Abstract:
In the integrated hydraulic rotary actuator according to the present invention, a valve, a sensor, a controller, and a driving unit for controlling the rotary actuator are integrated, so wires connecting them are not exposed to the outside. Accordingly, it is possible to prevent damage due to interference in operation and maintenance is easy. Further, since it is integrated, including a controller, when the actuator according to the present invention is used, connecting with other parts is easy and interference can be reduced. Therefore, it is easy to design and manufacture a resultant product.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of priority of Korean Patent application No. 10-2015-0045237, filed on Mar. 31, 2015, all of which are incorporated by reference in their entirety herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an integrated hydraulic rotary actuator and, more particularly, to a hydraulic rotary actuator in which a rotary actuator, a valve, a sensor, and a controller are integrated. 
         [0004]    2. Related Art 
         [0005]    Actuators based on hydraulic pressure are characterized in that they are small and can be precisely controlled and they have larger output-to-size than those of actuators based on a motor. In particular, rotary actuators that are rotated and linear actuators that are linearly operated are used for developing various robots such as a dog-horse robot, a wearable robot, a heavy robot arm, and, recently, an underwater manipulator capable of carrying out work under the deep sea that people have difficulty in doing. 
         [0006]    Such a hydraulic rotary actuator has been disclosed in Korean Patent No. 0956849, titled “Rotary Actuator and Rotary Actuator Type Joint Structure”, by the applicants. 
         [0007]    However, in the hydraulic rotary actuators of the related art, a sensor, a valve, and a controller for control are separated and several signal lines for connecting them are outside the actuators. Accordingly, there may be caused some problems such as loosening of bolts at joints due to vibration, interference between the parts and the signal lines in operation, and a short circuit of the signal lines due to the interference. Further, those problems need to be considered in design of robots to use the actuators, so the design is complicated and it is not easy to maintain the robots while using them. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides an integrated hydraulic rotary actuator solving the problems in the related art such as difficulty in designing due to a complicated configuration of an actuator, loosening of bolts due to vibration and interference and a short circuit of signal lines in operation. 
         [0009]    In an aspect, an integrated hydraulic rotary actuator includes: a stator that has a cavity therein; a rotor that is inserted in the stator and defines a plurality of cavities for receiving hydraulic oil, using its outer side in cooperation with the stator; a valve that is disposed at a side of the stator and rotates the rotor by changing the direction of the hydraulic oil supplied to the cavities; at least one sensor unit that measures the state of the hydraulic oil in the cavities or the state of the rotor; a controller that is disposed at a side of the stator and generates control input for controlling the rotor on the basis of a reference value inputted from the outside and a value measured by the sensor unit; and wires that electrically connect the controller with the valve and the controller with the sensor unit and are disposed inside the stator not to exposed to the outside. 
         [0010]    The stator may have at least one wire channel in which at least one of the wires is disposed. 
         [0011]    The wire channel may be formed at a predetermined distance from an inner surface of the stator not to be exposed to the cavities for receiving the hydraulic oil. 
         [0012]    The sensor unit may include a plurality of pressure sensors measuring pressure in the cavities receiving the hydraulic oil, respectively, the stator may include: a plurality of pressure sensor grooves where the pressure sensors are disposed; and a plurality of pressure measurement channels connecting the pressure sensor grooves and the cavities, and the pressure sensors are disposed in the pressure sensor grooves, respectively. 
         [0013]    The sensor unit may include a position sensor measuring a rotational position of the rotor, and the position sensor may be disposed axially on the outer side of the stator, close to the rotor, and the integrated hydraulic actuator may further include a position sensor cap axially combined with the stator from the outside so that the position sensor is not exposed to the outside. 
         [0014]    The controller may be disposed axially on the outer side of the stator, close to the rotor and may be positioned between the position sensor cap and the stator not to be exposed to the outside. 
         [0015]    The stator may include: a housing having a cylindrical shape; and housing caps in the center portion of which a portion of the rotor is inserted and which are axially combined with the housing. 
         [0016]    The wire channel may be formed at a predetermined distance from an inner surface of the housing and formed axially through the housing. 
         [0017]    The controller may be disposed at a side of the housing cap and may further include a positions sensor cap axially combined with the housing cap from the outside so that the controller is not exposed to the outside, the wire channels may be formed through the housing and the housing cap so that the wire connecting the valve on the housing or the position sensor to the controller is disposed through the wire channel, and the wire channel of the housing and the wire channel of the housing cap may communicate with each other, when the housing and the housing cap are combined. 
         [0018]    A valve groove may be radially formed on the outer side of the housing and the valve may be disposed in the valve groove. 
