Patent Abstract:
A walk-in chamber has a door opening closable by a door, which, when in the closed position can be either in a locked position or an unlocked position, dependent on the locking device, which includes a sliding bolt engageable with a locking bolt. To enable a person in the chamber to disengage the locking device, a safety mechanism is provided which enables moving the sliding bolt from an engaging position to a retracted position to enable a person to open the door.

Full Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention is directed to a safety mechanism or device for an accessible chamber closable by a door, particularly for an oven or a cooking device. The door for the accessible chamber is movable between an open position, in which access to the chamber is open; a closed position, in which access to the chamber is closed; an unlocked position or condition, in which the closed position is unlocked; and a locked condition or position, in which the closed position is locked. The door can be moved between the locked position and the unlocked position from a device which is operated from the outside of the chamber and has a lever, and a safety device, which can move it into the unlock position, which is operated from inside the chamber.  
           [0002]    Various safety devices for doors are known in the prior art. GB 2 154 646 A discloses a safety device or emergency release mechanism for doors of freight containers, transport vehicles and the like. This emergency release mechanism for a door lock enables a person accidentally enclosed in the container or the vehicle to open the container door from the interior. An operating rod rotatable by a lever is disposed on the outside of the door and has ends with cams for engaging and locking in holding means mounted on the door frame, so that the door can be locked from the exterior by rotating the control rod via the lever. When the door is locked, the lever is in a receiving device, which can be unfastened from the inside of the door. In an emergency, therefore, a person can release the receiving device from the door and push it away therefrom, which will lead to a turning of the lever and, thus, the operating rod to release the door. What is a disadvantage about this mechanism, however, is that the door cannot be opened from the inside when the outer lock mechanism is blocked from the inside or when a person is maliciously shut inside the container.  
           [0003]    EP 0 959 208 A1 also discloses a safety release mechanism for a door, for example a climatic chamber. This mechanism makes it possible to move a receptacle device for a lever connected to an operating rod from the inside of the door in order to achieve a rotation of the operating rod and, thus, an unlocking of the door. This device or mechanism, however, has the same disadvantage that was present in GB 2 154 646 A, for example the unlocking of the door can be prevented by blocking the lock mechanism from the exterior.  
           [0004]    U.S. Pat. No. 6,022,056 discloses an automatic door spring catch drive incorporated in a door frame and used for operating a locking bolt arrangement on a door. The arrangement comprises a spring bolt and a mortise bolt for locking the spring bolt. The drive is constructed so that the two bolts can be successively operated for opening the door. The complicated construction of this device is a disadvantage.  
         SUMMARY OF THE INVENTION  
         [0005]    An object of the present invention is to improve the safety mechanism or device for unlocking a door for a walk-in interior chamber, particularly for cooking devices or ovens, which mechanism overcomes the disadvantages of the prior art in a structurally simple way. In particular, a safety mechanism which enables unlocking a door for a walk-in chamber from the inside, even when the lock mechanism operable from the outside has been blocked.  
           [0006]    According to the invention, this problem is solved by a sliding bolt, which is biased by a spring to form a spring bolt, which is disposed either on the inside or the outside of the wall of the chamber for the moving door and from the inside or the outside of the chamber at the door opening and may be moved to a locked position in which the spring bolt engages a locking bolt which is operably connected with a lever, which can move the locking bolt between a locked position and an unlocked position. The improvements are that a release device, which is actuated from the interior of the chamber, can be passively or actively moved so as to unlock the door by moving the spring bolt.  
           [0007]    It can be provided that the release device is operated mechanically or pneumatically via at least one actuating element, such as a lever, a pull handle, a traction cable, a press-button or a rotary wheel and an element, preferably in the form of a grate or the like, which is disposed particularly at the bottom of the chamber, is movable in at least one direction of space, and is connected to at least one transmission element, for example in the form of a linkage, a fork device, a cam, a cable line, a drive, a guide pulley and the like.  
           [0008]    According to another proposed feature of the invention, the release device or triggering mechanism works electromagnetically upon utilization of at least one permanent magnet and at least one electromagnet, wherein the permanent magnet is preferably attached to the spring bolt.  
           [0009]    An advantageous embodiment of the invention is characterized by at least one detecting device for detecting the presence of a person in the interior of the chamber, which detection device has the form of a motion sensor, an infrared sensor, a weight sensor—which may be in the form of a strain gauge—, a reed contact or a microswitch, inside the interior of the chamber and the detecting device is respectively connectible to the triggering mechanism.  
