Abstract:
A motor drive system enabling detection of cutting fluid deposited at a housing of electronic components. A housing holding electronic components of a motor drive system has top faces slanted with respect to the horizontal plane so as to guide the deposited cutting fluid. The housing further includes storage parts collecting the cutting fluid guided along the top faces. The storage parts may be graduated so as to enable the collected amount of the cutting fluid to be measured. The storage parts may be configured to be detachable from the housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a housing holding electronic components and a motor drive system including that housing. 
         [0003]    2. Description of the Related Art 
         [0004]    A motor drive system for driving a machine tool is used in an environment in which dust, cutting fluid, and other foreign matter fills the air. The electronic components forming the motor drive system are housed in a control panel having the form of a locker and are protected from that foreign matter. However, in actuality, it is difficult to completely prevent foreign matter from entering the inside of the control panel. 
         [0005]    If foreign matter sticks to the electronic components inside of the control panel, over the years, it will cause the electronic components to corrode and can cause the motor drive system to malfunction. Therefore, proposals have been made to prevent deposition of foreign matter or identify deposition of foreign matter early. 
         [0006]    Japanese Patent Publication No. 2006-019405A discloses a printed circuit board including a circuit for detecting deterioration or malfunction of the printed circuit board occurring due to foreign matter, for example, dust or cutting fluid, deposited on the printed circuit board. 
         [0007]    According to the related art, to prevent foreign matter from depositing on electronic components, a mechanism has been provided for guiding cutting fluid away from the housing of the electronic components or the electronic components have been arranged at locations resistant to deposition of cutting fluid. Alternatively, to prevent cutting fluid from filling the air, it has been proposed not to use a fan motor for cooling use. 
       SUMMARY OF THE INVENTION 
       [0008]    According to the above-mentioned related art for protecting electronic components by a housing including a guide mechanism, an effect of prevention of deposition of cutting fluid can be expected to a certain extent. However, the cutting fluid moved away from the housing due to the guide mechanism drips down to the location where the motor drive system is installed, so it is difficult to obtain a grasp of the amount of cutting fluid entering the inside of the control panel. Therefore, a motor drive system designed to detect cutting fluid entering the inside of the control panel and prompt preventative measures to be taken before malfunctions of the motor drive system occur has been sought. 
         [0009]    According to the present invention, there is provided a housing holding electronic components of a motor drive system for driving a machine tool, the housing including at least one guide part for guiding cutting fluid at a surface of the housing and at least one storage part for collecting cutting fluid guided by the guide part. 
         [0010]    In a preferred embodiment, the surface is slanted with respect to a horizontal plane, and the at least one guide part is configured to guide the cutting fluid by the action of gravity. 
         [0011]    In a preferred embodiment, in the housing, at least one storage part is given graduations so as to enable measurement of the cutting fluid collected at that storage part. 
         [0012]    In a preferred embodiment, in the housing, the at least one storage part can be detached from the housing. 
         [0013]    In a preferred embodiment, the housing is provided with pluralities of the guide parts and the storage parts. 
         [0014]    In a preferred embodiment, there is provided a motor drive system comprising the above housing, an electronic component held in the housing, and a detecting part detecting the amount of cutting fluid collected at the at least one storage part. 
         [0015]    In a preferred embodiment, the motor drive system further comprises an alarm part issuing an alarm signal when the amount of the cutting fluid stored at the at least one storage part exceeds a predetermined threshold value. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    These and other objects, features, and advantages of the present invention will become clearer by referring to the detailed description of illustrative embodiments of the present invention shown in the drawings. 
           [0017]      FIG. 1  is a conceptual view of a motor drive system. 
           [0018]      FIG. 2  is a perspective view of a housing holding electronic components of a motor drive apparatus according to one embodiment. 
           [0019]      FIG. 3  is a cross-sectional view of the housing of  FIG. 2  cut along the plane passing through the lines III,III′. 
           [0020]      FIG. 4  is a view showing a housing according to another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Below, embodiments of the present invention will be explained with reference to the attached drawings. The component elements in the illustrated embodiments are suitably changed in scale for assisting understanding of the present invention. Further, the same or corresponding component elements use the same reference notations. 
         [0022]      FIG. 1  is a conceptual view showing a motor drive system  10 . The motor drive system  10  includes a plurality of electronic components  14 . The electronic components  14  include printed circuit boards and components mounted on the printed circuit boards and any other components. The electronic components  14  are housed in a control panel  12  having the form of a locker. The control panel  12  has an openable door and is configured to become accessible from the outside as needed. The control panel  12  forms an inside space generally sealed in the state where the door is closed. 
         [0023]    The motor drive system  10  controls motors (not shown) used for driving shafts of a machine tool. When using a machine tool for machining work, a cutting fluid is used for the purposes of suppressing wear and cooling. The motor drive system  10  is used in an environment in which not only cutting fluid but also chips generated from the workpiece etc. fill the air. As explained above, the control panel  12  forms a sealed inside space, but cutting fluid sometimes enters the inside space from clearances at the door etc. 
         [0024]    Therefore, the motor drive system  10  according to the present embodiment is configured to include a housing  20  for holding the electronic components  14  and preventing cutting fluid, dust, and other foreign matter from depositing on the electronic components  14 . 