         [0019]    The housing may further include a stator vane therein that protrudes toward the center of the rotor, and the valve groove may be formed in the protrusion direction of the stator vane from the outer side of the stator. 
         [0020]    The housing may have a sleeve in which a spool of the valve is inserted and slid and the valve groove may have an opening to communicate with the sleeve, and in detail, the sleeve may be formed axially through the stator vane, and the valve may be a flapper stage with a flapper and a nozzle in which the flapper may operate the spool through the opening. 
         [0021]    The housing may comprise: a plurality of pressure sensor grooves where the pressure sensors are disposed; and a plurality of pressure measurement channels connecting the pressure sensor grooves and the cavities, in which the pressure sensors may be disposed in the pressure sensor grooves, respectively. 
         [0022]    The pressure sensors may be two pressure sensors and may be axially formed from a side of the housing disposed at a predetermined distance from the cavities for receiving the hydraulic oil. 
         [0023]    The stator may further include an input port and an output port that define channels for the hydraulic oil from the outside to the valve so that the hydraulic oil flows into/out of the valve through the stator. 
         [0024]    The integrated hydraulic rotary actuator may further include: a connector that is disposed outside the stator to receive a reference value of the controller and power from the outside; and a wire that electrically connects the controller and the connector and is disposed through the wire cannels. 
         [0025]    In another aspect, the present invention may provide a robot including: the integrated hydraulic rotary actuator; a central control unit that controls the hydraulic rotary actuator; and a link that is connected with the hydraulic rotary actuator and rotated by torque. 
         [0026]    In the integrated hydraulic rotary actuator according to the present invention, a valve, a sensor, a controller, and a driving unit for controlling the rotary actuator are integrated, so wires connecting them are not exposed to the outside. Accordingly, it is possible to prevent damage due to interference in operation and maintenance is easy. 
         [0027]    Further, since it is integrated, including a controller, when the actuator according to the present invention is used, connecting with other parts is easy and interference can be reduced. Therefore, it is easy to design and manufacture a resultant product. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a perspective view of an embodiment according to the present invention. 
           [0029]      FIG. 2  is a partial cut view of the embodiment according to the present invention. 
           [0030]      FIG. 3  is an exploded perspective view of the embodiment according to the present invention. 
           [0031]      FIG. 4  is an exploded perspective view of the embodiment including a wire line. 
           [0032]      FIG. 5  is an enlarged perspective view of the wires and the wire channel of a stator of  FIG. 3 , seen from the rear side. 
           [0033]      FIG. 6  is a partial enlarged view of the wire channel of  FIG. 5 . 
           [0034]      FIG. 7  is an enlarged perspective view showing a valve groove of a second embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0035]    Hereinafter, an integrated hydraulic rotary actuator according to an embodiment of the present invention is described in detail with reference to the accompanying drawings. The names of components used in the following description may be referred to as other names in this field. However, even if modified embodiments are selected, they may be considered as equivalent configurations, as long as there are functional similarity and identity. Further, the reference numerals of the components are provided for the convenience of description. However, those indicated by the reference numerals in the drawings do not limit the components to the range shown in the drawings. Similarly, even if embodiments obtained by modifying some of the configurations in the drawings are selected, they may be considered as equivalent configurations, as long as there are functional similarity and identity. Further, when components are recognized as components that should be included at the level of those skilled in the art, they are not described. 
         [0036]      FIG. 1  is a perspective view of an embodiment according to the present invention,  FIG. 2  is a partial cut view of the embodiment according to the present invention,  FIG. 3  is an exploded perspective view of the embodiment according to the present invention, and  FIG. 4  is an exploded perspective view of the embodiment including a wire line. 
         [0037]    As shown in the figures, a hydraulic rotary actuator according to an embodiment of the present invention may include a stator  100 , a rotor  200 , a position sensor  400 , pressure sensors  500   a  and  500   b , a controller  600 , a connector  700 , and bearings  900 . 
         [0038]    The stator  100  may be formed in the shape of a cylinder, making the entire external appearance of the hydraulic rotary actuator, and the rotor  200  may be rotatably inserted in the stator  100 . The inner surface of the stator  100  defines a cavity for receiving hydraulic oil in cooperation with the outer side of the rotor  200 . 
         [0039]    The stator  100  may include a housing  110  making a cylindrical side and housing caps  120  coupled to both axial sides of the housing  100 . The rotor  200  is axially inserted in the housing  110  and the housing caps  120  are coupled to both axial sides of the housing  110 , thereby preventing the inserted rotor  200  from axially separating. Sealing members (not shown) may be disposed at the joints of the housing  110  and the housing caps  120  to prevent leakage of the hydraulic oil received inside. However, the housing  110  and the housing caps  120  are not limited to the shapes described above and may be modified in various configurations defining a cavity for receiving hydraulic oil inside. 
