Abstract:
An elbow fluid flow valve exhibiting reduced flow loss and including a body having a specified shape and size and defining a short radius associated with an elbow shaped fluid passageway characterized by a first fluid flow inlet and a second fluid flow outlet. A cover secures over the valve body, and such that a generally sleeve shaped annulus is defined therebetween. A light-weight and linearly translatable sleeve is mounted exteriorly of the valve body and within the intermediately defined annulus. The sleeve is operable to be displaced between a first location permitting fluid flow to the outlet and a second location interrupting fluid flow. A control element is operably connected to a pair of access ports, in turn communicated with one or a pair of interior regions in communication with locations of the displaceable sleeve and, upon experiencing at least one of a pressure and flow disparity between valve inlet and outlet, facilitates displacement of the sleeve to the second (flow interrupting) location.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a nonprovisional application of and claims priority benefit (under 35 USC 119(e)) from U.S. provisional application 60/842,533 filed on Sep. 6, 2006, and entitled “The Elbow-Plug, External Sleeve Valve, an Efficient Two-Way Valve with Multiple Applications.” 
    
    
     FIELD OF THE INVENTION 
     The present application discloses a two-way hydraulic valve incorporating a modulating element axially slidable over a cylindrical central body exhibiting a machined, cast or otherwise formed flow path approximating such as a ninety degree elbow. Specifically, the present design exhibits a smoother elbow configuration, by virtue of its central body exhibiting a cast or machined flow path, and which exhibits a greatly decreased pressure drop than as opposed to elbow valves of existing design. 
     BACKGROUND OF THE INVENTION 
     Description of the Prior Art 
     The prior art is well documented with examples of two-way valves, these including most notably poppet valves in which a moving interior element is either a poppet or a sleeve sliding within an associated sleeve or bore, this in order to provide flow modulation or a simple on/off function. A significant problem associated with the prior art designs is the instance of significant pressure drop (or head loss) associated with the fluid flow, in particular with valve designs exhibiting any significant angle of curvature or bend. This is most pronounced in instances where a standard ninety (90°) degree bend or elbow valve is specified. 
     Existing valve technology applied to attempts to reduce pressure drop/head loss for two way valves include such as ball valves, rotatable plug valves, and butterfly valves. While providing advantageous pressure drop profiles, such existing valve technologies suffer from the shortcoming of providing only a very narrow variety of control options, as well as slow response parameters. 
     An additional type of 2-way valve exhibits a specialty cast or otherwise manufactured flow vanes in order to guide fluid flow through the valve, including such as an internal sliding poppet. This category, which includes such as what are commercially known as Olmsted style valves (Olmsted Products Co.), exhibit only fairly small improvements in flow efficiency (such as on the order of a 10% reduction in pressure drop). 
     Other and additional types of valves are known with external sliding sleeves, such as commercially known as the Hurit Sliding Sleeve Valve, these further not constituting low pressure drop valves, nor incorporating any type of elbow-plug concept. 
     SUMMARY OF THE INVENTION 
     The present invention discloses an improved elbow fluid flow valve which exhibits reduced flow loss over such as a short radius and 90° (elbow) bend, this including a body having a specified shape and size and defining a fluid passageway characterized by a first fluid flow inlet and a second fluid flow outlet. A cover element secures over the valve body, and such that a generally sleeve shaped annulus is defined therebetween. 
     A linearly translatable sleeve is mounted exteriorly of the valve body and within the intermediately defined annulus. The sleeve is operable in response to either an internally mounted coil spring or other fluid pressuring means, and such that it can be displaced between a first location permitting fluid flow to the outlet and a second location interrupting fluid flow, and by which the sleeve abuts a likewise annular seating location defined in the valve body and which fully seals the associated fluid outlet from the fluid inlet. 
