Related Applications

This application claims the benefit of U.S. Provisional Application No.

61/986,193 filed April 30, 2014, which is hereby incorporated herein by reference.

Field of Invention

The present invention relates generally to a fluid control valve, and more particularly to a hydraulic sectional control valve having an integrated internal load transition check valve.

Background

Fluid control valves are used in a wide variety of applications for causing and controlling motion of various components. Hydraulic fluid control valves and systems are used in such applications when relatively large forces are to be transmitted and controlled through such components.

One type of hydraulic fluid control valve is a sectional valve. A sectional valve may typically include a plurality of separate cast and machined metal working valve sections. Each working valve section may include internal fluid passages, external ports, and spool bores with valve spools slidably disposed within each spool bore. The spool bores may include main control valve spool bores in which main directional control valve spools are slidably disposed, compensator spool bores in which compensator spools are slidably disposed to maintain predetermined pressure drops across the main control spools or to otherwise control fluid pressure, and/or load transition check valves.

Such working valve sections that include a load transition check valve may be used, for example, in hydraulic systems in which it is anticipated that a load to be moved by the hydraulic system may cause a work port pressure in the hydraulic fluid that exceeds the outlet pressure of the hydraulic pump of the system under certain conditions. This may occur, for example, when a load has been lifted off a support structure by the hydraulic system, and the load is then to be held in its lifted position while hydraulic pump pressure decreases. Under this condition, the load transition check valve may operate as a check valve to maintain the required work port pressure to hold the load in its lifted position without requiring continuous high hydraulic pump pressure. Further under this condition, the load transition check valve may operate as a transition valve to require pump pressure to build to a level above the work port pressure before communicating pump pressure to the work port to prevent undesirable back movement of the load.

Summary of Invention

In working valve sections of the type described above, the work ports, the pressure compensator spool bore, and the load transition check valve spool bore may all open to the top of the housing of the working valve section. To

accommodate all of these elements at the top of the housing, the size of the housing may be relatively large. Therefore, provided are exemplary embodiments reducing the size of the housing for a working valve section of a hydraulic sectional control valve that includes a load transition check valve. Specifically, exemplary embodiments include a load transition check valve spool bore that opens to the side of the housing of the working valve section, to reduce the required size of the top of the housing.

According to one aspect of the invention, a working valve section for a sectional fluid control valve includes a valve section housing having a substantially planar surface for being attached to an adjacent valve section housing; a main control valve spool bore extending into the housing and being substantially parallel to the planar surface; and a load transition check valve spool bore extending into the housing from the planar surface.

Optionally, the housing includes a work port and a pump pressure passage, and the main control valve spool bore and the load transition check valve spool bore are in a fluid flow path through the housing intermediate the pump pressure passage and the work port.

Optionally, the load transition check valve spool bore is in the fluid flow path intermediate the main control valve spool bore and the work port.

Optionally, a main control valve spool is slidably disposed in the main control spool bore and a load transition check valve spool slidably disposed in the load transition check valve spool bore.

Optionally, an end cap closing the load transition check valve spool bore, and the end cap is disposed completely within the load transition check valve spool bore.

Optionally, the valve section includes another work port, a compensator spool bore having a compensator spool slidably disposed therein, the work ports are substantially parallel to and adjacent the compensator spool bore, and the work ports and the compensator spool bore open to an outside surface of the housing that is disposed in a plane substantially perpendicular to the planar surface.

Optionally, a compensator spool bore is disposed parallel to the planar surface.

Optionally, a compensator spool bore is disposed perpendicular to the main control spool bore.

Optionally, a compensator spool bore is disposed perpendicular to the load transition check valve spool bore.

Optionally, a compensator spool bore is in a fluid flow path through the housing intermediate the pump pressure passage and the load transition check valve spool bore.

According to another aspect, a working valve section for a sectional fluid control valve includes a main control valve spool bore extending into the housing; a work port opening onto an outer side of the valve section and the opening faces perpendicular to a length of the main control valve spool bore; and a load transition check valve spool bore extending into the housing perpendicular to the workport opening and perpendicular to the length of the main control valve spool bore. Optionally, a valve section housing having a substantially planar surface for being attached to an adjacent valve section housing, and wherein the load transition check valve spool bore opens onto the planar surface.

Optionally, the housing includes a pump pressure passage, and the main control valve spool bore and the load transition check valve spool bore are in a fluid flow path through the housing intermediate the pump pressure passage and the work port.

