Patent Publication Number: US-10760596-B2

Title: Proportional sequence valve with pressure amplification device

Description:
FIELD OF INVENTION 
     The present invention relates to pressure control systems and in particular to a pressure control valve. 
     BACKGROUND OF THE INVENTION 
     Various systems and in particular, hydraulic systems, require pressure control of a fluid flow used in operation of components of the system. Pressure control valves are implemented for a variety of functions such as prohibiting system pressure from exceeding a predetermined pressure limit and maintaining a set pressure in the system. 
     A conventional type of pressure control valve is a pilot operated relief valve used to control a high pressure or high fluid flow feed to a hydraulic circuit or device, such as a pump. The pilot operated relief valve generally includes an inlet, a piston positioned on a seat of the inlet, a chamber positioned above the piston, a control orifice in communication with the chamber, and a pilot section that contains a spring-loaded poppet and sets a maximum system pressure. A flow path from an outlet of the control orifice on top of the piston leads to the pilot. Fluid used by the pilot section may return to a reservoir. In operation, fluid flows through the inlet to the hydraulic circuit and through the control orifice to the chamber. The fluid also travels to the spring-loaded poppet, where the fluid is blocked. When pressure is too low to unseat the spring-loaded poppet, pressure is the same on both sides of the piston and a spring holds the piston in a normally closed position. 
     When pressure exceeds the maximum system pressure, the spring-loaded poppet open slightly to allow a small amount of fluid to pass to the reservoir. However, the fluid passing the spring-loaded poppet also flows through the control orifice such that flow to the reservoir may be blocked. As pressure increases, the spring-loaded poppet in the pilot section is opened enough to allow a greater amount of flow than the flow through the control orifice such that pressure in the chamber decreases. When the pressure imbalance exceeds a predetermined value, the piston moves towards the decreased pressure and opens a flow path to the reservoir. When the system pressure decreases, the spring-loaded poppet reseats itself. A disadvantage of the pilot operated relief valve is that they generally operate at a lower maximum pressure and leakage than may occur at the valve seat during high pressure applications. 
     A direct acting pressure reducing valve may be used as an alternative to using a pilot operated valve in controlling high pressure in a hydraulic system. Direct acting pressure reducing valves respond more rapidly to pressure buildup in comparison with the pilot operated relief valve. The direct acting pressure reducing valve is generally controlled with a solenoid. However, a disadvantage of the direct acting pressure reducing valve is that in a high-pressure application, requirements for the solenoid may demand a solenoid that is disadvantageously large in size. 
     SUMMARY OF THE INVENTION 
     The present application is directed towards providing a proportional sequence valve for controlling high pressure between a fluid supply and a hydraulic actuating device. The valve uses a spool and a pin that is positioned within a body of the spool and moveable relative to the spool. Providing the pin effectively allows for two independent control pressures to act against an end of the spool, by way of high pressure acting an annular surface of the spool and a cross-sectional area of the pin. The relationship between the pin and the spool creates an amplification factor that is used to modulate the pressure in the valve. The diameter of the pin may be selected to increase or decrease the amplification factor, depending on the particular application in which the valve is to be implemented. 
     According to an aspect of the invention, a valve member for supplying and discharging fluid flow includes a valve body having a fluid passage, a spool moveable within the valve body, the spool having a first end, a second end opposite the first end, and a bore defined at the second end, wherein the second end is in fluid communication with the fluid passage, and a pin that is received within the bore of the spool and moveable relative to the spool, the pin and the spool being concentric and moveable along a common axis. A fluid flow through the fluid passage acts against a cross-sectional area of the pin and an annular area of the spool at the second end of the spool. 
     According to another aspect of the invention, a valve member for operating a hydraulic actuating device includes a valve body defining a supply port, a tank port, and a controlled port fluidly connectable between the hydraulic actuating device and at least one of the supply port and the tank port, a pressure control port, a slideable spool for fluidly connecting the controlled port with at least one of the supply port and the tank port, wherein the slideable spool has a first end, a second end, and a bore chamber extending between the first and second end, and a pin that is received within the bore chamber at the second end of the spool and slideable relative to the spool. The spool moves in a first direction in response to a biasing force that acts on a cross-sectional area of the spool at the first end of the spool within the valve body. The spool moves in a second direction opposite the first direction in response to pressure from the pressure control port that acts on an annular area of the spool and on a cross-sectional area of the pin at the second end of the spool. 
     According to another aspect of the invention, a method of controlling a supply pressure may be used in a valve member having a fluid inlet, fluid outlet, and a controlled port. The method includes positioning a spool within the valve member, the spool having a first end and a second end opposite the first end, positioning a pin within the spool at the second end of the spool, applying a control pressure against an annular area of the spool and a cross-sectional area of the pin at the second end of the spool, moving the spool for fluidly connecting and disconnecting at least one of the fluid inlet and the fluid outlet with the controlled port, and moving the pin relative to the spool to modulate the supply pressure in the valve member. 
     These and further features of the present invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the invention may be employed, but it is understood that the invention is not limited correspondingly in scope. Rather, the invention includes all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a drawing depicting a sectional view of a valve member according to an exemplary embodiment of the present application showing a controlled port, a tank port, a supply port, two control ports, a spool valve, and a pin. 
         FIG. 2  is a drawing depicting a detailed sectional view of the valve member of  FIG. 1  showing the spool and the pin in detail. 
         FIG. 3  is a drawing depicting a chart of the operation of the valve member according to an exemplary embodiment of the present application, showing an opening area between the controlled port and the tank port and an opening area between the controlled port and the supply port controlled by a position of the spool, where both of the opening areas are closed during a portion of the spool travel. 
         FIG. 4  is a drawing depicting a chart of the operation of the valve member according to another exemplary embodiment of the present application, showing an opening area between the controlled port and the tank port and an opening area between the controlled port and the supply port controlled by a position of the spool, where both of the opening areas are simultaneously open during a portion of the spool travel. 
     
