Abstract:
A regenerative valve includes a housing having a valve bore therein intersecting with an extension passage interconnecting a pump and a piston extension chamber, a retraction passage interconnecting a sump and a piston retraction chamber, and a regenerative passage for communicating fluid from the retraction to the extension chamber upon extension of the piston. A poppet member is movable in the bore to open and block fluid flow through the extension passage. A shuttle member is movable in the bore to either open or block one or the other of the regenerative and retraction passages. The shuttle member engages the poppet to cause the poppet to open the extension passage when the shuttle moves to close the retraction passage and open the regenerative passage.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a regenerative or speed-up valve which operates to enhance or speed up the extension of a reciprocating cylinder. 
     Many valve arrangements for speeding up the extension of a double-acting cylinder are known in the prior art. One type of such speed-up valve includes a single shuttle or spool member which is movable within a ported valve housing. This type of speed-up valve is described in U.S. Pat. Nos. 2,890,683; 2,590,454; and 1,812,587. However, the single shuttle type valve is subject to a failure condition wherein a rapid pressure buildup in the rod end of the cylinder (due to heavy loads on the cylinder) may prevent or delay the shuttle from shifting to the regenerative or speed-up mode wherein fluid is recirculated from the rod to the head end of the cylinder. In order to solve this problem, more complex or compound speed-up valves have been proposed which utilize a combination of separate check and shuttle valves. Such compound speed-up valves are disclosed in U.S. Pat. Nos. 4,194,436; 4,144,947; 3,654,835 and 3,568,707, for example. However, such compound speed-up valves have been costly, complex and bulky due to the physical arrangements of the separate shuttle and check valve elements. 
     SUMMARY OF THE INVENTION 
     An advantage of the present invention is that it provides a speed-up valve of simple and compact design. 
     Another advantage of the present invention is that it provides a speed-up valve which is not subject to pressure locks during extension of cylinders with heavy loading. 
     These and other advantages are achieved by the present invention which provides a speed-up valve with a housing having a valve bore therein, an extension passage for connecting a pressure source to a cylinder extension chamber, a retraction passage for connecting a fluid reservoir with the cylinder retraction chamber and a regeneration passage for interconnecting the cylinder retraction and extension chamber. These passages all intersect the valve bore. A directional control valve can reverse the connections between the source and reservoir and the extension and retraction chambers so that the cylinder may be extended or retracted. A poppet spring urges a poppet valve member, which moves in the bore, into sealing engagement with a seat in the extension passage to prevent fluid flow from the source to the extension chamber. A shuttle spring urges a hollow cylindrical shuttle valve member movable in the bore to a normal position blocking the regeneration passage and opening the retraction passage. The shuttle is movable to a regeneration position blocking the retraction passage and opening the regeneration passage. The poppet valve member includes a rod which slidably extends through the hollow shuttle and which rigidly interconnects a poppet head engageable with the seat and a flange. The shuttle is positioned between the head and the flange. The shuttle engages the flange as it moves to its regeneration position to unseat the poppet valve member and permit fluid flow through the extension passage to the extension chamber during extension of the cylinder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial sectional view of a speed-up valve constructed according to applicants&#39; invention and shown in a neutral operating position. 
     FIGS. 2 and 3 are views similar to that of FIG. 1, but showing the applicants&#39; speed-up valve in cylinder-retracting and cylinder-extending operating positions, respectively. 
    
    
     DETAILED DESCRIPTION 
     A hydraulic system 10 includes a pump 12 and reservoir 14 connected to a conventional 4-way, 3-position directional control valve 16. A regenerative or speed-up valve 18 is coupled between the directional control valve 16 and a 2-way hydraulic cylinder or fluid motor 20. 
     Speed-up valve 18 includes a housing 22 which defines a stepped valve bore 24 extending therein. The wall of stepped bore 24 defines a poppet seat at 26 and an annular axially facing shoulder at 28. A threaded end cap 30 is screwed into the end of bore 24 to fluidly seal bore 24 from the exterior environment. First and second control passages 32 and 34 intersect the valve bore 24 near opposite ends of bore 24 and communicate the valve bore 24 with the respective outlets of the directional control valve 16. A first work passage 36 communicates with the head end chamber 42 of the fluid motor 20 and includes a portion 40 which intersects valve bore 24 at shoulder 26. A second work passage 44 is communicated with the rod end 48 of fluid motor 20 and includes branches 50 and 52 which communicate with the valve bore 24 at annular grooves 54 and 56, respectively. A land 58 separates grooves 54 and 56. 
     A hollow cylindrical valve member or shuttle 60 is slidably and movably mounted in the valve bore 24. A central axial bore 62 extends through shuttle 60. Shuttle 60 includes an axially facing annular end face 64 which has an outer edge engageable with shoulder 28. The opposite end of shuttle 60 includes an axially raised central portion 66 received by a spring or resilient member 68 which is coupled between stopper 30 and shuttle 60 and which urges end face 64 towards engagement with shoulder 28. 