     A control element (e.g. not limited to such as a manual control valve, hydraulic pilot control valve, relief valve, electrohydraulic valve) is operably connected to a pair of access ports, in turn communicated with one or a pair of interior regions in communication with locations of the displaceable sleeve and, upon experiencing either an externally applied signal to shift or at least one of a pressure and flow disparity between valve inlet and outlet, facilitates displacement of the sleeve to the second (flow interrupting) location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference now will be made to the attached drawings, when read in combination with the following description, wherein like reference numerals refer to like parts throughout the several views, and in which: 
         FIG. 1  is a cutaway illustration of a first embodiment according to the present inventions and in the form of a cartridge type valve, this designed for insertion into a standard DIN pocket of an associated manifold; 
         FIG. 2  is an illustration of a flow shut-off valve configuration according to a second preferred embodiment and in which the valve is designed to close upon flow from an accumulator to outlet exceeding a predetermined amount; 
         FIG. 3  is an illustration of an elbow plug variant according to the present inventions, incorporating a relief valve function in a DIN cartridge arrangement, with pilot relief valve of either direct or remote operating design, control orifices, and optional seals; 
         FIG. 4  is an illustration similar to that shown in  FIG. 1 , and further depicting the valve mounted in a cast body, suitable for right angle (90°) in-piping mounting; 
         FIG. 5  is an illustration of an in-tank prefill valve according to a still further embodiment of the present invention and illustrating the valve mounted to a back end of a press cylinder exhibiting a rear mounted hydraulic reservoir within which the prefill valve is submerged; 
         FIG. 6  is an illustration, again in cutaway, of an isolation type valve, and such as which are typically employed to isolate a drilling heave compensation cylinder from its associated accumulator, and which operates to rapidly close upon a sudden loss of pressure; 
         FIG. 7A  is a cutaway illustration of a plurality of internal grooves formed in a portion of the valve sleeve according to any of several embodiments of the present inventions, and in order to pressure balance the sleeve to minimize side load during operation; 
         FIG. 7B  is a further illustration of a dummy passage machined or cast into the elbow valve and in a pressure balancing direction opposite that of the angled outlet; 
         FIG. 8  is a side cutaway illustration of a profile associated with a valve profile side port, and by which a standard circular/oval shaped opening has been modified to a generally oval shape with an incorporated “V” shaped bottom portion and which, upon initial opening the internal flow permitting sleeve member, only a small amount of flow (through the bottom “V” profile) passes, thereby providing good low speed control to the assembly; and 
         FIG. 9  is an illustration of an anti-recoil valve assembly according to a still further preferred embodiment and, additional to the characteristics associated with the valve assembly of  FIG. 2  provides the further feature of disabling the flow shut-off features and turning control of the sleeve position over to a position control feedback system, thereby controlling recoil of the drilling riser during such as emergency disconnect of the riser from such as a subsea BOP stack. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , a cutaway illustration is shown at  10  of a cartridge type valve, and such as is designed for insertion into a standard DIN pocket of an associated manifold. As previously described, present disclosure discloses a two-way hydraulic valve incorporating a modulating element axially slidable over a cylindrical central body exhibiting a machined flow path approximating such as a ninety degree elbow. Specifically, the present design exhibits a smoother elbow configuration, by virtue of its central body exhibiting a cast or machined flow path, and which exhibits a greatly decreased pressure drop than as opposed to elbow valves of existing design. 
     Referencing again  FIG. 1 , a central cylindrical body is illustrated at  12 , this typically constructed of a suitable metal material such as a steel, although additional material considerations, such as a very sturdy/heavy duty plasticized material may also be utilized and which exhibits the necessary properties of durability and resilience. A substantially angled (e.g. 90°) elbow shaped interior passageway is defined in the cutaway illustration of the body  12 , this including an inlet  14  corresponding to a first extending centerline  14 , and an outlet  16  corresponding to a second perpendicular extending centerline  18 , and which further defines a main fluid flow path. While not clearly evident from the cutaway illustration of  FIG. 1 , the elbow defines in cross section a circular or other suitable polygonal shape which is formed into the cylindrical body  12  by either a machining, casting or other process known to one of ordinary skill in the art. 
     An interior and displaceable annular sleeve is provided and is illustrated in a modified cutaway fashion in both a first fully opened position, at  20 , as well as a second fully closed position  20 ′. The sleeve may be constructed of a high strength material, in order to minimize associated wall thickness, and operates as a pressure vessel when the valve  10  is closed. The sleeve as shown further exhibits a generally annular shaped body, including both a spring seating upper end  22  and an arcuate configured bottom  24 . 
