Abstract:
Systems and methods use selective regeneration to aid in controllability and efficiency of a hydraulic circuit. A regeneration deactivation valve can react to a differential pressure when the function is in free air and at risk of cavitating or when then function is doing positive work and needs to be efficient. When the function is at risk of cavitating, the regeneration deactivation valve can react to the potential for cavitation and the regeneration deactivation valve closes so the function regenerates. The regeneration deactivation valve can also react when the function is not at a risk of cavitating and can open up allowing the function to move with more power and efficiency.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 62/015,620, filed on Jun. 23, 2014, and entitled “REGENERATION DEACTIVATION VALVE,” which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION  
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to hydraulic systems that control operation of a hydraulic cylinder, and more particularly to a valve arrangement and method incorporating a regeneration function for controlling operation of such a hydraulic cylinder. 
         [0005]    2. Description of the Related Art 
         [0006]    In excavating machinery and other heavy equipment and equipment hydraulically controlled generally, controllability and efficiency are several metrics that can be used to quantify the profitability and operator “feel” of the machine. 
         [0007]    As a normal machine metric, operators can test for cavitation of functions. Cavitation is an unwanted condition that can occur when a function has an overrunning load. In an excavator, for example, the hydraulic cylinder used to control the excavator arm is susceptible to cavitation due to the arm having a large amount of potential energy when it is fully out, and the cylinder has a rather large cylinder area to fill with hydraulic fluid as the arm comes in towards the excavator. 
         [0008]    One method to keep the arm from cavitating is to use regeneration of the arm cylinder where some of the rod exhaust fluid is pushed back into the head of the cylinder to help makeup (regenerate) fluid as the head chamber is expanding. This requires a connection from the rod side of the cylinder to the head side of the cylinder and normally a smaller connection from the rod side of the cylinder to the tank. 
         [0009]    However, when the excavator is digging, the head side of the cylinder can have a higher pressure then the rod side of the cylinder, which does not allow for regeneration. Therefore, all of the rod fluid must go to tank through the smaller rod side to tank connection. This causes a large differential pressure across the control valve, which results in a high rod side pressure. This rod side pressure works against the head side pressure when digging, which reduces the force and efficiency of the machine. 
         [0010]    Hydraulic circuits have attempted to better control the regeneration function by sensing pressure at the fluid source to determine if regeneration should occur. Based on the sensed pressure at the fluid source, the circuit can open a secondary passage to reduce the differential pressure across the control valve. Yet, these circuits still fail to provide better control for regenerating as the sensed pressure at the fluid source does not always provide the appropriate pressure value for determining when regeneration should occur. 
         [0011]    Therefore, there is a desire to provide an improved valve arrangement incorporating a regeneration function for controlling operation of such a hydraulic cylinder. 
       SUMMARY OF THE INVENTION  
       [0012]    The present technology overcomes the aforementioned drawbacks by providing systems and methods that use selective regeneration to aid in controllability and efficiency of a hydraulic circuit. A regeneration deactivation valve according to the present technology can “sense,” i.e., react to a differential pressure, when the function is in free air and the function&#39;s cylinder is at risk of cavitating or when then function is doing positive work and the function&#39;s cylinder is not at risk of cavitation. When the cylinder is at risk of cavitating, the regeneration deactivation valve can react to the potential for cavitation by closing, or opening, a fluid path so the cylinder regenerates. The regeneration deactivation valve can also react when the cylinder is not at a risk of cavitating and can open up, or close, a fluid path allowing the function to move with more power and efficiency. 
         [0013]    In accordance with one embodiment of the invention, a hydraulic regeneration deactivation valve is disclosed to deactivate regeneration of a hydraulic cylinder. The hydraulic regeneration deactivation valve comprises a body including a tank return node for connection to a tank, a driving workport for connection to a first chamber of the hydraulic cylinder, a return workport for connection to a second chamber of the hydraulic cylinder, the first chamber and the second chamber separated by a piston, and a regeneration node, the regeneration node for connection to the driving workport and for connection to the return workport. A flow control valve is received in the body and having a first fluid path between the regeneration node and the tank return node, the first fluid path being substantially unrestricted in a first flow control valve position, and the first fluid path being restricted in a second flow control valve position. And the flow control valve is responsive to a sense pressure in the driving workport to move between the first flow control valve position and the second flow control valve position. 
         [0014]    In accordance with another embodiment of the invention, a hydraulic control valve is disclosed. The hydraulic control valve comprises a control valve body having a spool bore therein and a node for connection to a fluid source, a tank return node for connection to a tank, a driving workport for connection to a first chamber of the hydraulic cylinder, a return workport for connection to a second chamber of the hydraulic cylinder, the first chamber and the second chamber separated by a piston, and a regeneration node, the regeneration node for connection to the driving workport and for connection to the return workport. A spool is slidably received in the spool bore and having a spool first position in which a first fluid path is provided between the node and the driving workport, a spool second position in which a second fluid path is provided between the driving workport and the tank return node, and a spool neutral position in which the driving workport is closed off from both the node and the tank return node. A flow control valve is slidably received in the spool bore and having a first fluid path between the regeneration node and the tank return node when the spool is in the spool first position, the first fluid path being substantially unrestricted in a first flow control valve position, and the first fluid path being restricted in a second flow control valve position. And the flow control valve is responsive to a sense pressure in the driving workport to move between the first flow control valve position and the second flow control valve position. 
