Abstract:
A pressure cooker handle assembly that relieves pressure in the cooker and unlocks the lid by pushing a single button twice. The button includes a tab that directly activates a pressure relief valve to release the pressure and a leg that depresses a stopbar to unlock the lid. Pressing of the button a first time releases the pressure in the cooker, but does not unlock the lid. A latch system prevents the cooker from again building pressure once the button is pressed. When the button is pressed a second time the leg depresses the stopbar to unlock the lid from the cooker.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 09/683,398 filed Dec. 21, 2001 and entitled BUTTON ACTUATED PRESSURE RELEASE AND LOCKING DEVICES FOR PRESSURE COOKERS. 
    
    
     FIELD OF INVENTION 
     This invention relates to a safety pressure release mechanism and a safety lock for pressure cookers. 
     BACKGROUND OF INVENTION AND PRIOR ART 
     The prior art discloses a variety of locking and pressure release mechanisms for pressure cookers. For example, Sebillotte U.S. Pat. No. 4,620,643 discloses a manually actuated safety device to prevent closure of a pressure valve if the handles of the cooker are not in the closed position and prevent opening of the lid when both the handles and the pressure valve are in a closed position. Chen U.S. Pat. No. 4,294,377 discloses a coupling steel ring and spring band on the cover of a pressure cooker that prevents the pressure in the cooker from exceeding a predetermined saturated pressure, thus keeping the pressure in the cooker constant. Brewer U.S. Pat. No. 4,840,287 discloses a pressure cooker locking mechanism having a camshaft assembly that prevents the cooker lid from being locked if the camshaft is not fully extended; a pressure responsive safety mechanism is also provided to prevent the opening of the locking mechanism when the cooker is under pressure. 
     Additional examples include Moucha U.S. Pat. No. 4,932,550, which discloses an interlock structure that prevents pressurization of the cooker if the lid is not securely attached to the cooker and prevents removal of the lid until the pressure in the cooker has dropped below a preset maximum. Seethaler U.S. Pat. No. 3,559,839 discloses a pressure cooker that is opened and closed by the rotation of upper and lower handles; the lower handle has a heat expandable element that urges a lock pin into a slot in the upper handle so that the cooker cannot be opened until the temperature has been lowered to a selected value and the lock pin has retracted from the slot. 
     Further, in Walker U.S. Pat. No. 4,103,801 the pressure cooker has a slidably mounted, manually operated lock member that must be unlocked in order to open the cover. Pressure in the cooker urges the stem of a sealing plug in the cover of the cooker upwardly and into engagement with the lock member when the handles are properly aligned and pressure builds in the cooker, thus preventing the cooker from being opened until the pressure decreases. A similar safety button is shown in the lid of Chen U.S. Pat. No. 6,257,124; when the cooker is under pressure, the safety button is positioned such that the lid cannot be manually opened. Zabel U.S. Pat. No. 4,257,394 discloses locking means connected with flanges in the lid and cooker body such that the lid will not rotate when the cooker is pressurized; a spring actuated relief valve is connected to a timer so that pressure is maintained in the cooker for a predetermined period of time after which the lid can be removed. In Demeyere U.S. Pat. No. 4,735,192 the cooker cannot be opened until the operator manipulates a knob, the movement of the stem of which allows a pin or peg to push a seal ring away from its seats, thus depressurizing the cooker and allowing the lid to be removed. Abstract 
     In Mendonca U.S. Pat. No. 6,105,808 a pop up valve prevents the lid from being turned to open the cooker when it is under pressure; the pop up valve also prevents pressure from building in the cooker if the lid is not properly installed on the cooker. Similarly, in Barrena U.S. Pat. No. 6,135,013 a valve remains in the up position when the cooker is pressurized and prevents a locking member from being released, and, in Elorza U.S. Pat. No. 6,067,896 a valve must drop in order to permit the lid to be opened. In Chameroy U.S. Pat. No. 5,370,259 the lid is sealed to the cooker via lock jaws; pressure developed during cooking is transmitted to internal faces of the lid, causing the lid and lock jaws to be forced together so that the lid cannot be removed until the internal pressure is reduced, and, in Chameroy U.S. Pat. No. 5,370,257, the cooker cannot be opened under pressure because a flow limiting valve, then in an up position, prevents the sliding of a latch or bolt that is necessary to open the cooker. 
     None of the prior art devices or patents, however, appear to provide: a simple means to reliably and safely install and lock the lid in sealing engagement on the cooker; simple, single-button means to relieve the pressure in the cooker, prevent the cooker from re-pressurizing, and unlock the lid of the cooker; means to automatically reset the various safety and convenience features of the cooker during the installation and removal of the lid of the cooker; positive latch means that allow an operator to perform other tasks while the cooker is depressurizing; means to automatically lock the lid on the cooker as it is being placed on the cooker; and means to make such a the cooker without the use of timers, pressure sensitive materials or parts, heat sensitive materials or parts, or moving parts that are preset to predetermined tolerances, pressure levels, heat levels, or weight levels so that they operate properly during pressurization and depressurization of the cooker. 