         [0040]    On the other hand, corresponding to a rotor vane  201  on the rotor  200  to be described below, a stator vane  101  protruding toward the center of a rotational axis may be formed on the inner side of the stator  100 . The side facing the center of the rotational axis of the stator vane  101  is in contact with the outer side of the rotor and the radial side of the rotor vane  201  is in contact with the inner side of the stator, so the cavity for receiving hydraulic oil is divided into two parts. The rotor is operated by a pressure difference of the hydraulic oil in the two cavities. That is, torque can be generated by the pressure difference of the hydraulic oil in the cavities at both sides in the rotational direction from the rotor vane  201 . Meanwhile, as in the present embodiment, when it is a single-vane type, the driving angle may be large over 270 degrees. However, the numbers of the vanes are just examples, so two or more vanes may be provided and the actuator may be modified to operate with various torque and rotation angles by changing the shape, and the width etc., in accordance with operation purposes. 
         [0041]    A rotor vane seal  102  and a stator vane seal  202  may be axially disposed at the ends of the stator vane  101  and the rotor vane  201 , respectively. When hydraulic oil leaks between the cavities at both sides of the vanes  101  and  201 , the efficiency of the rotor  200  reduces, so the seals are provided to prevent the leakage. A shaft seal (not shown) may be provided between the housing caps  120  and the rotor  200  to prevent axial leakage of hydraulic oil between the rotor  200  and the housing caps  120 . The shapes of the vane seals  102  and  202  and the shaft seal (not shown) are just examples and may be changed in various ways and those seals are used in many fields, so they are no longer described in detail. 
         [0042]    As described above, the stator  100  and the rotor  200  generate torque and are connected to external parts to rotate them relative to each other. For example, when the actuator is applied to a robot arm, the stator  100  and the rotor  200  function as a joint connecting two parts and may rotating two links relative to each other in order to rotate the robot arm. A connection groove for connection with a link is formed on the side of the stator  100  and a link connector block  210  for connection with another link is fastened to an axial end of the rotor  200 . However, although the link connector block  210  is axially coupled to the rotor  200 , it is just an example and the rotor  200  itself may be connected an external part. 
         [0043]    The bearings  900 , which resist an axial force at both axial ends of the rotor  200  for smooth rotation, may be axially inserted into the housing caps  120  from outside the housing caps  120 . 
         [0044]    As for the stator  100  again, a valve  300 , a sensor unit, and the controller  600  are mounted on the stator  100  and an input port  300 , and output port  340  are formed on the stator  100 . 
         [0045]    The valve  300  is provided to supply hydraulic oil to the cavities in the stator  100 . The valve  300  may be a servo valve  300  and can change the supply direction of hydraulic oil in response to operation signals. An operation signal from a user or an external central control unit can be received by the controller  600  to be described below and the valve  300  can be operated in response to the operation signal. The operation principle of the valve  300  is widely applied, so it is no longer described. 
         [0046]    The valve  300  may be disposed in the valve groove  160  on the housing  110 . The valve groove  160  is formed on the outer side of the housing  110  to be concave toward the inside of the stator vane  101 . The valve groove  160  may communicate with a passage, the input port  330 , and the output port  340  that are connected to valve  300  and the cavities for receiving hydraulic oil in the housing  110 . However, this configuration exemplifies and various types of servo valves such as a nozzle flapper type valve  300 , a zet-nozzle and a DDV (Direct Drive Valve) can be applied. Further, the valve groove  160  and the valve  300  may be modified so that the entire or a portion of a servo valve can be disposed in the valve groove  160 . 
         [0047]    The input port  330  and the output port  340  make a passage for hydraulic oil from the outer side of the stator  100  to the valve  300  at the inside. The input port  330  provides a channel through which hydraulic oil flows inside from the outside and the output port  340  provides a channel through which hydraulic oil flows outside. The input port  330  and the output port  340  extend to the valve on the stator  100  through the stator  100 . 
         [0048]    The input port  330  and the output port  340  axially pass through the housing cap  120  at the rear portion in  FIG. 3  and axially extend to the valve  300  through the housing  110 . The shape and position of the input port  330  and the output port  340  may be variously changed. 
         [0049]    Hydraulic oil flows into the stator  100  from the outside through the input port  330 , moves to the valve  300 , and is then selectively supplied to the cavities for receiving hydraulic oil in the stator  100  from the valve  300 . In this process, hydraulic pressure is applied to the rotor vane  202 , so the rotor  200  is rotated. Further, the hydraulic oil in the opposite cavity, in contrast, passes through the valve  300  and the flows out of the actuator through the output port  340 . The configuration of the valve will be described below. 
