thereof, as herein described, engages to inhibit rotation of a knob). The pin portion  76  thereby locks the control knob  50  in the OFF position and prevents a user from rotating the control knob  50  to another position. In the embodiment shown in  FIG. 5 , the notch  16   a  is generally curved to correspond closely to the outer surface of the distal end  76   b  of the pin portion  76 . It is contemplated that providing a separate hole or recess (not shown) in the panel  12  for receiving the distal end  76   b  would also be acceptable. 
         [0040]    To turn the control knob  50  to another position other than the OFF position, a user first pulls on the locking element  72  thereby causing the distal end  76   b  of the pin portion  76  to withdraw from the notch  16   a .  FIGS. 2 and 4  show the locking element  72  in the second position. Once the distal end  76   b  of the pin portion  76  is withdrawn from the notch  16   a , the user may rotate the control knob  50  to a desired position to control the operation of the related component. 
         [0041]    The biasing element  84  continues to bias the locking element  72  toward panel  12  such that the distal end  76   b  of the pin portion  76  slides along the surface of the panel  12  along a circular arc as the knob body  52  is rotated. Once the body  52  is rotated back to the OFF position, the locking element  72  realigns with the notch  16   a  and the biasing element  84  forces the distal end  76   b  of the pin portion  76  into the notch  16   a , i.e., back into the first position of the pin portion  76 . As such, the control knob  50  is re-secured or locked back into the OFF position. 
         [0042]    Referring now to  FIGS. 6-10 , a second control knob  150  is shown. The control knob  150  has a front end oriented toward a user and a second end oriented toward the appliance. The control knob  150  includes a body  152  and a locking element  162 . The body  152  is generally cylindrical in shape and includes a contoured grip  152   a , a front face  152   b  and a rear face  152   c  similarly as the preceding embodiment. The grip  152   a  is contoured in a customary manner (having opposing side flats  153 ) to allow for easy gripping by a user. The body  152  is made of a conventional material, including but not limited to, plastic and aluminum. A longitudinal axis “B” extends through the body  152 . 
         [0043]    An opening  152   d , best seen in  FIG. 10 , extends into the rear face  152   c  of the body  152  a predetermined distance. The opening  152   d  is axially aligned with the longitudinal axis “B.” In the embodiment shown, the opening  152   d  has a generally rectangular cross-section when viewed along axis B, and extends longitudinally into the body  152  from its rear face  152   c  until reaching surface  155 . In the illustrated embodiment, lateral portions of the opening  152   d  are open to the outside such that corresponding side openings (communicating with the opening  152   d ) are provided in the opposing side flats  153  of the grip portion  152   a  of the knob body  152 . 
         [0044]    An elongated boss  151  extends longitudinally from the surface  155  defined by opening  152   d . The elongated boss  151  is generally circular in cross section and extends past the rear face  152   c  of the body  152 . The boss  151  is axially aligned with the longitudinal axis “B.” An opening  154  extends into the boss  151  from its distal end. The opening  154  is axially aligned with the longitudinal axis “B.” In the embodiment shown, the opening  154  is “D-shaped” to correspond to the shape of the distal portion  14   a  of rod  14 . 
         [0045]    A recess  158  is formed in the opposing side flats  153  and the front face  152   b  of the body  152 . The recess  158  is generally U-shaped when viewed in side cross-section as in  FIGS. 8 and 9 , and is dimensioned to seat the locking element  172 . 
         [0046]    The locking element  172  is a generally U-shaped element having a first leg  172   a , a second leg  172   b  and a base  172   c . An angled, substantially L-shaped tab  174  extends outwardly (radially) from a distal end of the first leg  172   a . A stop  176  is formed at and extends from a distal end of the outer leg of tab  174 . Raised locking tabs  178   a ,  178   b  are formed on an inner surface of the first leg  172   a  and the second leg  172   b , respectively. The tabs  178   a ,  178   b  extend laterally along each of the first leg  172   a  and the second leg  172   b , respectively, preferably across their full width from one lateral edge thereof to an opposite edge. In the embodiment shown, the tabs  178   a ,  178   b  are triangular in shape. 
