Device for manually unlocking a holding mechanism to which a load can be applied

Abstract

The invention relates to a device ( 50 ) for manually unlocking a holding mechanism ( 10 ) to which a load can be applied, comprising an operating element ( 62 ) which is to be operated manually for unlocking the holding mechanism ( 10 ) with an operating force becoming larger as the load increases, a conversion mechanism ( 64, 90 ) which includes a force transfer element ( 72 ) coupled to the operating element ( 62 ), and a trigger ( 66 ) coupled to the force transfer element ( 72 ), wherein in order to unlock the holding mechanism ( 10 ) the trigger is movable by the operating force transferred by the force transfer element ( 72 ) to the trigger ( 66 ) from a locked position in which the trigger ( 66 ) is operatively decoupled from the holding mechanism into an unlocked position in which the trigger ( 66 ) is operatively coupled to the holding mechanism in order to unlock said holding mechanism. The conversion mechanism ( 64, 90 ) includes an elastically deformable force limiter ( 80 ) via which the force transfer element ( 72 ) is coupled to the trigger ( 66 ) and which prevents the transfer of the operating force to the trigger ( 66 ) due to the elastic deformation thereof, if the operating force exceeds a predetermined force.

What is claimed is: 
     
         1 . A device for manually unlocking a holding mechanism to which a load can be applied, comprising:
 an operating element which is to be operated manually for unlocking the holding mechanism with an operating force becoming larger as the load increases,   a conversion mechanism which includes a force transfer element coupled to the operating element, and   a trigger coupled to the force transfer element, wherein in order to unlock the holding mechanism the trigger is movable by the operating force transferred by the force transfer element to the trigger from a locked position in which the trigger is operatively decoupled from the holding mechanism into an unlocked position in which the trigger is operatively coupled to the holding mechanism for unlocking said holding mechanism,   wherein   the conversion mechanism includes an elastically deformable force limiter via which the force transfer element is coupled to the trigger and which prevents due to the elastic deformation thereof the transfer of the operating force to the trigger, if the operating force exceeds a predetermined force.   
     
     
         2 . The device according to  claim 1 , wherein an elongated housing, in which the conversion mechanism converts the operating force manually exerted on the operating element into a movement of the force transfer element along a housing longitudinal axis and the force limiter is elastically deformable along the housing longitudinal axis. 
     
     
         3 . The device according to  claim 1 , wherein the force limiter is a spring, the restoring force of which is dimensioned such that the spring maintains its original form, if the operating force is less than or equal to the predetermined force, and that the spring deforms elastically, if the operating force exceeds the predetermined force. 
     
     
         4 . The device according to  claim 3 , wherein the spring is formed as pressure spring. 
     
     
         5 . The device according to  claim 1 , wherein the conversion mechanism comprises a first toothing formed at the operating element and a second toothing formed at the force transfer element which is meshed with the first toothing. 
     
     
         6 . The device according to  claim 1 , wherein
 the conversion mechanism comprises a pressing surface formed at the operating element and a toggle lever having a longer first leg and a shorter second leg,   the longer first leg of the toggle lever is rotatably supported at one end in a first center of rotation stationary inside the device,   the shorter second leg of the toggle lever is rotatably supported at one end in a second center of rotation which is stationary relative to the movably guided force transfer element,   the two legs are rotatably supported respectively at their other end in a common third center of rotation, and   the pressing surface during manual operation of the operating element presses onto the toggle lever in the region of the third center of rotation.   
     
     
         7 . The device according to  claim 1 , wherein the operating element is a pivotably supported handle. 
     
     
         8 . The device according to  claim 1 , wherein the force transfer element includes a hollow cylindrical portion in which the force limiter is supported. 
     
     
         9 . The device according to  claim 1 , wherein the trigger comprises a trigger rod which is linearly guided in the direction of the longitudinal axis thereof. 
     
     
         10 . The device according to  claim 9 , wherein the trigger rod is guided at least partially inside the oblong force limiter. 
     
     
         11 . The device according to  claim 1 , wherein an end stop which limits the elastic deformation of the force limiter. 
     
     
         12 . The device according to  claim 11 , wherein the end stop is formed by an end stop surface that abuts the force transfer element. 
     
     
         13 . A holding mechanism to which a load can be applied, comprising a device for unlocking said holding mechanism according to  claim 1 . 
     
     
         14 . The holding mechanism according to  claim 13 , wherein the holding mechanism is a holding arm formed for supporting a body portion of a patient, which has at least two rigid holding members and a joint, which connects the two holding members together, and an unlocking mechanism, which cooperates with the trigger such that the joint rigidly couples the two holding members together in the locking position of the trigger and movably couples the two holding members in the unlocking position of the trigger. 
     
     
         15 . The device according to  claim 2 , wherein the force limiter is a spring, the restoring force of which is dimensioned such that the spring maintains its original form, if the operating force is less than or equal to the predetermined force, and that the spring deforms elastically, if the operating force exceeds the predetermined force. 
     
     
         16 . The device according to  claim 2 , wherein
 the conversion mechanism comprises a pressing surface formed at the operating element and a toggle lever having a longer first leg and a shorter second leg,   the longer first leg of the toggle lever is rotatably supported at one end in a first center of rotation stationary inside the device,   the shorter second leg of the toggle lever is rotatably supported at one end in a second center of rotation which is stationary relative to the movably guided force transfer element,   the two legs are rotatably supported respectively at their other end in a common third center of rotation, and   the pressing surface during manual operation of the operating element presses onto the toggle lever in the region of the third center of rotation.   
     
     
         17 . The device according to  claim 3 , wherein
 the conversion mechanism comprises a pressing surface formed at the operating element and a toggle lever having a longer first leg and a shorter second leg,   the longer first leg of the toggle lever is rotatably supported at one end in a first center of rotation stationary inside the device,   the shorter second leg of the toggle lever is rotatably supported at one end in a second center of rotation which is stationary relative to the movably guided force transfer element,   the two legs are rotatably supported respectively at their other end in a common third center of rotation, and   the pressing surface during manual operation of the operating element presses onto the toggle lever in the region of the third center of rotation.   
     
     
         18 . The device according to  claim 4 , wherein
 the conversion mechanism comprises a pressing surface formed at the operating element and a toggle lever having a longer first leg and a shorter second leg,   the longer first leg of the toggle lever is rotatably supported at one end in a first center of rotation stationary inside the device,   the shorter second leg of the toggle lever is rotatably supported at one end in a second center of rotation which is stationary relative to the movably guided force transfer element,   the two legs are rotatably supported respectively at their other end in a common third center of rotation, and   the pressing surface during manual operation of the operating element presses onto the toggle lever in the region of the third center of rotation.