Abstract:
A pressure reducing valve assembly ( 10 ) for receiving fluid from a high pressure line and delivering the fluid to a low pressure line includes an elongated tubular body ( 12 ), a pressure reducing valve (14) having a single, valved opening ( 54 ) interposed between high and low pressure ports ( 68 ),( 70 ), and a pressure reducing reservoir ( 16 ) defined substantially between the body ( 12 ) and the pressure reducing valve ( 14 ). The pressure reducing reservoir ( 16 ) comprises the only substantial fluid communication between the body ( 12 ) and the pressure reducing valve ( 14 ) and fluidly communicates with the high pressure port ( 68 ) by the single, valved opening ( 54 ). In preferred forms, the pressure reducing valve ( 14 ) includes a valve insert ( 64 ) housing a spring ( 62 ) that, among other functions, serves as a reset valve to further reduce the space requirements and decreasing the cost and complexity of the valve assembly ( 10 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to pressure reducing valves, such as are used for reducing the pressure of hydraulic fluid supplied from a common high pressure source and delivered to low pressure components of a hydraulic circuit. More particularly, the invention relates to a pressure reducing valve assembly having a single, valved opening interposed between high and low pressure ports therefore providing for a simple, cost-effective, durable construction relative to more parts-intensive conventional valves. 
     2. Discussion of Prior Art 
     Pressure reducing valves are commonly used when it is desired to use a common high pressure fluid source (e.g., a pump) to supply multiple components of a hydraulic circuit wherein one or more of the components require low pressure fluid and one or more of the components require high pressure fluid. For example, in a hydraulic clamping system having a single pump and multiple clamps operating at various pressure levels, a pressure reducing valve may be interposed between the high pressure hydraulic pump and one or more low pressure clamps. The valve delivers low pressure fluid to the selected clamps while allowing the remaining clamps to operate at a higher fluid pressure, thus eliminating the need for a separate hydraulic pump for each required pressure level. 
     A problem with prior art pressure reducing valves is that they are typically bulky and therefore require a great deal of space. This is problematic in applications where space is limited such as in clamping operations where numerous clamps requiring different fluid pressure levels may be mounted to a single fixture. 
     Another problem with prior art pressure reducing valves is that they are not efficiently designed and therefore include a large number of parts. This not only increases the overall size of the valves, which contributes to the problems described above, but also increases the cost and the complexity of the valves. 
     SUMMARY OF THE INVENTION 
     The present invention solves the above-described problems and provides a distinct advance in the art of pressure reducing valves by providing a pressure reducing valve assembly having a single, valved opening and limited fluid communication with a body providing a compact and efficiently designed valve with a fewer number of parts. 
     One embodiment of the pressure reducing valve assembly of the present invention broadly includes an elongated tubular body, a pressure reducing valve including a single, valved opening interposed between high and low pressure ports, and a pressure reducing reservoir defined substantially between the body and the pressure reducing valve. The pressure reducing reservoir comprises the only substantial fluid communication between the body and the pressure reducing valve and fluidly communicates with the high pressure port by the single, valved opening. 
     In preferred forms, the pressure reducing valve includes an inner chamber housing a spring that, among other functions, serves as a reset valve to further reduce the space requirements and decreasing the cost and complexity of the valve assembly. 
     Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiment and the accompanying drawing figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     A preferred embodiment of the invention is described in detail below with reference to the attached drawing figures, wherein: 
     FIG. 1 is a side elevational view of a pressure reducing valve assembly constructed in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is a plan view of the valve assembly; 
     FIG. 3 is a bottom view of the valve assembly; 
     FIG. 4 is a vertical sectional view of the valve assembly—with the spool and ball valve illustrated in elevation—shown mounted to the base and illustrating the pressure reducing valve out of its closed position; 
     FIG. 5 is a fragmentary vertical sectional view of the valve assembly—with the ball valve illustrated in elevation—shown mounted to the base and illustrating the pressure reducing valve in its closed position; 
     FIG. 6 is a fragmentary vertical sectional view of the valve assembly—with the ball valve illustrated in elevation—shown mounted to the base and illustrating the pressure reducing valve in a reset orientation; and 
     FIG. 7 is a horizontal cross-sectional view taken substantially along line  7 — 7  of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a pressure reducing valve assembly  10  constructed in accordance with a preferred embodiment of the present invention and configured for receiving fluid from a high pressure line and delivering the fluid to a low pressure line. The valve assembly  10  broadly includes an elongated tubular body  12 , a pressure reducing valve  14  having a single, valved opening, a pressure reducing reservoir  16  defined therebetween, and a base  18  which can be threadably coupled with the body  12  so that the valve  14  is disposed therebetween (see FIG.  4 ). 
