Abstract:
The present invention locates the gravity of a handiwork instrument at the front part by deposing a rotation device right after a tool of the instrument, so that its size is reduced, its operation becomes easier, and its handling is firmed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a handiwork instrument; more particularly, relates to locating a gravity of a whole handiwork instrument at a front part of a handle unit to obtain a reduced size, an easy actuation and a firm holding.  
       DESCRIPTION OF THE RELATED ART  
       [0002]     A prior art, “A handiwork instrument with a handle”, is proclaimed in Taiwan, as shown in  FIG. 10 , comprising a handle  7  and a cover  8 , where the handle  7  has an axial line. The handle  7  comprises at least a working member  71  for fastening a tool  72 ; a handle pivot  73  having a revolving axis perpendicular to the axial line for movably pivoting the cover  8 ; and, at least a containing space  74  at a side of the handle  7  for possessing a room to keep tools  72 . The cover  8  comprises an inner surface  81 , an outer surface  82  and a cover pivot  83 , where the cover pivot  83  of the cover  8  and the handle pivot  73  of the handle  7  are pivoted for the cover  8  to turn between a first position and a second position. When the cover  8  is positioned at the first position, the inner surface  81  has an angle of about 90 degrees to the handle  7 ; and, when the cover  2  is positioned at the second position, the inner surface  81  is roughly cover the containing space  74  of the handle  7  along the axial line. By the above structure, the handiwork instrument obtains a firm handling and a light weight.  
         [0003]     Although the above priro art obtains a firm handling and a light weight, the shape and the size of the priro art depends on the motor size for the motor of the handiwork instrument (not shown in the figure) is usually deposed in the handle  7 . Yet, the size of the handle  7  becomes bigger if the size of the motor is bigger, so that, because the handle  7  is designed according to the size of the motor, the handle  7  for the handiwork instrument is bigger and is not conformed to the human-factors engineering. In another hand, the gravity of the handiwork instrument is located at the middle of the handle  7 ; because the tool  72  is deposed at an end of the handiwork instrument and so the gravity for the operation is not focused on the tool  72 , a user has to hold the handiwork instrument at the center of the handle  7  and, at the same time, to add a pressing force to the tool  72  at the end of the handle. In addition, the motor is a general coil sensing motor so that it may be often over-heated with its lifetime shortened. Hence, the prior art does not fulfill users&#39; requests on actual use.  
       SUMMARY OF THE INVENTION  
       [0004]     The main purpose of the present invention is to depose a transmission unit at an end of a handle unit so that a gravity of a handiwork instrument is located at a front part of the handle unit to obtain a reduced size, an easy actuation and a firm holding.  
         [0005]     To achieve the above purpose, the present invention is a handiwork instrument using a coreless brushless motor, comprising a handle unit, a transmission device, a sensing unit and a chuck seat, where the transmission device is deposed at an end of the handle unit; the handle unit has a shell; the shell has an axle movably deposed at center; the axle is deposed with a coreless wired stator; the coreless wired stator is connected with a power supply unit to obtain an outside power; the shell has two collar plates inside corresponding to two end surfaces of the coreless wired stator; at lease a collar plate is deposed with a permanent magnet corresponding to the coreless wired stator; a sensing unit senses a pole of the core less wired stator corresponding to that of the permanent magnet; the chuck seat is connected with the axle; and the chuck seat is deposed with a working unit. Accordingly, a novel handiwork instrument using a coreless brushless motor is obtained.  
     
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0006]     The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in conjunction with the accompanying drawings, in which  
         [0007]      FIG. 1  is a perspective view showing a preferred embodiment according to the present invention;  
         [0008]      FIG. 2  is an explosive view showing the preferred embodiment according to the present invention;  
         [0009]      FIG. 3  is a cross-sectional view showing a transmission device of the preferred embodiment according to the present invention;  
         [0010]      FIG. 4  is a view showing a sensing unit utilizing CEMF according to the preferred embodiment of the present invention;  
         [0011]      FIG. 5  is a view showing a first handle unit according to the preferred embodiment of the present invention;  
         [0012]      FIG. 6  is a view showing a second handle unit according to the preferred embodiment of the present invention;  
         [0013]      FIG. 7  is a view showing a third handle unit according to the preferred embodiment of the present invention;  
         [0014]      FIG. 8  is a view showing an open loop according to the preferred embodiment of the present invention;  
         [0015]      FIG. 9  is a view showing a close loop according to the preferred embodiment of the present invention; and  
         [0016]      FIG. 10  is a perspective view of a prior art. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     The following description of the preferred embodiment is provided to understand the features and the structures of the present invention.  
         [0018]     Please refer to  FIG. 1  through  FIG. 4 , which are a perspective view and an explosive view showing a preferred embodiment, a cross-sectional view showing a transmission device of the preferred embodiment and a view showing a sensing unit utilizing counter-electromotive force (CEMF), according to the present invention. As shown in the figures, the present invention is a handiwork instrument using a coreless brushless motor, comprising a handle unit  1 , a transmission device  2 , a sensing unit  3  and a chuck seat  4 , where a gravity of the whole handiwork instrument is located at the front part of the handle unit  1  so that a reduced size, an easy actuation and a firm holding are obtained.  
         [0019]     The handle unit  1  is fabricated utilizing human-factors engineering, where the handle unit  1  is cylinder shaped with a concaves part  11  on the surface utilizing human-factors engineering.  
