Patent Abstract:
A device ( 1 ) maintains a locked and closed state of a space separating device ( 2 ) in a releasable manner, in particular a protective device of a machine ( 4 ). The device has a first part ( 6 ) with an opening and a second part ( 8 ). The parts are movable relative to one another. The opening is at least partially closable. The device ( 1 ) includes a latch ( 18 ) for locking the closed state of the space-separating device ( 2 ), a holding element ( 30 ) for keeping the latch ( 18 ) in the latched position, and a release element ( 36 ) for releasing the catch of the latch ( 18 ). The catch of the latch ( 18 ) may be lifted by a rotational movement of the release element ( 36 ) relative to the latch ( 18 ).

Full Description:
FIELD OF THE INVENTION 
     This invention relates to a device for maintaining a locked and closed state of a space-separating device in a releasable manner, in particular the protective device of a machine. 
     BACKGROUND OF THE INVENTION 
     In production engineering, for example, among other things, for safety reasons, machines and systems are set up within a space separated from the exterior and in which a person is not permitted to remain during operation of the machine. For example, to have access to the machine for maintenance work, the space-separating device generally has a closable opening. Generally speaking, operation of the machine should only be possible when the opening is closed, and the closed state is locked. Access to the machine is only possible when the locking of the closed state is neutralized. 
     DE 203 15 959 U1 discloses a device for monitoring the state of a space-separating device, in which it is ensured that a person located within the separated space is not able to close the space-separating device and lock it from the inside. Otherwise, there would be the risk that the machine could start inadvertently or intentionally while a person is located within the space-separating device. 
     DE 196 32 962 A1 discloses a door actuation device. From the interior of the space-separating device, a latch locking the closed state can be transferred into its unlocking position. The space-separating device can then be opened. Conversely, the latch cannot be transferred into its locking position, this movement possible only from the outside. In this way a type of “escape unlocking” is implemented. 
     DE 10 2005 057 108 A1, published at a later date, discloses a safety switch for producing a release signal depending on the position of a movable protective door. The part to be attached to the protective door has an actuator movable between a first position and a second position. The part to be attached to the frame has a recess engagable by the actuator in the second position. A blocking element can block the actuator in the second position. 
     DE 298 24 200 U1 discloses a device enabling an individual inadvertently locked within the protective enclosure to leave this protective enclosure. At the same time, the machines located within the protective enclosure can only be operated when the door on which the device is located is not only closed, but locked. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide a device for maintaining a locked and closed state of a space-separating device in a releasable manner which overcomes the disadvantages of the prior art. 
     In one embodiment, the device is intended to enable not only locking of the closed state of the space-separating device, but to maintain the locked and closed state, for example, as long as the machine located within the space-separating device is in an operating state hazardous to people, for example, when the machine is running down after it has been turned off. 
     In one embodiment, in spite of maintaining the locked and closed state, the locking of the latch can be neutralized from within the space-separating device. The device is intended to ensure permanently reliable and safe operation. 
     This object is basically achieved by a device where the space-separating device can be protective hoods, protective doors, or an arrangement of partitions or separating gratings by which the inner region around a machine, such as a machine tool or an industrial robot, is separated from an outer region in which individuals can remain even during operation of the machine. The first part of the space-separating device can be designed, for example, as a frame part. A second part such as, for example, a door or window is movable. In the case of a door, conventionally the second part is pivotally coupled to the first part or is movably guided thereon. 
     The device has a latch for locking the closed state of the space-separating device. In one embodiment the latch is movably supported in the device and can be transferred from the retracted position into the locking position by an actuation element, such as a knob, to engage a latch receiver by blocking it and to lock the closed state. By the holding element, the latch can be blocked in its locking position. The locked and closed state of the protective device can then be blocked and maintained closed. 
     One or more sensors can detect the closed state of the protective device, locking of the closed state and/or maintaining the locked and closed state and can signal that status to a device controlling the machine. By this control, the machine can be started only when the space-separating device is closed, the closed state is locked and/or the locked and closed state is blocked. The blocking and/or the neutralization of the blocking can take place likewise in a signal-controlled manner. For example, the control can provide for the blocking of the latch to be neutralized only when the machine is in the safe state, for example, when a machine tool or an industrial robot is stopped, so that it cannot pose a danger to people. The blocking and/or release can be driven in a controlled manner for this purpose. 
