Abstract:
A transmission for a motor, which gives a normal rotation and constant speed output to an output cover when a driving shaft of the motor rotates in a normal direction and a normal rotation and speed-changed output to the output cover when the driving shaft of the motor rotates in a reverse direction, is provided. Interference caused by a reverse input can be prevented although rotation is reversely input from the output cover. The driving shaft includes a polygonal outer circumference; a ball-mounting ring is coupled to the outer circumference, the ball-mounting ring including, therein a constant speed ball and a speed changing ball spaced apart from each other by a predetermined distance so that upper and lower sides of them protrude; and the ball-mounting ring is frictionally fixed by an additionally fixed friction pin.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a speed controller for motor, and more particularly, to a speed controller for motor preventing interference from reverse input, which is configured to rotate only in one direction when being driven in normal and reverse directions and has a function of preventing interference caused by a reverse input to prevent a shut-down of the operation of the speed controller by dispersing the reverse input and receiving only one direction input when rotating force is reversely input from an output side. 
     2. Description of the Related Art 
     Generally, a rotation device, such as a carrier or industrial machine, obtains driving force from a motor. In this case, the rotating force output from the motor may be transferred through an additional transmission. In other cases, a transmission may be provided in the motor itself so that the rotating force may be output directly or through an additional transmission. 
     In a case where a transmission is provided in a motor itself, two pawls  11  and  12  are generally mounted to a driving shaft  10  as shown in  FIG. 1  so that any one pawl (constant speed pawl)  11  is directly restricted to an output unit  20  and the other pawl (speed changing pawl)  12  is restricted to the output unit  20  via a speed changing means. 
     More specifically, the constant speed pawl  11  bent clockwise is mounted to one side of the outer circumference of the driving shaft  10 , and the constant speed pawl  11  is directly restricted at a portion  20   a  to the output unit  20 . Also, the speed changing pawl  12  bent counterclockwise is mounted to the other side of the outer circumference of the driving shaft  10 , and the speed changing pawl  12  is restricted at a portion  30   a  to a sun gear  30 . Then, the sun gear  30  is engaged with a planetary gear  40 , and the planetary gear  40  is engaged with the output unit  20 . 
     Thus, if the driving shaft  10  of the motor (not shown) rotates in a normal direction, the constant speed pawl  11  is restricted to the output unit  20  to give a normal direction output, while if the driving shaft  10  rotates in a reverse direction, the speed changing pawl  12  is restricted to a speed changing means to give a speed-changed normal direction output to the output unit  20 . 
     However, if the driving shaft  10  does not rotate in the transmission for a motor and rotation is reversely input from the output unit  20  by external force, the output unit  20  is rotated counterclockwise, so that the output unit  20  and the constant speed pawl  11  are restricted to each other first. Also, the output unit  20  rotating counterclockwise makes the planetary gear  40  rotate clockwise, the planetary gear  40  rotates the sun gear  30  counterclockwise, and then, the sun gear  30  is restricted to the speed changing pawl  12 . 
     Thus, when the output unit  20  rotates counterclockwise, the constant speed pawl  11  and the speed changing pawl  12  are all restricted, so that the transmission does not work. 
     SUMMARY OF THE INVENTION 
     The present invention is conceived to solve the aforementioned problems. An object of the present invention is to provide a speed controller for motor preventing interference from reverse input, wherein when pawls are coupled to a driving shaft, any one of the two pawls is not restricted even in any position so that the two pawls do not interfere with each other although a reverse input is made. 
     The present invention for achieving the objects provides a speed controller for motor preventing interference from reverse input, which gives a normal rotation and constant speed output to an output cover when a driving shaft of the motor rotates in a normal direction and a normal rotation and speed-changed output to the output cover when the driving shaft of the motor rotates in a reverse direction, wherein a key is formed to protrude on an outer circumference of the driving shaft; a pawl-mounting ring having a key groove with a greater width than the key is coupled to the key; a constant speed pawl and a speed changing pawl having opposite directions are mounted to the pawl-mounting ring so that lower portions of them extend to the key groove; and the pawl-mounting ring is frictionally fixed by an additionally fixed friction pin, whereby at least one of the constant speed pawl and the speed changing pawl is made lie down by the key according to a rotation direction of the driving shaft. 