         [0047]    The control knob  150  is assembly by placing the locking element  172  on the body  152 . In particular, the first leg  172   a  is disposed in a portion of the recess  158  disposed on one side (e.g., at one of opposing flats  153 ) of the body  152 . The second leg  172   b  is disposed in a portion of the recess  158  disposed on an opposite side (e.g., at the other opposing flat  153 ) of the body  152 . The base  172   c  is disposed in a portion of the recess  158  at the front face  152   b  of the body  152 . As shown in  FIG. 8 , the distal ends of the first leg  172   a  and the second leg  172   b  extend over the lateral portions of the opening  152   d  formed in the body  152  along the side openings in the opposing flats  153  of the grip portion  152  as described above. Accordingly, the first and second legs  172   a  and  172   b  substantially bound the opening  152   d  when installed on the body  152 . 
         [0048]    The locking tabs  178   a ,  178   b  of the locking element  172  are disposed to mate with the surface  155 . In this respect, the tabs  178   a ,  178   b  define a “snap-fit” connection for securing the locking element  172  to the body  152  as the locking element  172  is advanced longitudinally over the body  152  toward the rear face  152   c.    
         [0049]    The locking element  172  is moveable between a first, relaxed position, shown in  FIGS. 6 and 8  and a second, deflected position, shown in  FIGS. 7 and 9 . When the locking element  172  is in the first position, the first leg  172   a  and the second leg  172   b  are in a relaxed condition and are spaced apart from one another, preferably extending in generally parallel planes. As shown in  FIGS. 7 and 9 , when the locking element is in the first position, the distal end of the first leg  172   a  is a first radial distance from the longitudinal axis “B.” When the locking element  172  is in the second position, at least the first leg  172   a  is elastically deflected inward, toward the second leg  172   b , at its distal end against the modulus of the material. The stop  176  thereon correspondingly is deflected radially inward toward the longitudinal axis “B.” In other words, when the locking element  172  is in the second position, the distal end of the first leg  172   a  is a second radial distance from the longitudinal axis “B,” wherein the second radial distance is smaller than the first radial distance. 
         [0050]    Referring again to  FIG. 10 , the attachment of the control knob  150  to the distal portion  14   a  of the rod  14  on the panel  12  is shown. As noted above, the front end of the control knob  150  is oriented toward a user and the rear end of the control knob  150  is oriented toward the appliance. In particular, the opening  154  of the body  152  is dimensioned to receive the distal portion  14   a  of the rod  14 . It is contemplated that other attachment means, such as, but not limited to, screws, set screws, threads, interference fits, knurled surfaces, etc., may be used alone or in combination to secure control knob  150  to rod  14 . It is also contemplated that the rear end of the control knob  150  may extend into or through the opening  16  in the panel  12 . 
         [0051]    The control knob  150  will now be described with reference to the operation of the control knob  150 . In  FIGS. 6 and 8  the control knob  150  is shown in a first rotational position, hereinafter referred to as an OFF position. When the control knob  150  is in the OFF position, the locking element  172  is in the first position such that the stop  176  extends radially into the notch  16   a  in the panel  12 . To turn the control knob  150  to another position other than the OFF position, a user first moves the locking element  172  to the second position by at least depressing the first leg  172   a  radially inward. As the first leg  172   a  deflects toward longitudinal axis “B,” the stop  176  is withdrawn radially out of the notch  16   a , as shown in  FIGS. 7 and 9 , thus removing it as an impediment to rotation of the knob  150 . Once the stop  176  is withdrawn, the user may rotate the control knob  150  to a desired position to control the operation of the related component. 