     SUMMARY OF THE INVENTION 
     The inventive cooker handle assembly contains an automatic pressure release system that allows the operator to press a button a first time—i.e., down to a first level—in order to relieve the pressure in the cooker. Once the button is pressed down to the first level, a latch arrangement prevents the button from returning to its up position and, thus, prevents pressure from again building in the cooker. The latch arrangement must be reset in order to allow pressure to again build in the cooker, and, in order to reset the latch arrangement, the lid must be removed from, and then replaced on, the pot. Thus, the operator need not tend the cooker or continue to press the button in order to fully depressurize the cooker, but, may, instead perform other tasks while the pressure is being relieved. 
     Nevertheless, when the button is pressed to the first level, the lid is still locked on the pot and cannot be removed. In order to remove the lid from the pot, the same button must be pressed a second time, or downward to a second level, and held in the second position while the lid is removed. Premature removal of the lid from the pot is resisted by flanges on the lid and pot. The flanges are held tightly together when there is pressure in the cooker, which makes it difficult to rotate the lid off of the pot while the cooker is pressurized. The lid may be easily removed, however, when the cooker is depressurized, and the flanges are not as tightly held together. 
     The inventive handle assembly has upper and lower locking handles that are rotated into and out of alignment in order to, respectively lock and unlock the lid to the pot of the cooker. The upper handle is attached to the lid. The lower handle is attached to the pot. When the lid is rotated on the pot, a guide groove and spring-biased guidepost in the handle assembly cooperate to set the latch arrangement so that pressure can build in the cooker. The guidepost is part of a lock guide that is housed and secured in an internal cavity in the upper handle of the cooker. The lock guide has an outward extending spring-biased spring post, an inward extending push post, and laterally extending latch dogs, as well as the downward extending guidepost. The downward extending guidepost extends down beyond the bottom of the upper handle and is aligned above and cooperates with the guide groove that is formed in the lower handle. The inward extending push post is aligned with a hole in the rim of the pot. In addition, as the lid is being rotated on the pot, a spring-biased stopbar in the lower handle is pressed downward into a slot in the lower handle, allowing the upper handle and lid to rotate to the sealed position on the pot. However, when the lid reaches its sealed position, the spring-biased stopbar pops up into a slot in the upper handle and locks the lid on the pot. 
     The upper handle also has an upper opening that receives and houses a button that is used to activate various features of the inventive handle. The button has, on its lower side, a downward extending, rounded tab that is aligned generally above a plunger or pin of a pressure relief valve that is installed in the lid. The button also has flexible, downward extending legs. The downward extending legs have latch arms that extend laterally from the sides of the legs. One of the downward extending legs of the button is longer than the other leg. The longer leg of the button is aligned immediately above the stopbar in the lower handle. 
     As the lid is rotated on the pot, the guidepost of the lock guide slides along a curved edge of the guide groove. As the guidepost slides along the curved edge of the guide groove, the lock guide in the upper handle is forced outward against the bias of the spring on the spring post of the lock guide. When the lid is fully rotated into its sealed position on the pot, the lock guide is positioned such that its laterally extending latch dogs are aligned below the laterally extending latch arms on the downward extending legs of the button. 
     When the button is pressed down the first time, or to its first level, the latch arms on the legs of the button are forced around and under the latch dogs of the latch guide and the downward extending, rounded tab of the button contacts and moves the pin or plunger of the safety relief valve, causing pressurized air and steam air to begin escaping from and depressurizing the cooker. In this position, the latch dogs of the latch guide are directly above the latch arms of the legs of the button and block the upward movement of the latch arms on the latch arms, thus preventing the button from returning to its up position and, in turn, preventing the rounded tab from moving out of contact with the pin or plunger of the safety relief valve. Accordingly, when the button is pressed once and is in its first position, the safety relief valve remains activated and does not permit pressure to be rebuilt in the cooker. 
     After the cooker is depressurized, the button is pressed down again, or to its second level. As the button is pressed down farther, the longer leg of the button comes into contact with the stopbar that is extended into the upper handle and pushes the stopbar down into its slot in the lower handle as long as the button is continuously pressed downward at the second level. When the stopbar is pressed down into its slot, the lid is unlocked and may be rotated back out of sealed engagement with the pot by rotating it in the opposite direction. As the lid is rotated in the opposite direction, the lower surface of the upper handle prevents the stopbar from moving upward, and the guidepost of the lock guide reverses it path along the curved edge of the guide groove of the lower handle. As the guidepost slides along the curved edge of the guide groove, the spring associated with the spring post of the lock guide biases and moves the lock guide inward. As the lock guide moves back inward, the latch dogs move out of alignment with the latch arms of the legs of the button and the button is permitted to move back to its up position. Thus, it is only when the lid is rotated off the pot that the latch arms of the legs of the button can be reset to a position above the latch dogs of the lock guide. When the lid is rotated sufficiently so that the lid and pot flanges are no longer one above the other, the lid may be removed from the pot. 