     In one embodiment the holding element is spring-loaded and can, for example, engage the latch and block it as soon as the latch and holding element have sufficiently approached one another. The blocking can also be neutralized by a controllable drive, for example, by an electromagnet or a piezoelectric drive. Alternatively, the holding element can also be kept spring-loaded in a non-blocking position and can be transferred by a drive into the state blocking the latch in its locking position. In another alternative embodiment, the holding element can also have two stable states and can be switched back and forth between those two states by a drive. 
     The device moreover has a release element permitting neutralizing of the blocking of the latch. This release element can also be actuated from the inside of the space-separating device, optionally even against the action of a driving or spring force acting on the holding element. This arrangement ensures that a person located within the space-separating device is easily able, in particular without actuating an EMERGENCY OFF button, to neutralize the maintaining of the locked and closed state. Optionally, by neutralizing the blocking of the latch the device can produce a signal which signals to be machine control that the machine is to be transferred into the safe operating state, for example, is to be turned off. 
     The blocking of the latch can be neutralized by the rotary motion of the release element relative to the latch. In one embodiment the release element is located and pivotally supported on the latch for this purpose. Reliable neutralization of the blocking of the latch thus can be enabled with simple mechanical elements. 
     In one embodiment, following the rotary motion, the release element together with the latch can be moved. The locked and closed state of the space-separating device can then also be neutralized, whereupon the space-separating device can be opened. In one embodiment the actuating element located within the space-separating device dictates dynamic coupling in only one direction, specifically in the direction of neutralizing the locking position of the latch. Conversely in the other direction a trip-free mechanism prevents the position located within the space-separating device from being able to transfer the latch into its locking position. 
     In one embodiment the release element is a dual-arm lever which can be turned around an axis of rotation. The configuration as a dual-arm lever can implement different force and path ratios, for example, a relatively high torque for neutralizing the blocking of the latch can be made available with comparatively small actuating forces. Conversely, a correspondingly large lever arm can make available a comparatively large path, for example, for lifting the holding element out of a catch depression and thus for neutralizing the blocking of the latch. Moreover, the interval between delivering the force for neutralizing the blocking of the latch on the one hand and the position of the lever in contact with the holding element on the other hand can be chosen to be large. In this way the mechanical elements necessary for actuation can be located within the device such that the design is small. Alternatively or in addition, the actuating elements located on the inside and outside for neutralizing the blocking of the latch and the actuating elements provided for transferring the latch into its locking position can be located at a distance to one another. This spacing is especially advantageous for some applications. 
     In one embodiment the release element can be actuated by a knob. The initial rotary motion of the knob at the outset results in rotary motion of the release element with which the locking of the latch can be neutralized. As turning continues the latch moves linearly out of the locked position. 
     The release element can be turned, for example, by an element movably supported in the device and connected to the first knob by a coupling device. The coupling device in this case converts the rotary motion of the first knob by 90° into linear motion of the displacement element. For this purpose the coupling device can have first and second levers hinged to one another at an articulation point as a hinged joint. The first lever is nonrotatably connected to the first knob. The second lever is connected directly or indirectly to the displacement element by other elements. When the first lever is turned, the displacement element is moved. As a result first the blocking of the latch can be neutralized, and then the latch can be guided out of its locking position. In the reverse direction there is no motion coupling between the displacement element and the latch, in particular not with respect to linear motion. 
     In one embodiment the device has a second knob actuatable from the outside of the space-separating device, specifically located on the outside of the device. By the second knob, the latch can be moved into its position locking the closed state. In one embodiment the axes of rotation of the first and second knobs have an offset to one another. This offsetting has the advantage that each part of the space-separating device to which the device is attached need not be provided with a through hole for the common axis of rotation of the two knobs, as is necessary in the prior art. This metal-cutting at the installation site is disadvantageous for many reasons. On the other hand, the offset of the two axes of rotation ensures that in the closed state of the space-separating device there are no light gaps which are disadvantageous especially when within the space-separating device a laser machining device is present, and the emergence of laser light from the space-separating device must be reliably prevented. 
     In one embodiment the latch and/or the holding element are made such that they positively engage one another in the position blocking the latch. For example, the latch can have a recess with a catch flank in which the holding element catches in the position blocking the latch. The positive locking ensures that the resulting self-locking can implement a high holding force without correspondingly high drive forces having to be made available by a motor. This arrangement is especially advantageous because the release element optionally must overcome those forces activating the holding element. 
