Abstract:
The invention relates to a control method for a quick change device of a work tool, comprising the steps of: receiving a command to disengage a work tool clamping device; determining whether the work tool clamping device is in an engaged state; detecting functionality of a disengagement alarm if the work tool is in the engaged state; switching to an emergency state upon the detection of failure of the disengagement alarm. The present invention further relates to a corresponding control apparatus and work machine.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a control method and a control apparatus for a quick change device of a work tool. 
       BACKGROUND ART 
       [0002]    The mechanical machines, e.g. engineering machines or agriculture machines in the art are designed to perform various tasks, wherein different work tools are mounted by unified or standard work tool clamping devices. For these multi-functionality machines, usually corresponding work tools have to be changed during switching among different tasks. For this, a corresponding quick change device of a work tool is provided. 
         [0003]    Generally speaking, current quick change device of a work tool is equipped with an alarming horn, which sounds when a work tool clamping device is in a disengaged position. The alarming horn is used to remind an operator of the fact that the work tool clamping device is in the disengaged position and that the work tool is not connected or fastened. However, if the alarming horn fails to work due to failure of an electric circuit thereof, the operator will not be informed that the work tool clamping device is in the disengaged position. In this case, the operator may perform the operation when the work tool clamping device is not engaged or the work tool is not fastened, because he/she is not aware of the fact that the work tool clamping device in the disengaged position. The work tool therefore may come loose and fall down, even resulting in safety accident. 
       SUMMARY OF THE INVENTION 
       [0004]    Based on the prior art, the present invention is directed provide a control method and a control apparatus for a quick change device of a work tool, so as to improve safety of the quick change device of the work tool. 
         [0005]    In the present invention, a control method for a quick change device of a work tool is provided, comprising the steps of:
       receiving a command to disengage a work tool clamping device;   determining whether the work tool clamping device is in an engaged state;   detecting functionality of a disengagement alarm if the work tool clamping device is in the engaged state;   switching to an emergency state upon detection of failure of the disengagement alarm.       
 
         [0010]    This method enables an emergency state, so that accident can be avoided in the failure of the alarm. 
         [0011]    The present invention further relates to a control apparatus for carrying out the control method according to the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic view of an embodiment of the control apparatus for a quick change device of a work tool according to the present invention; 
           [0013]      FIG. 2  is a schematic view of another embodiment of the control apparatus for a quick change device of a work tool according to the present invention; 
           [0014]      FIG. 3  is a flow chat of an embodiment of the control method for the quick change device of the work tool according to the present invention; 
           [0015]      FIG. 4  is a flow chat of another embodiment of the control method for the quick change device of the work tool according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0016]      FIG. 1  is a schematic view of the control apparatus of the present invention. The control apparatus controls a quick change device of a work tool, which includes a work tool clamping device for clamping and maintaining the work tool in a working state. 
         [0017]    The control apparatus comprises an electronic control unit  1 . A quick change operation member  2  is provided for the quick change device and is controlled by a user, such as but not limited to a switch or a button. The signal of the quick change operation member is transmitted to the electronic control unit  1 , which generates multiple control signals based on the signal received from the quick change operation member  2 . 
         [0018]    A first control signal is transmitted to an engaging means  3  for the work tool clamping device, wherein the engaging means engages the work tool clamping device so that the work tool is fastened on the machine and hence in a working state. The engaging means  3  for the work tool clamping device for example may be an electromagnetic valve in a hydraulic line for controlling the work tool clamping device. 
         [0019]    A second control signal is transmitted to a disengaging means  4  for the work tool clamping device, wherein the disengaging means disengages the work tool clamping device so that the work tool is released and in a changeable state. The disengaging means  4  for the work tool clamping device for example may also be an electromagnetic valve in a hydraulic line for controlling the work tool clamping device. 
