Abstract:
A system has an actuator having a rotor or a linear piston, and ports for hydraulic fluid, an electro-mechanical sensor sensing position of the rotor or linear piston, a valve having a 1 plug in a bore of a valve body, the plug having cross bores aligning with passages within the valve body communicating inlet and outlet ports depending on relative position of the plug in the bore of the valve body, a servo motor to move the plug around or along the axis to different positions to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports, and a programmable controller coupled to the electro-mechanical sensor and to the servo motor, the controller enabled to control the servo motor to accomplish programmed movement and position of the rotor or linear piston of the hydraulically-driven actuator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention is a continuation-in-part of a pending U.S. application Ser. No. 13/904,985 filed May 29, 2013, and incorporates at least by reference all of the disclosure of that prior application. 
     
    
     BACKGROUND  
       [0002]    1. Field of the Invention 
         [0003]    The present invention is the technical area of controlling hydraulic actuators, and pertains more particularly to precise control of movement of hydraulic cylinders and rotary hydraulic motors. 
         [0004]    2. Description of Related Art 
         [0005]    Hydraulic motivation of cylinders and motors is quite well-known in the art. There are always areas for improvement, however, and in the field of robotics in particular there is a need for very precise control of position and rate of change, acceleration, and force. The present invention addresses these unmet needs. 
       SUMMARY 
       [0006]    A system is provided comprising a hydraulically-driven actuator having one of a rotor or a linear piston, and ports for hydraulic fluid to move the rotor or linear piston in either of two directions to different positions, an electro-mechanical sensor enabled to sense position of the rotor or linear piston, a valve having a substantially cylindrical plug in a bore of a valve body, the plug having cross bores at right angles to an axis of the plug, the cross bores aligning with passages within the valve body communicating with individual ones of a plurality of inlet and outlet ports to and from the valve body, depending on relative position of the plug in the bore of the valve body, a servo motor coupled mechanically to the cylindrical plug in a manner to move the plug around or along the axis to different positions to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports, and a programmable controller coupled to the electro-mechanical sensor and to the servo motor, the controller enabled to control the servo motor to accomplish programmed movement and position of the rotor or linear piston of the hydraulically-driven actuator. 
         [0007]    In one embodiment the hydraulically-driven actuator is a linear cylinder, and the electro-mechanical sensor comprises a linear-potentiometer enabled to detect linear position of a piston within the linear cylinder. Also in one embodiment the programmable controller is enabled to determine velocity and acceleration of the piston from position information and passage of time. 
         [0008]    Also in one embodiment the hydraulically-driven actuator is a rotary hydraulic motor, and the electro-mechanical sensor comprises a detector enabled to detect radial position of a driven rotor within the hydraulic motor. 
         [0009]    In one embodiment the programmable controller is enabled to determine velocity and acceleration of the rotor from position information and passage of time. Also in one embodiment the servo motor is coupled to the cylindrical plug by gears to rotate the plug around the axis to different positions to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports. In one embodiment the servo motor is coupled to the cylindrical plug by gears and by a cam arrangement, to rotate the plug around the axis to different rotary positions and to different linear positions along the axis of the plug to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports. 
         [0010]    In another embodiment the system further comprises pressure sensors in hydraulic lines proceeding from the valve to the actuator, the sensors providing information to the controller enabling pressure to be used as a variable in a program executed by the controller. Also in one embodiment the controller is coupled to a computerized appliance enabled to execute software enabling a user to prepare and upload programs for the controller to execute. 
         [0011]    In another aspect of the invention a method is provided for controlling movement of a hydraulically-driven actuator, comprising steps of (a) connecting outlet ports of a hydraulic control valve having a valve body to ports of a hydraulically-driven actuator having one of a rotor or a linear piston, and ports for hydraulic fluid to move the rotor or linear piston in either of two directions to different positions, (b) providing an electro-mechanical sensor enabled to sense position of the rotor or linear piston, (c) moving a cylindrical plug having an axis and cross-bores substantially at right angles to the axis, by a servo motor coupled to the plug, in a bore of the valve body, to align individual ones of the cross bores with individual ones of a plurality of inlet and outlet ports to and from the valve body, depending on relative position of the plug in the bore of the valve body, (d) sensing positions of the rotor or linear piston by the electro-mechanical sensor and transmitting the position information to a programmable controller coupled to the servo motor and to the electro-mechanical sensor, and (e) controlling the servo motor to accomplish programmed movement of the rotor or linear piston of the hydraulically-driven actuator. 