     A coil spring (which along with the sleeve  20  defines the only moving elements of the assembly such as between compressed spring position  26  and expanded spring position  26 ′) is seated within an associated upper annular cavity  28  defined in a cover plate  30  in turn secured to the cylindrical body  12 . A lower sleeve shaped annulus  32  communicates with the coil spring  26  seated in the upper cavity  28  and such that a bottom defined end  34  of the annulus  32  further consists of a seat with cushioning and/or seal and defines a sealing location between the inlet  14  and outlet  18  locations of the elbow shaped interior passageway. 
     An upper disposed control valve  36 , defining a first of several to be discussed versions of a control element, is seated atop or imbedded in the cover plate  30  which may be machined in order to match the porting patterns of any desired control valve which can also consist of any of an air, hydraulic or electric input source. A first control port  38  communicates the control valve  36  to a first region defined in the spring located upper cavity  28 , whereas a second control port  40  communicates the control valve  36  to a second region (see further at  42 ) defined in a generally central location of the cylindrical body  12  which is co-linear with the inlet flow axis  14 . The second region  42  further communicates, at  44 , with an optional hydraulic cushion  46 . It is further understood that the inlet and outlet flow axes associated with this valve design may be reversed, and without affecting the other features associated with the valve. 
     Additional features include orientation dowels, such as at  48  for mounting the cover plate  30  to an upper end of the central cylindrical body  12 , as well as at  50  for securing a further bottom end location of the cover plate to a manifold/valve body  52 , within which is seated the central body  12 . Other features include a static seal, see at  54 , for sealing between an inner and outwardly facing annular surface of the cover plate  30  and an opposing and inner abutting/annular surface associated with an upper end of the central body  12 , and between which is defined the second interior region  42 . 
     In operation, the central body  12  with interior defined elbow passageway is located with the alignment dowl  48  in order to prevent rotation of the cover plate  30 . The cover plate  30  is in turn fixed in location to prevent rotation of the plate relative to the manifold  52 . The sleeve is further illustrated in its fully open position, again at  20 , as evident from the right side of the valve&#39;s axial centerline  14 , as well as fully closed, again at  20 ′, as shown on the left side of the centerline  14 . Actuation of the valve between its open  20  and closed  20 ′ positions is accomplished via selective pressure applied through the control ports  38  and  40 . 
     As again shown in  FIG. 1 , the sleeve  20  can be guided by closely controlled tolerances established between the sleeve and the large diameter of the central body (see again upper annular cavity  28 ), and the smaller diameter associated with the upper portion of the body. When fully open, the fluid flow path through the valve is identical to or closely approximates that of a short radius elbow, and which further exhibits a small fraction of pressure drop through a cartridge style poppet valve exhibiting an equally sized main flow path. 
     In applications where little or no leakage is desirable in the closed position, the manifold  52  and central body  12  can be equipped with dynamic seals (see at  55 ) and the seat  34  at the bottom end of the valve  10  can also incorporate a like seal. Given the relatively small mass associated with the movable sleeve (between positions  20  and  20 ′), the valve  10  can exhibit a high degree of responsiveness, and when employed with the proper controls and given reasonably generous flow paths  38  and  40 . 
     Referring now to  FIG. 2 , an illustration of a flow shut-off valve configuration is generally shown at  56  according to a second preferred embodiment, and in which the valve is designed to close upon flow from an accumulator to an outlet exceed exceeding a predetermined amount. Specifically, a main valve body is illustrated at  58  in the cutaway view of  FIG. 2 . A top cap  59  is also shown and which is secured to an end of the main body  58 , such as through each of a plurality of dowels, such as is representatively shown at  60 . 
     The elbow sleeve is illustrated with inlet  62  (along first centerline  64 ) and outlet (to cylinder) at  66 , and along second perpendicular centerline  68 . A modification of the sleeve is shown at  70  and which is biased in a normally open direction by a coil spring  72  seating against an interior configuration  74  associated with an end of the sleeve  70 , and which biases against a seat/seal or other like cushioning support  74  in turn defining an inner end wall stop of an annulus  76 , within which is seated the sleeve  70 . The spring is further illustrated in a compressed condition, at  72 ′, this corresponding to the sleeve  70  being displaced in a translating direction (not shown) corresponding to seating over and closing the elbow outlet  66  from its associated inlet  62  (see opposite end displaced locations  78 ). 