     Turning initially to FIGS. 1 and 4, the body  12  is generally cylindrical and includes a hollow upper spring-housing section  20  that houses a spring assembly  22  and a spool  24 , and a relatively diametrically smaller lower valve-receiving section  26 . A cap assembly  28  is threadably coupled to the open upper end of the upper section  20 . 
     The upper body section  20  has a hexagonal shaped exterior sidewall defining a cylindrically shaped internal spool-receiving chamber  30  (see FIG.  4 ). The chamber  30  comprises an enlarged spring-receiving section  30   a  at its upper end and a diametrically smaller stem-receiving section  30   b  at its lower end. The spring-receiving section  30   a  preferably includes a vent aperture  30   c  bored through the sidewall providing air communication between the chamber  30  and the atmosphere so that no undesired motion-inhibiting air pressure buildup occurs in the otherwise sealed chamber  30 . 
     The spring assembly  22  is housed within the section  30   a  and includes a spring guide  32 , a needle bearing  34 , a spring support  36 , and a compression spring  38 . The spring guide  32  has a disk shaped distal section  32   a  having a smooth, flat top surface that abuts the protruding portion of a set screw (as will be subsequently described). The distal section  32   a  is diametrically larger than the portion of the set screw that projects into the chamber  30 . The spring guide  32  has a cylindrical shaped proximate section  32   b  configured to slidably engage the spring support  36  (see FIG.  4 ). The needle bearing  34  is received on the proximate section  32   b  so that it is disposed between the bottom surface of the distal section  32   a  and the top of the spring support  36 . The spring support  36  is generally cylindrical shaped having a center bore  36   a  and a rimmed portion  36   b . The bore  36   a  is configured to receive the proximate section  32   b  of the guide  32 . The support  36  is configured so that the cylindrical portion is received within the upper throat of the spring  38  and the rimmed portion  36   b  is engagingly disposed between the needle bearing  34  and the upper-most coil of the spring  38 . The upper end of the compression spring  38  is received on the spring support  36  and the lower end is received on the spool  24 . 
     The spool  24  includes a cylindrically shaped spring-receiving portion  24   a  at its upper end, a diametrically smaller stem  24   b  at its lower end, and a retention disk  24   c  generally at its center (see FIG.  4 ). The spring-receiving portion  24   a  is configured to be received within the lower end of the spring  38  so that the lower-most coil of the spring  38  abuts the top surface of the disk  24   c . The disk  24   c  is configured to move freely within the spring-receiving section  30   a  of the chamber  30  but is prevented from entering the stem-receiving section  30   b  thereof. The stem  24   b  is configured to be slidably and sealingly received in the stem-receiving section  30   b  of the chamber  30 . The upper portion of the stem  24   b  is cylindrically shaped and has exterior circumferential grooves  24   d . The grooves  24   d  provide a means for any fluid that leaks into the chamber  30  to seal between the stem  24   b  and the surface of the stem-receiving section  30   b . This provides a backup seal for the chamber  30  and facilitates the alignment and sliding of the stem  24   b  relative to the stem-receiving section  30   b  of the chamber  30 . The lower portion of the stem  24   b  is bottle shaped and has a diametrically reduced neck  24   e  configured to be received by the valve  14 . The lower portion of the stem  24   b  is diametrically smaller than its upper portion so that a lip seal  40  can be couplably received thereon (see FIG.  5 ). The seal  40  provides a fluid-tight seal between the chamber  30  and the valve  14  so that substantially no fluid enters the chamber  30 . As previously discussed, small amounts of fluid are expected to leak around the moving seal  40 , however, this fluid will be captured in the grooves  24   d.    
     The lower valve-receiving section  26  is integrally formed with the upper body section  20  and includes a cylindrically shaped, externally threaded sidewall  42  defining a central bored valve-receiving chamber open at its lower end. The sidewall  42  includes a circumferential wire-receiving groove  42   a  extending along the inside surface and an associated wire-receiving aperture  42   b  opposite the groove  42   a  and located on the outside surface of the sidewall  42 . The upper and lower body sections  20 ,  26  share a common chamber-dividing wall  44  having a central stem-receiving aperture operable to slidably receive the stem  24   b.    