     In order to remove the lid from the cooker, the button must be pressed a second time. When the button is pressed a second time, the latch system permits a downward extending leg of the button mechanically depressing the stopbar into its housing slot to permit the lid to be rotated off of the cooker. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a pressure cooker including a handle assembly embodying the present invention and showing pressure being released from the cooker. 
     FIG. 2 is an exploded perspective view of the upper handle of the handle assembly. 
     FIG. 3 is an end view of the handle assembly in the latched position with the button and stopbar thereof shown in hidden lines. 
     FIG. 4 is a fragmentary side view of the pressure cooker and handle assembly with the handle assembly in the latched position. 
     FIG. 5 is a fragmentary side view of the pressure cooker and handle assembly with the handle assembly in the pressure release position. 
     FIG. 6 is an end view of the handle assembly in the latched position with the bodies of the upper and lower handles shown in phantom lines. 
     FIG. 7 is an end view of the handle assembly in the pressure release position with the bodies of the upper and lower handles shown in phantom lines. 
     FIG. 8 is an end view of the handle assembly in the latch released position with the bodies of the upper and lower handles shown in phantom lines. 
     FIG. 9 is a fragmentary perspective view of the pressure cooker showing the upper handle rotated away from the lower handle. 
     FIG. 10 is a bottom view of the lid of the pressure cooker showing the bottom of the upper handle, the scalloped portion of the rim, the flexible seal, and the safety relief valve. 
     FIG. 11 is a top view of the pot of the pressure cooker with the lid removed showing the top surface of the lower locking handle, the flanges on the rim of the pot, and the spring biased stopbar in the lower locking handle. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following convention is used in describing various directions with respect to the inventive cooker. The cooker is assumed to be setting on a counter or other surface in an upright position for normal use. When the cooker is in this upright, normal orientation, the following terms have the following meanings: The terms “up” or “upward” mean the vertical direction extending from the bottom of the cooker toward the top of the cooker and beyond; the terms “down” or “downward” mean the vertical direction that is the opposite of the “up” or “upward” direction—i.e., the vertical direction extending from the top of the cooker toward the bottom of the cooker; the terms “in” or “inward” means the horizontal direction from the periphery or side of the cooker toward the center of the cooker; and the terms “out” or “outward” means the opposite horizontal direction—i.e., the direction from the center of the pot toward the periphery or side of the cooker. If a part or object is “above” another part or object, the part or object is in a position or location that is in the upward direction from the other part or object; thus, the lid of the cooker is above the bottom of the pot of the cooker when the cooker is in its normal upright position; similarly if a part or object is “below” another part or object, the part or object is in a position that is in the downward direction from the other part or object; thus, the bottom of the cooker is below the lid of the cooker when the cooker is in its normal upright position. 
     As shown in FIG. 1, pressure cooker  1  has a pot  2  and a lid  3 . The pot  2  has an outwardly extending rim  4 , which has outward extending flanges  5  spaced around its circumference. The outward extending flanges  5  have lower surfaces  6 . The pot  2  and the lid  3  are preferably made of stainless steel, although other materials of sufficient strength to resist failure or deformation from the pressures usually encountered in pressure cookers and to resist failure or deformation from the temperatures encountered in heating the cooker  1  may be used. 
     The cooker  1  has a locking handle assembly  10  and side handles  11  and  12 . The locking handle  10  comprises a lower locking handle  15  and an upper locking handle  20 . The lower locking handle  15  is attached to the pot  2 , and the upper locking handle  20  is attached to the lid  3  such that, when the cooker is in use, upper locking handle  20  is positioned immediately above lower locking handle  15 , as shown in FIGS. 1,  4  and  5 . In the preferred embodiment the upper locking handle  20  and the lower locking handle  15  are made of a phenolic or durable plastic material, although other materials of sufficient strength could be used for such handles. 
     As shown in FIG. 9, the lower locking handle  15  is formed with a top surface  16 , a guide groove  25  with a curved edge or cam surface  26 , and a slot  30 . A stopbar  35  having an upper portion  40  is positioned within, and spring-biased upward through, the slot  30  so that the upper portion  40  of the stopbar  35  is above the top surface  16  of the lower locking handle  15 . The upper portion of the stopbar  35  has a curved edge or corner  41  and a squared edge or corner  42 . The stopbar  35  is preferably made of nylon, although phenolic, a hard resilient plastic material, and other materials of sufficient strength and resilience would suffice. Similarly, the stopbar  35  is preferably spring biased, however, other resilient biasing means could be used such as a resilient metal band or other resilient means know in the art. 