         [0020]    A third control signal is transmitted into a disengagement alarm  5 , which is activated in a disengaged and changeable state of the work tool. Generally, the disengagement alarm  5  may be an alarm horn, or of course may be an optical alarm or other types of alarm. According to another embodiment of the invention, a further alarming device (see  FIG. 2 ) may be provided to inform an operator that the disengagement alarm  5  fails or malfunctions. 
         [0021]    Generally, if the signal from the quick change operation member  2  is “ON”, the electronic control unit activates disengaging means  4  for the work tool clamping device and the disengagement alarm  5  at the same time, so that a work tool quick change procedure is accompanied by continuous alarming. Generally, the work tool clamping device is disengaged, and then the current work tool is replaced by a work tool to be used, and finally the work tool clamping device is engaged again to fasten the new work tool. 
         [0022]    If the signal from the quick change operation member  2  is “OFF”, the electronic control unit activates the engaging means  3  for the work tool clamping device, so that the work tool clamping device is kept in an engaged state. 
         [0023]      FIG. 3  is a flow chat of an embodiment of the control method for quick change device of a work tool according to the present invention. In step S 00  the method is started and turned to step S 01 , in which the electronic control unit  1  detects the signal from the quick change operation member  2 , i.e. receives a command to disengage the work tool clamping device and determines whether the user wants to change the work tool. 
         [0024]    The method is terminated if the determination in step S 01  is negative, i.e. the quick change operation member  2  is “OFF”. If the determination in step S 01  is positive, i.e. the quick change operation member  2  is switched “ON”, step S 02  starts. 
         [0025]    In step S 02 , it is determined whether the work tool clamping device is in an engaged state. If the determination is negative in step S 02 , i.e. the work tool clamping device is already disengaged, the method is terminated and turned to a further work tool change procedure. If the determination is positive in step S 02 , i.e. the work tool clamping device is in an engaged state, step S 03  starts. 
         [0026]    In step S 03  it is determined whether the disengagement alarm functions properly. The detection of the functionality of the disengagement alarm includes detection of a short circuit to the grounding and/or a short circuit to the power and/or an open circuit for the disengagement alarm. 
         [0027]    If the determination in step S 03  is positive, i.e. the disengagement alarm well functions, the method is terminated and a further work tool change procedure is started. If the determination of Step S 03  is negative, i.e. the disengagement alarm fails, step S 04  is started. 
         [0028]    In step S 04 , the work tool clamping device is prevented from being disengaged by the electronic control unit  1 , so that the work tool can not be changed by operating the quick change device. The engaging means  3  for the work tool clamping device is kept in an engaged state and/or disengaging means  4  for the work tool clamping device is deactivated. The method is then terminated. 
         [0029]    In this way, a so-called “emergency state” is initiated at the failure of the disengagement alarm, so that the work tool clamping device is kept in an engaged state and hence danger caused by disengagement of the work tool clamping device is avoided and the safety performance of the apparatus is improved. 
         [0030]    Depending on the configuration of the work tool clamping device, “preventing the work tool clamping device from being disengaged” may include any control means, for example hydraulically or electromechanically, acting on the control line of the work tool clamping device. In particular, said control means may include controlling the engaging means  3  for the work tool clamping device and/or the disengaging means  4  for the work tool clamping device. 
         [0031]      FIG. 4  shows a flow chat of another embodiment of the control method for the quick change device of the work tool according to the present invention. This embodiment is different from the embodiment of  FIG. 3  only in the presence of step S 05 , in which the operator is warned of the failure of the disengagement alarm. 
         [0032]    The present invention further includes such technical solutions, in which only a warning is triggered to inform the operator of the failure of the disengagement alarm while the step of “preventing the work tool clamping device from being disengaged” is not carried out. 
         [0033]    To sum up, the so-called “emergency state” is activated by preventing the work tool clamping device from being disengaged or by triggering an alarm at the failure of the disengagement alarm, so that danger caused by accidental disengagement of the work tool can be avoided.