           [0010]    A development of the inventive safety mechanism is characterized by at least one spring device by means of which a pre-stressed spring bolt forces the door into its unlocked position or locked position when a person is not present in the chamber. Optionally, according to the present invention, the spring bolt is disposed outside the chamber and the release mechanism is disposed at least partially inside the chamber and the spring bolt is connectible to the release mechanism inside the chamber through a wall of the chamber or through the door, particularly via a shaft that is preferably conducted vapor-tight through the wall of the door by means of a radial seal.  
           [0011]    It can be inventively provided that the spring bolt is movable with an electric motor, particularly via the shaft.  
           [0012]    It is also inventively preferred if an auxiliary energy supply in the form of, for instance, a battery, a rechargeable photovoltaic cell and/or a rechargeable accumulator, is provided with the triggering mechanism.  
           [0013]    Over and above this, it is proposed that the spring bolt and the locking bolt are implemented complementary relative to one another in the region of the mutual engagement and particularly comprise correspondingly beveled surfaces.  
           [0014]    It can also be provided that an element, such as a lever, is arranged in the interior, particularly the actuating element, is detachable and is fashioned as a tool, particularly for breaking a pane of glass installed in a door or for jimmying the door open.  
           [0015]    Finally, an inventive safety mechanism can be characterized by a display unit via which the presence of a person in the interior can be displayed, particularly in the closed position and/or locked position of the door, preferably upon emission of an alarm signal or, in particular, an acoustic and/or optical nature, whereby the display unit is preferably connectible to the sensor, to the triggering mechanism and/or to a regulating and/or control device.  
           [0016]    The invention is based on the surprising perception that a safety mechanism can be implemented so that the opening of, particularly, a cooking chamber door is possible proceeding from the interior of the cooking chamber of the cooking device, even when a lock mechanism arranged on the outside of the cooking chamber door is blocked such that it holds the cooking chamber door in a locked position. The spring bolt for engaging the locking mechanism in the locked position can be unlocked by a release device, thus, moving the cooking chamber door into an unlocked position. The device comprises an accessible inner chamber, which is equipped with a safety device according to the invention can thus be safely used in a number of situations, for example, even in penal institutions and the like.  
           [0017]    Other advantages and features of the invention will be readily apparent from the following description, the claims and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a front elevational view of an oven with a closed cooking chamber which has a first embodiment of the safety device according to the present invention;  
         [0019]    [0019]FIG. 2 is a top plan view of the oven or cooking device of FIG. 1;  
         [0020]    [0020]FIG. 3 is an enlarged detailed view with portions broken away for purposes of illustration of a portion in the circle A of FIG. 1;  
         [0021]    [0021]FIG. 4 is an enlarged detailed view with portions broken away for purposes of illustration of a portion in the circle B of FIG. 2;  
         [0022]    [0022]FIG. 5 is a front elevational view of an oven with an open cooking chamber showing a second embodiment of the safety device according to the present invention;  
         [0023]    [0023]FIG. 6 a  is an enlarged detailed view with portions broken away for purposes of illustration of a third embodiment of the safety device of the present invention with the spring bolt in an unlocked position;  
         [0024]    [0024]FIG. 6 b  is an enlarged detailed view with portions broken away for purposes of illustration of a third embodiment of the safety device according to FIG. 6 a  with the spring bolt in the locked position;  
         [0025]    [0025]FIG. 7 is a partial front view of an oven with a fourth embodiment of the safety device according to the present invention with portions broken away for purposes of illustration; and  
         [0026]    [0026]FIG. 8 is a cross sectional view of the fourth embodiment taken along the line D-D of FIG. 7. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    The principles of the present invention are particularly useful when incorporated in a safety device, generally indicated at  3 , for a cooking device or oven, generally indicated at  1 . The safety device  3  comprises a sliding bolt which is biased by a spring to form a spring bolt  5  and an operating lever  7  for opening and closing the cooking chamber door  9  from the outside of the cooking chamber or oven. The cooking chamber door  9  shown in the closed position or locked position in a door opening also has an inspection window  11 .  
