Abstract:
A control valve system including a housing having an inlet, a first output, and a second output. The control valve system further includes a slidable valve positionable in a first position, where fluid communication is established between the inlet and the first output; a second position, where fluid communication is established between the inlet and the second output; and a third position, where fluid communication is prevented between the inlet and the first or second output. A solenoid valve assembly is coupled in fluid communication with the inlet and is positionable in an actuated position, where fluid communication is established with the inlet to move the valve from the first position to the second position, and a deactuated position. A feedback passage extends between the first output and the valve so as to position the valve in the third position in response to fluid pressure within the first output.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/309,843, filed Aug. 3, 2001, the disclosure of which is incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to control valves and, more particularly, relates to a control valve capable of reducing the energy consumption thereof. 
     BACKGROUND OF THE INVENTION 
     As is well known in the art, control valves have frequently been used to control and supply a working fluid, such as air, to a working device. Typically, these control valves employ a moveable valve spool disposed in a valve housing. The valve housing includes a plurality of fluid passages that are selectively interconnected in response to movement of the valve spool so as to control the flow of the fluid and, thus, the output of the control valve. 
     Conventional control valves often employ a solenoid valve mounted thereto for actuating the valve spool. The solenoid valve is controlled via an electrical input signal between a first position, where the solenoid valve is de-energized so as to close a fluid passage between an input pilot pressure and an output controlling pressure, and a second position, where the solenoid is energized via the electrical input so as to open a passageway between the input pilot pressure and the output controlling pressure. 
     It should be readily appreciated to one skilled in the art that in order to apply a constant controlling pressure, the electrical control signal must continue to energize the solenoid valve. That is, in order for a conventional control valve to maintain the spool in a predetermined position, it is necessary to maintain a constant control pressure upon one side of the spool. Therefore, in order to maintain this constant control pressure on the spool, it is necessary to maintain the solenoid valve in an opened and, thus, energized state. Moreover, it is necessary to employ full line fluid pressure to actuate the spool into the predetermined positions. Therefore, it should be understood that if it is preferred that the control valve be in this predetermined position for fluid output, electrical energy consumption to drive compressors to supply full line pressure will increase. 
     Accordingly, there exists a need in the relevant art to provide a control valve capable of producing an output of working fluid to be used with a conventional working device that is capable of minimizing the energy consumed during actuation. Furthermore, there exists a need in the relevant art to provide a control valve that maintains the position of a control element at a pressure less than full line pressure. Still further, there exists a need in the relevant art to overcome the disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     A control valve system having an advantageous construction is provided. The control valve system includes a slidable valve positionable in a first position, where fluid communication is established between the inlet and the first output; a second position, where fluid communication is established between the inlet and the second output; and a third position, where fluid communication is prevented between the inlet and the first or second output. A solenoid valve assembly is coupled in fluid communication with the inlet and is positionable in an actuated position, where fluid communication is established with the inlet to move the valve from the first position to the second position, and a deactuated position. A feedback passage extends between the first output and the valve so as to position the valve in the third position in response to fluid pressure within the first output. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view of a control valve system according to a first embodiment of the present invention illustrated in a normal operation mode where the solenoid valve assembly is energized; 
     FIG. 2 is a cross-sectional view illustrating the control valve system of FIG. 1 wherein the solenoid valve assembly is de-energized; 
     FIG. 3 is a cross-sectional view illustrating the control valve system of FIG. 1 being maintained in a predetermined position while the solenoid valve assembly remains de-energized and the valve spool is in an equilibrium position; 
     FIG. 4 is a circuit diagram illustrating the control valve system according to the first embodiment of the present invention; 
     FIG. 5 is a cross-sectional view of a control valve system according to a second embodiment of the present invention illustrated in an initial position where the first and second solenoid valve assemblies are de-energized and the piston is stationary; 
     FIG. 6 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first solenoid valve assembly is energized and the second solenoid valve assembly is de-energized; 
     FIG. 7 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first and second solenoid valve assemblies are de-energized and the piston continues to extend; 
     FIG. 8 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first solenoid valve assembly is de-energized and the second solenoid valve assembly is energized; 
     FIG. 9 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first and second solenoid valve assemblies are de-energized and the piston continues to retract; 
     FIG. 10 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first and second solenoid valve assemblies are de-energized and the piston is stationary; 
     FIG. 11 is a circuit diagram illustrating the control valve system according to the second embodiment of the present invention; 
     FIG. 12 is a circuit diagram of a control valve system according to a third embodiment of the present invention illustrated in an initial position where the solenoid valve assembly is de-energized and the piston is stationary; 
     FIG. 13 is a schematic diagram illustrating the feedback passage being disposed externally from the housing; and 
     FIG. 14 is a schematic diagram illustrating the feedback passage being disposed internally in the housing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For example, the principles of the present invention are equally applicable to a wide variety of valve systems, such as spool valves, poppet valves (i.e. resilient, metal, ceramic, and the like), trapping presses, and feedback controls. 