         [0020]     The transmission device  2  is deposed at the front end of the handle unit  1 ; the transmission device  2  has a shell  21  connecting to the handle unit  1 ; the shell  21  has an axle  22  movably deposed at the center; the axle  22  is deposed with a coreless wired stator  23 ; the coreless wired stator  23  connects to a power supply unit  24  to obtain an outside power; the power supply unit  24  connects to an on/off switch  241  deposed at a proper place of the handle unit  1 ; the shell  21  has two collar plates  25  inside corresponding to two end surfaces of the coreless wired stator  23 ; and, at least one collar plate  25  is deposed with a permanent magnet  26  corresponding to the coreless wired stator  23 .  
         [0021]     The sensing unit  3  senses a pole of the coreless wired stator  23  corresponding to that of the permanent magnet  26 . The sensing unit  3  is a Hall element deposed on the coreless wired stator  23 , or at a place corresponding to the coreless wired stator  23  in the shell  2 . The sensing unit  3  is connected with an inverter  5  deposed in the handle unit  1  to obtain the pole of the coreless wired stator  23  to control the phase change of the coreless wired stator  23 . Besides, the sensing unit  3   a  processes a phase change of the coreless wired stator  23  according to a CEMF of a coil of the coreless wired stator  23 , as shown in  FIG. 4 ; and, the inverter  5  has a detecting unit  51  inside to receive the CEMF.  
         [0022]     The chuck seat  4  is connected with the axle  22  of the transmission device  2 ; and, the chuck seat  4  is deposed with a working unit  41 . Hence, with the above structure, a novel handiwork instrument using a coreless brushless motor is obtained.  
         [0023]     When using the present invention, the chuck seat  4  is deposed with a required working unit  41 , such as a drill, a polisher or a locking tool; the transmission device  2  is supplied with an outside power by the power supply unit  2 ; the on/off switch  241  on the handle unit  1  is switched on to contineously process phase changes of the coreless wired stator  23  by the sensing unit  3  to obtain repulsive phases to the permanent magnet  26 ; as a result, the axle  22  of the transmission device  2  keeps rotating and so the working unit  41  deposed on the chuck seat  4  rotates too for a user to do a required work. Because the transmission device  2  is fixed to the handle unit  1 , the gravity of the whole handiwork instrument is located at front part of the handle unit so that a down-pressing force is obtained at the working unit  41  of the chuck seat  4  for an easy actuation.  
         [0024]     Please refer to  FIG. 5  till  FIG. 7 , which are a view showing a first, a second and a third handle units according to the preferred embodiment of the present invention. As shown in the figures, the handle unit  1  of the present invention is fabricated according to human-factors engineering; and, besides being cylinder shaped, the handle unit  1   a  can be ‘L’ shaped. The handle unit  1   b  can be cylinder shaped with a cross handle  12  at an end; or the handle unit  1   c  can be cylinder shaped with a grasp handle  13  at a side. And, the human-factors engineering is realized to the various handle units  1   a,    1   b,    1   c.    
         [0025]     Please refer to  FIG. 8 , which is a view showing an open loop according to the preferred embodiment of the present invention. As shown in the figure, when using the present invention, a control unit  63  is deposed on a handle unit  1  according to requirements. The control unit  63  comprises a plurality of switches  61  to control the rotation speed of a transmission device  2  with setup values for the rotation speed, such as speeds of 300 revolutions per minute (rpm), 600 rpm and 1200 rpm, where an open loop control is formed by the transmission device  2 , an inverter  5  and a control unit  6 . When operating, the user turns on a required tachometer  62  to form a loop with the transmission device  2 , the inverter  5  and the tachometer  62  so that the transmission device  2  reaches the required speed according to the setup value of speed for the required tachometer  62  the user turns on. In this way, the rotation speed of the working unit  41  deposed on the chuck seat can be switched.  
         [0026]     Please refer to  FIG. 9 , which is a view showing a close loop according to the preferred embodiment of the present invention. As shown in the figure, in addition to the open loop control formed as shown in  FIG. 8 , a control unit  63  can comprise a tachometer  62  connected with an axle  22  of a transmission device  2 , and a differential amplifier  63  connected to the tachometer  62  and an inverter  5 , so that a close loop control is formed by the transmission device  2 , the inverter  5  and the control unit  6 . When operating, a value for rotation speed is setup in the differential amplifier  63 . As the transmission device  2  is turned on and powered, it is rotated in a speed according to the setup value. According to the rotation speed of the transmission device  2  reported promptly and continuously to the differential amplifier  63  in the feedbacks of the tachometer  62 , the differential of rotation speed to the setup rotation speed is analyzed. If the differential amount is getting smaller, the commutation speed is turned smaller by the inverter  5  so that the rotation speed can reach the setup value. On the contrary, if the differential amount is getting bigger, the commutation speed is turned greater by the inverter  5  so that the rotation speed can reach the setup value. By doing so, the working unit  41  deposed on the chuck seat  4  is rotated at a fixed rotation speed.  
         [0027]     To sum up, the present invention is a handiwork instrument using a coreless brushless motor, where a transmission device is deposed at an end of a handle unit utilizing human-factors engineering so that a gravity of the whole handiwork instrument is located at a front part of the handle unit to obtain a reduced size, an easy actuation, a firm holding, and, furthermore, a stability in use.  
         [0028]     The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.