         [0012]    In one embodiment of the method the hydraulically-driven actuator is a linear cylinder, and the electro-mechanical sensor comprises a linear-potentiometer enabled to detect linear position of a piston within the linear cylinder. Also in one embodiment the programmable controller is enabled to determine velocity and acceleration of the piston from position information and passage of time. Also in one embodiment the hydraulically-driven actuator is a rotary hydraulic motor, and the electro-mechanical sensor comprises a detector enabled to detect radial position of a driven rotor within the hydraulic motor. 
         [0013]    In one embodiment the programmable controller is enabled to determine velocity and acceleration of the rotor from position information and passage of time. Also in one embodiment the servo motor is coupled to the cylindrical plug by gears to rotate the plug around the axis to different positions to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports. And in one embodiment the servo motor is coupled to the cylindrical plug by gears and by a cam arrangement, to rotate the plug around the axis to different rotary positions and to different linear positions along the axis of the plug to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0014]    Detailed description of some embodiments of the invention is made below with reference to the accompanying figures, wherein like numerals represent corresponding parts of the figures. 
           [0015]      FIG. 1  is a perspective view in one embodiment of the invention. 
           [0016]      FIG. 2  is a top view of the embodiment of  FIG. 1 . 
           [0017]      FIG. 3  is an exploded view of the valve plug and valve body of the embodiment of  FIG. 1 . 
           [0018]      FIG. 4  is a cross-sectional perspective view of the valve body of  FIG. 3 . 
           [0019]      FIG. 5  is a top view of the valve body of  FIG. 3 . 
           [0020]      FIGS. 6 ,  11  and  16  are schematic side views of the valve body of  FIG. 3  shown in connection with an example of hydraulic cylinder in a first open position, a closed position, and a second open position, respectively. 
           [0021]      FIGS. 7-10 ,  FIGS. 12-15  and  FIGS. 17-20  are cross-sectional views of the valve body of  FIG. 3  taken through cross-section lines designated in  FIGS. 6 ,  11  and  16 , showing the relative position of the valve plug vis-à-vis the valve body when the valve is in a first open position, a closed position, and a second open position, respectively. 
           [0022]      FIG. 21  is a schematic perspective view of the system embodiment of  FIG. 1  shown in electrical and fluid connection with an example of a hydraulic cylinder employing a linear detection sensor, such as a linear-potentiometer, by example. 
           [0023]      FIG. 22  is a perspective view similar to  FIG. 21 , adding additional detail concerning control mechanisms in embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    By way of example, and referring to  FIGS. 1 and 2 , one embodiment of the present inventive multi-port valve system  10  comprises a valve  12  and a servo motor  14  within a valve body housing  34 . The system comprises a plurality of fluid ports  24  configured for the delivery of fluid to and from the valve system. In the example illustrated herein, there are four ports  24 . However, the number of ports, and the arrangement of those ports relative to each other is not limited as shown, but indeed may include more than four ports and may orient the ports to have some being parallel to each other, perpendicular to each other, or any other one of a number of possible configurations within the housing  34 . 
         [0025]    Referring to  FIG. 3  momentarily, the valve  14  comprises a valve plug  22  configured to be housed within a valve plug bore  38  within the valve body of the multi-port valve system  10 . In one embodiment, the valve plug comprises a plurality of holes  16  therethrough, where each of the plurality of holes  16  are spaced axially along the length of the valve plug  22 . At least one set of holes  16  is aligned parallel to each other (in this example of embodiment the top hole and the second from the bottom hole), while another set of holes  16  is also aligned parallel to each other (in this example of embodiment the second hole from the top and the bottom hole), but out of alignment with the first set. Of course, the set of holes may be arranged in any number of configurations and radial positions, as may be appreciated further below. And additional holes and/or sets of holes may be employed where additional fluid ports are desired for the valve to control. 