     Also, the present invention provides a speed controller for motor preventing interference from reverse input, which gives a normal rotation and constant speed output to an output cover when a driving shaft of the motor rotates in a normal direction and a normal rotation and speed-changed output to the output cover when the driving shaft of the motor rotates in a reverse direction, wherein the driving shaft has a polygonal outer circumference; a ball-mounting ring is coupled to the outer circumference, the ball-mounting ring including therein a constant speed ball and a speed changing ball spaced apart from each other by a predetermined distance so that upper and lower sides of them protrude; and the ball-mounting ring is frictionally fixed by an additionally fixed friction pin, whereby at least one of the constant speed ball and the speed changing ball escapes from the outer circumference according to a rotation direction of the driving shaft. 
     Here, the outer circumference may have a side with a concavely curved shape. 
     Further, the outer circumference may have a side with a concavely angled shape. 
     Furthermore, the outer circumference may have a side with a wave shape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a transmission for a motor which gives a constant speed output and a speed-changed output in one direction; 
         FIG. 2  is a sectional view showing a speed controller for motor preventing interference from reverse input according to a first embodiment of the present invention; 
         FIG. 3  is a side view showing a pawl-mounting ring of  FIG. 2 ; 
         FIG. 4  is a sectional view showing another example wherein a friction pin shown in  FIG. 2  is mounted; 
         FIGS. 5 and 6  are side views illustrating the operation of the pawl-mounting ring of  FIG. 2 ; 
         FIG. 7  is a sectional view showing a speed controller for motor preventing interference from reverse input according to a second embodiment of the present invention; 
         FIG. 8  is a side view showing a ball-mounting ring of  FIG. 7 ; 
         FIG. 9  is a sectional view showing another example wherein a friction pin shown in  FIG. 7  is mounted; 
         FIGS. 10 and 11  are side views illustrating the operation of the ball-mounting ring of  FIG. 7 ; and 
         FIGS. 12 ,  13  and  14  are views of modifications of the polygonal outer circumference of a driving shaft shown in  FIG. 8 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, preferred embodiments of a speed controller for motor preventing interference from reverse input according to the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 2  is a sectional view showing a speed controller for motor preventing interference from reverse input according to a first embodiment of the present invention,  FIG. 3  is a side view showing a major portion of a pawl-mounting ring of  FIG. 2 , and  FIG. 4  is a sectional view showing another example wherein a friction pin shown in  FIG. 2  is mounted. 
     Referring to  FIGS. 2 and 3 , a speed controller  100  for motor preventing interference from reverse input according to the first embodiment of the present invention includes a driving shaft  10  rotating in normal and reverse directions, a pawl-mounting ring  15  surrounding an outer circumference of the driving shaft  10 , a constant speed pawl  11  and a speed changing pawl  12  coupled to the pawl-mounting ring  15 , an output cover  20  restricted at a portion  20   a  to the constant speed pawl  11 , a sun gear  30  restricted at a portion  30   a  to the speed changing pawl  12 , a planetary gear  40  engaged with the sun gear  30  at its inner side and the output cover  20  at its outer side, and a friction pin  60  for giving frictional force to the pawl-mounting ring  15 . 
     First, the driving shaft  10  and the pawl-mounting ring  15  transmit rotation through a key  10   a  formed on the outer circumference of the driving shaft  10  and a key groove  15   a  formed on an inner side of the pawl-mounting ring  15 . The key groove  15   a  is designed to have a greater width than the key  10   a.    
     Also, the constant speed pawl  11  and the speed changing pawl  12  mounted to the pawl-mounting ring  15  and having opposite directions are elastically supported by a spring (not shown) to always erect. In addition, lower portions of the constant speed pawl  11  and the speed changing pawl  12  extend to protrude toward the key groove  15   a . An end of the key  10   a  is positioned between the constant speed pawl  11  and the speed changing pawl  12 , which are mounted to cross each other, as shown in  FIG. 3 , so that the key  10   a  serves to make the constant speed pawl  11  and the speed changing pawl  12  erect or lie down. 