Optionally, the load transition check valve spool bore is in the fluid flow path intermediate the main control valve spool bore and the work port.

Optionally, the section includes a main control valve spool slidably disposed in the main control spool bore and a load transition check valve spool slidably disposed in the load transition check valve spool bore.

Optionally, an end cap closes the load transition check valve spool bore, and the end cap is disposed completely within the load transition check valve spool bore.

Optionally, the section includes another work port, a compensator spool bore having a compensator spool slidably disposed therein, the work ports are

substantially parallel to and adjacent the compensator spool bore, and the work ports and the compensator spool bore open to an outside surface of the housing that is disposed in a plane substantially perpendicular to the planar surface.

Optionally, a compensator spool bore is disposed parallel to the planar surface.

Optionally, a compensator spool bore is disposed perpendicular to the main control spool bore.

Optionally, a compensator spool bore is disposed perpendicular to the load transition check valve spool bore.

The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings. Brief Description of the Drawings

Figure 1 is a cross sectional view of a conventional working valve section of a hydraulic sectional control valve;

Figures 2a-2h are various views of an exemplary working valve section of a hydraulic sectional control valve; and

Figures 3a-3c are various additional views of the working valve section illustrated in Figures 2a-2h, further showing pilot control valves for the main control valve spool of the working valve section. Detailed Description

Referring now to the drawings in greater detail, Figure 1 illustrates a prior art pilot operated hydraulic valve work section 10. The valve section 10 is one section of a complete sectional hydraulic valve (not shown) that includes multiple sections secured together by tie rods (not shown). The valve section 10 includes a cast and machined housing 1 1 having a main directional control valve spool bore 12 in which a pilot operated directional control valve spool 13 is slidably disposed. A pump pressure core or passage 14 receives hydraulic fluid under pressure from a hydraulic system pump (not shown), and the valve spool 13 opens and closes fluid flow from pump pressure passage 14 to flow metering port 15. The housing 1 1 further includes a compensator spool bore 16 in which a compensator spool 17 is slidably disposed to control flow to a regulated flow core or passage 18. The housing 1 1 further includes a transition check valve spool bore 19, in which a transition check valve poppet or spool 20 is slidably disposed to control flow to a supply passage 21 .

When main control valve spool 13 is in its centered or off position illustrated in Figure 1 , no hydraulic fluid flows through valve section 10. When main control valve spool 13 is shifted to the right as viewed in Figure 1 by its pilot operators, hydraulic fluid flows through passage 14 past main control spool 13 to passage 15, past compensator spool 17 to passage 18, and past load transition check valve spool 20 to supply passage 21 . From supply passage 21 , hydraulic fluid flows past main spool 13 to active work port 22. When main control valve spool 13 is shifted to the left as viewed in Figure 1 by its pilot operators, hydraulic fluid flows through passage 14 past main control spool 13 to passage 15, past compensator spool 17 to passage 18, and past load transition check valve spool 20 to supply passage 21 . From supply passage 21 , hydraulic fluid flows past main control spool 13 to active work port 23 through passage 24. Relief valves 25 and 26 provide shock protection and high pressure limit for work ports 22 and 23, respectively, by connection to a tank passage. When the hydraulic fluid pressure in regulated flow passage 18 exceeds pressure in the active one of work ports 22 or 23, load transition check valve spool 20 opens to allow hydraulic fluid flow to the active work port. When the hydraulic fluid pressure in regulated flow passage 18 is less than the pressure in the active one of work ports 22 or 23, transition load check valve spool 20 closes to maintain the pressure in the active work port 22 or 23 and thereby prevent back flow and movement of the load supported by fluid pressure in the active one of work ports 22 or 23 until fluid pressure in regulated flow passage 18 exceeds the pressure in the active one of work ports 22 or 23. The housing 1 1 also includes tie rod holes 27, and a tie rod (not shown) extends through each hole 27 and through corresponding holes in adjacent valve sections (not shown) and are torqued to assemble all of the valve sections of the complete hydraulic fluid control sectional valve together in fluid tight relationship.