     A poppet member 70 includes a head 72 with a frustoconical sealing surface 74 which is sealingly engageable with the poppet seat 26. The head 72 is coaxially fixed to an end of a cylindrical rod 76 which extends axially away from the head 72 and extends through the central bore 62 in shuttle 60. A cylindrical flange 78 with a notch 79 is mounted or fixed in a reduced diameter portion of rod 76 so that the shuttle 60 is interposed between the head 72 and the flange 78 of poppet member 70. The outer portions of flange 78 are turned axially away from shuttle 60 so that the flange 78 may receive one end of a spring or resilient member 80. The other end of spring 80 engages stopper 30 so that spring 80 urges head 72 toward sealing engagement with poppet seat 26. Note that both springs 68 and 80 are biased to urge the shuttle and poppet members 60 and 72, respectively, to the left, viewing the figures. The threaded end cap 30 includes a blind bore 90 extending therein for receiving an end of the poppet rod 76 and for receiving an end of spring 80. A raised annular ridge 92 surrounds the open end of bore 90 and is received by spring 68. 
     The shuttle 60 and the poppet member 70 cooperate with the wall of bore 24 to define first and second valve chambers 82 and 84. First valve chamber 82 communicates with control passage 32 and work passage 40. Valve chamber 84 communicates with control passage 34 and with work passage 44 via branch passage 50 and groove 54. Note that no matter what position the shuttle 60 or poppet member 70 are in, the valve chambers 82 and 84 are never in fluid communication with each other. This is because only one, but not both, of the grooves 54 and 56 may be opened to the bore 24 by the shuttle 60 at any one time. 
     It should be noted that service passages 36 and 44 may be branch connected to serve additional fluid motors (not shown) via branch lines 37 and 45. The branch connections may, of course, be made interior or exterior to the housing 22 of bypass valve 18. 
     MODE OF OPERATION 
     With directional control valve 16 in a neutral (no-flow) position, the speed-up valve 18 will be in the position shown in FIG. 1. In this position, spring 68 maintains shuttle 60 in contact with shoulder 28 so that fluid communication is open between control passage 34 and work passage 44 and so that fluid communication is closed between work passage 44 and control passage 32 and closed between work passage 44 and work passage 36. Also, spring 80 lightly maintains poppet head 72 in engagement with poppet seat 26. 
     Now, if it is desired to retract the fluid motor 20, the directional control valve 16 is operated to connect control passage 34 to pump or supply pressure and to connect control passage 32 to sump or reservoir pressure. The relatively high pressure in passage 34, as compared to passage 32, maintains shuttle 60 seated against shoulder 28 so that fluid flows from passage 34, through valve bore 24, branch passage 50, work passage 44 to rod end chamber 48. This retracts fluid motor 20 and causes the piston 21 of fluid motor 20 to move to the left, viewing FIG. 1, thus forcing fluid out of head chamber 42. The fluid exiting from head chamber 42 flows through work passage 40 and portion 36 and moves poppet head 72 away from poppet seat 26 and against the bias of spring 80 and the fluid pressure in chamber 84 so that the fluid from head chamber 42 may exit to sump via valve bore 24, control passage 32 and directional control valve 16. 
     Now, if it is desired to shift from the neutral mode (shown in FIG. 1) to the extend or dump mode (shown in FIG. 3) to extend the fluid motor 20, the directional control valve 16 is operated to connect control passage 32 to pump pressure and to connect control passage 34 to sump or reservoir pressure. A heavy load acing to extend the cylinder will cause a pressure buildup in the rod chamber 48 which will act in valve chamber 84 to resist the motion of shuttle 60 to the right. However, as fluid enters valve chamber 82 from control passage 32, the poppet head 72 is seated against seat 26, thus preventing fluid from exiting from chamber 82. This causes a pressure buildup in valve chamber 82. Because valve chamber 84 is vented to sump 14 via control passage 34 and directional control valve 16, the pressure in valve chamber 82 will rapidly exceed the pressure in valve chamber 84. The resulting pressure differential between the end faces 64 and 66 of shuttle 60 moves the shuttle 60 in the bore 24 and with respect to the poppet member 70, to the right from its seated position shown in FIGS. 1 and 2. While poppet member 70 remains seated against seat 26, shuttle 60 first moves across groove 54 and blocks branch passage 50 while branch passage 52 remains blocked, thus closing communication between service passage 44 and control passage 34, thus momentarily preventing the escape of fluid from rod end chamber 48. At this point, valve chamber 84 is now connected only to sump via control passage 34, thus further increasing the pressure differential between valve chambers 82 and 84. As the shuttle 60 continues to move to the right, it next engages the flange 78 and pulls poppet head 72 away from poppet seat 26. Finally, shuttle 60 uncovers groove 56 and opens communication between rod end chamber 48 and head end chamber 42 via a regeneration passage which includes portions of service passage 44, branch passage 52, the bore 24, valve chamber 82 and passages 40 and 36. Further motion of the shuttle 60 and poppet member 70 is prevented when the end of rod 76 engages the bottom of bore 90 of end cap 39. At this point, the shuttle 60 and poppet 70 are in a regeneration position, thus opening the head end chamber 42 to fluid from the pump 12 via control passage 32, valve chamber 82 and passages 40 and 36 and to fluid from the rod end chamber 48 via the regeneration passage. Thus, as the piston of fluid motor 20 moves to the right, fluid from the rod end chamber 48 is diverted or regenerated back to the head and chamber. This extra diverted flow to head end chamber 42 compensates for the fact that head end chamber 42 has a larger volume than chamber 48 and thus reduces the amount of fluid which must otherwise be supplied to head end chamber 42 from the pump 12 during extension of fluid motor 20. This permits a rapid extension of fluid motor 20.