         [0015]    To the accomplishment of the foregoing and related ends, the technology, then, comprises the features hereinafter fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the technology. However, these aspects are indicative of but a few of the various ways in which the principles of the technology can be employed. Other aspects, advantages and novel features of the technology will become apparent from the following detailed description of the technology when considered in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0016]      FIG. 1  illustrates a schematic of a hydraulic circuit including a regeneration deactivation valve according to embodiments of the technology; 
           [0017]      FIG. 2  illustrates a schematic of a control valve in a hydraulic circuit, the control valve including a regeneration deactivation valve according to embodiments of the technology; 
           [0018]      FIG. 3  depicts a close-up view of the construction of an embodiment of the regeneration deactivation valve as shown in  FIG. 2 ; and 
           [0019]      FIGS. 4-10  illustrate schematic views of a hydraulic circuit including alternative embodiments of a regeneration deactivation valve according to embodiments of the technology. 
       
    
    
       [0020]    While the technology is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the technology to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the technology as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    The term “directly connected” means that the associated components are connected together by a conduit without any intervening element, such as a valve, an orifice or other device, which restricts or controls the flow of fluid beyond the inherent restriction of any conduit. 
         [0022]    As used herein, the term “hydraulic cylinder” generically refers to a hydraulic actuator that comprises a cylinder body in which a piston moves in response to hydraulic fluid being fed into and drained from the cylinder body and in which a rod is connected to the piston so as the extend from and retract into the cylinder as the piston moves. 
         [0023]    Reference herein to directional relationships and movement, such as raise and lower or left and right, refer to the relationship and movement of components in the orientation illustrated in the drawings and on the exemplary application of the invention being described, and other relationships and orientations of the components may exist in other applications of the present invention. 
         [0024]    Although the inventive concepts can be described in the context of a hydraulic cylinder usable on heavy machinery such as a front end loader of an excavator, for example, the concepts described herein have broad applicability to controlling a variety of hydraulic devices, such as a hydraulic motor, as a non-limiting example. 
         [0025]    With reference to  FIG. 1 , an exemplary embodiment of the technology includes a regeneration deactivation valve  20  connected in a hydraulic circuit including a cylinder  22 , a fluid source  24 , and a tank  26 . The cylinder  22  includes an internal bore in which a piston  28  is slidably received, thereby forming a rod chamber  30  and a head chamber  32  within the cylinder  22  on opposite sides of the piston  28 . The regeneration deactivation valve  20  includes a flow control valve  48  in a body  49 , the flow control valve  48  able to react to a differential pressure between a sense pressure  31  at node  33 , which can be directly connected to the driving workport  34 , and a reference pressure  36  at node  37 , which in some embodiments can be connected or directly connected to a regeneration gallery  38 , to function according to what type of machinery operation is being done. The reference pressure  36  can be the same pressure as the return workport  40  or lower, for example. It is to be appreciated that the body  49  is shown generally in relation to the regeneration deactivation valve  20  as the body  49  can take any applicable shape. 
         [0026]    When at risk of cavitating, the function can be overrunning, and in the case of an arm on an excavator, for example, the reference pressure  36 , such as at the regeneration gallery  38 , can be at a higher pressure than the sense pressure  31  at the driving workport  34 . In this example, the regeneration deactivation valve  20  can react to the higher reference pressure  36  by restricting or closing a fluid path including a regeneration node  44  to a tank return node  46 , so the function regenerates by allowing fluid to flow from the rod chamber  30  through the return workport  40 , through a regeneration fluid path  42 , through the driving workport  34 , and to the head chamber  32 . The regeneration fluid path  42  can include a check valve  43  to prevent the reverse flow of fluid from the head chamber  32  to the rod chamber  30 . In some embodiments, the regeneration fluid path can also include a variable orifice  66  to meter the flow from the return workport  40 . 
         [0027]    When digging, such as with the case of the arm on an excavator, for example, the regeneration deactivation valve  20  can react to a higher sense pressure  31  at the driving workport  34  than the reference pressure  36  by opening or substantially unrestricting the fluid path including the regeneration node  44  to the tank return node  46 , which allows for a low differential pressure across a restriction  50  (see  FIGS. 1 and 3 ) in the regeneration deactivation valve  20 , and creating a low pressure at return workport  40  and an improved efficient dig. 