         [0052]    The locking element  172  is made from an elastic material, such as, but not limited to, plastic or metal, such that the deflection of the first leg  172   a  radially toward the longitudinal axis “B” is resisted based on the modulus of the material by a force that tends to return the first leg  172   a  to its resting condition (i.e. to its first position). This force biases the stop  176  on the first leg  172   a  in a radially outward direction toward the cylindrical surface that defines the opening  16  in the panel  12 . In particular, the stop  176  on the first leg  172   a  is positioned and dimensioned to slide along the cylindrical surface that defines the opening  16 . Once the body  152  is rotated back to the OFF position, the stop  176  realigns with the notch  16   a  and is forced into the notch  16   a , i.e., back into the first position. As such, the control knob  150  is re-secured or locked back into the OFF position. 
         [0053]    Referring now to  FIGS. 11-15 , a third control knob  250  is shown. The control knob  250  includes a front end oriented toward a user and a second end oriented toward the appliance. In general, the control knob  250  includes a body  252  and a locking element  272 . The body  252  is generally cylindrical in shape and includes a contoured grip  252   a , a front face  252   b  and a rear face  252   c . Grip  252   a  is contoured in a customary manner (having opposing side flats  253 ) to allow for easy gripping by a user. The body  252  is made of a conventional material, including but not limited to, plastic and aluminum. A longitudinal axis “C” extends through the body  252 . The control knob  250  includes a front end facing a user and a rear end facing the appliance. 
         [0054]    An opening  254 , best seen in  FIG. 15 , extends into the rear face  252   c  of the body  252 . The opening  254  is axially aligned with the longitudinal axis “C.” In the embodiment shown, the opening  254  is “D-shaped” to correspond to the shape of the distal portion  14   a  of the rod  14 . A boss  256  extends from the rear face  252   c  and the opening  254  extends through the boss  256 . 
         [0055]    A slot  262  is provided in an outer cylindrical surface of the body  252  from the rear face  252   c  to a location approaching the front face  252   b . The slot  262  extends in a direction generally parallel to the longitudinal axis “C.” In the embodiment shown, the slot  262  includes a narrow first portion  262   a  and a wider second portion  262   b . A bottom of the slot  262  includes a recess  262   c  (best seen in  FIGS. 13 and 14 ) that is dimensioned as described in detail below. The slot  262  is dimensioned to receive the locking element  272   
         [0056]    Referring now to  FIG. 15 , the locking element  272  is best seen. The locking element  172  includes a pressing portion  274  and a lever portion  276 . The pressing portion  274  is disposed at an end of the locking element  272  and includes a generally rectangular-shaped portion. The lever portion  276  extends from the pressing portion  274 . The pressing portion  274  and the lever portion  276  are formed such that an angle between an upper surface of the pressing portion  274  and an upper surface of the lever portion  276  is less than 180°. A curved tab  278  extends from a lower surface of the locking element  272  at the location where the pressing portion  274  and the lever portion  276  meet. A hole  278   a  extends through the tab  278  from one side of the locking element  272  to an opposite side of the locking element  272 . 
         [0057]    A hole  282  also extends laterally through the grip  252   a  of the body  252 . The hole  282  is aligned with the recess  262   c  of the slot  262  and is dimensioned to receive a pin  283  therein for securement of the locking element  272 . 
         [0058]    A biasing element  284  is positioned within the slot  262 . The biasing element  284  can be a conventional torsional spring having a predetermined spring constant, and having a first leg  284   a , a second leg  284   b  and a coil portion  284   c . It is also contemplated that biasing element  284  may be a compression spring (not shown) that is placed between pressing portion  274  and a bottom of the slot  262 . 
         [0059]    The control knob  250  is assembled by placing the locking element  272  and the biasing element  284  into the slot  262 . The pressing portion  274  is received in the second portion  262   b  of the slot  262  and the lever portion  276  is received in the first portion  262   a  of the slot  262 . The biasing element  284  is placed to one side of the locking element  272  such that the first leg  284   a  of the biasing element  284  engages a bottom of the pressing portion  274  and the second leg  284   b  of the biasing element  284  engages a bottom of the slot  262 . The biasing element  284  and the locking element  272  are positioned such that the coil portion  284   c  of the biasing element  284  and the hole  278   a  in the locking element  272  align with the hole  282  in the body  252 . The pin  283  is then inserted into the hole  278   a  and through the coil portion  284   c  and the hole  278   a  in the locking element  272 . 