     As shown in FIGS. 3,  4 , and  5 , the upper locking handle  20  comprises a housing  45  that has an interior cavity  55 , a lower edge  56 , a bottom slot  57  with a right most inner side  58 , a elongated slot  59 , and an upper opening  60 . A spring-biased button  65  fits moveably within the upper opening  60  of the upper handle  20  and is spring-biased in an upward position. The button  65  has a downward extending leg  70 , which has a lower end  71 , forms an oval slot  75 , and a laterally extending latch arm  80 . The button  65  also has a downward extending leg  85 , which forms an oval slot  90  and has a laterally extending latch arm  95 . The latch arm  80  has a rounded lower surface  81  and a flat upper surface  82 ; similarly, the latch arm  95  has a rounded lower surface  83  and a Rat upper surface  84 . (See FIG. 8.) The downward extending leg  70  is longer than the downward extending leg  85  and is positioned on the button  65  so that when the upper locking handle  20  is immediately above the lower locking handle  15 , the leg  70  is immediately above the spring-biased stopbar  35  in the lower handle  15 . It is preferable to make the downward extending legs  70  and  85  somewhat flexible for reasons that will become apparent. In the preferred embodiment, the button  65  downward extending legs  70  and  85  are made of nylon, although other resilient, wear resistant, durable material could be used. 
     The button  65  also has a downward extending rounded tab  100 , a downward extending post  105 , and a downward extending block  110 . 
     As shown in FIGS. 4 and 5, the lid  3  has a downwardly extending rim  115  having scalloped portions  116 , the lower ends  117  of which are bent inward approximately 90 degrees so that the lower bent ends  117  of the scalloped potions  116  are substantially horizontal and parallel to the flanges  5  around the circumference of the rim  4  of the pot  2  when the lid  3  is on the pot  2 . In this orientation, the lower bent ends  117  have upper surfaces  118 . A flexible seal  119  fits immediately inside the downward extending rim  115  and sits on top of the outwardly extending rim  4  of the pot  2 . Posts  120  and  125  are attached to the rim  115  proximate the upper handle  20  so that the posts  120  and  125  extend outward from the rim  115  and through the oval slots  75  and  80 , respectively, of the downward extending legs  70  and  75  of the button  65  of the upper handle  20 . A safety relief valve  130  is secured in the lid  3  proximate the upper handle  20  so that an activation plunger  135  of the safety relief valve  130  extends at outward and upward through the lid  3  or the rim  115  of the lid  3 . 
     As shown in FIGS. 2,  4 , and  5 , a lockguide  140  is moveably positioned within the interior cavity  55  of the upper handle  20 . The lockguide  140  has a downward extending guidepost  145  that extends downward through the elongated slot  59  of the upper handle  20 . The lockguide  140  also has a horizontal inward extending push post  155  and a horizontal outward extending spring post  156 . The lockguide  140  is spring biased by a spring  157  which is inserted over and around the outward extending spring post  156  so that the push post  155  is spring biased inward and, when the lid  3  is not installed on the pot  2 , extends through a hole  160  in the rim  115  of the lid  3  and abuts the flexible seal  119  inside the downwardly extending rim  115  of the lid  3 . In addition, the lockguide  140  has latchdogs  170  and  175  extending from each side of an end  180  of the lockguide  140 . 
     As shown in FIGS. 4 and 6, when the lid  3  is not secured to the pot  2 , the stopbar  35  of the lower handle  15  is biased upward, the push post  155  and the lockguide  140  (of which push post  155  is a part) are biased inward, and the button  65  is biased upward. 
     In order to secure the lid  3  to the pot  2 , the lid  3  is registered with and placed upon the outward extending rim of the pot  2  and rotated clockwise until the upper locking handle  20  is positioned immediately above the lower locking handle  15 . When the lid  3  is rotated on the pot  2 , the upper surfaces  118  of the lower bent ends  117  or the scalloped portions  116  of the lid  3  are in sliding contact with the lower surfaces  6  of the flanges  5  of the rim  4  of the pot  2 . See FIGS. 4 and 5. When there is pressure in the cooker  1 , the lid  3  is subject to an upward force caused by the pressure in the cooker. This upward force is resisted by the contact between the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3  and the lower surfaces  6  of the flanges  5  on the rim  4  of the pot  2 , which not only keeps the lid  3  on the pot  2 , but also makes it very difficult to rotate the lid  3  when there is pressure in the cooker  1  due to the increased upward force of the upper surfaces  118  of the lower bent ends  117  on the lower surfaces  6  of the flanges  5 . 