     Referring now to FIGS. 1-4 in which like reference numerals designate like or corresponding parts throughout the several views, there is illustrated a control valve system, which is designated generally by the reference numeral  10 . Control valve system  10  is shown as a fluid control valve in FIGS. 1-3 and as a fluid circuit in FIG.  4 . 
     Referring in particular to FIGS. 1-3, control valve system  10  comprises a main valve assembly  12  and a solenoid valve assembly  14 . Main valve assembly  12  is positioned adjacent to and operably coupled to solenoid valve assembly  14 . Main valve assembly  12  includes a fluid inlet passage  16 , a first exhaust passage  18 , a second exhaust passage  20 , and a valve bore  22 . Disposed within valve bore  22  is a valve member or spool  24 . Spool  24  is normally biased via a spring  26  into a seated position where a face portion  28  of spool  24  contacts a first stop  30  disposed in valve bore  22  to exhaust fluid from a backside chamber  32  of a piston member assembly  34  out second exhaust passage  20 . As will be described below, spool  24  is further positionable in an unseated position where face portion  28  of spool  24  is spaced apart from first stop  30  of valve bore  22 , yet a shoulder portion  36  disposed on an opposing side of spool  24  contacts a second stop  38  disposed in valve bore  22  to exhaust fluid from a front side chamber  40  of piston member assembly  34  through first exhaust passage  18 . 
     It should be appreciated that spring  26  may be eliminated. In this case, spool  24  would be actuated in response to differential fluid pressure exerted upon opposing faces of spool  24 . It is also anticipated that these faces could include differently sized surfaces areas (i.e. different area ratios), which would enable control valve system  10  to be easily modified to produce a wide range of different output pressures. 
     Control valve system  10  further includes a plurality of fluid passages interconnecting fluid inlet passage  16 , first exhaust passage  18 , and second exhaust passage  20 . A fluid passage  42  extends between fluid inlet passage  16  and an inlet to solenoid valve assembly  14 . Fluid passage  42  serves as a pilot passage to supply a pilot pressure to solenoid valve assembly  14 . A fluid passage  44  extends between an outlet of solenoid valve assembly  14  and a shuttle valve  46 . 
     Shuttle valve  46  generally includes a shuttle ball  48  moveably disposed in a shuttle chamber  50 . As will be described below, shuttle valve  46  moves in response to fluid pressure to fluidly block opposing ends of shuttle valve  46  against fluid flow. Shuttle valve  46  is fluidly coupled to a valve chamber  52  via a fluid passage  54 . Valve chamber  52  is adjacent face portion  28  of spool  24  and disposed within valve bore  22  such that fluid pressure within valve chamber  52  acts upon face portion  28  to move spool  24  against the biasing force of spring  26 . 
     However, as seen in FIGS. 12-14, shuttle ball  48  may be eliminated to provide a more simplified design. Specifically, a fluid passage  100  extends between front side chamber  40  and solenoid  58 . Fluid passage  100  permits the flow or exhaust of pilot fluid from valve chamber  52  to front side chamber  40  when solenoid  58  is in the position shown in FIG.  12 . However, it should be appreciated that fluid passage  100  may extend either externally (see FIG. 13) or internally (FIG. 14) of main valve assembly  12 . 
     Control valve system  10  further includes a feedback passage  56  extending between shuttle valve  46  and first exhaust passage  18 . Accordingly, shuttle ball  48  of shuttle valve  46  is moveable within shuttle chamber  50  into a first position, where shuttle ball  48  prevents fluid flow through feedback passage  56 , and a second position, where shuttle ball  48  prevents back flow of fluid through fluid passage  44 . 