    
    
     DETAILED DESCRIPTION 
     The principles of the present application have particular application in a pressure control valve having a supply pressure for operation of an associated device or system, such as a hydraulic system. Other applications may include any suitable application that currently implements pressure relief valves, pressure reducing valves, unloading valves, sequence valves, counterbalance valves, or other suitable valves for pressure control. The valve member according to the present application includes a pin slideable within a bore of a spool of the valve member, allowing a control pressure to act on both an area of the pin and an area of the spool, at the end of the spool where the pin is positioned. Using the pin is advantageous over conventional pressure control valves in that allowing high pressure to act on the area of the pin and the spool allows the supply pressure to be more efficiently controlled through modulation of the pin and the spool. 
     Embodiments of the present invention will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. It will be understood that the figures are not necessarily to scale. 
     Referring to  FIG. 1 , a valve member  10  includes a valve body  12 . The valve body  12  may include a first main port or a supply port  14 . The supply port  14  may be fluidly connected to a source  16  of hydraulic pressure, such as a pump or an accumulator. The valve member  10  may include a second main port or a tank port  18 . The tank port  18  may be connected to a hydraulic reservoir or tank  20  that is maintained at a null pressure value. The valve member  10  may further include a controlled port  22  that is connected to a hydraulic actuating device  24 . The controlled port  22  may be connected to any suitable hydraulic actuating device, such as a cylinder or a motor. The controlled port  22  may be in fluid communication with at least one of the supply port  14  and the tank port  18 . An amount of fluid flow may be supplied to the valve body  12  from the supply port  14  and discharged through the second main port  18  or the controlled port  22  for operating the hydraulic actuating device  24 . Continuous flow into the supply port  14 , into and out of the controlled port  22 , and out of the tank port  18  may occur such that flow through the valve member  10  is continuous. 
     The valve member  10  may include at least one control port  26 ,  28  defined by the valve body  12 . The valve member  10  may include a first control port  26  and a second control port  28  that are positioned distally opposite one another at a first end  30  of the valve body  12  and at a second end  32  of the valve body  12 . Each of the control ports  26 ,  28  may define a smaller cross-section flow area relative to the supply port  14 , tank port  18 , and controlled port  22 . Each of the control ports  26 ,  28  may be in fluid communication with a pressure control device  34 , such as a relief valve or reducing valve. The control ports  26 ,  28  may be used to transmit a signal pressure from the pressure control device  34  to the valve member  10 . It should be recognized that the control ports  26 ,  28  are optional components of the valve body  12  and are configured to provide pressure control for the valve member  10  and the hydraulic circuit in which the valve member  10  may be implemented. 
     The valve body  12  defines an internal cylindrical bore  36  that is configured to receive a spool  38 . The cylindrical bore  36  may have a predetermined and close tolerance radial clearance that is configured to allow longitudinal movement of the spool  38  within the cylindrical bore  36 . The valve body  12  includes a pin  40  that is located within a bore  42  of the spool  38  and positioned along a longitudinal axis of the bore  42 . The pin  40  and the spool  38  may be concentric along the longitudinal axis, and the spool  38  may circumscribe the pin  40 . The pin  40  may be a push pin or a plunger. The pin  40  is slideable within the bore  42  relative to the spool  38 . The stroke of the pin  40  is limited at a first end  44  of the bore  42  and at a second end  46  of the bore  42  by the valve body  12 . The stroke of the pin  40  may be limited by a stop member formed at the first end  44  within the bore  42  that is drilled inside the spool  38 . The pin  40  and the second end  46  of the bore  42  of the spool  38  may define a chamber  47  that is in fluid communication with the control port  26  located at the second end  32  of the valve body  12 . 
     The spool  38  may include at least one metering land. In the example of  FIG. 1 , the spool  38  may include a first metering land  48  and a second metering land  50  that are spaced apart along the spool  38 . The first metering land  48  and the second metering land  50  define an area opening  52  therebetween. The area opening  52  may be fixed and moveable within the valve body  12  for fluidly connecting and disconnecting the controlled port  22  with at least one of the supply port  14  and the tank port  18 . The valve body  12  may define a longitudinal axis along which the spool  38  may oscillate between a first direction and a second direction opposite the first direction, such that the area opening  52  oscillates with the spool  38 . 