     The cap assembly  28  includes a hexagonal shaped cap  46 , a set screw  48  screwably received therein, and a lock washer  50  operable to lockingly couple the cap  46  and the screw  48 . The cap  46  includes external threading for mating it to the upper section  20  and the hexagonal shape is operable to receive a driving device (e.g., a wrench) for facilitating the mating. The cap  46  further includes an axial bore spanning the entire width of the cap  46  and having internal threading for receiving the set screw  48 . The set screw  48  has external, complemental threading for mating to the cap  46  and includes a center bored recess  48   a  operable to receive a driving device (e.g., an allen wrench) for facilitating the mating. The set screw  48  has an axial length greater than the width of the cap  46  so that both ends of the screw  48  extend beyond the respective top and bottom surfaces of the cap  46 . The screw  48  is screwably received within the cap  46  so that the extent its proximate end extends into the upper section  20  is adjustable, for example, by using a driving device in the recess  48   a . Once the desired position is achieved, the lock washer  50  is threaded onto the screw  48  until it is flush with the top surface of the cap  46  so that the screw  48  is retained in the desired position. 
     The pressure educing valve  14  includes a valve body  52 , a single valved opening  54 , a valve seat  56 , ball valve  58 , a ball retainer  60 , a spring  62 , and a valve insert  64 . The valve body  5  is generally cylindrically shaped and has an upper end configured to sealably engage the valve-receiving chamber in the lower body section  26  and a lower end configured to sealably engage the base  18 . The valve body  52  includes circumferential grooves at each end for receiving  0 -ring type valve seals  52   a,   52   b,   52   c,   52   d  that facilitate the fluid seal between the valve body  52  and the corresponding valve-receiving chamber and base  18 . The valve body  52  has a circumferential wire-receiving groove  66  and an associated aperture (not shown) located toward the center o its upper end that cooperate to receive wire (as will subsequently be described) o retain the position of the valve  14  relative to the lower body section  26 . The valve body  52  is diametrically smaller at its lower end (relative to its upper end) to facilitate mating to the base  18 . 
     The valve body  52  has an internal central bore defining a high pressure chamber  68  and a low pressure chamber  70  with the single valved opening  54  disposed therebetween. The high pressure chamber  68  has a stepped configuration with internal threading on its lower-most step. The low pressure chamber  70  has a generally conical shape complementing the bottle shaped portion of the stem neck  24   e . The valve body  52  includes a high pressure port comprising a plurality of fluid-receiving channels  72  located generally along the center circumferential surface and extending into the high pressure chamber  68  (see FIG.  7 ). The valve body  52  further includes a low pressure port comprising a plurality of fluid-discharging channels  74  along its top surface that are bored the entire axial length of the valve body  52  (see FIGS.  4  and  7 ). The fluid-discharging channels  74  must not intersect either the fluid-receiving channels  72  or the high and low pressure chambers  68 ,  70 . 
     The single valved opening  54  is defined along the internal central bore of the valve body  52  disposed between the high pressure chamber  68  and the low pressure chamber  70 . Although there are other openings in the valve  14  (e.g., the channels  72 ,  74 ), the opening  54  is the only opening that fluidly connects the high pressure side of the valve  14  (i.e., the high pressure line, the fluid-receiving channels  72 , and the high pressure chamber  68 ) with the low pressure side of the valve (i.e., the low pressure line, the fluid-discharging channels  74 , and the low pressure chamber  70 ). The opening  54  is also the only valved opening in the valve assembly  10 . The valve seat  56  is defined by shoulders formed in the lower end of the low pressure chamber  70  at the opening  54  (see FIG.  6 ). 
