Abstract:
A flow control valve controls the flow rate of heated water supplied from a boiler. The valve can normally/reversely turn and control the flow rate in a pipeline using first and second one-way motors, and stops power for one motor when the other motor is rotated. The valve includes a motor assembly including the first and second motors that have power transmission shafts which rotate in opposite directions, a gear assembly including first and second planetary gears that receive power from the motors and a sun gear disposed between and engaged with the planetary gears, a clutch structure between the first planetary gear and motor, and the second planetary gear and motor, that transmits or stops power, and a valve actuator including a shaft that reciprocates up/down by rotation of the sun gear and a valve unit fitted on the lower portion of the shaft that opens/closes the valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a US National Stage Patent Application under 35 USC §371 of International Application No. PCT/KR2008/000260 filed Jan. 16, 2008, and claims priority of KR10-2007-0006244 filed Jan. 19, 2007. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a flow control valve, particularly a flow control valve that controls the flow rate of heated water that is supplied from a boiler, in a pipe line through which the heated water flows. 
     2. Background Art 
     In general, a boiler system is equipped with a water distributor that distributes heated water to each room that needs to be heated. The water distributor receives water heated by a heat exchanger of the boiler through a water supply pipe and then distributes the heated water to each room, and the heated water is cooled by transferring heat energy to the rooms and then delivered to an expansion tank through a return pipe. The water distributor is equipped with a flow control valve to control the flow rate of the heated water that is supplied to each room. 
     It is not economical to use a two-way motor, which can rotate normally and reversely, for the flow control valve to open/close a channel, because the two-way motor is expensive. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, there is provided a flow control valve that can normally/reversely turn and control the flow rate using two low-price, one-way motors. Further, according to another object of the invention, there is provided a flow control valve that can stop power for one of the two one-way motors while the other one-way motor rotates by applying a simple clutch structure to a gear assembly connected with the two one-way motors. 
     According to an aspect of one or more embodiments of the present invention, a flow control valve includes: a motor assembly including a first motor that has a first power transmission shaft and rotates in one direction and a second motor that has a second power transmission shaft and rotates in the opposite direction of the first motor; a gear assembly including a first planetary gear that receives power from the first motor, a second planetary gear that receives power from the second motor, and a sun gear that is disposed between the first planetary gear and the second planetary gear and engaged with the first and second planetary gears, and having a clutch structure between the first planetary gear and the first motor, and the second planetary gear and the second motor to transmit or stop power; and a valve actuator including a shaft that reciprocates up/down by rotation of the sun gear and a valve unit that is fitted on the lower portion of the shaft and opens/closes the valve. 
     A plurality of locking portions may protrude from the power transmission shaft of the first motor and the power transmission shaft of the second motor, respectively. Further, the power may be transmitted or stopped by engaging or disengaging the locking portions of the first and second power transmission shafts and continuous saw tooth-shaped protrusions formed on the upper sides of the first planetary gear and the second planetary gear, in the clutch structure of the gear assembly. 
     Elastic members may be disposed under the first planetary gear and the second planetary gear to elastically return the first planetary gear and the second planetary gear when the plurality of locking portions slip upward onto the protrusions. 
     A cam may be formed on the lower side of the sun gear. Further, the valve actuator may include a lower cam member that is in contact with the cam of the sun gear and reciprocates up/down by rotation of the sun gear, and an elastic member that elastically supports the lower side of the lower cam member. 
     The lower cam member may be guided by a guide member that protrudes upward inside the lower cam member, reciprocating with rotation of the sun gear. 
     As described above in detail, according to a flow control valve of an embodiment of the invention, since one-way motors are used and the clutch structure is provided, it is possible to achieve a simple-structured valve and reduce the price of the valve, compared to using a two-way motor. Further, since the contact surfaces of the sun gear and the lower cam member are formed in a cam shape, it is possible to control the flow rate by controlling the opening amount of the valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cross-sectional view of a flow control valve according to an embodiment of the invention; 
         FIG. 2  is a perspective view showing a gear assembly and a clutch member according to an embodiment of the invention; 
         FIG. 3  is a side view of  FIG. 2 ; 
         FIG. 4  is an exploded perspective view showing a valve actuator according to an embodiment of the invention; 
         FIG. 5  is a side view showing a lower cam member of  FIG. 4 ; 
         FIGS. 6A to 6C  are views illustrating the operation of planetary gears and locking portions of power transmission shafts according to an embodiment of the invention; and 
         FIGS. 7 and 8  are views illustrating that a valve is opened or closed according to an embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The configuration and operation according to preferred embodiments of the invention is described hereafter in detail with reference to the accompanying drawings. 
       FIG. 1  is a side cross-sectional view of a flow control valve according to an embodiment of the invention,  FIG. 2  is a perspective view showing a gear assembly and a clutch member according to an embodiment of the invention,  FIG. 3  is a side view of  FIG. 2 ,  FIG. 4  is an exploded perspective view showing a valve actuator according to an embodiment of the invention, and  FIG. 5  is a side view showing a lower cam member of  FIG. 4 . 