     OPERATION 
     FIG. 1 illustrates control valve system  10  in a normal operation mode in which pressurized fluid from fluid inlet passage  16  is directed into backside chamber  32  of piston member assembly  34  to drive a piston  62  outward (to the right in the figures). Specifically, pressurized fluid from fluid inlet passage  16  is provided in fluid passage  42 . As seen in FIG. 4, solenoid valve assembly  14  is energized such that fluid communication is established between fluid passage  42  and fluid passage  44 . That is, a solenoid  58  of solenoid valve assembly  14  is energized such that a solenoid spool  59  is moved to the right in FIG. 4 against the biasing force of a solenoid spring  60 . Pressurized fluid is then introduced from fluid passage  44  into shuttle valve  46 , thereby moving shuttle ball  48  against feedback passage  56 . Pressurized fluid within shuttle valve  46  is then directed into valve chamber  52 . The fluid pressure within valve chamber  52  acts upon face portion  28  of spool  24 . Once the fluid pressure within valve chamber  52  is greater than the biasing force of spring  26 , spool  24  moves to the right until shoulder portion  36  of spool  24  is seated upon second stop  38 . This movement of spool  24  enables fluid to flow from fluid inlet passage  16  into backside chamber  32  of piston member assembly  34 , thereby extending piston  62  outward (to the right in FIGS.  1 - 4 ). Accordingly, when control valve system  10  is in the position illustrated in FIG. 1, fluid inlet passage  16 , backside chamber  32  of piston member assembly  34 , fluid passage  42 , shuttle valve  46 , and valve chamber  52  are all at the same fluid pressure, namely equal to the fluid pressure of fluid inlet passage  16 . 
     Referring now to FIG. 2, solenoid valve assembly  14  is de-energized and therefore pilot fluid from fluid passage  42  is prevented from entering shuttle valve  46  and, consequently, valve chamber  52 . Therefore, the biasing force of spring  26  acting on shoulder portion  36  of spool  24  biases spool  24  leftward until face portion  28  generally contacts first stop  30 . This leftward movement of spool  24  enables fluid communication between fluid inlet passage  16  and front side chamber  40  of piston member assembly  34 , thereby retracting piston  62 . 
     As can be appreciated from FIG. 2, feedback passage  56  is in fluid communication with front side chamber  40  of piston member assembly  34  and, therefore, is at the same fluid pressure. The introduction of pressurized fluid from fluid inlet passage  16  into front side chamber  40  and feedback passage  56  forces shuttle ball  48  of shuttle valve  46  leftward, since the fluid pressure of fluid inlet passage  16  is now greater than the fluid pressure within valve chamber  52 . This leftward movement of shuttle ball  48  and shuttle valve  46  then permits fluid flow from front side chamber  40  of piston member assembly  34  into valve chamber  52 , thereby increasing the fluid pressure within valve chamber  52  once again. During this time, fluid is exhausted from backside chamber  32  of piston member assembly  34  through second exhaust passage  20 . 
     As best seen in FIG. 3, fluid flow from fluid inlet passage  16  into front side chamber  40  of piston member assembly  34  and valve chamber  52  will continue until the pressure within valve chamber  52  is equal to the biasing force of spring  26 . When the fluid pressure within valve chamber  52  equals the biasing force of spring  26 , spool  24  reaches an intermediate equilibrium position wherein fluid flow from fluid inlet passage  16  into any of the remaining fluid passages is prevented. However, it should be appreciated by one skilled in the art that any fluid leaks or other anomalies which decrease the fluid pressure in front side chamber  40  of piston member assembly  34  will cause a simultaneous decrease in fluid pressure within valve chamber  52 . This decrease in fluid pressure in valve chamber  52  enables spring  26  to move spool  24  leftward, thereby again opening fluid communication between fluid inlet passage  16  and front side chamber  40  of piston member assembly  34 . As explained above, this fluid communication will continue until the fluid pressure within front side chamber  40 , feedback passage  56 , and valve chamber  52  is equal to the biasing force of spring  26 . Therefore, it should be clear that feedback passage  56  serves to provide a method of automatically maintaining a fluid pressure in front side chamber  40  of piston member assembly  34  simply by choosing an appropriate biasing force in spring  26 . The preferred fluid pressure to be maintained is directly proportional to the force of spring  26  and, therefore, spring  26  may be selected to determine the equilibrium fluid pressure. 