         [0026]    With reference back to  FIGS. 1 and 2 , in this embodiment, the servo motor  14  is configured to have a mechanical output which, in this case, is in the form of a servo gear  18  configured to rotate in clockwise and counterclockwise motion. Servo gear  18  is preferably positioned to be in engagement with valve gear  20  that is affixed to valve plug  22  so that rotation of the servo gear  18  causes rotation of valve gear  20 , to drive rotation of valve plug  22 . Such rotation of the valve plug  22  causes the first and second holes to come within and without of alignment with fluid pathway ports, as described below. 
         [0027]    It should be noted that the radial size and number of teeth in the servo motor gear  18  and the valve gear  20  are set dependent upon the desired control of valve movement and the mechanical output of the servo motor. The larger or smaller the ratio between gears impacts the speed of movement of the valve. In some cases, it may be desired to have very small movement of the valve plug to correspond with fine piston movement within the hydraulic cylinder. In other cases, micro-movement control may not be necessary, so that the gear ratio may be smaller. 
         [0028]    Importantly, it should be noted that movement of the valve plug  22  within valve plug bore  38  need not be limited to rotational movement, but indeed may comprise axial movement instead of rotational movement or in addition to rotation movement. Axial movement may be achieved via a combination of bevel gears, or a rack and pinion arrangement, for example, where the servo motor may drive axial movement of the valve plug. It may also be desired that the valve plug be spring loaded either axially or rotationally where the combination of the servo motor and the force of the spring act to control fine movement of the valve plug relative to the valve plug bore. It is contemplated that a number of possible configurations may be employed to cause the valve plug to bring into alignment certain of the valve plug holes with ports that extend radialy outward from the valve plug bore  38 , as described further below. 
         [0029]    Regardless of how the valve plug  22  moves within valve plug bore  38 , the holes  16  are brought into and out of alignment with ports to control the flow of fluid through the valve body ports  24  in a manner that permits, at least in one application, the actuation of a hydraulic cylinder, for example. In  FIG. 6 , one example of hydraulic cylinder  26  comprises a cylinder housing  44  and a piston  28 . With reference to  FIG. 21 , the position of the piston  28  relative to the cylinder housing  44  is controlled by the delivery of fluid from the multi-port servo embodiment  10  of the present invention through valve body ports  24  to and from cylinder ports  46  and  48 , where the source of fluid pressure (e.g., pump—not shown) is supplied to the valve body  10  through line  54  and returned to the source of fluid pressure through line  56 , both connected to the other set of valve body ports  24 . 
         [0030]    Referring back to  FIG. 3 , the valve body  34  comprises valve port bores  36  into which valve ports  24  may be affixed (in one of numerous possible mechanical and/or adhesive connections), depending upon the material chosen for the valve ports  24  and the valve body  34 . In a high-pressure hydraulic fluid system, the valve body  34  and the valve ports  24  are both made of high strength metals capable of withstanding the high pressures associated with the control of hydraulic cylinders. As may be appreciated, the valve plug  22  comprises a generally cylindrical configuration that may include parallel surfaces and/or tapered surfaces between holes  16 , or a single or plurality of grooves along the axial length. The grooves may provide functional value of being aligned within internal collars within the valve plug bore, in some examples, or may simply reflect the addition of material around the holes for enhanced structural integrity to withstand high pressure flows. 
         [0031]    With reference to  FIGS. 4 and 5 , one example of a series of fluid pathways within the valve body housing  34  may be described, where the fluid pathways permit fluid communication between the valve ports  24  through holes  16  of valve plug  22 . In one embodiment of the multi-port valve body, the port bores comprise one bore  40  connected to one cylinder port  48  and another valve body port bore  42  connected to cylinder port  46 . Likewise, valve body port  58  is connected to the fluid delivery line  54  from the pressure source while valve body port  60  is connected to the fluid return line  56  to the pressure source. The internal pathways within the valve body housing  34 , combined with the controlled movement of the valve plug  22  within valve plug bore  38 —and the concomitant alignment of holes  16  with radial ports of the valve plug bore—permit the controlled direction of fluid from fluid delivery port  58  to either cylinder ports  40  or  42  for the alternating control of piston movement in one linear direction or the other. In the example of multi-port valve body system shown here, a plurality of bores generally aligned parallel to the valve plug bore  38  are in respective communication with a port in each of the delivery and return ports  58  and  60 , on the one hand, and a set of valve plug bore ports, on the other hand. 