     The spool  38  may be configured to have at least two positions within the valve body  12 . The first position, shown in  FIG. 1 , is the biased or normal position of the spool  38 . The first position is defined by the tank port  18  being fluidly connected to the controlled port  22  via the second metering land  50 , and the first metering land  48  is positioned such that the spool blocks the supply port  14  from fluid communication with the controlled port  22 . In the first position, fluid flow may be discharged through the tank port  18 . The second position of the spool  38  is defined by the supply port  14  being fluidly connected to the controlled port  22  via the first metering land  48 , and the second metering land  50  being positioned such that the spool blocks fluid communication between the tank port  18  and the controlled port  22 . In the second position, fluid flow may be supplied through the supply port  14 . The spool  38  may also be configured to have a third position that is between the first position and the second position. The third position of the spool  38  may be defined at any location along the path of travel of the spool between the first position and the second position. The third position of the spool  38  may be defined by the first metering land  48  being positioned such that the spool  38  blocks the supply port  14  from being fluidly connected to the controlled port  22 , and the second metering land  50  being positioned such that the spool also blocks the tank port  18  from being fluidly connected to the controlled port  22 . In an alternative configuration of the spool  38 , the third position may be defined by the first metering land  48  being positioned to allow the supply port  14  to be fluidly connected to the controlled port  22 , and the second metering land  50  being positioned also to allow the tank port  18  to be fluidly connected to the controlled port  22 . 
     The spool has a first end  53  and a second end  54  opposite the first end  53 . The pin  40  is positioned within the bore  42  of the spool  38  at the second end  54  of the spool  38 . The first end  53  may be in contact with a biasing member  56  through a guide member  58 , and the biasing member may be a spring  56 . The guide member  58  and the spring  56  may be positioned within a chamber  60  located along the longitudinal axis of the valve body  12 . A portion of the first end  53  of the spool  38  may be engageable with the guide member  58  through an opening  62  of the chamber  60  such that the spring  56  and the guide member  58  may move the spool  38  along the longitudinal axis. The chamber  60  may be in fluid communication with the control port  28 . 
     A method of controlling a supply pressure in the valve member  10  may be provided. The valve member  10  includes a fluid inlet, or the supply port  14 , a fluid outlet, or the tank port  18 , and the controlled port  22 . The method includes positioning the spool  38  within the valve member  10  and positioning the pin  40  within the spool  38  at the second end  54  of the spool  38 . Referring in addition to  FIG. 2 , the method further includes applying a control pressure against an annular area  64  of the spool  38  and a cross-sectional area  66  (ω) of the pin  40  to move the spool  38  towards the second position of the spool  38 . The method also includes moving the spool  38  for fluidly connecting and disconnecting at least one of the fluid inlet  14  and the fluid outlet  18  with the controlled port  22 , and moving the pin  40  relative to the spool  38  to modulate the supply pressure in the valve member  10 . The spool  38  is moveable within the bore  36  to control fluid pressure through the valve body  12  to the controlled port  22  and the hydraulic actuating device  24 . 
     The spool  38  is also moveable along the longitudinal axis in a first direction, or a negative direction, towards the first position of the spool  38 , where the tank port  18  is fluidly connected to the controlled port  22 . The spool  38  is moveable in a second direction that is opposite the first direction, or a positive direction, towards the second position of the spool  38  where the supply port  14  is fluidly connected to the controlled port  22 . The position of the spool  38  is dependent on the fluid pressure acting on the spool  38 , or the forces acting on the spool  38 . The forces acting on the spool  38  in the positive direction, F+, include fluid pressure, or main supply pressure p 1 , within the chamber  47  defined by the pin  40  and the second end  46  of the spool bore  42  such that the supply pressure p 1  acts on an effective area of the spool  38  comprising interior surfaces of the spool  38  bounding the spool bore  42 , the effective are being equal to the cross-sectional area  66  (ω) of the pin  40 , and fluid pressure p s1  from the first control port  26  acting on the second end  54  of the spool  38 . Referring to  FIG. 2 , the fluid pressure p s1  acts on the annular area  64  of the spool  38  and on the cross-sectional area  66  (ω) of the pin  40  at the second end  54  of the spool  38 . The annular area  64  of the spool  38  against which the fluid pressure acts is equal to a cross-sectional area  68  (Ω) of the spool  38  minus the cross-sectional area  66  of the pin  40 . Effectively, providing the pin  40  allows two independent pressures to act on the second end  54  of the spool  38 . 
     The method of controlling the supply pressure may further include biasing the spool  38  in the negative direction and moving the spool  38  in the positive direction in response to the control pressure. The forces acting on the spool  38  in the negative direction, F − , include a force of the spring  56  acting on the spool  38  at the first end  53  of the spool  38 . The force of the spring  56  acting on the spool  38  is equal to F 0 -kx, where F 0  is a pre-loaded force of the spring  56  and kx is the force needed to compress the spring by a distance x, k being a spring constant. The method may further include applying a second control pressure, or fluid pressure p s2 , against the cross-sectional area  68  (Ω) of the spool at the first end  53  of the spool  38  and moving the spool  36  in the negative direction in response to the second control pressure. The total forces acting on the spool  38  may be represented by equation (1) which represents the forces acting on the spool  38  in the positive direction, and equation (2) which represents the forces acting on the spool  38  in the negative direction.
 