     Moreover, it should be appreciated that the pressure regulation feature of the present invention is accomplished without the need to provide full line pressure, which would otherwise consume an excessive amount of electrical energy. That is, by way of non-limiting example, traditional double action cylinders often operate such that their return to their initial position is only accomplished through the use of full-line pressure. This use of full-line pressure in the return stroke consumes an equivalent amount of compressed air as that consumed during a power stroke. This consumption of compressed air during the return stroke is believed to be unnecessary. According to the principles of the present invention, the low pressure in one outlet is sufficient for a rapid return stroke, which reduces the amount of compressed air that is consumed, thereby reducing the energy consumed by the work element. Additionally, due to the low pressure that is applied, the potential for leaks in the cylinder and/or fittings is also reduced. These advantages are obtained through the operation of the spool as a pressure regulator. 
     ALTERNATIVE EMBODIMENT 
     Referring now to FIGS. 5-11, in which like reference numerals designate like or corresponding parts throughout the several views and those views of the first embodiment, there is illustrated a control valve system  10 ′ in accordance with a second embodiment of the present invention. Control valve system  10 ′ is illustrated as a fluid control valve in FIGS. 5-10 and as a schematic fluid circuit in FIG.  11 . 
     Referring now to FIG. 5, control valve system  10 ′ comprises a second solenoid valve assembly  70  that is mounted to a main valve assembly  12 ′. Main valve assembly  12 ′ is positioned adjacent to and operably coupled to first solenoid valve assembly  14  and second solenoid valve assembly  70 . Main valve assembly  12 ′ includes fluid inlet passage  16 , first exhaust passage  18 , second exhaust passage  20 , and valve bore  22 . Disposed within valve bore  22  is spool  24 . Spool  24  is normally biased via spring  26  into a seated position where face portion  28  of spool  24  contacts first stop  30  disposed in valve bore  22  to exhaust fluid from backside chamber  32  of piston member assembly  34  out second exhaust passage  20 . As described above, spool  24  is positionable in an unseated position where face portion  28  of spool  24  is spaced apart from first stop  30  of valve bore  22 , yet shoulder portion  36  contacts second stop  38  disposed in valve bore  22  to exhaust fluid from front side chamber  40  of piston member assembly  34  through first exhaust passage  18 . 
     Control valve system  10 ′ further includes a plurality of fluid passages interconnecting fluid inlet passage  16 , first exhaust passage  18 , and second exhaust passage  20 . Fluid passage  42  extends between fluid inlet passage  16  and the inlet to solenoid valve assembly  14 . Fluid passage  42  serves as a pilot passage to supply pilot pressure to solenoid valve assembly  14 . Fluid passage  44  extends between the outlet of solenoid valve assembly  14  and shuttle valve  46 . Shuttle valve  46  generally includes shuttle ball  48  moveably disposed in a shuttle chamber  50 . Shuttle valve  46  moves in response to fluid pressure to fluidly block opposing ends of shuttle valve  46  against fluid flow. Shuttle valve  46  is fluidly coupled to valve chamber  52  via fluid passage  54 . Valve chamber  52  is adjacent face portion  28  of spool  24  and disposed within valve bore  22  such that fluid pressure within valve chamber  52  acts upon face portion  28  to move spool  24  against the biasing force of spring  26 . 
     Control valve system  10 ′ further includes a first feedback passage  72  extending between backside chamber  32  of piston member assembly  34  and an inlet of second solenoid valve assembly  70 . A restrictor  74  is disposed within fluid passage  70  to limit the amount of fluid flow through first feedback passage  72 . A fluid passage  76  extends between second solenoid valve assembly  70  and a second shuttle valve  78 . Fluid passage  76  is further in fluid communication with first feedback passage  72  downstream of restrictor  74 . 
     Second shuttle valve  78  generally includes a shuttle ball  80  moveably disposed within a shuttle chamber  82 . As will be described below, second shuttle valve  78  moves in response to fluid pressure to fluidly block opposing ends of second shuttle valve  78  against fluid flow. Second shuttle valve  78  is fluidly coupled to front side chamber  40  of piston member assembly  34  via a fluid passage  84 . Furthermore, a second feedback passage  86  extends between second shuttle valve  78  and first shuttle valve  46 . Accordingly, shuttle ball  48  of first shuttle valve  46  is moveable within shuttle chamber  50  into a first position, where shuttle ball  48  prevents fluid flow from first shuttle valve  46  to second shuttle valve  78  and permits fluid flow into valve chamber  52 , and a second position, where shuttle ball  48  prevents back flow of fluid through fluid passage  44  and permits fluid flow from second feedback passage  86  to valve chamber  52 . Furthermore, shuttle ball  80  of second shuttle valve  78  is moveable within shuttle chamber  82  into a first position, where shuttle ball  80  prevents fluid flow from fluid passage  76  to fluid passage  84 , and a second position, where shuttle ball  80  prevents back flow of fluid from second feedback passage  86  to fluid passage  76 . It should be noted, however, that shuttle ball  80  of second shuttle valve  78  can not block second feedback passage  86 , hence second feedback passage  86  is always in fluid communication with either fluid passage  76  or fluid passage  84 . 