     The pawl-mounting ring  15  formed as described above is rotated just by means of the key  10   a  and the key groove  15   a  and is frictionally fixed by means of a friction pin  60  in order not to return or run idle. 
     That is, the friction pin  60  is mounted to the rotating sun gear  30  or the output cover  20  as shown in  FIG. 2  to press the outer circumference of the pawl-mounting ring  15 . Alternatively, the friction pin  60  may be configured such that it is mounted to a fixed frame  50  of the speed controller  100  for a motor as shown in  FIG. 4  to press the outer circumference of the pawl-mounting ring  15 . 
       FIGS. 5 and 6  are side views illustrating the operation of the speed controller for motor preventing interference from reverse input according to the first embodiment of the present invention. 
     When the driving shaft  10  stops while rotating in the normal direction, the speed controller  100  preventing interference from reverse input according to the first embodiment of the present invention erects only the constant speed pawl  11  and makes the speed changing pawl  12  lie down as shown in  FIG. 3 . Thus, in such a state, if rotation is reversely transferred from the output cover  20  counterclockwise, the output cover  20  transmits the reverse rotation toward both of the constant speed pawl  11  and the planetary gear  40 . 
     First, the rotation reversely input from the output cover  20  toward the constant speed pawl  11  is restricted at the portion  20   a  to the constant speed pawl  11  while rotating counterclockwise, and the pawl-mounting ring  15  rotates counterclockwise by the rotation of the constant speed pawl  11 . Also, the pawl-mounting ring  15  rotates the driving shaft  10  in the reverse direction by means of the key groove  15   a  and the key  10   a.    
     Then, the rotation reversely input from the output cover  20  toward the planetary gear  40  rotates counterclockwise and makes the planetary gear  40  rotate clockwise, and the planetary gear  40  rotates the sun gear  30  counterclockwise. Also, the sun gear  30  rotating counterclockwise is not restricted at the portion  30   a  to the speed changing pawl  12  but runs idle, thereby not transmitting the reversely input rotation toward the driving shaft  10 . 
     Meanwhile, when the driving shaft  10  stops while rotating in the reverse direction, the speed controller  100  for a motor makes the constant speed pawl  11  lie down and erects the speed changing pawl  12  as shown in  FIG. 5 . Also, if the driving shaft  10  stops intermediately while rotating in either the normal direction or the reverse direction, both of the constant speed pawl  11  and the speed changing pawl  12  are made lie down. 
     Thus, in the speed controller  100  for a motor according to the first embodiment of the present invention, one or both of the constant speed pawl and the speed changing pawl are made lie down in any state, even when rotation is reversely input from the outside. 
     Hereinafter, a speed controller for motor preventing interference from reverse input according to a second embodiment of the present invention will be described. 
       FIG. 7  is a sectional view showing a speed controller for motor preventing interference from reverse input according to the second embodiment of the present invention,  FIG. 8  is a side view showing a major portion of a ball-mounting ring of  FIG. 7 , and  FIG. 9  is a sectional view showing another example wherein a friction pin shown in  FIG. 7  is mounted. 
     Referring to  FIGS. 7 and 8 , the speed controller  200  for motor preventing interference from reverse input according to the second embodiment of the present invention includes a driving shaft  10  rotating in normal and reverse directions, a ball-mounting ring  16  surrounding an outer circumference of the driving shaft  10 , constant speed balls  13  and speed changing balls  14  coupled to the ball-mounting ring  16 , an output cover  20  restricted at a portion  20   a  to the constant speed balls  13 , a sun gear  30  restricted at a portion  30   a  to the speed changing balls  14 , a planetary gear  40  engaged with the sun gear  30  at its inner side and the output cover  20  at its outer side, and a friction pin  60  for giving a frictional force to the ball-mounting ring  16 . 
     First, the rotation is transmitted from the driving shaft  10  to the output cover  20  and the sun gear  30  by means of the ball-mounting ring  16  surrounding the driving shaft  10  and the constant speed balls  13  and the speed changing balls  14  mounted to the ball-mounting ring  16 . 
     The speed controller  200  for motor preventing interference from reverse input according to the second embodiment of the present invention transmits rotation in such a manner that the driving shaft  10  surrounded by the ball-mounting ring  16  is formed to have a polygonal outer circumference  10   b  and the constant speed balls  13  and the speed changing balls  14  are caught between the upper restriction portions  20   a  and  30   a  and the polygonal outer circumference  10   b.    