     A flow path  80  communicates with the accumulator inlet  62  (this defining an upstream pressure source) into a first region  82  which affects an end surface of the sleeve  70  in baising contact with end wall stop  76  of the associated annulus (thus influencing the sleeve  70  in a spring opening and closing direction relative the flow path elbow). A further flow path  84  is at a downstream location of the elbow (i.e. to the outlet  66 ) and further communicates with a further interior region  86  accessible to an inner defined end surface  88  of the sleeve  70 , this in turn influencing, via progressively narrow diameter orifices  90 ,  92  and  94  communicating the second flow path  84  with the further interior region  86 , cushioning of sleeve deceleration when actuated to the closed position. 
     Of note, the flow shut-off configuration illustrated in  FIG. 2 , constitutes a safety valve designed to rapidly close, in the event that flow from the accumulator (e.g. inlet  62 ) to the outlet  66  exceeds a predetermined amount. In normal operation, the sleeve  70  is held open by the spring (at expanded position  72 ). Accordingly, and in the absence of flow, the pressure is the same everywhere within the valve. 
     During normal operation, flow from the accumulator  62  (via flow path  80 ) exists at a higher pressure than the outlet pressure (via flow path  84 ), this as a result of the pressure drop of flow (or head loss) as it travels around the elbow. As flow increases, the pressure drop likewise increases, until the point is reached in which the difference in the pressures in regions  82  and  86  is such that the pressure in region  82  is sufficiently great to act upon the sleeve  70  to overcome the spring force (or other counter-biasing force), thus causing the sleeve to translate to the closed position, thus creating an even greater pressure drop, in turn resulting in very rapid closure of the valve  56 . It is further noted that the cushioning orifices  90 ,  92  and  94  come into play at this point to provide a cushioning effect to the sleeve  70  as it deflects to an inner deflected end position (see further at  74 ′) and corresponding to the spring being deflected to its fully closed position  72 ′ and the annular extending end of the sleeve  70  abutting the inner sealing end stops  78 . 
     By virtue of the importance of the rapid response required of this type of valve application, the mass of the sleeve  70  is kept intentionally as small as possible and while again employing high strength materials. The flow passages (e.g. again at  80  and  84 ) are reciprocally designed to be as large as practical, and so that restriction in these passages does not limit the responsiveness of the valve assembly  56 . 
     Given again that the sleeve closes with sufficiently great speed, the hydraulic cushion is provided via the orifices  90 - 94 , and in order to provide the necessary cushioning effect. As illustrated, the desired cushioning effect is achieved by successively cutting off a series of flow passages in the region  86 . Alternatively, the hydraulic cushion can be relocated to the bottom end of the sleeve stroke (see approximate end stops  78 ). 
     Referencing now  FIG. 3 , an illustration is generally shown at  96  of an elbow plug variant according to the present inventions, incorporating a relief valve function in a DIN cartridge arrangement, with pilot relief valve of either direct or remote operating design, control orifices, and optional seals. Repeating the description previously given in reference to  FIG. 1 , identical features are repetitively numbered and the description of this figure will be limited to the revised features forming a part of the alternate embodiment  96 . 
     The control valve, generally referenced at  36  in  FIG. 1 , is substituted by a relief valve  98  in the current variant, this communicating to a modified control port  100  (in comparison to that shown at  38  in  FIG. 1 ). A further passageway  102  exists between the input pressure/flow source  14  and the region  42  (this being closed in  FIG. 1 ). The cover plate of  FIG. 1  is reconfigured as a top cap  30 ′ in  FIG. 3  and further includes control orifices  104  and  106 , these respectively intercommunicating the relief valve  98  with both the annulus  28  and the interior defined region  42 , respectively, via a modification of the flow control port, at  40 ′. 
     Repeating the explanation of the valve operation associated with  FIG. 1 , a greatly increased inlet pressure will cause the fluid flow to travel through the passageway  102 , into region  42 , through modified port  40 ′, via again the opening control orifices  104  and  106 , and to thereby provide downward/closing translating pressure on the sleeve  20 , concurrent with the biasing effect of the spring  26  and via the seating annulus  28 . As previously described, the elbow plug design allows for significantly greater fluid flow to pass through a given cartridge size. 
       FIG. 4  is an illustration, generally at  108 , similar to that shown in  FIG. 1 , and further depicting the valve mounted in a cast body, suitable for right angle (90°) in-piping mounting. Specifically, the manifold construction is redesigned, as shown at  52 ′ and as opposed to at  52  in  FIG. 1 . It is further understood that any of the valve configurations illustrated or discussed herein can be modified/designed to operate in this variant. Again, one advantage of the present inventions is the reduction of pressure drop as compared to prior art valve assemblies previously discussed. 