     OPERATION 
     FIG. 5 illustrates control valve system  10 ′ in its initial equilibrium position. As illustrated in FIG. 6, first solenoid valve assembly  14  is then energized 
     FIG. 6 illustrates control valve system  10 ′ in a normal operation mode in which pressurized fluid from fluid inlet passage  16  is directed into backside chamber  32  of piston member assembly  34  to drive piston  62  outward (to the right in the FIGS.). Specifically, pressurized fluid from fluid inlet passage  16  is provided in fluid passage  42 . First solenoid valve assembly  14  is energized such that fluid communication is established between fluid passage  42  and fluid passage  44 . Pressurized fluid is then introduced from fluid passage  44  into first shuttle valve  46 , thereby moving shuttle ball  48  against second feedback passage  86 . Pressurized fluid within first shuttle valve  46  is then directed into valve chamber  52 . The fluid pressure within valve chamber  52  acts upon face portion  28  of spool  24 . Once the fluid pressure within valve chamber  52  is greater than the biasing force of spring  26 , spool  24  moves to the right until shoulder portion  36  of spool  24  is seated upon second stop  38 . This movement of spool  24  enables fluid to flow from fluid inlet passage  16  into backside chamber  32  of piston member assembly  34 , thereby extending piston  62  outward (to the right in FIGS.  5 - 11 ). Fluid flow is consequently established between backside chamber  32  and first feedback passage  72 , second solenoid valve assembly  70 , and second shuttle valve  78 . Due to the pressure difference in second shuttle valve  78 , shuttle ball  80  will shift to close fluid passage  84  and to open second feedback passage  86 . Accordingly, when control valve system  10  is in the position illustrated in FIG. 6, fluid inlet passage  16 , backside chamber  32  of piston member assembly  34 , fluid passage  42 , first shuttle valve  46 , and valve chamber  52  are all at the same fluid pressure, namely equal to the fluid pressure of fluid inlet passage  16 . 
     Referring now to FIG. 7, first solenoid valve assembly  14  and second solenoid valve assembly  70  are de-energized and therefore pilot fluid from fluid passage  42  is prevented from entering first shuttle valve  46  and, consequently, valve chamber  52 . Therefore, the biasing force of spring  26  acting on shoulder portion  36  of spool  24  begins to move spool  24  leftward until face portion  28  generally contacts first stop  30  (as shown in FIG.  9 ). This leftward movement of spool  24  enables fluid communication between fluid inlet passage  16  and front side chamber  40  of piston member assembly  34 , thereby retracting piston  62 . 
     As best seen in FIG. 8, when second solenoid valve assembly  70  is energized such that fluid communication is established between fluid passage  76  and an exhaust passage  88 . Consequently, fluid pressure is relieved from valve chamber  52 , first shuttle valve  46 , second feedback passage  86 , second shuttle valve  78 , and at least a portion of first feedback passage  72  downstream of restrictor  74 . This reduction of fluid pressure in valve chamber  52  causes spool  24  to move to the left under the biasing force of spring  26  as illustrated in FIG.  9 . Therefore, fluid flow is established between fluid inlet passage  16  and front side chamber  40  of piston chamber assembly  32  to retract piston  62 . 
     As can be appreciated from FIG. 10, fluid passage  84 , second shuttle valve  78 , second feedback passage  86 , and first shuttle valve  46  establish fluid communication between front side chamber  40  of piston member assembly  34  and valve chamber  52  and, therefore, are at the same fluid pressure in this state. As in the first embodiment, these passages serve to maintain the fluid pressure within front side chamber  40  at a pressure directly proportional to spring  26  and are able to overcome pressure leakage and the like using a pressure less than full line pressure, thereby reducing the amount of energy consumed. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.