         [0028]    As illustrated in FIG. 2, the door  9  can be swung to an open position  9 ′, which is shown in broken lines. As also shown in FIG. 2, the oven  1  comprises a cooking chamber  13  shown in broken lines and an auxiliary energy supply in the form of a photovoltaic cell  15 . The safety device  3  comprises a release lever  17 , which is positioned inside the cooking chamber  13 .  
         [0029]    The operation of the first embodiment of the safety device according to the present invention will be now described with reference to FIGS. 3 and 4, which are detailed views of the safety device  3  enclosed in a circle A of FIG. 1 and B of FIG. 2. In FIGS. 3 and 4, the cooking chamber door  9  is shown in a locked position in which the spring bolt  5  is in engagement with a locking bolt  19 .  
         [0030]    The door  9  can be locked in two ways. On the one hand, the lever  7  can be in an unlocked position while the door is closed. When the door is in the unlocked closed position, the lever  7  and, consequently, the locking bolt  19  can be moved into the locked position so that the bolt  19  comes into engagement with the spring bolt in the locked position and locks the door  9  in a closed position. If, on the other hand, the lever  7  and, consequently, the bolt  19  are already in the locked position when the cooking chamber door  9  closes, the spring bolt  5  will be designed so that it can briefly move out of the locking position shown in FIGS. 3 and 4 to allow it to pass behind the bolt  19 . To this end, the bolt  19  and the spring bolt  5  have correspondingly beveled surfaces, so that while the door is closing, the spring bolt  5  is moved against the action of a spring device  21  out of the locked position and is finally snapped back into the locked position by the force built up by the spring device  21  as soon as the door  9  has reached the closed position and, thus, the spring bolt  5  will engage the locking bolt  19  to lock the door.  
         [0031]    To open the door, the lever  7  must be rotated so that the bolt  19  rotates out of engagement with the spring bolt  5 , for example it is moved out of the locked position into an unlocked position. When the bolt  19  is disengaged from the spring bolt  5 , the door  9  is unlocked and can be opened into the open position.  
         [0032]    According to the invention, after actuating and opening the door  9 , the lever  7  is automatically moved back by a spring device (not shown) into a locked position shown in FIGS. 3 and 4.  
         [0033]    The door  9  may also be actively opened by a person in the chamber  13  via a release lever  17 , which is connected to a shaft  23  extending through a wall  25  of the cooking chamber. The passage for the shaft  23  in the wall  25  is sealed in a vapor-tight manner by a seal  27 , such as a radial or motor shaft seal, so that a steamed cooking process can be implemented in the cooking chamber  13  of the cooking device essentially without an escape of steam. A fork device  29  for connecting the shaft  23  to the spring bolt  5  is disposed at the end of the shaft  23  remote from the lever  17 . If, when the door  9  is in the locked position, the person in the cooking chamber rotates the lever  17  in a clockwise direction or presses down on the lever  17 , as illustrated in FIGS. 3 and 4, the fork device  29  will engage the spring bolt  5  and retract the spring bolt from the locked position. The bolt  19  is thus disengaged from the spring bolt  5  and unlocks the door  9  from the inside so that it can be subsequently opened. The unlocking occurs independent of the state of the lever  7  and, consequently, independent of the position of the bolt  19 , particularly even when the lever  7  is in the locked position. Even if the lever  7  is in the locked position and the door  9  is in the closed position, the safety device can open the cooking chamber door  9 .  
         [0034]    Optionally, the connection between the release lever  17  and the shaft  23  is made releasable and the lever  17  can also be used to break the inspection window  11  of the door  9  or can be used as a tool, such as a crowbar, for jimmying the cooking chamber door open, even if the door is blocked from the exterior by an article of furniture or the like.  
         [0035]    A second embodiment of the safety device is generally indicated at  3 ′ in FIG. 5. In contrast to the first embodiment of the safety device  3  of FIGS. 3 and 4, the second embodiment of the safety device  3 ′ does not have a release lever  17 . Instead, the shaft  23  is connected to a wire cable  31  connected via a guide pulley  33  to a bearing  35  of a grating  37  disposed at the bottom of the cooking chamber  13 . If a person is shut in the cooking device  13 , he can rotate the grating  37 . The rotation is transmitted via the wire cable  31  to the safety device  3 ′, so that the spring bolt  5  is moved out of its locked position into an unlocked position and consequently unlocks the door  9  so that it may be opened to the position  9 ′. Optionally, also, the spring bolt  5  can be moved not only by rotation of the grating  37  but also by horizontal or vertical movement thereof, more particularly vertical movement of the grating  37  under the weight of the user on the grating, so that the user shut in the chamber  13  can operate the safety device  3 ′ passively instead of actively. Optionally, also, the motion of the grating  37  is transmitted to the safety device  3 ′ by a linkage, which is not shown.  