         [0028]    As seen in  FIG. 1 , in some embodiments, the flow control valve  48  can include a spring  52 . The preload and rate of the spring  52  can be controlled to help bias the regeneration deactivation valve  20  closed and make for a stable transition from open to closed. Also, in some embodiments, an orifice  54  can be added between regeneration node  44  and the reference pressure  36  at node  37 . This can make for a more stable transition from closed to open or from open to closed. In addition to orifice  54 , orifice  56  (see  FIGS. 5 and 8 ) can be added connecting the reference node  37  to the tank return node  46  and creating a pressure divider. In this arrangement, as pressure in the regeneration gallery  38  changes, the reference pressure  36  will follow, but at a lower level based on the relative sizes of orifice  54  and orifice  56 . 
         [0029]    Referring to  FIGS. 2 and 3 , the regeneration deactivation valve  20  is shown incorporated into an exemplary control valve  62 . It is to be appreciated that the regeneration deactivation valve  20  can be a standalone device as shown in  FIG. 1  in body  49 , or the regeneration deactivation valve  20  can be integrated with the control valve  62 . The control valve  62  is shown including a control valve body  70  having a spool bore  72 , with a spool  74  in the spool bore  72 , and variable orifices  64 ,  66 , and  68  on the spool  74  (see  FIG. 3 ). Variable orifice  64  serves to meter flow from the fluid source  24  to the driving workport  34 . Variable orifice  66  serves to meter flow from the return workport  40 , and variable orifice  68  serves to meter flow to the tank  26 . When the regeneration deactivation valve  20  is a standalone device, variable orifices  64 ,  66 , and  68  can be included in a hydraulic circuit to control the cylinder  22 , as can be seen in  FIG. 1 . 
         [0030]    In  FIG. 3 , the regeneration deactivation valve  20  is shown in a non-regenerating open position, such that the regeneration gallery  38  is connected to tank  26  (not shown in  FIG. 3 ) through the fluid path including the regeneration node  44  to the tank return node  46 . 
         [0031]      FIGS. 4-10  show alternative embodiments of a regeneration deactivation valve connected to a cylinder  22 , a source of fluid  24 , and a tank  26 . Each regeneration deactivation valve can be the same as the regeneration deactivation valve  20 , other than restrictive elements can be added to or removed from the hydraulic circuit to influence performance. 
         [0032]      FIG. 4  is similar to  FIG. 1 , except orifice  54  has been removed. Orifice  54  (without orifice  56 , discussed below) serves as a damping orifice. In other words, it serves to slow down the flow control valve velocity when the valve is transitioning from one position to the next. 
         [0033]      FIG. 5  is similar to  FIG. 1 , except orifice  56  has been added. The two orifices in series ( 54  and  56 ) set up a flow path from the reference node  37  to the tank return node  46  and create a pressure divider. In some embodiments, when the orifices are fixed, then there is a ratio-metric relationship between the pressure drop from regeneration gallery  38  to reference pressure  36  as a function of the pressure drop between regeneration gallery  38  and the tank return node  46 . In other words, as pressure in the regeneration gallery  38  changes, the reference pressure  36  will follow, but at a lower level based on the relative sizes of orifice  54  and orifice  56 . 
         [0034]      FIG. 6  is similar to  FIG. 1 , except that the reference node  37  is shown connected to the return workport  40 . The reference pressure  36  will be higher than the pressure at the regeneration node  44 , which feeds the regeneration fluid path  42 . In this arrangement, the flow control valve  48  can sense a pressure differential closer to the pressure differential between the cylinder rod chamber  30  and the head chamber  32 . When a pressure at the driving workport  34  becomes higher than a pressure at regeneration node  44 , check valve  43  will close preventing regeneration flow, but the regeneration deactivation valve  20  will not shift until a pressure at the return workport  40  becomes higher than a pressure at the driving workport  34 . This arrangement can set up a delay in the regeneration deactivation valve shifting that can help stabilize the hydraulic circuit. As discussed above, orifice  54  can serve as a damping orifice. 
         [0035]      FIG. 7  is similar to  FIG. 6 , except without the damping orifice  54 . 
         [0036]      FIG. 8  is similar to  FIG. 5 , except that the reference node  37  is shown connected to the return workport  40  rather than from the regeneration gallery  38 . This hydraulic circuit can have the same advantages as the hydraulic circuits of  FIGS. 5 and 6 . 
         [0037]      FIG. 9  is similar to  FIG. 1 , except the reference pressure  36  is shown connected to the tank return node  46 . In this arrangement, the regeneration deactivation valve  20  can shift if the force due to the difference between a pressure in the driving work port  34  and the tank return node  46  exceeds the preload on spring  52 . 
         [0038]      FIG. 10  is similar to  FIG. 9 , except without the damping orifice  54 . 
         [0039]    The regeneration deactivation valve  20  can be used any time regeneration of a cylinder is possible, including either extension or retraction of the cylinder. 
         [0040]    The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.