     Referring now to  FIG. 5 , an illustration  110  is provided of an in-tank prefill valve according to a still further embodiment of the present invention and illustrating the valve mounted to a back end of a press cylinder exhibiting a rear mounted hydraulic reservoir within which the prefill valve is submerged. The press cylinder is illustrated at  112 , from which the upwardly extending side walls  114  define therein a fluid filled reservoir  116 . 
     A central body  118  is illustrated and is positionally mounted within the reservoir  116  and such that a downwardly displaceable sleeve (see open position  120  and closed position  120 ′) selectively opens and closes a fluid inlet  122  (see vertical centerline  124 ), with opposite fluid outlets  126  and  128  (see further curved centerlines  130  and  132 , respectively). Mounting bolts, see at  134  and  136 , are secured to the back of the cylinder  112 . An elbow plug  138  with multiple passages is also provided for mounting the bolt flange and hardened seat. 
     A bolted-on top cap  140  (see also bolt  141  shown in phantom) is secured over the central valve (dual elbow defining) body  118 , over which is secured a control valve  142  with both supply and return fluid ports. An optional porting for three-way prefill is further referenced at  144  and which generally corresponds to a centerline of the valve assembly illustrated in cutaway. 
     Fluid flow ports include such as that illustrated at  146  (leading to a sleeve closing inducing region  148 ), this in turn defining an annulus above the sleeve  120 . An additional flow port  150  leads to a further contact location  152 , this corresponding to an inner/underside projecting upper annular surface associated with the sleeve (this is also referenced by region  154 , and which corresponds to the sleeve in an upwardly displaced and open position  120 ). 
     As illustrated, the flow path achieved by the design of  FIG. 5  provides advantages over prior art valves, such as the assisting and guiding of the flow path through the multiple elbow arrangements (multiple outlets  126  and  128 ) designed into the embodiment. Another advantage is the reduced cost of manufacturing, resulting from the incorporation of the external sleeve  120 , this reducing the weight associated with the casted body. 
     In one preferred operation, the pre-fill valve  118  is mounted in the associated piping (not shown) running to the cylinder  112 , and rather than submerged within the reservoir  116 . An additional option contemplates construction of a valve incorporating a body such as shown in the variant  108  of  FIG. 4 , however with the features shown in  FIG. 5 , thereby netting a much simpler in-piping pre-fill valve that results in both flow efficiency and cost savings, this further eliminating the necessity of an expensive shroud. 
     Referencing now  FIG. 6 , an illustration is shown at  156 , again in cutaway, of an isolation type valve, and such as which are typically employed to isolate a drilling heave compensation cylinder from its associated accumulator, this operating to rapidly close upon a sudden loss of pressure. Features again include a fixed outer body  158 , a valve body  160  defined within said outer body  158  and collectively defining an elbow with an inlet  162  and substantially ninety degree angled outlet  164 . As shown, the inlet and outlet exhibit enlarged diameter locations, these narrowing in the turning region  166  corresponding to the inner valve body  160  and the displaceable sleeve, further shown at  168 . 
     A control intake or manifold is shown at  170  and appropriate venting which communicates to an interior region  172 . Upon a sudden loss of pressure along the inlet side  162 , pressure from the control intake  170  exerts upon an annular defined top end location, at  174 , associated with the sleeve  168 , thereby causing the sleeve  168  to displace downwardly to an elbow closed position (see annular bottom end  176  of sleeve  168  biasingly seating against bottom defined annular seat  178 . 
     In use, the isolation valve  156  operates to protect against both drill string and hose or piping failure, and by rapidly closing upon experiencing a sudden loss of pressure. The valve is further closed manually each and every time the associated drill bit (not shown) is lifted from its contact location with the hole. These valves have further been historically produced in castings, and with a more recent trend of machining them out of steel manifolds. 
     As illustrated, both the casted and machined valves incorporate internal poppets sliding within a bore (see again displaceable sleeve  168 ). It has been found that the cast valves are somewhat more efficient as a result of the flow directing vanes created, however either design constitutes a significant improvement over prior art valves given the external and slidable sleeve (again at  168  in this embodiment). Additionally, and while the valve  156  of  FIG. 6  is illustrated without two side ports, it is understood that dual side ports can be designed into its architecture, and as is again clearly referenced in the related embodiment of  FIG. 5 . 