     As the lid  3  is rotated clockwise around the outwardly extending rim  4  of the pot  2 , the downward extending guidepost  145  of the lockguide  140  slides along the curved edge  26  of the guide groove  25 , moving the downward extending guidepost  145 , and with it the lock guide  140 , outward against the bias of the spring  157  on the spring post  156 . When lockguide  140  has moved outward, the latchdogs  170  and  175  of the lockguide  140  are positioned directly below or under the latch arms  80  and  95  of the downward extending legs  70  and  85 , respectively, of the button  65 , as shown in FIG.  6 . 
     Also, as the lid  3  is rotated clockwise, the lower edge  56  of the upper locking handle  20  contacts and slides over the rounded edge  41  of the stopbar  35 , causing the spring-biased stopbar  35  to move downward into the slot  30  and allowing the upper locking handle  20  to continue to rotated clockwise until it is immediately above the lower locking handle  15 . (See FIGS. 6 and 9) However, when the upper locking handle  20  is immediately above the lower locking handle  15 , the spring-biased stop guide  35  is directly below the bottom slot  57  of the upper locking handle  20 , allowing the stopbar  35  to be spring-biased upward into the bottom slot  57  of the upper locking handle  20 , as shown in FIG.  6 . When the stopbar  35  is spring-biased upward into and within the bottom slot  57 , the upper locking handle cannot rotate, and, more specifically, cannot rotate counterclockwise to an open position, because, if such rotation is attempted, the squared edge or corner  42  of the stopbar  35  comes into contact with the right most inner side  58  of the bottom slot  57 , preventing such movement. Thus, when the stopbar  35  is biased upward into the slot  57  of the upper locking handle  20 , the lid  3  is locked on the pot  2 . 
     When the lid  3  is so locked on the pot  2 , the lid  3 , with the aid of the flexible seal  119 , is sealed on the pot  2  so that the contents of the pot  2  may be heated and cooking can begin inside the pot  2 . As the contents (typically water and food) of the sealed pot  2  are heated, the temperature and pressure inside the pot  2  rises, steam may be produced, and the contents of the pot  2  become very hot. 
     In order to remove the lid  3  without a rapid and potentially dangerous escape of the steam and the hot contents of the pot  2 , it is necessary to reduce the pressure inside the pot  2 . 
     In order to reduce the pressure in the pot  2 , the button  65  is pushed downward. As the button  65  is pushed downward, the latch arms  80  and  95  of the flexible downward extending legs  70  and  85  of the button  65  slidingly pass or snap by the latchdogs  170  and  175  of the lockguide  140 . When the latch arms  80  and  95  have slidingly snapped or passed downward by the latch dogs  140 , the upwardly spring-biased button  65  is at a first downward position, as shown in FIG.  7 . In this position, the latchdogs  170  and  175  prevent the upwardly spring-biased button  65  from returning to the up position (FIG.  6 ), because, although the button  65  is biased upward, the latch dogs  170  and  175  of the lockguide  140  are then directly above the latch arms  80  and  95  of the legs  70  and  85  of the button  65  and prevent the latch arms  80  and  95  from passing by the latch dogs  170  and  175 , thus keeping the button  65  in its first downward position and preventing it from returning to its original upward position. 
     As indicated above, in the preferred embodiment, the downward extending legs  70  and  85  of the button  65  are somewhat flexible due to their length, shape, thickness, and the presence of oval slots  75  and  90 . The downward extending legs  70  and  85  are, in any event, more flexible than the lockguide  140  due to the box-like central structure of the lockguide  140 , the short latch dogs  170  and  175  of the lockguide  140 , the rigid push post  155  extending from the lockguide  140 , and the rigid spring post  156  extending from the lockguide. As a result of this relative difference in flexibility, when the button  65  is pressed downward and the latch arms  80  and  95  come into contact with the latch dogs  170  and  175  of the lockguide  140 , the downward extending legs  70  and  85  of the button  65  flex and move laterally away from the latch dogs  170  and  175  of the lock guide and, due to this flexing, the latch arms  80  and  95  slide around and pass or snap by the latch dogs  170  and  175  of the lockguide  140 . After the latch arms  80  and  95  have slid or passed by the latch dogs  170  and  175 , the latch arms  80  and  95  are below the latch dogs  170  and  175  and are no longer in contact with the latch dogs  170  and  175 . When the latch arms  80  and  95  are below the latch dogs  170  and  175 , the flexing of the downward extending legs  70  and  85  has relaxed, and the legs  70  and  85  are no longer flexed, having returned to their original, unflexed position. When the legs  70  and  85  return to their original, unflexed position, the latch arms  80  and  95  of the legs  70  and  85  of the button  65  are directly below the latch dogs  170  and  175  of the lockguide  140 . In this position the latch arms  70  and  85  cannot move upward past the latch dogs  170  and  175 , because the latch dogs  170  and  175  block this movement and the button  65  cannot be forced upward, there being no way to grasp or obtain sufficient leverage on the button  65  to force it in an upward direction and thus reflex the legs  70  and  85  so that the latch arms  80  and  95  can pass or slide by the latch dogs  170  and  175  of the lock guide  140 . The return of the latch arms  80  and  95  to their positions above the latch dogs  170  and  175  may be further hindered by rounding the lower surfaces  81  and  83  of the latch arms  80  and  95  and flattening or squaring the upper surfaces  82  and  84  of the latch arms  80  and  95 . The rounding of the lower surfaces  81  and  83  of the latch arms  80  and  95  would facilitate the sliding of the latch arms  80  and  95  down around, or the passing or snapping of the latch arms  80  and  95  by the latch dogs  170  and  175  when the button  65  (and with it the legs  70  and  85  and latch arms  80  and  95 ) is pressed downward. The flattening or squaring of the upper surfaces  82  and  84  of the latch arms  80  and  95  would make it more difficult, if not impossible, for the latch arms  80  and  95  to slide by or pass or snap around the latch dogs  170  and  175  in the upward direction. 