     In one embodiment, the device has a first sensor by which the position of the latch locking the closed state of the space-separating device can be signaled. The first sensor can be a safety switch as is conventionally used in safety engineering. In addition to contact safety switches in which a mechanically encoded actuator is introduced into the switch head and triggers a switching process there, non-contact or electronic safety switches can also be used which wirelessly transmit signals between an actuator and a read head. In one embodiment an actuator is in the form of a transponder on the latch. In the position locking the closed state of the space-separating device, the actuator moves into the response region of a read head so that only in the position of the latch locking the closed state of the space-separating device is signal transmission between the read head and the transponder possible. In one embodiment the transponder is located near the jacket surface of the latch, and the read head is located near or on the wall of the latch receiver. Alternatively, the actuator can also be located on or near the face-side end of the latch. 
     In one embodiment the device has a second sensor for signaling the position of the holding element blocking the latch. This second sensor can also be made generally as a non-contact safety switch. The holding element could be made specifically as a coupling element, for example, for signal coupling between the transponder located on the latch and the read head. Fundamentally, the first sensor and the second sensor can be made separately. Alternatively, the holding element can couple the transponder of the first sensor to a second read head of the second sensor so that there would be only one transponder on the latch. In this case it would also be possible to separately detect whether the latch is in its blocking position and whether the locked position is blocked by the holding element. In another alternative, signal coupling between the transponder and read head of the first sensor could only be possible when the holding element is in its position blocking the latch. 
     In one embodiment, the second sensor is an optical or magnetic sensor, such as a photoelectric barrier or a Hall sensor. Those sensors can be easily configured in a small design and optionally also directly on a circuit board. The holding element can be made as a pivotable lever, with a catch projection located at a distance from the axis of rotation for interaction with the lock. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings which form a part of this disclosure: 
         FIG. 1  is a schematic top plan view of a device according to an exemplary embodiment of the invention in the locked and blocked condition; 
         FIG. 2  is an enlarged top plan view in section of the device of  FIG. 1  in the locked and blocked condition; 
         FIG. 3  is an enlarged top plan view in section of the device of  FIG. 1  in the locked and unblocked condition; 
         FIG. 4  is an enlarged top plan view in section of the device of  FIG. 1  in the unlocked condition; and 
         FIG. 5  is a side elevational view in section of the device of  FIG. 1  in the locked condition. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a schematic top view of one exemplary embodiment of the device  1  according to the invention for maintaining the locked and closed state of the space-separating device  2 , in particular the protective device of a machine  4 , in a releasable manner. A first stationary part  6  has an opening closable by a second part  8 . The first and second parts  6 ,  8  can be moved relative to one another allowing the opening to be at least partially closed. In the illustrated embodiment the second part  8  is a door pivotable around the first axis  10  according to the first arrow  12 . The open state of the door is shown by the broken lines. A person can enter the interior of the space-separating device  2  through the opening and can, for example, equip, maintain, or repair the machine  4 . During operation of the machine  4 , a person is not permitted or is not to remain within the space-separating device  2 . 
     For this purpose the device  1  has a first component  14  located on the first part  6  and a second component  16  located on the second part  8 . The first component  14  has a receiver for a latch  18  movably supported in the second component  16 . The closed state of the space-separating device  2  shown in solid lines can be locked by latch  18  so that the space-separating device  2  cannot be opened in this state. 
     The locked state can be signaled by a safety switch by way of a first connecting line  22  on a control device  20  which controls the machine  4  according to the filed control program by way of a second connecting line  24 . Conversely, the machine  4 , by way of the second connecting line  24 , delivers feedback about the operating state to the control device  20 . The control device  20  can control the device  1 , for example, with respect to maintaining the locked state. The safety switch in the embodiment has a read head  26  located on the first component  14  and an actuator  28  located on the latch  18 . Signal exchange between the read head  26  and actuator  28  is possible only in the illustrated locked state. 
     The device  1  moreover has a holding element  30  located in the first component  14  in the embodiment. Holding element  30  can be pivoted around a second axis  32  according to the arrow  34 . The latch  18  can be blocked in the illustrated locking position by the holding element  30 . The holding element  30  and the latch  18  are positively engaged. In the embodiment, the holding element  30  for this purpose engages a recess in the latch  18 . The recess has a catch flank providing self-locking relative to the reset motion of the latch  18 . 