     The ball valve  58  rides in the ball retainer  6 O and is shiftable into and out of a closed position as shown in FIG. 5 wherein the ball valve  58  is in sealing engagement with the valve s at  56 . The ball valve is configured to completely close the opening  54  when in the closed position so that fluid communication between the high and low pressure chambers  68 , 70  is prevented. The ball retainer  60  is configured to be slidably received within the upper-most step of the high pressure chamber  68 . The retainer  60  is generally cylindrically shaped having a ball-receiving cup  60   a  at its upper end configured to receive the ball valve  58 so that a sufficient portion of the ball valve  58  protrudes out of the pup  60   a  to seal the opening  54  when the valve  14  is in the closed position. The upper end of the retainer  60  further includes a flange  60   b  that both prevents the retainer  60  from retracting too far into the valve insert  64  and facilitates maintaining engagement of the ball valve  58  with either the stem  24   b  or the valve seat  56  (e.g., high pressure fluid exerts a lifting force against the underside of the flange  60   b ). The retainer  60  includes a central spring-receiving bore in its lower end configured to receive the spring  62  and having a bleeder vent  60   c  therein to prevent undesired hydraulic locking conditions. The spring  62  is received in this bore and is configured to exert a spring force between the retainer  60  and the insert  64  sufficient to maintain substantially constant engagement of the ball valve  58  with either the stem  24   b  (i.e., when the valve  14  is pot in the closed position) or the valve seat  56  (i.e., when the valve  14  is in the closed position). The spring force of the spring  62  must be such that it never overcomes the spring force of the compression spring  38  (i.e., the spring  62  does not cause the spool  24  to move). 
     The valve insert  64  is configured to be sealingly received within the high pressure chamber  68  of the valve body  52 . The lower end of the insert  64  includes external circumferential threading, configured to threadably mate the insert  64  to the internal threading of the valve body  52 , and a center bored recess  76  operable to receive a driving device (e.g., an allen wrench) for facilitating the mating. The insert  64  includes a circumferential groove generally located at the center of the insert  64  (but in any event below the fluid receiving channels  72  of the valve body  52 ) and operable to receive O-ring type insert seals  64   a,   64   b.  The upper end of the insert  64  includes a central bore operable to receive the spring  62  and the lower end of the ball retainer  60  (see FIG.  4 ). The upper end of the insert  64  has a triangular shaped perimeter that further defines the high pressure chamber  68  to provide clearance for high pressure fluid moving through the chamber  68  (see FIG.  7 ). The upper end of the insert  64  is further configured so that when it is fully received in the valve body  52 , it does not protrude into the upper-most step of the high pressure chamber  68 . This allows sufficient clearance for the ball valve  58  (and the retainer  60 ) to slide into and out of the closed position. 
     The pressure reducing reservoir  16  is defined in the lower body section  26  between the upper end of the valve  14  and the chamber-dividing wall  44 . The valve  14  is pressure fit into the lower body section  26  and a lock wire  78  is wound into the wire-receiving grooves  42   a , 66  to maintain a reservoir defining position (see FIGS.  4  and  6 ). Particularly, the wire  78  has a crimped end that fits through the wire-receiving aperture  42   b  in the lower section sidewall  42  and is received in the aperture in the groove  66  on the valve body  52 . The valve body  52  is then rotated to wind the wire  78  into the grooves  42   a , 66 . The pressure reducing valve  14  and the body  12  are not designed to be uncoupled once they have been mated together (for manufacturing purposes they have been machined as separate components), therefore, the wire-receiving aperture  42   b  in the sidewall  42  can be closed after the mating is completed to prevent uncoupling of the components, for example, by peening it closed. Fluid in the reservoir  16  is low pressure fluid and the reservoir  16  provides adequate clearance to allow the fluid passing through the opening  54  to enter the fluid-discharging channels  74 . As will subsequently be described in detail, the reservoir  16  provides the only fluid communication between the body  12  and the valve  14 . 
     As illustrated in FIGS. 4,  5 , and  6 , the valve assembly  10  is attached to the base  18 . The base  18  includes a recess  80 , inlet and outlet ports  82 ,  84 , respectively, and corresponding fluid passageways  86 ,  88 . The recess  80  is configured to sealingly receive the valve  14  mated to the body  12 . The recess  80  includes threading operable to threadably receive the external threading of the lower section  26  of the body  12 . An O-ring type base seal  18   a  prevents fluid leakage between the body  12  and the base  18 . The inlet and outlet ports  82 ,  84  include internal threading for connecting with externally threaded high and low pressure lines, respectively. The fluid passageways  86 ,  88  provide fluid communication between the inlet and outlet ports  82 ,  84 , respectively, and the corresponding fluid-receiving and fluid-discharging channels  72 ,  74 . 