     Referring to  FIG. 7A , a cutaway illustration is shown at  108  of a plurality of internal grooves  182  formed in an internally disposed surface of a further configured valve sleeve, this according to any of several embodiments of the present inventions described herein. As previously described, the internal groove design operates in order to pressure balance the sleeve  180 , and such as to minimize side load during operation. 
     Referring further to  FIG. 7B , a valve body  184  is shown and includes such features as an elbow defined section with inlet  186  and outlet  188 , an upper region  190  fluidly communicated with a control valve (not shown) and further including a side disposed hydraulic cushion  192 . As with  FIG. 7A , the control valve  184  is illustrated in section (without reference to the several remaining components of a completed valve assembly, reference further being had to the previous embodiments described herein). A dummy passage is illustrated at  194 , this being machined or cast into a side disposed location associated with the elbow valve  184 , and which operates in a pressure balancing direction, opposite that of the angled outlet  188 . As is understood by one of ordinary skill in the art, no flow is delivered to the valve side associated with the dummy passageway, as there is no port at that location, it further being understood that an associated sleeve (not shown) would in operation be exposed to a balanced pressure exerted from both sides thereof. 
       FIG. 8  illustrates at  196  a side cutaway profile in section of a valve elbow (or port), and by which a standard circular/oval shaped opening has been modified to a generally oval shape (see interior curved surface  198 ) with an incorporated “V” shaped bottom portion, see angled bottom surfaces  200  and  202 ). In operation, and upon initial opening the internal flow permitting sleeve member (again not referenced in the sectional view of  FIG. 8 ), only a small amount of flow (through the bottom “V” profile) passes. As a result, the valve body configuration  192  operates to provide improved low speed/flow control to the assembly, while the oval shaping of the elbow passageway accommodates increased flow volume. 
     Finally, and referring to  FIG. 9 , an illustration is provided at  204  of an anti-recoil valve assembly, this according to a still further preferred embodiment and, additional to the characteristics associated with the valve assembly previously described in  FIG. 2 , provides the further feature of disabling the flow shut-off features and turning control of the sleeve position over to a position control feedback system, thereby controlling recoil of the drilling riser during such as emergency disconnect of the riser from such as a sub-sea BOP stack. 
     As with the flow valve shut off configuration previously illustrated at  56  in  FIG. 2 , the anti-recoil valve  204  is mounted between an accumulator (not shown by communicated to valve via inlet location previously shown at  62  in  FIG. 2 ) and a drilling riser tensioner (also not shown but communicated through corresponding outlet  66 ). As previously done, identical reference numbers are used for features also shown in the prior embodiment of  FIG. 2 , and new reference callouts will be reserved for new features associated with the embodiment  204 . 
     Contrasting to the elements recited in  FIG. 2 , a variation of the main valve body is illustrated at  206 , and a top cap  208  is also shown which is secured to an end of the main body  206 , such as again through each of a plurality of dowels, again representatively shown at  60 . 
     The elbow sleeve is again illustrated with inlet  62  (along first centerline  64 ) and outlet (to cylinder) at  66 , and along second perpendicular centerline  68 . Likewise, the sleeve is again shown at  70  and which is biased in a normally open direction by a coil spring  72  seating against an interior configuration  74  associated with an end of the sleeve  70 , and which biases against a seat/seal or other like cushioning support  74  in turn defining an inner end wall stop of an annulus  76 , within which is seated the sleeve  70 . The spring is further illustrated in a compressed condition, at  72 ′, this corresponding to the sleeve  70  being displaced in a translating direction (not shown) corresponding to seating over and closing the elbow outlet  66  from its associated inlet  62  (see opposite end displaced locations  78 ). 
     The flow path previously referenced at  80  in  FIG. 2  is substituted by a redesigned flow path in  FIG. 9 , shown at  210 , and which communicates with the accumulator inlet  62 . This again defines an upstream pressure source and which communicates with a first  212  of a pair of two-way valves (see also secondary two-way valve  214  which, as will be described, operates in tandem with two-way valve  212  in order to close to disable flow through the elbow valve). 