As illustrated in Figure 1 , work ports 22 and 23, compensator spool bore 16, and transition check valve spool bore 19 all open to the top surface 28 of housing 1 1 of working valve section 10. Bores 16 and 19 receive a threaded fitting end cap 29 and 30, respectively, and work ports 22 and 23 receive suitable fittings (not shown) for securing a suitable hose or tube or pipe or other device for conveying hydraulic fluid. The longitudinal length of the housing 1 1 along its longitudinal axis 31 is determined primarily by the presence of work ports 22 and 23 and bores 16 and 19 and their associated fittings along top surface 28 of housing 1 1 , and this results in a relatively long or large longitudinal extent for the housing 1 1 . The present invention eliminates the load transition check valve bore 19 and its associated fitting end cap 30 from the top surface 28 of housing 1 1 of prior art valve section 10, to permit the longitudinal extent of housing 1 1 to be reduced from that of the prior art sectional valve illustrated in Figure 1 . Referring now to Figures 2a-2h and 3a-3c, a preferred embodiment of the invention provides a pilot operated hydraulic valve work section 120. The valve section 120 is one section of a complete sectional hydraulic valve (not shown) that includes multiple sections secured together by tie rods (not shown). The valve section 120 includes a cast and machined housing 121 having a main directional control valve spool bore 122 in which a pilot operated directional control valve spool 123 is slidably disposed. A pump pressure core or passage 124 receives hydraulic fluid under pressure from a hydraulic system pump (not shown), and the valve spool 123 opens and closes fluid flow from pump pressure passage 124 to flow metering port 125. The housing 121 further includes a compensator spool bore 126 in which a compensator spool 127 is slidably disposed to control flow to a regulated flow core or passage 128 (shown in both Figure 2c and Figure 2f). The housing 121 further includes a transition check valve spool bore 129, in which a transition check valve poppet or spool 130 is slidably disposed to control flow to a supply passage 131 .

When main control valve spool 123 is in its centered or off position illustrated in Figure 2c, no hydraulic fluid flows through valve section 120. When main control valve spool 123 is shifted to the right as viewed in Figure 2c by its pilot operators, hydraulic fluid flows through passage 124 to passage 125, past compensator spool 127 to passage 128, and past load transition check valve spool 130 to supply passage 131 . From supply passage 131 , hydraulic fluid flows past main spool 123 to active work port 132. When main control valve spool 13 is shifted to the left as viewed in Figure 2c by its pilot operators, hydraulic fluid flows through passage 124 to passage 125, past compensator spool 127 to passage 128, and past load transition check valve spool 130 to supply passage 131 . From supply passage 131 , hydraulic fluid flows past main control spool 123 to active work port 133 through passage 134. Relief valves 135 and 136 provide shock protection and high pressure limit for work ports 132 and 133, respectively, by connection to a tank passage. When the hydraulic fluid pressure in regulated flow passage 128 exceeds pressure in the active one of work ports 132 or 133, load transition check valve spool 130 opens to allow hydraulic fluid flow to the active work port. When the hydraulic fluid pressure in regulated flow passage 128 is less than the pressure in the active one of work ports 132 or 133, transition load check valve spool 130 closes to maintain the pressure in the active work port 132 or 133 and thereby prevent back flow and movement of the load supported by fluid pressure in the active one of work ports 132 or 133 until fluid pressure in regulated flow passage 128 exceeds the pressure in the active one of work ports 132 or 133. The housing 121 also includes tie rod holes 137, and a tie rod (not shown) extends through each hole 137 and through corresponding holes in adjacent valve sections (not shown) and are torqued to assemble all of the valve sections of the complete hydraulic fluid control sectional valve together in fluid tight relationship.

As best illustrated in Figure 2f and 3a-3c, load transition check valve spool bore 129 opens to a substantially planar side surface 142 of housing 121 and is closed by a threaded end cap or plug 143. The threaded end cap 143 includes an internal blind bore 144 in which load transition valve spool or poppet 130 is slidably disposed, and a biasing spring is provided in blind bore 144 to bias spool 130 to its closed position illustrated in Figure 2f and 3b-3c. The threaded end cap 143 includes a shaped head 145 that may be gripped with a wrench or other tool during assembly, and the outwardly facing end surface of shaped head 145 is substantially planar and is disposed in substantially coplanar relationship to surface side 142. When work section 120 is assembled as part of a complete hydraulic sectional control valve as described above, a generally planar side surface of an adjacent valve section (not shown) engages and is compressed against side surface 142 with sealing engagement and prevents loosening of end cap 145 during operation of valve section 120. This arrangement of end cap 145 and transition load check transition valve spool 130 opens the load check transition valve spool bore 129 to the side surface 142 of housing 121 instead of top surface 138 of housing 121 , to reduce the longitudinal extent of housing 121 along its longitudinal axis 141 while locking the load check transition valve spool 130 in place between adjacent valve sections.

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.