     Thus, the constant speed balls  13  and speed changing balls  14  of the same in number as sides of the polygonal outer circumference  10   b  are mounted to the ball-mounting ring  16  such that their upper and lower sides partially protrude to the outside. The constant speed ball  13  and the speed changing ball  14  are mounted not coaxially but adjacently. Preferably, a distance between the constant speed ball  13  and the speed changing ball  14  adjacent to each other is smaller than a length of one side of the polygonal outer circumference  10   b , and the constant speed ball  13  and the speed changing ball  14  are designed to be spaced apart from the restriction portions  20   a  and  30   a  when being located at the center of the side of the outer circumference  10   b.    
     Also, a friction pin  60  is mounted to the ball-mounting ring  16  to give friction force thereto such that it does not run idle, as in the first embodiment. The friction pin  60  may be fixed to the rotating sun gear  30  and the output cover  20  or may be fixed to the fixed frame  50 . 
       FIGS. 10 and 11  are side views illustrating the operation of the speed controller for motor preventing interference from reverse input according to the second embodiment of the present invention. 
     In the speed controller  200  for motor preventing interference from reverse input according to the second embodiment of the present invention, when the driving shaft  10  stops while rotating in the normal direction, the constant speed ball  13  adjacent to a vertex of the outer circumference  10   b  of the driving shaft  10  is caught to be restricted at the portion  20   a  to the output cover  20  as shown in  FIG. 8 . Also, the speed changing ball  14  is located at the center of the side of the outer circumference  10   b  of the driving shaft  10  to become free. 
     In such a state, if rotation is reversely transferred from the outer cover  20  counterclockwise, the output cover  20  reversely transmits rotation toward the constant speed ball  11  and the planetary gear  40 . 
     First, the rotation reversely input from the output cover  20  to the constant speed ball  13  is restricted at the portion  20   a  to the constant speed ball  13  while rotating counterclockwise, and the restricted constant speed ball  13  is rotated counterclockwise together with the ball-mounting ring  16  and the driving shaft  10 . 
     Then, the rotation reversely input from the output cover  20  toward the planetary gear  40  rotates counterclockwise and makes the planetary gear  40  rotate clockwise, and the planetary gear  40  rotates the sun gear  30  counterclockwise. Also, the sun gear  30  rotating counterclockwise is not restricted at the portion  30   a  to the speed changing ball  14  but runs idle, thereby not transferring the reversely input rotation toward the driving shaft  10 . 
     Meanwhile, in the speed controller  200  for a motor, when the driving shaft  10  stops while rotating in the reverse direction, the speed changing ball  14  is caught to be restricted as shown in  FIG. 10 , and the constant speed ball  13  becomes free. Also, if the driving shaft  10  stops intermediately while rotating in either the normal direction or the reverse direction, both of the constant speed ball  13  and the speed changing ball  14  become free. 
     Thus, in the speed controller  200  for a motor according to the second embodiment of the present invention, one or both of the constant speed ball  13  and the speed changing ball  14  become free in any state, even when rotation is reversely input from the outside. 
       FIGS. 12 to 14  are views showing modifications of the outer circumference of the driving shaft in the speed controller for motor preventing interference from reverse input according to the second embodiment of the present invention. 
     That is, in the speed controller  200  for motor preventing interference from reverse input according to the second embodiment of the present invention, the driving shaft  10  basically has a polygonal outer circumference  10   b , but the polygonal outer circumference  10   b  may have concave sides as shown in  FIG. 12 . Alternatively, the polygonal outer circumference  10   b  may have concavely angled sides as shown in  FIG. 13 . Moreover, the polygonal outer circumference  10   b  may also have wave-shaped sides as shown in  FIG. 14 . 
     As mentioned above, the speed controller for motor preventing interference from reverse input according to the present invention is configured such that at least one of two pawls is not restricted, thereby preventing a shut-down of the operation of the speed controller although rotation is reversely input from an output side. 
     Although the present invention has been described in connection with the preferred embodiments, it will be understood by those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the invention defined by the appended claims.