Abstract:
A hydraulic accumulator having a closing arrangement. The accumulator has a housing, a removable end cap, a segmented locking ring, and a pilot ring. The housing has at least one opening, an interior space, and a ring recess adjacent the opening. The removable end cap is sized to close the opening when in a closed position. The segmented locking ring is removably positioned within the ring recess adjacent the end cap opposite the interior space to stop the end cap from moving in a first direction away from the interior space. The locking ring may be segmented. The pilot ring is removably connected to the end cap and positioned to hold the locking ring in the ring recess when connected to the end cap.

Description:
This application claims the benefit of U.S. provisional patent application No. 61/968,620, filed on Mar. 21, 2014, which is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates in general to hydraulic accumulators. 
     BACKGROUND OF THE INVENTION 
     An accumulator is known to enable a hydraulic system to handle peak demand with a less powerful pump, increase response time to demands, and smooth pulsations. Accumulators are able to store energy for use in hydraulic systems. 
     U.S. Pat. No. 7,520,129 discloses an accumulator having interior space than is enclosed at the ends by end caps that are threaded to the accumulator housing. The present inventors recognized that the threaded securement of an end cap has disadvantages. One disadvantage arises when the accumulator is located in a harsh environment, such as on the sea floor, where the cap&#39;s connection to the accumulator housing can rust, corrode, or become encumbered by debris or organic matter from the environment so as to make it very difficult to unscrew and remove the cap from the accumulator housing for disassembly or maintenance. 
     The present inventors recognized the need for an accumulator that is better adapted for maintenance after operating in certain environmental conditions, such as when located on the sea floor or at significant depth below a water surface. The present inventor recognized that it would be desirable to provide an end cap securing mechanism that is easier to operate. 
     SUMMARY OF THE INVENTION 
     A hydraulic accumulator having a closing arrangement is disclosed. The accumulator comprises a housing, a removable end cap, a segmented locking ring, and a pilot ring. The housing has at least one opening, an interior space, and a ring recess adjacent the opening. The removable end cap is sized to close the opening when in a closed position. The segmented locking ring is removably positioned within the ring recess adjacent the end cap opposite the interior space to stop the end cap from moving in a first direction away from the interior space. The locking ring may be segmented. The pilot ring is removably connected to the end cap and positioned to hold the locking ring in the ring recess when connected to the end cap. 
     In some embodiments, the cap comprises a peripheral step wall. The housing comprises an internal stop wall adjacent the opening to engage the peripheral step wall and prevent the end cap from moving in a second direction toward the interior space. 
     In some embodiments, the end cap has a circumferential wall comprising a first portion, a second portion, and a step portion. The step portion extends transverse to the first and second portions. The step portion is positioned to contact the stop wall of the housing adjacent to the opening to stop the end cap from moving in a second direction toward the interior space. 
     In some embodiments, the first portion of the circumferential wall of the end cap is in contact with a first wall portion of the housing and the second portion of the circumferential wall is in contact with at least a portion of a second wall portion of the housing and the step wall is in contact with the stop wall when the end cap is in the closed position. The stop wall extends transverse to the first wall portion and the second wall portion. The ring recess is located along the second wall portion of the housing. 
     In some embodiments, the pilot ring comprises a peripheral lip. The peripheral lip at least partially blocks the locking ring from moving in the first direction away from the interior space of the housing. 
     In some embodiments, the segmented locking ring comprises a rectangle cross-section and the ring recess comprises at least a partial rectangle cross-section recess. 
     In some embodiments, the accumulator has a movable piston located in the interior space of the housing. The piston divides the interior space in to a first hydraulic fluid chamber and a second inert gas chamber. 
     In some embodiments, the end cap comprises a fill port providing fluid communication between an exterior of the end cap and at least a portion of the interior space. 
     A method of closing a hydraulic accumulator is disclosed. The end cap is slid into an opening of the accumulator until the end cap is prevented from further inward movement in a first direction by a stop element of the accumulator. Each of the segments of a plurality of segments of a segmented ring are placed in a ring recess of the accumulator adjacent a front surface of the end cap to prevent the end cap from moving outward in a second direction. A pilot ring is releasably attached to a front surface of the end cap to hold the segmented ring in the ring recess. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims, and from the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an end view of a hydraulic accumulator having a closing arrangement. 
         FIG. 2  is a side section view of the hydraulic accumulator taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is an enlarged side section view of a portion of the hydraulic accumulator from  FIG. 2 . 
         FIG. 4  is an enlarged side section view of a portion of the hydraulic accumulator from  FIG. 2 . 
         FIG. 5  is a partially exploded perspective view of the hydraulic accumulator of  FIG. 2 . 
         FIG. 6  is a perspective view of the hydraulic accumulator of  FIG. 2  with a pilot ring removed. 
         FIG. 7  is a segmented ring of the closing arrangement of  FIG. 2 . 
         FIG. 8  is a perspective view of the hydraulic accumulator of  FIG. 2  with the segmented ring partially installed. 
         FIG. 9  is a perspective view of the hydraulic accumulator of  FIG. 2  with a portion of the segmented ring ready to be installed. 
     