         [0060]    The locking element  272  is moveable between a first, forward position, shown in  FIGS. 11 and 13  and a second, retracted position, shown in  FIGS. 12 and 14 . When the locking element  272  is in the first position, the biasing element  284  applies an upwardly directed force to the bottom of the pressing portion  274  to bias the lever portion  276  against the bottom surface of the slot  262  based on the angle between the pressing portion  274  and the lever portion  276 . In this first position, the pressing portion  274  is positioned slightly proud of the outer surface of the body  252  and the distal end of the lever portion  276  is spaced a predetermined distance from the front end of the control knob  250 . When the locking element  272  is in the second position, the pressing portion  274  is depressed so that it is at least partially recessed within the second portion  262   b  of the slot  262 , while the lever portion  276  becomes displaced from the first portion  262   a  of the slot  262  to be positioned slightly proud of the outer surface of the body  252  via pivoting of the locking element  272  about the pin  283 . In this second position, the distal end of the lever portion  276  is withdrawn from the first, forward position toward the front end of the control knob  250 . 
         [0061]    Referring again to  FIG. 15 , the attachment of the control knob  250  to the distal portion  14   a  of the rod  14  on the panel  12  is shown. As noted above, the front end of the control knob  250  is oriented toward a user and the rear end of the control knob  250  is oriented toward the appliance. In particular, the opening  254  of the body  252  is dimensioned to receive the distal portion  14   a  of the rod  14  such that when a user rotates the body  252 , the rod  14  will also rotate. It is contemplated that other attachment means, such as, but not limited to, screws, set screws, threads, interference fits, knurled surfaces, etc., may be used alone or in combination to secure the control knob  250  to the rod  14 . It is also contemplated that the rear end of the control knob  250  may extend into or through the opening  16  in the panel  12 . 
         [0062]    The control knob  250  will now be described with reference to the operation of the control knob  250 .  FIGS. 11 and 13  show the control knob  250  in a first rotational position, hereinafter referred to as an OFF position. When the control knob  250  is in the OFF position, the locking element  272  is in the first, forward position such that the distal end of the lever portion  276  extends into the notch  16   a  in the panel  12 . To turn the control knob  250  to another position besides the OFF position, a user first moves the locking element  272  to the second, retracted position by depressing the pressing portion  274 . As the locking element  272  pivots, the lever portion  276  is withdrawn from the notch  16   a  in the panel  12 , as shown in  FIGS. 12 and 14 , thus being removed as an impediment to rotation of the knob  250  from the OFF position. Once the lever portion  276  is withdrawn from the notch  16   a , the user may rotate the control knob  250  to a desired position to control the operation of the related component. 
         [0063]    The biasing element  284  continues to bias the lever portion  276  of the locking element  272  toward the panel  12  such that its distal end slides along a circular arc on the surface of the panel  12  as the knob  250  turns. Once the body  252  is rotated back to the OFF position, the locking element  272  realigns with the notch  16   a  and the biasing element  284  forces the distal end of the lever portion  276  back into the notch  16   a , i.e., forces the locking element  272  back into the first position. As such, the control knob  250  is re-secured or locked into the OFF position. 
         [0064]    The control knobs  50 ,  150 ,  250  described herein each provides a control knob with a safe lockout feature wherein a user must manipulate a locking element to move the control knob from the OFF position. In particular, the user must possess a minimum level of dexterity to actuate the locking element of the control knob while simultaneously turning (and optionally pushing) the control knob from the OFF position. 
         [0065]    Illustrative embodiments have been described, hereinabove. It will be apparent to those skilled in the art that the above apparatuses and methods may incorporate changes and modifications without departing from the scope of this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.