     As shown in FIGS. 5 and 7, when the button  65  is pushed downward to its first downward position, the rounded tab  100  of the of the button  65  comes into contact with the activation pin or plunger  135  of the safety relief valve  130 , activating the valve and reducing the pressure inside the pot  2 . When the safety relief valve  130  is activated, steam  181  escapes through the valve  130  into a channel  185  in the upper handle  20 , and escapes to the atmosphere through a vent  190  at the end of the channel  185  in the upper handle  20 . 
     Moreover, since the rounded tab  100  of the button  65  comes into contact with the pin or plunger  135  to activate the safety relief valve  130  when the button is in its first downward position, and since the latch dogs  170  and  175  keep the button in its first downward position once the button  65  is pressed downward, it will be noted that the tab  100  also remains in contact with the pin or plunger  135  and continues to activate the safety relief valve  130  once the button  65  is pressed downward to its first downward position. Thus, as shown in FIGS. 5 and 7, the latch dogs  170  and  175  also prevent the safety relief valve  130  from being deactivated (and allowing pressure to again build in the pot  2 ) even if the button  65  is not continually pressed downward. Thus, an operator simply need press button  65  once to relieve pressure in the pot  2 . 
     Nevertheless, when the button  65  is in its first downward position, the lid  3  still cannot be removed from the pot  2 . This is so because, as shown in FIG. 7, when the button  65  is in the first downward position, the stopbar  30  is still spring-biased upward into the bottom slot  57  of upper handle  20 , and, accordingly, the lid  3  cannot rotate and is locked on the pot  2 . 
     In order to unlock and remove the lid  3  from the pot  2 , the button  65  must be pushed downward farther, or pushed downward a second time if the operator has ceased pressing on the button  65  after it is in the first downward position. As shown in FIG. 8, when the button  65  is pushed down farther (or a second time) the lower end  71  of the longer downward extending leg  70  of the button  65  comes into contact with the upper portion  40  of the stopbar  35  and forces the upwardly spring-biased stopbar  30  downward into the slot  30  against the spring biasing of stopbar  35 . When the downward extending leg  70  has pushed the stopbar down into the slot  30  the button  65  is in a second downward position. When the button  65  is in its second downward position and the stopbar  35  has been forced downward into the slot  30 , the squared edge or corner  42  of the upper portion of stopbar  35  is no longer an obstacle to the counterclockwise movement of the lid  3 , and the lid  3  can be rotated counterclockwise and removed from the pot  2 , provided the operator continues to press down on the button  65  to maintain it in its second downward position. The button  65  must be maintained in its second downward position by continued pressing on the button, because the button  65  is spring-biased upward. If the button  65  is not continuously pressed, the upwardly spring-biased button  65  will return to its first downward position (but will not return to its original position due to the position of the latch dogs  170  and  175  above the latch arms  80  and  95 ), and the spring-biased stopbar  35  will be biased up into the slot  57 , thus relocking the lid  3 . Thus, downward force must be maintained on the button  65  in order to rotate the lid  3  and remove it from the pot  2 . 