         [0025]    Referring to  FIG. 2  and  FIG. 3 , the housing  20  for holding the electronic components  14  of the motor drive system  10  will be explained.  FIG. 2  is a perspective view showing the housing  20 , while  FIG. 3  is a cross-sectional view of the housing  20  of  FIG. 2  cut along the plane extending in the vertical direction passing through the line III and the line III′. 
         [0026]    The housing  20  has a hollow body  22  having a generally box shape. The body  22  has a rectangular bottom  22   a , side walls  22   b  extending upward in the vertical direction from the bottom  22   a , and a top  22   c  closing an upwardly facing opening formed by the side walls  22   b.    
         [0027]    The top  22   c  has the shape of a four-sided pyramid extending upward. In other words, the faces of the top  22   c  are slanted so as to form predetermined angles with the horizontal plane. 
         [0028]    The top  22   c  includes four storage parts  26  along its circumference. The storage parts  26  are box-shaped containers open facing upward. As will be clearly understood if referring to  FIG. 3 , there are no step differences between the storage parts  26  and the top  22   c . These are connected to each other generally smoothly. 
         [0029]    According to the housing having the above-mentioned configuration, cutting fluid dripping down to the top  22   c  of the housing  20  moves downward along the faces of the top  22   c  due to the action of gravity (see arrows of  FIG. 3 ) and is collected at the storage parts  26 . The hatched locations in  FIG. 3  show the cutting fluid X in the storage parts  26 . 
         [0030]    In this way, according to the present embodiment, the slanted faces formed by the top  22   c  function as guide parts guiding the cutting fluid X to the storage parts  26 . Due to this, an operator can visually determine the amount of cutting fluid C collected at the storage parts  26 . Therefore, the operator can improve the air-tightness of the control panel  12  or change the location of installation of the motor drive system  10  as required to thereby take preventative measures to prevent trouble from occurring at the motor drive system  10 . 
         [0031]    Further, according to the motor drive system  10  according to the present embodiment, it is possible to prevent trouble in the motor drive system  10  due to deposition of the cutting fluid X, so it is possible to use a cooling fan motor. As a result, the freedom of thermal design is enhanced. 
         [0032]    Further, since the storage parts  26  are provided at the sides of the top  22   c  of the housing  20 , the operator can estimate the path of entry of cutting fluid X. Due to this, the operator can select effective measures for preventing the entry of cutting fluid X. 
         [0033]    In one embodiment, the storage parts  26  may be formed with graduations. In this case, the operator can read the graduations of the storage parts  26  to thereby quantitatively measure the amounts of cutting fluid X in the storage parts  26 . 
         [0034]    In one embodiment, the storage parts  26  may be configured to be detachable from the housing  20 . In that case, the operator can take out the storage parts  26  from the control panel  12 , discard the cutting fluid X, and wash the storage parts  26 , so the maintenance work becomes easy. Further, if a storage part  26  becomes damaged, it is possible to replace the storage part  26  at a low cost. 
         [0035]    In the illustrated embodiment, four storage parts  26  are included around the top  22   c . However, in another embodiment, three or less storage parts may also be formed. Alternatively, five or more storage parts may be formed. 
         [0036]    In another embodiment, the housing may have a conical shape. In still another embodiment, the guide parts for guiding the cutting fluid to the storage parts may be grooves formed in the surface of the housing and extending at a slant with respect to the horizontal plane. 
         [0037]      FIG. 4  shows a housing  20  according to another embodiment. In the present embodiment, the housing  20  is equipped with a weight detector  30 . Further, the electronic components  14  include a detecting part  32  and an alarm part  34 . 
         [0038]    The weight detector  30  is configured to detect the weights of the storage parts  26  and in turn the weight of the cutting fluid X in the storage parts  26 . 
         [0039]    The detecting part  32  is configured to find the amount of cutting fluid X collected at the storage parts  26  from the output value of the weight detector  30 . 
         [0040]    The alarm part  34  is configured to emit an alarm signal when the amount of the cutting fluid X found by the detecting part  32  exceeds a predetermined threshold value. The motor drive system  10  sends a warning to the operator through sound, light, etc. in response to an alarm signal. 
         [0041]    According to the present embodiment, an operator need not directly check the storage parts  26 . The operator can be alerted when the amount of cutting fluid X collected at the storage parts  26  exceeds a predetermined amount. The operator can take measures as required upon receiving the warning, so trouble in the motor drive system  10  can be prevented. 
         [0042]    In another embodiment, the motor drive system may be configured to use an optical detector instead of a weight detector  30  to obtain the amount of the cutting fluid X. 
         [0043]    Above, various embodiments of the present invention were explained, but a person skilled in the art would recognize that other embodiments as well may be used to realize the actions and effects intended by the present invention. In particular, the component elements of the embodiments explained above can be deleted or replaced without departing from the scope of the present invention and known means can be further added. Further, the fact that the features of the plurality of embodiments which are explicitly or implicitly disclosed in this specification can also be freely combined so as to work the present invention is self evident to a person skilled in the art. 
         [0044]    According to the housing and motor drive system including the housing according to the present invention, cutting fluid entering the inside of the control panel moves along the surface of the housing and is collected at the storage parts due to the action of the guide parts. Due to this, an operator can visually detect the entering cutting fluid and can be prompted to take preventative measures as required before trouble occurs at the motor drive system.