         [0050]    The sensor unit may include the position sensor  400  and the pressure sensors  500   a  and  500   b . The position sensor  400  may measure the rotational position of the rotor  200  and the pressure sensors  500   a  and  500   b  may measure the pressure of hydraulic oil applied to the cavity for receiving hydraulic oil in the stator  100 . 
         [0051]    The position sensor  400  is axially fitted on the outer side of the housing cap  120  to cover a portion of the rotator  200  that protrudes out of the housing cap  120  and measures the rotational angle of the rotor  200 . A groove corresponding to the shape of the position sensor  400  may be formed on the outer side of the housing cap  120  where the position sensor  400  is disposed to provide a cavity for holding the position sensor  400 . The position sensor  400  may be formed in the shape of a flat ring to be seated in the groove. However, the shape of the position sensor  400  is just an example and may be changed in various ways. 
         [0052]    A position sensor cap  410  may be disposed axially outside the housing cap  120 . The position sensor cap  410  may be combined with the housing cap  120  so that a cavity is defined axially therein. The position sensor  400  and the controller  600  to be described below can be disposed in this cavity. 
         [0053]    However, since the position sensor  400  is widely used, the configuration and the operation principle of the position sensor  400  are not described in detail. 
         [0054]    The pressure sensor grooves  510  may be formed on both axial sides of the housing  110 . The pressure sensor grooves  510  may be concave to correspond to the shape of the pressure sensors  500   a  and  500   b  to be described below. A side of each of the pressure sensor grooves  510  may communicate with the cavity for receiving hydraulic oil through passages. 
         [0055]    The pressure sensors  500   a  and  500   b  can measure the pressure of the hydraulic oil in the cavity for receiving hydraulic oil. The pressure sensors  500   a  and  500   b  may be inserted in the pressure sensor grooves  510 , respectively. The pressure sensors  500   a  and  500   b  can be fitted in the pressure sensor grooves  510  and measure the pressure of hydraulic oil in pressure measurement channels (not shown) formed from sides of the pressure sensor groove  510  to the cavity for receiving hydraulic oil. 
         [0056]    However, the shape of the pressure sensor grooves  510  are just examples and the pressure sensor grooves  510  may be changed in various shapes so that the pressure sensors  500   a  and  500   b  can be inserted into the stator  100 . Alternatively, the pressure sensors  500   a  and  500   b  may be disposed at various positions such as being disposed directly in the cavity for receiving hydraulic oil or being inserted radially in the stator  100 . 
         [0057]    The controller  600  is provided to receive a reference input value for rotating the rotor  200  from the outside and to rotate the rotor  200  at a desired angle by controlling the valve  300 . In this configuration, it is possible to calculate a control input value for driving the valve  300  by feeding back the values measured by the positions sensor  400  and the pressure sensors  500   a  and  500   b.    
         [0058]    The controller  600  is disposed outside the stator  100 , and may be disposed at a position where it covers the rotor  200  outside the housing cap  120 . The controller  600  is disposed, together with the positions sensor  400 , axially in the cavity between the housing cap  120  and the position sensor cap  410 . Accordingly, it is not exposed to the outside by the positions sensor cap  410  and the housing cap  120 . The controller  600  may be formed in the shape of a ring to be disposed in the cavity between the position sensor cap  410  and the housing cap  120 . The position and the shape of the controller  600  may be modified in various ways as long as it is not exposed to the outside, not being limited to the shape and the position described above. 
         [0059]    The controller  600  may generate a signal for driving the valve ( 300 ) in response to a reference input value to rotate the rotor  200  and may generate various input in accordance with external loads applied to the rotor  200 . In detail, when the pressure is changed in the cavities for receiving hydraulic oil by an external force applied to the rotor  200  fixed at a position, it may perform compliance control, using pressure measured by the pressure sensors  500   a  and  500   b . However, the function of the controller  600  is not limited to the compliance control and other various control methods for controlling the valve  300  by feeding back values measured by the sensor unit may be applied. 
         [0060]    The connector  700  is radially disposed outside the stator  100 , transmits a signal to the controller  600 , and transmits power for driving the valve  300 , the pressure sensors  500   a  and  500   b , the position sensor  400 , and the controller  600 . The connector  700  is connected with a central control unit or a computer at the outside to receive reference input for driving the rotary actuator. The connector may be disposed at various positions on the outer side of the rotary actuator and the configuration of the connector  700  has been well known in the art, it is no longer described in detail. 