     Referring to  FIGS. 1-5 , a motor assembly  100  is comprised of a first motor  110  that rotates in one direction and a second motor  120  that is disposed opposite to the first motor  110  and rotates in the opposite direction of the first motor  110 . A low-price AC motor, for example, may be used for the first motor  110  and second motor  120 . Power transmission shafts  111 ,  121  protrude down from the first motor  110  and the second motor  120 , respectively, to transmit power from the motors to a gear assembly  200 . 
     A plurality of locking portions  111   a ,  121   a  protrude from the lower sides of the power transmission shafts  111 ,  121  and are locked to the top sides of a first planetary gear  210  and a second planetary gear  220  for an operation of a clutch including the plurality of locking portions  111   a ,  121   a  and saw tooth-shaped continuous protrusions  211 ,  221 , as further described below. 
     The gear assembly  200  is comprised of the first planetary gear  210  connected with the power transmission shaft  111  of the first motor  110  for power transmission, the second planetary gear  220  connected with the power transmission shaft  121  of the second motor  120  for power transmission, and a sun gear  230  located between and engaged with the first planetary gear  210  and the second planetary gear  220  to transmit rotational force of the motors to a valve actuator  300 . 
     The saw tooth-shaped continuous protrusions  211 ,  221  are formed on the top sides of the first planetary gear  210  and the second planetary gear  220  to engage or disengage the locking portions  111   a ,  121   a  of the power transmission shafts  111 ,  121  for the operation of the clutch. 
     Apexes  211   a ,  221   a  are formed at the top of the protrusions  211 ,  221  and bottoms  211   b ,  221   b  are formed at the lower side. The bottoms  211   b ,  221   b  have a predetermined width to seat the locking portions  111   a ,  121   a.    
     Slopes  211   c ,  221   c  having a predetermined angle are formed between the apexes  211   a ,  221   a  and the bottoms  211   b ,  221   b  and power that is received from the first and second motors  110 ,  120  is stopped by disengaging the locking portions  111   a ,  121   a  of the power transmission shafts  111 ,  121  when the first and second planetary gears  210 ,  220  are in rotation. 
     Further, vertical surfaces  211   d ,  221   d  are positioned opposite to the slopes  211   c ,  221   c  and lock the locking portions  111   a ,  121   a  when the first and second motors  110 ,  120  rotate, such that power is transmitted to the first planetary gear  210  and the second planetary gear  220 . 
     The lower sides of the first planetary gear  210  and the second planetary gear  220  are elastically supported by elastic members  240 , such as a spring. 
     The valve actuator  300  includes a shaft  330  reciprocating up/down by rotation of the sun gear  230  and a valve unit  350  fitted on the lower portion of the shaft  330  to open/close the valve. 
     A variety of structures are available to reciprocate the shaft  330  with rotation of the sun gear  230 , but according to this embodiment, the shaft  330  is reciprocated by the cam motion of a cam  231  formed on the lower side of the sun gear  230  and a lower cam member  310  of the valve actuator  300 . 
     In detail, the cam  231  protrudes in a predetermined length from the lower side of the sun gear  230 , and a cam contact surface  232  that is curved in a cam shape is formed along the circumference on the lower side of the cam  231 . The cam contact surface  232  has two top dead points  232   a , which are the uppermost points of an arc-shaped surface, and two bottom dead points  232   b , which are the lowermost points from the top dead points  232   a.    
     Further, a lower cam contact surface  311  is formed on the top side of the lower cam member  310 , taking the shape of the cam contact surface  232  of the cam  231 . The lower cam contact surface  311  has two top dead points  311   a  that are the uppermost points of an arc-shaped surface that is concave upward, and two bottom dead points  311   b  that are the lowermost points from the top dead points  311   a.    
     Therefore, the lower cam member  310  reciprocates up/down with rotation of the sun gear  230  by the above cam shape. 
     In the lower cam member  310 , four guide shaft insert holes  312  are formed at predetermined distances along the edge, and a shaft insert hole  313  is formed at the center. Further, the lower side of the lower cam member  310  is elastically supported by an elastic member  340 , such as a spring. According to the above configuration, the elastic member  340  applies elastic force upward to the lower side of the lower cam member  310 , such that it provides elastic return force, when the lower cam member  340 , which has moved down, moves up. 
     It is preferable for the lower cam member  310  reciprocating up/down to be guided by a guide member  320 . The guide member  320  has four guide shafts  321  that are inserted in the guide shaft insert holes  312  of the lower cam member  310 , a circular elastic member insert groove  322  where the elastic member  340  is inserted, the elastic member  340  being located inside from the guide shafts  321 , and a shaft-through hole  323  where the shaft  330  is inserted, the shaft-through hole  323  being located inside the elastic member insert groove  322 . Further, an O-ring insert groove  324  where an O-ring  381  is fitted is positioned on the circumference of the guide member  320  for airtight sealing. 