     By a release element  36  ( FIG. 2 ), the blocking of the latch  18  can be neutralized. Specifically, the holding element  30  can be lifted out of its position shown in  FIG. 1 . The blocking is neutralized by a first actuating element actuatable from the interior of the space-separating device  2  and formed by a first knob  42  rotatable around a third axis  38  according to the third arrow  40  ( FIG. 1 ). Following the neutralization of the blocking of the latch  18 , as the first knob continues to turn, the latch is retracted into the second component  16  so that the locking of the closed state is also neutralized and the second part  8  can be opened. 
     In one embodiment, the holding element  30  can be manually disengaged from the latch  18  only in this way. Specifically, the holding element  30  cannot be disengaged by the second actuating element accessible from the outside of the space-separating device  2  formed by a second knob  48  around the fourth axis  44  according to the fourth arrow  46  ( FIG. 1 ). With the second knob  48  the second part  8  can be closed, and by turning the second knob  48  the latch  18  can be extended into the illustrated locking position. 
     The space-separating device  2  in the embodiment is a protective cab or a protective grating having flat elements attached to profiled rails  50 ,  52  extending perpendicular to the plane of the drawing of  FIG. 1 . The components  14 ,  16  of the device  1  can also be attached to these rails. As is apparent from the schematic of  FIG. 1 , the third axis  38  of the first knob  42  and the fourth axis  44  of the second knob  48  extend parallel to one another and are laterally offset relative to one another so that it is not necessary to drill through the profile rails  52  into the interior of the space-separating device  2  for passage of the fourth axis  44 . 
       FIG. 2  shows a cutaway view of the embodiment of the device  1  which has been enlarged compared to  FIG. 1 . The first component  14  is connected to the first profile rails  50  and thus to the first part  6  ( FIG. 1 ) by connecting means (not shown). Within the first component  14  the holding element  30  is mounted to be able to pivot around the second axis  32  extending perpendicular to the plane of  FIG. 1  and in the illustrated maintained locked state. A projection  54  on the end side of holding element  30  engages a recess  56  of the latch  18 . 
     The essentially cylindrical latch  18  in cross section can be shaped to be circular or essentially rectangular is formed of a plastic base part, with a metal insert part  58 . Specifically, the insert part  58  is a metal sheet bent into a U-shape in cross section. The insert part  58  forms the recess  56  and is used in particular to accommodate the blocking forces. In a part inserted into the latch receiver  60  in the illustrated locked and blocked state, near the jacket surface on the latch  18  an actuator  28  is made as a transponder and can be read out from the read head  26  only in the illustrated position so that the locked and closed state of the space-separating device  2  can be signaled. 
     The projection  54  of the holding element  30  and the recess  56  in the insert part  58  each form a surface essentially parallel to one another and enclose a right angle with the direction of motion of the latch  18  for unlocking. In an attempt to retract the latch  18  by turning the second knob  48  around the fourth axis  44 , this action results in positive locking between the latch  18  and the holding element  30  by which very high holding forces can be applied. The control device  20  or, for example, a manual EMERGENCY OFF can route the holding element  30  out of its holding position, for example, by an electromagnet  62  located in the first component  14  being energized. The magnet armature  64  then comes into contact with the arm of holding element  30  opposite the projection  54  relative to the second axis  32 , with the holding element  30  turning counterclockwise in  FIG. 2 . 
     Regardless of such controlled neutralization of holding or blocking, turning the first knob  42  around the third axis  38  moves a displacement element  66  within the second component  16 . A release element  36  is then turned clockwise around a fifth axis  68  extending perpendicular to the plane of  FIG. 2 . In this way, a release element section assigned to the holding element  30  comes into contact with the holding element  30  and lifts it in the course of rotary motion out of the recess  56  to neutralize holding or blocking. Conversion of the rotary motion of the first knob  42  into linear motion of the displacement element  66  takes place by a coupling device having first and second levers  82 ,  86  and shown in a side view in  FIG. 5 . Coupling of the motion between the second knob  48  and the latch  18  can take place in a similar manner. 
     When the first knob  42  is turning, the displacement element  66  and a pin  70  located thereon are moved to the right in  FIG. 2 . The pin  70  then comes into contact with the oblique surface  72  and the linear motion of the pin  70  is converted into rotary motion of the release element  36  by interaction of the pin  70  with the oblique surface  72  of release element  36 . The release element  36  is made as a lever having two arms relative to the fifth axis  68 . The action surface of the displacement element  66  lies on the side opposite the contact surface for the holding element projection  54  relative to the fifth axis  68 . The axis pin for supporting the release element  36  is formed by the latch  18  or is fixed on it. 