 F+=p 1·ω+ ps 1·Ω  (1)
 
 F−=ps 2·Ω+ F 0− kx   (2)
 
     Moving the spool  38  in the negative direction may further include moving the spool  38  towards the first position of the spool  38  and discharging fluid pressure from the controlled port  22 . If the forces acting in the negative direction, F − , are greater than the forces acting in the positive direction, F + , the spool  38  will be held at an end of its stroke against the valve body  12 , in the first position where the first metering land  48  is positioned such that the spool  38  blocks fluid communication between the controlled port  22  and the supply port  14 , and the second metering land  50  allows fluid communication between the controlled port  22  and the tank port  18 . 
     Moving the spool  38  in the positive direction may further include moving the spool  38  towards the second position of the spool  38  and supplying fluid pressure to the controlled port  22 . When at least one of the main supply pressure p 1  within the chamber  47  is increased, fluid pressure p s1  from the first control port  26  is increased, or the fluid pressure p s2  at the second control pressure port  28  is decreased, the spool  38  will start to move in the positive direction towards the second position of the spool  38 . The second position of the spool  38  is defined by the supply port  14  being fluidly connected to the controlled port  22 . The equilibrium position x of the spool  38 , or the position of the spool as a function of the different pressure in the valve member  10  will be represented by equation (3). 
     
       
         
           
             
               
                 
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                               p 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               s 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               2 
                             
                             - 
                             
                               p 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               s 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               1 
                             
                           
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                         · 
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                       - 
                       
                         p 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           1 
                           · 
                           ω 
                         