     The shaft  330  has E-ring insert grooves  330   a ,  330   c  at the upper and lower end portions, respectively, to insert E-rings  371 ,  372 , and an O-ring insert groove  330   b  at the middle portion to insert an O-ring  382  for airtight sealing. 
     Fitted on the lower portion of the shaft  330 , the valve unit  350  includes a packing support member  351  made of synthetic resin and a packing  352  that opens/closes the valve by contacting/separating with/from a valve seat  430   a . Rubber is preferably used for the packing  352 . 
     A body assembly  400  is disposed at the most outside in this embodiment. The body assembly  400  is composed of an upper cover  410  covering the upper side of the sun gear  230 , a gear-sided body  420  covering the sides of the first and second planetary gears  210 ,  220 , and a valve-sided body  430  covering the circumference of the valve actuator  300 . The valve-sided body  430  has an inlet  431  for the inflow of heated water and an outlet  432  for the outflow of the heated water passing through the valve unit  350 . 
     The operation of the flow control valve having the above configuration, such as a clutch, according to an embodiment of the invention is described hereafter. For the sake of convenience of description, it is assumed that the rotational direction of the first motor  110  is in the normal direction and the rotational direction of the second motor  120  is in the reverse direction. 
       FIGS. 6A to 6C  are views illustrating the operation of planetary gears and locking portions of power transmission shafts according to an embodiment of the invention. As shown in  FIG. 6A , as the first motor  110  rotates in the normal direction, the locking portions  111   a  of the power transmission shaft  111  are locked to the protrusions  211  of the first planetary gear  210  while rotating in the direction of an arrow, such that the first planetary gear  210  rotates in the same direction and power is transmitted to the sun gear  230 . 
     The power transmitted to the sun gear  230  is transmitted to the second planetary gear  220  engaged with the sun gear  230 . As shown in  FIGS. 6B and 6C , the second planetary gear  220  rotates in the direction of the arrow, but the locking portions  121   a  of the power transmission shaft  121  that are in contact with the bottoms  221   b  slip on the slope  221   c  toward the apexes  221   a . As a result, the power is not transmitted to the second motor  120  due to this operation, such as a clutch. The second planetary gear  220  that has been moved downward due to the slip of the locking portions  121   a  is returned by the elastic member  240  supporting the lower side. 
     Further, when the first motor  110  is stopped and the second motor  120  rotates in the reverse direction, the second planetary gear  210 , sun gear  230 , and first planetary gear  210  are rotated by transmitted power; however, when the first planetary gear  210  is in rotation, the locking portions  111   a  of the power transmission shaft  111  slip upward on the slope  211   c  of the protrusions  211  of the first planetary gear  210 . As a result, power is transmitted to the first motor  110  by this operation, such as a clutch. 
       FIGS. 7 and 8  are views illustrating that a valve opens and closes according to an embodiment of the invention. 
       FIG. 7  shows the valve closed. In detail, the bottom dead points  232   b  are positioned at both sides of the sun gear  230  and the top dead points  311   a  of the lower cam member  310  are in contact with the bottom dead points  232   b  of the sun gear  230 . Therefore, the lower cam member  310  is pushed down by the bottom dead points  232   b  of the sun gear  230 , such that the shaft  330  and the valve unit  350  are moved down, causing the packing  352  to contact with the valve seat  430   a  and closing the valve, in which the top dead points  232   a  of the sun gear  230  and the bottom dead points  311   b  of the lower cam member  310  are spaced apart. 
       FIG. 8  shows the valve open. In detail, as shown in  FIG. 7 , with the valve closed, when the first motor  110  or the second motor  120  is in rotation, the bottom dead points  232   b  of the sun gear  230  and the bottom dead points  311   b  of the lower cam member  310 , and the top dead points  232   a  of the sun gear  230  and the top dead points  311   da  of the lower cam member  310  are in contact with each other, respectively. Therefore, as the lower cam member  310  is pushed up by the elastic force of the elastic member  340 , the shaft  330  and the valve unit  350  are moved up and the packing  352  is separated from the valve seat  430   a , such that the valve is opened. 
     The valve is completely (100%) closed in  FIG. 7  and completely open (100%) in  FIG. 8 , but it is possible to control the flow rate by controlling the number of rotations of the first motor  110  and the second motor  120  to control the opening amount of the valve. 
     Further, since the first motor  110  and the second motor  120  rotate in the opposite directions, it is possible to control the valve with a desired flow rate. That is, if only one of the first motor  110  and the second motor  120  is provided, it is required to rotate the motor such that the valve shifts from opening 50% to 100% then opening 20% in order to shift the valve from opening 50% to 20%; therefore, the response speed of the valve is decreased. However, since two motors are provided in this embodiment of the invention, it is possible to rapidly shift the valve to have a 20% opening by rotating the other motor in the reverse direction when the valve is at 50% open. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.