       FIG. 3  shows a cross-sectional view of the embodiment of device  1  corresponding to  FIG. 2 , but in the state in which the first knob  42  is turned around the third axis  38  so far that the pin  70  is moved completely along the oblique surface  72  and is held in a sector-shaped receiver  74  of the release element  36 . In this state the release element  36  is turned maximally around the fifth axis  68 . The holding element  30  is lifted completely out of the recess  56  so that holding or blocking is neutralized. As the first knob  42  continues to turn, as the displacement element  66  continues to move, the pin  70  entrains the release element  36 . By way of the release element&#39;s support on the fifth axis  68  and the latch  18 , and the pin  70  moves latch  18  in  FIG. 3  to the right so that the latch  18  emerges completely from the latch receiver  60 . Accordingly, the locking is also neutralized. 
     If the holding element  30 , for example, is monitored in its position by a photoelectric barrier or a Hall sensor, the state shown in  FIG. 3  can be signaled such that there is no longer any holding or blocking. At the same time it can also be signaled by the actuator  28  and the read head  26  that the space-separating device  2  is still in a closed and locked state. 
       FIG. 4  shows an enlargement comparable to  FIGS. 2 and 3 , but in the state of the device  1  in which the latch  18  is retracted almost completely into the second component  16  by complete turning of the first knob  42 . The displacement element  66  is located like the latch  18  on its rear stop. Continued turning of the first knob  42  in the direction of rotation leading to neutralization of blocking is no longer possible. 
     Based on the existing motion coupling, on the outside of the space-separating device  2  the second knob  48  is now in its end position which is opposite relative to  FIG. 2  and has been turned back in particular by turning the first knob  42 . In the illustrated state the second part  8  ( FIG. 1 ) can be opened relative to the first part  6 . The actuator  28  is no longer located in the read region of the read head  26  so that the unlocked state can be signaled. If it is necessary or advantageous that the closed state of the second part  8  still is to be signaled, an additional safety switch can be located, for example, on the facing end sides of the first and second part  6 ,  8  and, independently of the locking position of the latch  18 , signals the closed position of the second part  8 . 
     For relocking from the position shown in  FIG. 4  the latch  18  must again be introduced into the latch receiver  60 . This is not possible by turning the first knob  42  because the displacement element  66  in  FIG. 4  is indeed moved to the left, but there is no respective motion coupling with the latch  18 . This arrangement reliably prevents a person located on the inside of the space-separating device  2  from moving the latch  18  into its position locking the closed state. Rather, for this purpose the second knob  48  must be turned to move the latch  18  out of the second component  16 . 
     On or near its face-side end, the latch has a bevel  76 . With the bevel  76 , the latch  18  can lift the holding element  30  out of its position shown in  FIG. 4 , in which the holding element  30  with its projection  54  projects over the recess  56  into the latch receiver  60 . When the latch  18  has been fully inserted into the latch receiver  60 , the projection  54  in turn engages the recess  56  and blocks the latch  18  in its locking position. In this motion of the latch  18 , based on the motion coupling between the release element  36  and the displacement element  66 , especially due to the contact of the sector-shaped receiver  74  with the pin  70 , the first knob  42  undergoes a reset motion until it again assumes the initial position shown in  FIG. 2 . 
     Preferably, the holding element  30  integrally forms an action surface  90  which is accessible from the outside of the device  1 . In any case after removing a cover, holding or blocking can be manually neutralized, preferably with a suitable tool. 
       FIG. 5  shows a side view of the device  1  offset by 90° relative to  FIGS. 2 to 4 , in particular of the component  16  from the direction of the position of the first knob  42 . A coupling device is shown for converting the rotary motion of the first knob  42  into linear motion of the displacement element  66 .  FIG. 5  corresponds to the position of the latch  18  in  FIG. 2 . A square  78  turnable by a first knob  42  is nonrotatably connected by its shape to a driver shaft  80 . Shaft  80  in turn is nonrotatably connected to the first lever  82 . At the articulation point  84  formed, for example, by a pin, the first lever  82  is connected to the second lever  86 , which is in turn connected to the displacement element  66  at a position spaced apart from the articulation point  84 . Second lever  86  is articulated in particular at another articulation point  88  on the displacement element  66 . In this way, as the first knob  42  turns around the third axis  38  which runs perpendicular to the plane of the drawing of  FIG. 5 , the displacement element  66  is moved back and forth, there being motion coupling with the release element  36  only in one direction. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.

Technology Classification (CPC): 4