         [0036]    A third embodiment of the safety device, generally indicated at  3 ″ in FIGS. 6 a  and  6   b.  The safety device  3 ″ has a spring bolt  5 ′ and a spring device  21 ′. A permanent magnet  39  is disposed on the spring bolt  5 ′ near an electromagnet  41 . As illustrated in FIG. 6 a,  the spring bolt  5 ′ is in the unlocked position when the electromagnet  41  is not energized. The spring device  21 ′ forces the spring bolt  5 ′ to the unlocked position so that it cannot engage the bolt  19  on the door  9 . This insures that the door  9  cannot be locked when the energy supply fails. If, however, an electrical current flows through the electromagnet  41 , the magnetic interaction between the electromagnet  41  and the permanent magnet  39  causes the spring bolt  5 ′ to move against the action of the spring device  21 ′ into the locked position shown in FIG. 6 b,  wherein it engages the bolt or catch  19  on the door.  
         [0037]    Optionally, the door  9  can be unlocked if a person who is shut in the interior of the cooking chamber  13  actuates a switch or the like, which actively influences the current flowing through the electromagnet so that an unlocking of the door  9  occurs. Optionally, also, the door  9  can be passively unlocked by this person. To this end, the electromagnet  41  is connected to a control device (not shown), which is connected to a sensor (also not shown). If the sensor detects a person in the cooking chamber  13 , the power supply to the electromagnet  41  is broken or deactivated and the spring bolt  5 ′ is moved by the spring device  21 ′ into the unlocked position shown in FIG. 6 a.  The sensor can also be an electrical switch, such as a microswitch or a reed contact disposed on the bottom of the chamber and triggered by deformation of the chamber floor caused by the weight of the person.  
         [0038]    In a modification of the embodiment of FIG. 3 of the safety device, the spring device holds a spring bolt having the permanent magnet in a locked position. The electromagnet, such as  41 , is offset to the left from the position shown in FIG. 6 b  when the spring bolt  5 ′ is in the locked position. If an electrical current is then sent to the electromagnet, the interaction between the electromagnet and the permanent magnet moves the spring bolt out of the locked position and into an unlocked position similar to that of FIG. 6 a.  To prevent the unlocking of the cooking door becoming impossible if the main energy supply to the oven is interrupted, the safety device is connected, in this case, to a control device via an auxiliary energy supply, for example in the form of a photovoltaic cell  15 .  
         [0039]    A fourth embodiment of the safety device is generally indicated at  3 ″′ in FIGS. 7 and 8. A release lever  17 ′ is disposed on the side of the wall  25  facing inward to the cooking chamber  13 . The lever  17 ′ is connected to a shaft  23 ′ extending through the wall  25 , as shown in FIG. 8. A cam  43  is mounted on the shaft  23 ′ and mechanically interacts with a fork device  29 ′, which is coupled as before to the spring bolt  5 ″, which is biased to a locking position by a spring device  21 ″.  
         [0040]    The safety device  3 ″′ is released as follows: If a person is inside the chamber  13 , he can release the safety device  3 ″′ by swinging the lever  17 ′ into an open position, as indicated by the arrow  45  of FIG. 7. This rotation of the shaft  23  thus moves the cam  43  outward. Owing to the interaction between the cam  43  and the fork device  29 ′, the movement also results in moving the fork device  29 ′ and, thus, retracting the spring bolt  5 ″ in the direction indicated by the arrow  47  to an unlocked position. The spring bolt  5 ″ is thus moved out of the locked position shown in FIGS. 7 and 8 into an unlocked position against the action of the spring device  21 ″, which is a compression spring. Since the spring bolt  5 ″ cannot engage when a cooking chamber door (not shown in FIGS. 7 and 8) is in the unlocked position, the door can be opened by the person in the chamber after actuation of the lever  17 ′.  
         [0041]    Although various minor modifications may be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent granted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

Technology Classification (CPC): 8