     OPERATION 
     High pressure fluid (e.g., 5000 psi) from the high pressure line (originating from a high pressure fluid source such as a pump) enters the pressure reducing valve assembly  10  through the inlet port  82  of the base  18 , where it passes through the fluid passageway  6  into the fluid-receiving channels  72  and enters the high pressure chamber  68  of the pressure reducing valve  14 . When fluid is initially delivered to the inlet port  82  the valve assembly  10  is in the state illustrated in FIG.  4 . Specifically, the compression spring  38  overcomes the spring force of the spring  62  and biases the pressure reducing valve  14  out of the closed position. The neck  24   e  of the stem  24   b  protrudes though the opening  54  displacing the ball valve  58  off of the valve seat  56 . The ball valve  58  is retained in the ball-receiving cup  60   a  of the ball retainer  60  which is depressed into the central bore of the valve insert  64 . Fluid freely flows from the high pressure chamber  68  through the single valve opening  54  into the low pressure chamber  70 . Once in the low pressure chamber  70 , fluid is received in the pressure reducing reservoir  16 , passes through the fluid-discharging channels  74  through the fluid passageway  88  out the outlet port  84  and into the low pressure line where it is delivered to a low pressure component such as a clamp. 
     Fluid freely flow into the low pressure line until the fluid pressure reaches a pre-selected operating level (e.g., 750 to 4500 psi), wherein the valve assembly  10  shifts into the state illustrated in FIG.  5 . Specifically, fluid pressure in the reservoir  16  exerts a force against the stem  24   b  that overcomes the spring force in the compression spring  38  causing the neck  24   e  of the stem  24   b  to recess out of the opening  54  and allowing the force of the spring  62  to simultaneously slide the ball valve  58  into sealing engagement with the valve seat  56  (corresponding to the valve  14  being in the closed position). When the valve  14  is in the closed position, fluid is prevented from flowing through the opening  54  between the high and low pressure chambers  68 , 70 . The pressure differentiation between the high and low pressure chambers  68 , 10  occurs at the single valved opening  54 . Fluid in the high pressure chamber  68  is under high pressure and fluid in the low pressure chamber  70  is under low pressure. 
     The pre-selected operating level pressure is selected in accordance with the needs of the low pressure component being controlled by the valve assembly  10 . The illustrated valve assembly  10  is capable of delivering low pressure fluid at a pressure between 500 psi and 4500 psi. The valve assembly  10  is set to control this level by adjusting the set screw  48  until the desired spring force in the compression spring  38  is achieved—i.e., a spring force that is completely overcome only by fluid pressure at or just above the operating level pressure. To increase the spring force exerted by the compression spring  38 , the screw  48  is turned in a clockwise direction when viewed from above as illustrated in FIG. 2 so that it protrudes further into the spool-receiving chamber  30  and further depresses the spring guide  32 . To decrease the spring force exerted by the compression spring  38 , the process just described is reversed. As the fluid pressure approaches the pre-selected operating level, it will begin to overcome the spring force of the compression spring  38  thereby causing the stem  24   b  to retract out of the opening  54 . As the ball valve  58  slides toward the closed position, less fluid is allowed through the opening  54 ; however, until the spring force of the compression spring  38  is completely overcome and the stem  24   b  fully retracts out of contact with the ball valve  58 , some fluid passes between the high and low pressure chambers  68 , 70 . 
     The valve assembly  10  provides and maintains low pressure fluid in the low pressure line at a constant and steady pressure. The valve assembly  10  reacts only to pressure changes in the low pressure line (except when performing its reset function as described below). The valve  14  is shifted into and out of the closed position based on the pressure level in the low pressure chamber  70 . The valve  14  does not react to pressure changes in the high pressure line with one exception: the valve  14  provides a reset function if the fluid pressure in the high pressure chamber  68  drops sufficiently below the fluid pressure in the low pressure chamber, for example if the fluid source is shut off and/or does not maintain static high pressure conditions. This pressure differential will overcome the spring force of the spring  62  causing the ball retainer  60  to retract into the valve insert  64  and shifting the ball valve  58  off of the valve seat  56  (corresponding to the valve assembly  10  being in the state illustrated in FIG.  6 ). Accordingly, the century spring  62  provides a reset function obviating the need for a separate reset valve. The state depicted in FIG. 6 is illustrated for descriptive purposes only. In application, depending on the conditions, the valve assembly construction, and the valve settings, the force of the compression spring  38  may instantaneously overcome the reduced pressure in the low pressure chamber  70  as the ball valve  58  shifts off of the valve seat  56 , thereby shifting the assembly  10  into the state illustrated in FIG.  4 . 
     The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiment, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.