         [0061]    Wires and a wire channel are described hereafter with reference to  FIGS. 5 and 6 . 
         [0062]      FIG. 5  is an enlarged perspective view of the wires and the wire channel of a stator of  FIG. 3 , seen from the rear side and  FIG. 6  is a partial enlarged view of a wire channel of  FIG. 5 . 
         [0063]    As shown in the figures, wires  800  may connect the valve  300 , the positions sensor  400 , the pressure sensors  500   a  and  500   b , and the connector  700  to the controller  600 . 
         [0064]    A wire channel  150  allows wires  800  connecting the components at both sides axially from the housing  110  to pass through the housing  110 . The wire channel  150  is formed axially through the housing  110  and the housing cap  120 . The wire channel  150  may be formed axially at a predetermined distance from the inner rotational surface of the housing  110  and the housing cap  120  with which hydraulic oil comes in contact, in order not to influence the cavities for receiving the hydraulic oil. Further, the wire channel  150  may be formed at an appropriate position in order not to interfere with the valve  300  on the housing  110  and the passages for the hydraulic oil. 
         [0065]    Although the wire channel  150  is formed axially through the housing  110  in the figures, it may be formed at various angles and in various cross-sections, for example in the shape of a groove on the outer side across the housing  110  so that the wires  800  can be disposed. Further, it may be changed in various ways in accordance with the positions of the components that are electrically connected, such as the valve  300 , the position sensor  400 , and the pressure sensors  500   a  and  500   b , and a plurality of wire channels may be provided. 
         [0066]    The wires  800  may be disposed at a predetermined distance from the inner surface of the stator  100  that comes in contact with hydraulic oil to prevent the passages from the components to the wire channel  150  for arranging the wires  800  from influencing the cavities for receiving hydraulic oil. 
         [0067]    Referring to  FIG. 5  again, the wire  800  connected to the pressure sensor  500   a  closer to the controller  600  is arranged around the outer side of the housing  110  and connected to the controller  600  through the wire channel  150  formed through the housing cap  120 . On the other hand, the wire  800  connected to the pressure sensor  500   b  at the opposite side is arranged around the outer side of the housing  110  and passes through the wire channel  150  of the housing  110  and is then connected to the controller  600  through the wire channel  150  of the housing cap  120 . When the wires  800  are arranged, as described above, they cannot be exposed to the outside and cannot influence to the cavities for receiving hydraulic oil. 
         [0068]    The arrangement of the wires  800  connecting the pressure sensors  500   a  and  500   b  to the controller  600 , respectively, is just an example and may be changed in various ways. For example, when the pressure sensors  500   a  and  500   b  are disposed at other positions, as described above, that is, when the pressure sensors  500   a  and  500   b  are both disposed on the side of the housing  100  closer to the controller  600 , the wires connecting the pressure sensors  500   a  and  500   b  to the controller  600  may not pass through the wire channel  150  of the housing  110  but the wire channel of the housing cap  120 . Further, when the position sensor  400  and the controller  600  are disposed on a side of the housing cap  120 , they may be connected not through the wire channel  150 . 
         [0069]    A wire  800  receiving reference input by connecting the controller  600  and the connector  700  may be disposed with other wires  800  through the wire channels  150 . Power may be supplied to at least one of the controller  600 , the position sensor  400 , the pressure sensor  500   a ,  500   b  and the valve  300  through the wires  800  disposed from the connector  700  through the wire channels  150 . 
         [0070]    The wire  800  connecting the controller  600  and the valve  300  may also be disposed through a wire channel  150 . 
         [0071]    As described above, since the wires  800  can be disposed through the wire channels  150  formed in the stator  100 , the wires  800  are not exposed to the outside. 
         [0072]      FIG. 7  is an enlarged perspective view showing a valve groove of a second embodiment of the present invention. 
         [0073]    As shown in the figure, a valve groove  160  may be formed on a side of the housing  110  and a sleeve  311  allowing a spool  310  of the valve  300  to slide may be formed on a side of the housing  110  which close to the valve groove  160 . 
         [0074]    That is, a spool stage of the valve  300  is integrated with the housing  110  and a flapper stage  320  is disposed in the valve groove  160 , thereby completing the valve  300 . Hydraulic lines A and B that communicate with the cavities for receiving hydraulic oil communicate with the sleeve  311  and may communicate with the input port  330  and the output port  340  that are passages for hydraulic oil flowing inside/outside. When a hydraulic rotary actuator having this configuration is formed in a small size, it is possible to solve the problem of a small valve space by forming some of the structure of the valve  300  at the housing  110 .