         [0032]    Referring to  FIGS. 6  though  20 , the sequence of operation may be appreciated, where the relative position of the valve plug  22  (and holes  16 ) within the valve plug bore  38  is shown in three different positions: a first valve open position (shown in  FIGS. 6 through 10 ), a closed position (shown in  FIGS. 11-15 ), and a second valve open position (shown in  FIGS. 16-20 ). Each cross-section view associated with schematic  FIGS. 6 ,  11  and  16  show the relative position of each of the holes  16  relative to a corresponding valve plug bore port. For example, in  FIG. 7 , the upper most hole is shown in fluid communication with cylinder port  40 , while the second hole from the bottom is in fluid communication with cylinder port  42 , as shown in  FIG. 9 . Meanwhile, the second hole from the top and the bottom most hole are not in fluid communication with any port. The result, as shown in  FIGS. 6 and 21 , is that the fluid delivery line  54  permits fluid to flow through valve body port  58  directly to valve body port  40  and then to cylinder port  48 , with the return of fluid coming from cylinder port  46  through valve body port  42  through to valve body port  60  and back to the pressure source. 
         [0033]    With reference to  FIGS. 11 through 15 , the position of valve plug  22  within valve plug bore  38  is such that none of the valve plug holes  16  are in fluid communication with any ports. Thus, the valve is essentially closed and no flow is occurring between the pressure source, the valve body and the hydraulic cylinder. It should be note that the static pressure may be such that overtime, the pressure may cause undue stress on one or more of the components. Thus, it may be desirable to include within the system a pressure-relief valve to permit the exhaust of at least some of the fluid to a sink or simply to the ambient to temporarily reduce the pressure until the valve is turned back on to the first or second valve open positions. 
         [0034]    Referring to  FIGS. 16 through 20 , relative position of the valve plug  22  and the valve plug bore  38  is shown. There, the valve plug holes  16  are aligned such the resultant flow path is shown by the arrows in  FIG. 16  to reflect the flow of fluid from delivery line  54  permits to valve body port  58  directly to valve body port  42  and then to cylinder port  46 , with the return of fluid coming from cylinder port  48  through valve body port  40  through to valve body port  60  and back to the pressure source. This alternating “second” valve open position directs the piston in the opposite linear direction as results when the valve is in the “first” valve open position. Thus, reciprocating piston movement may be controlled within the hydraulic cylinder  44  to accomplish the task desired. Importantly, it should be noted that the orientation of the fluid paths and ports within the valve body example illustrated and described herein may be varied considerably and still achieve the desired fluid dynamic result. 
         [0035]    Referring back to  FIGS. 1 and 2 , as well as  FIG. 21 , the automated control feature of embodiments of the present invention may be described. In that regard, embodiments of the multi-port servo valve system comprises a control circuit assembly  62  that may be affixed directly to the valve housing  34  or simply electrically connected to the valve housing in one form of the other, either wired or wirelessly. Preferably, the circuit assembly  62  comprises a controller  64  that may be programmed to designate the desired linear position of piston  28  within the cylinder housing  44  over time. In that regard, a sensor  50  is provided in association with the hydraulic cylinder  26 , either directly attached to the cylinder housing  44  or linked in some other configuration, to detect that position of the piston  28  within the housing  44  at any one moment in time. The position is continuously or periodically fed to the controller  64  so that the controller may compare in real time or periodically the actual position of the piston to the desire position of the piston. The controller is electrically connected to the servo motor, either wired or wirelessly, to direct the servo motor to actuate the valve when necessary. If the controller&#39;s programmed comparative function reveals that there is a delta between the actual and desired piston position, the servo motor may be directed to move the valve plug in one direction or the other; i.e., to a first open or second open position, to adjust the piston position accordingly. If there is no delta directed, the valve may be either actuated to a closed position or left in a closed position, depending upon where the sequence of operation is at. In one example of a sensor  50 , a linear-potentiometer may be employed. Other sensors may be employed as well to provide meaningful information about the present situation of the cylinder  26  vis-à-vis the desired situation dictated by the program entered into the controller. 