     It will be noted that, when there is pressure in the cooker  1 , the upward force on the lid  3  is resisted by the contact between the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3  and the lower surfaces  6  of the flanges  5  on the rim  4  of the pot  2 . (See FIGS. 4 and 5) As noted above this resistance not only keeps the lid  3  on the pot  2 , but also makes it very difficult to rotate the lid  3  when there is pressure in the cooker  1  due to the increased upward force of the upper surfaces  118  of the lower bent ends  117  on the lower surfaces  6  of the flanges  5 . Any attempt to remove of the lid  3  from the pot  2  by pressing the button  65  to its second downward position and rotating the lid  3  before the pressure in the cooker  1  has been fully relieved will be strongly resisted by the increased force of the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3  on the lower surfaces  6  of the flanges  5  on the rim  4  of the pot  2 . Thus, premature removal of the lid  3  from the pot  2  is significantly more difficult than removal of the lid  3  when the pressure in the cooker  1  has been fully relieved; and the premature removal of the lid  3  from the pot  2 , as well as the potentially dangerous results associated with such premature removal, are much less likely in the inventive cooker  1 . 
     In order to use the cooker  1 , food and other cooking materials are placed in the pot  2 . The lid  3  is then placed on the pot  2  with the upper locking handle  20  to the right of (or in a counterclockwise direction from) the lower locking handle  15 . The lid  3  is then rotated in a clockwise direction. 
     As the lid  3  is so rotated on the pot  2 , the following occur: 
     (a) the guidepost  145  of the inwardly spring-biased lock guide  140  in the upper handle  20  slides along the curved edge  26  of the guide groove  25  in the lower handle  15 , and, as the guidepost  145  slides along the curved edge  26  of the guide groove  25 , the lock guide  140  is forced outward (See FIGS.  5  and  9 ); 
     (b) the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3  are in sliding contact with the lower surfaces  6  of the flanges  5  of the rim  4  of the pot  2 , as shown in FIGS. 4 and 5; 
     (c) the inwardly biased push post  155  of the lockguide  140  has been forced outward and no longer extends inward through the hole  160  in the rim  115  of the lid  3 ; and 
     (d) the lower edge  56  of the upper locking handle  20  contacts and slides over the rounded edge  41 of the stopbar  35 , causing the spring-biased stopbar  35  to move downward into the slot  30  and allowing the upper locking handle  20  to continue to rotated clockwise toward a position where the upper locking handle  20  is immediately above the lower locking handle  15 , as shown in FIGS. 4 and 6; 
     When the upper locking handle  20  has been rotated to a position directly above the lower locking handle  15 , the following takes place or pertains: 
     (e) the spring-biased stopbar  35  is positioned directly below the bottom slot  57  of the upper locking handle  20 , and the stopbar  35  is biased upward into the bottom slot  57 , locking the lid  3  on the pot  2 , as shown in FIG. 6; 
     (f) the latchdogs  170  and  175  of the lockguide  140  are positioned directly below the latch arms  80  and  95  of the downward extending legs  70  and  85 , respectively, of the button  65 , as shown in FIG. 6; 
     (g) the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3  are in contact with the lower surfaces  6  of the flanges  5  of the rim  4  of the pot  2 , as shown in FIGS. 4 and 5; and 
     (h) the lid  3  is sealed on the pot  2 , and cooker  1  may be heated to cook its food or other contents. 
     As the cooker  1  is heated, the following occur: 
     (i) the pressure in the pot  2  rises, creating an upward force on the lid  3  that is resisted by the lower surfaces  6  of the flanges  5  on the rim  4  of the pot  2  which are immediately above and in contact with the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3 , thus keeping the lid  3  on the pot  2 ; and 
     (j) steam and pressurized air are created in the cooker  1  and are, in part, prevented from escaping from the cooker  1  by the flexible seal  119 . 
     When the heating and cooking of the cooker  1  have been completed, the button  65  is pressed down, whereupon, the following occurs or pertains: 
     (k) the latch arms  80  and  95  of the flexible downward extending legs  70  and  85  of the button  65  slidingly snap by and past the latchdogs  170  and  175  of the lockguide  140 , placing the button in its first downward position (FIG.  7 ), after which the latch dogs  170  and  175  are immediately above the larch arms  80  and  95  and prevent the upward return of the latch arms  80  and  95  to their position above the latch dogs  170  and  175 , which, in turn, prevents the button  65  from returning to its original position in the upper opening  60  of the upper handle  20 ; 
     (l) as shown in FIG. 5, the rounded tab  100  of the of the button  65  comes into contact with the activation pin or plunger  135  of the safety relief valve  130 , activating the valve and reducing the pressure inside the pot  2  by allowing the steam  180  and pressurized air to pass through the valve  130  into the channel  185  in the upper handle  20  and escape to the atmosphere through the vent  190  at the end of the channel  185  in the upper handle  20 ; due to the position of the latch dogs  170  and  175  directly above the larch arms  80  and  95 , the latch arms  170  and  175  cannot return to their position above latch dogs  170  and  175 , and the button  65  cannot return to its original position above its first downward position; accordingly, the tab  100  remains in contact with the plunger or pin  135  of the safety relief valve  130 , and the safety relief valve remains activated until the cooker  1  is fully depressurized and the steam in the cooker  1  is fully vented; 
     In order to remove the lid  3  from the pot  2  after the cooker  1  is depressurized and vented, the button  65  is pressed down farther (or a second time) to its second position show in FIG.  8 . As the button is pushed down to its second position, the following occurs: 
     (m) the lower end  71  of the longer downward extending leg  70  of the button  65  comes into contact with the upper portion  40  of the stopbar  35  and forces the upwardly spring-biased stopbar  30  downward into the slot  30  against the spring biasing of stopbar  35 , thus unlocking the lid  3  from the pot  2 . 