     The valve  214  operates to block the passageway  210  leading to a first interior region  216  and which affects an surface of the sleeve  70  in biasing contact with end wall stop  76  of the associated annulus (thus influencing the sleeve  70  in a spring opening and closing direction relative the flow path elbow). A further flow path  218  (contrast to flow path  84  in  FIG. 2 ) is further located at a downstream location of the elbow (i.e. proximate to the outlet  66 ) and further communicates with a further interior region  220  (compared to at  86  in  FIG. 2 ), via the second two-way valve  214 . This is in turn accessible to an inner defined end surface  88  of the sleeve  70 , and which correspondingly in turn influences, via modified and progressively narrow diameter orifices  222 ,  224  and  226  (see previously at  90 ,  92  and  94 ) communicating the second flow path  84  with the further interior region  220 , thereby cushioning sleeve deceleration upon the sleeve being actuated to the closed position. 
     Additionally features of note include a sleeve position indicator  228 , this typically being an electrically operated module and which senses and identifies the condition of the sleeve (i.e. between open  72  and closed  72 ′ positions). An electrohydraulic valve  230  is also referenced and communicates, via passageways  232  (to assist in sleeve opening control), as well as at  234  in turn communicable with the annular back surface of the sleeve in sub-region  236  and to assist in sleeve closing control in order to further assist with sleeve position control. 
     Of note, the flow shut-off configuration illustrated in  FIG. 2 , constitutes a safety valve designed to rapidly close, in the event that flow from the accumulator (e.g. inlet  62 ) to the outlet  66  exceed exceeds a predetermined amount. In normal operation, the sleeve  70  is held open by the spring (at expanded position  72 ). Accordingly, and in the absence of flow, the pressure is the same everywhere within the valve. 
     The design of  FIG. 9  otherwise operates similar to that previously described in reference to  FIG. 2  and such that, during normal operation, flow from the accumulator  62  (via flow path  210 ) exists at a higher pressure than the outlet pressure (via flow path  218 ), this as a result of the pressure drop of flow (or head loss) as it travels around the elbow. As flow increases, the pressure drop likewise increases, until the point is reached in which the difference in the pressures in regions  82  and  220  is such that the pressure in region  82  is sufficiently great to act upon the sleeve  70  to overcome the spring force, thus causing the sleeve to translate to the closed position, thus creating an even greater pressure drop, in turn resulting in very rapid closure of the valve  56 . It is further again noted that the cushioning orifices  222 ,  224  and  226  come into play at this point to provide a cushioning effect to the sleeve  70  as it deflects to an inner deflected end position (see further at  74 ′) and corresponding to the spring being deflected to its fully closed position  72 ′ and the annular extending end of the sleeve  70  abutting the inner sealing end stops  78 . 
     As with the variant described in  FIG. 2 , and by virtue of the importance of the rapid response required of this type of valve application, the mass of the sleeve  70  is kept intentionally as small as possible and while again employing high strength materials. The flow passages (e.g. again at  210  and  218 ) are reciprocally again designed to be as large as practical, and so that restriction in these passages does not limit the responsiveness of the valve assembly  204 . 
     Given again that the sleeve closes with sufficiently great speed, the hydraulic cushion is provided via the orifices  222   224 , and  226 , again and in order to provide the necessary cushioning effect. As illustrated, the desired cushioning effect is achieved by successively cutting off a series of flow passages in the region  220 . Alternatively, the hydraulic cushion can again be relocated to the bottom end of the sleeve stroke (see approximate end stops  78 ). 
     Having described my invention, other and additional preferred embodiments will become apparent to those skilled in the art to which it pertains. In particular, the present inventions can be adapted for incorporation to air, hydraulic, or electrical control of the sliding sleeve position. 
     Control can be further established by a simple on/off function (e.g. through an externally applied signal), as well as proportionately controlled (e.g. as a variable of flow/pressure). Including the several valve examples previously described, additional commercial applications of valve assemblies incorporating the elbow-plug, external sleeve valve design with minimal flow pressure loss, are possible. These include, without limitation, such as two-way valves (both normally closed and open), relief valves (both direct and remote operated), flow shut-off valves, pressure reducing/pressure compensating flow control valves, isolation valves and anti-recoil valves for offshore tensioner and heave compensation systems, prefill valves for press and other operations, and in-piping mounted, right-angle, two way valve design.