                       
                       + 
                       
                         F 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         0 
                       
                     
                     k 
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     While an increase in the main supply pressure p 1  or in the fluid pressure p s1  from the first control port  26  shifts the spool  38  in the positive direction, an increase in the fluid pressure p s2  generated at the second control pressure port  28  located at the opposite end of the valve body  12  shifts the spool  38  in the negative direction. 
     In addition to moving the spool  38  in the negative and positive direction towards the first and second position of the spool  38 , respectively, the method of controlling the supply pressure may still further include holding the spool  38  in a third position between the first position and the second position. The third position may be defined by the fluid inlet  14  and the fluid outlet  18  both being fluidly connected to the controlled port  22 , or the supply port  14  and the tank port  18  both being blocked from fluid connection with the controlled port  22 . 
     The spool  38  includes an opening area  70  between the controlled port  22  and the tank port  18 , and an opening area  72  between the controlled port  22  and the supply port  14 .  FIGS. 3 and 4  illustrate graphs showing the relationship between the opening areas  70 ,  72 , along the y-axis  74 , as the spool moves to different positions x from the negative direction to the positive direction, or to the right along the x-axis  76 . As shown in  FIGS. 3 and 4 , as the spool  38  moves in the positive direction, the opening area  70  decreases and the opening area  72  increases. When the spool  38  moves in the negative direction, the opening area  70  increases and the opening area  72  decreases. As also indicated by  FIGS. 3 and 4 , flow may be controlled at every position x of the spool  36 . 
     As shown in  FIG. 3 , in one exemplary embodiment the spool  38  may be configured such that during a portion of travel  78  of the spool  36 , both opening areas  70  and  72  are closed. When both opening areas  70 ,  72  are closed, the first metering land  48  is positioned such that the spool blocks fluid communication between the controlled port  22  and the supply port  14 , and the second metering land  50  is positioned such that the spool blocks fluid communication between the controlled port  22  and the tank port  18 . As shown in  FIG. 4 , in an alternative exemplary embodiment the spool  38  may be configured such that during a portion of travel  80 , both opening areas  70  and  72  are at least partially open. When both opening areas  70 ,  72  are at least partially open, the first metering land  48  may allow fluid communication between the controlled port  22  and the supply port  14  and the second metering land  50  may allow fluid communication between the controlled port  22  and the tank port  18 . For the given position x of the spool  38 , the main supply pressure p 1  may be represented by equation (4), as a function of the pressure at the control ports  26 ,  28 . 
                     p   ⁢           ⁢   1     =         (       p   ⁢           ⁢   s   ⁢           ⁢   2     -     p   ⁢           ⁢   s   ⁢           ⁢   1       )     ⁢     Ω   ω       +         F   ⁢           ⁢   0     -   kx     ω               (   4   )               
Equation (4) includes an amplification factor
 
             Ω   ω         
constituting a ratio of the cross-sectional areas  68  of the spool  38  and  66  of the pin  40 . The main supply pressure p 1  may be modulated by either of the fluid pressure p s1  at the first control port  26  or p s2  at the second control port  28 . The change between the fluid pressures will be multiplied by the amplification factor
 
               Ω   ω     .         
For example if the amplification factor is ten, a change of pressure of ten bar, or 1000 kilopascals, between the fluid pressure p s1  at the first control port  26  and the fluid pressure p s2  at the second control port  28  will determine a change of 100 bar in the setting pressure of the valve member  10 .
 
     In one exemplary embodiment, the valve member  12  may be configured such that the first control port  26  is always connected to the tank port  18  such that the fluid pressure p s1  at the first control port  26  will be zero at any given time, and equation (4) becomes equation (5). 
                     p   ⁢           ⁢   1     =         (     p   ⁢           ⁢   s   ⁢           ⁢   2     )     ⁢     Ω   ω       +         F   ⁢           ⁢   0     -   kx     ω               (   5   )               
The fluid pressure p s2  at the second control port  28  and the main supply pressure p 1  are directly proportional. An increase in the fluid pressure p s2  at the second control port  28  will thus determine an increase in the main supply pressure p 1  by the amplification factor
 
     
       
         
           
             
               Ω 
               ω 
             
             . 
           
         
       
     
     In still another example, the valve member  12  may be configured such that the second control port  28  is always connected to the tank port  18 . The fluid pressure p s2  at the second control port  28  will be zero at any given time, and equation (4) becomes equation (6). 
                     p   ⁢           ⁢   1     =         (       -   p     ⁢           ⁢   s   ⁢           ⁢   1     )     ⁢     Ω   ω       +         F   ⁢           ⁢   0     -   kx     ω               (   6   )               
The relationship between the fluid pressure p s1  at the first control port  26  and the main supply pressure p 1  is indirectly proportional such that an increase in the fluid pressure p s1  at the first control port  26  will decrease the value of the main supply pressure p 1  by the amplification factor
 
     
       
         
           
             
               Ω 
               ω 
             
             . 
           
         
       
     
     A diameter of the pin  40  may be selected or changed in accordance with a particular application, to accordingly control the cross-sectional area ω of the pin and the amplification factor 
               Ω   ω     .         
For example, me pin may nave a diameter between 2 mm and 15 mm and the spool may have a diameter between 6 mm and 20 mm, such that the amplification factor may have a value between 1 and 10. The diameter of the pin has an inversely proportional relationship to the amplification factor, such that increasing the diameter will decrease the amplification factor. For example, in an application where a low pressure supply to the actuating device is desired, the pin diameter may be selected to be half the length of the spool diameter, such that the amplification factor is two. In another application where a greater pressure supply is desired, the pin diameter may be selected to be ten times smaller than the diameter of the spool, such that the amplification factor is ten.
 
     Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.