         [0036]    Indeed, other applications are possible for the inventive embodiments of the multi-port servo valve, as described herein. For example, instead of controlling the flow of hydraulic fluid to a linear piston-style hydraulic cylinder through the use of linear position feedback, the embodiments may be employed to control the movement of a rotational cylinder, where rotational movement of a rotor in one direction or the other may be controlled through the delivery and return of pressurized fluid through embodiments of the multi-port servo valve. One example of a rotational cylinder might be a hydraulic motor configured so that the rotor rotates in a single direction, but at varying speeds and/or for varying time periods., One type of feedback sensor may be one that is configured to detect the rotational position of the rotor within its housing, or the angular velocity at any point in time. 
         [0037]      FIG. 22  is a diagram illustrating more detail in operation and control of a hydraulic actuator in an embodiment of the invention.  FIG. 22  illustrates a linear hydraulic cylinder  70 , as does  FIG. 21 , but it should be apparent to the skilled person that cylinder  70  could also be a rotary actuator like a hydraulic motor. 
         [0038]    In the arrangement of  FIG. 22  piston  72  of the cylinder is driven in opposite directions by supply of hydraulic fluid under pressure from valve assembly  80 , which includes a servo motor, and is operationally identical to valve assembly  10  in  FIG. 21 . Hydraulic fluid under pressure is supplied by pump  91  through conduit  78  to the valve, and depending on the rotary and linear position of valve plug  80  (equivalent to plug  22  described above, through the valve to either of conduits  76  or  77  to drive the cylinder. Cylinder  70  has a linear potentiometer  75  connected at a far end of piston  72  at element  73 , such that a signal may be generated regarding the position of the piston in the cylinder. That signal is provided via line  85  to a programmable controller  84 . Controller  84  also receives pressure signals from pressure sensors  82  and  83  in lines  76  and  77 . Controller  84  is provided with a program  95  for cylinder operation by a coupled computerized appliance  89  running SW  94  via path  93 . SW  94  provides a user with an interactive interface for preparing different programs for cylinder (actuator) operation. 
         [0039]    Controller  84  provides signals via path  92  to operate pump  91  and via path  86  to operate the servo motor in valve assembly  80 . A user may program sophisticated programs for movement of the piston of the cylinder, or for rotation of a rotor in a rotary actuator. By virtue of the fine position control of valve plug  8 , described in detail above with reference to valve plug  22 , one may for example, position valve bores  16  (see  FIGS. 3 and 7  through  10 ) relative to matching bores in the valve body, such that fine speed control is attained. For example, one may program position of valve plug  81  relative to matching bores in the valve body, such that a bore  61  is not directly aligned with the matching bore, so the area for passage of hydraulic fluid is restricted, depending on the position of the valve plug. Consider the area as the full cross-sectional area of the bore  16  when alignment is direct. Then, when the valve plug begins to turn, the area diminishes over a few degrees until the flow is completely shut off. This phenomena may be used in control to get very fine changes in rate and acceleration. The same principle works in the opposite circumstance as the plug is turned from a full off position over a few degrees to a full on position. 
         [0040]    In some embodiments of the invention pressure information from sensors  82  and  83  may be used in programming and control to control piston movement and pressure applied, which translates to force exerted by the piston, or a rotary member of a rotary actuator. Further, in some embodiments of the invention the actuator, be it a linear cylinder or a rotary actuator, may operate one or more mechanisms for pushing or pulling a load, or for gripping an object for example. Sensor  95  in  FIG. 22  is meant to represent any such sensors that may be implemented in driven mechanisms to sense force against elements manifested by movement of and contact with a portion of the actuator. Such sensors provide force data to programmable controller  84  via path  96 , and this data may be used in programming operation of the actuator. 
         [0041]    Persons of ordinary skill in the art may appreciate that numerous design configurations may be possible to enjoy the functional benefits of the inventive systems. Thus, given the wide variety of configurations and arrangements of embodiments of the present invention the scope of the invention is reflected by the breadth of the claims below rather than narrowed by the embodiments described above.