     When the lid  3  is unlocked from the pot  2  and the button  65  is continuously held in its second position, the lid  3  may be rotated counterclockwise to place it in a position where it may be removed from the pot  2 . When the lid  3  is so rotated counterclockwise, the following occurs: 
     (n) the downward extending guidepost  145  of the lockguide  140  slides along the curved edge  26  of the guide groove  25  in a direction opposite to that in which it slid when the lid  3  was being installed on the pot  3 , and as a result, the inwardly biased lockguide  140  moves inward (See FIG.  9 ); 
     (o) the latchdogs  170  and  175  of the lockguide  140  move inward with the lockguide  140  and are no longer positioned directly below or under the latch arms  80  and  95  of the downward extending legs  70  and  85 , respectively, of the button  65 , thus allowing the upwardly spring-biased button  65  to return to its original position above its first position and, at the same time, resetting the latch arms  80  and  95  to their original positions above latch dogs  170  and  175 ; 
     (p) the push post  155  moves inward with the lockguide  140  and moves inward and through the hole  160  in the rim  115  of the lid  3 , where it contacts the flexible seal  119  and pushes the flexible seal  119  away from the rim  115 , thus breaking the sealing action of the seal and allowing any remaining pressurized air or steam to escape from the pot  2 ; and 
     (q) the upper surfaces  118  of the lower bent ends  117  of the scalloped portions  116  of the lid  3  sliding move counterclockwise out of contact with the lower surfaces  6  of the flanges  5  of the rim  4  of the pot  2 , whereupon the lid  3  may be lifted off of the pot  2 . 
     It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown. 
     For example, the parts of the locking handle  10  could be reversed such that lockguide  140  and button  65  are in the part of the locking handle  10  that is attached to the pot  2 , and the stopbar  35  and guide groove  25  are in the part of the locking handle  10  attached to the lid  3 , provided that the safety relieve valve  130  and the push post  155  are positioned on the pot  2  and lockguide  140 , respectively, such that the pressing of the button  65  activates the safety relief valve  130  and that the rotation of the lid  3  causes the push post  155  to assist in the unsealing of the flexible seal  119 . 
     Similarly, the handle assembly  10  could be made without all of the features described above. For example, the push post  155  could be eliminated from the lock guide  140 ; the button assembly  65  could be used to lock and unlock the lid  3  from the pot  2  without the additional function (via the tab  100 ) of activating the safety relief valve  130 . The installation of the lid  3  on the pot  2  could be accomplished by other means, making it unnecessary to incorporate the guide groove  25  in the lower handle  15  or to include the guidepost  145  in the lock guide  140 . Or, a two button arrangement could be used, one button relieving the pressure relief valve  130  and a second button assembly unlocking the lid  3  from the pot  2 , each separately latched via its own latch dog/latch arm arrangement similar to that employed above via the latch arms  80  and  95  and the latch dogs  170  and  175 . Indeed, the two-button arrangement could be made by having the latch arm  80  and the latch dog  170  serve as the latch for one of the buttons and the latch arm  95  and the latch dog  175  serve as the latch for the second button. In this arrangement the latch comprising latch arm  95  and latch dog  175  could be used activate the safety relief valve  130  and prevent the subsequent deactivation of the safety relief valve  130 , and the latch comprising latch arm  80  and latch dog  170  could be used to press the stopbar  35  down into the lower handle  15 , but only when the button  65  is pressed continuously a second time. Similarly, in the two-button arrangement, the latch arm/latch dog,  80  and  170 , respectively might be eliminated, allowing the corresponding button to simply be pressed continuously to move the stopbar  35  down into the slot  57  while the lid  3  is rotated off the pot  2 . 
     And, although the lockguide  140 , the stopbar  35 , and the button  65  (among other parts) of the locking handle assembly  10  are noted as being spring-biased, it is understood that other resilient means such as resilient metal bands, resiliently deformable parts (for example resilient rubber or rubber-like materials) could be used in the place of springs. Similarly, it would be possible to use separate levers and mechanical switches instead of resilient means. An example might be a lever, switch, or separate button to move the stopbar  35  from its locking position in the slot  57  to its unlocked position in the slot  30 . Another example might be a lever, switch, or separate button to move lockguide  140  or button  65  to one or more positions.