    
    
     DETAILED DESCRIPTION 
     A hydraulic accumulator and an end closing arrangement for a hydraulic accumulator are disclosed. The following description is presented to enable any person skilled in the art to make and use the invention. For the purposes of explanation, specific nomenclature is set forth to provide a plural understanding of the present invention. While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
       FIGS. 1-3  show an accumulator  100  having an embodiment of closing arrangements  106 ,  108 . The accumulator  100  comprises a housing  102  surrounding an interior space  101 ,  105 , a piston  104  within the space  105 , and two end closing arrangements  106 ,  108 . 
     The end closing arrangements  106 ,  108  are identical, and therefore only closing arrangement  106  will be described in detail. The closing arrangement  106  comprises an end cap  110 , a segmented ring  112 , and a pilot ring  114 . The pilot ring  114  is recessed from the end face housing wall  111 . The end face housing wall has upper and lower cover fastener openings  107 . 
     The piston  104  divides the interior space  101 ,  105  into a first chamber  101  and a second chamber  105 . The first chamber  101  may be fluidly coupled to a hydraulic system, such as through fluid port  127 , to receive pressurized hydraulic fluid. The second chamber  105  can be filled with an inert gas such as a nitrogen gas. The inert gas can be filled through gas port  129 . One or more seals  135  and piston rings  125  surround the piston to prevent hydraulic fluid and/or the inert gas from leaking across the piston between the first and second chambers. Port  129  may be closed and sealed by means known in the art, such as a closing element, cap, or nut, when not being filled with gas or connected to a gas source. Likewise port  127  can be closed and sealed by means known in the art when not connected to a hydraulic system or otherwise when closing of the port is desired. 
     During operation, pressurized hydraulic fluid is stored in the first chamber  101  via a pump (not shown) in fluid-communication with port  127 . The hydraulic fluid acts on a first side  121  of the piston  104  in the first chamber, causing the piston to move toward the second chamber  105  to a loaded position. As the piston moves toward the loaded position, the volume of the second chamber  105  is reduced and the gas in the second chamber is compressed between the piston and the end cap. Therefore, the pressure of the gas in the second chamber increases until a force exerted on the first side  121  of the piston by the pressure of the hydraulic fluid in the first chamber is substantially equal to a force exerted on a second side  123  of the piston  104  by the pressure of the compressed gas in the second chamber. During operation, accumulators can remain in the loaded position for a relatively long period of time. Therefore, the hydraulic fluid in the first chamber  101  and gas in the second chamber can be subjected to high levels of pressure for a relatively long period of time. The end closing arrangements  106 ,  108  close and seal the ends of the accumulator and prevent leaks from the pressure of the fluid or gas. 
     When the demand in a hydraulic system having an accumulator increases, the pressure of the hydraulic fluid in the first chamber  101  decreases. When the pressure of the hydraulic fluid in the first chamber  101  decreases below the pressure provided by the compressed gas in the second chamber  105 , the gas expands and drives the piston toward the first chamber  101  exerting a force on the hydraulic fluid via the piston. As a result, the accumulator apparatus supplies the hydraulic system with previously stored pressurized hydraulic fluid. The pre-load pressure of the gas in the second chamber determines the minimum system pressure provided by the accumulator. It will be recognized that chambers  101 ,  105  can be swapped so that chamber  101  contains the gas and chamber  105  contains the hydraulic fluid. The end closing arrangement  106 ,  108  can be used with other non-piston hydraulic accumulators, such as elastic diaphragm hydraulic accumulators, enclosed bladder hydraulic accumulators, and spring-type accumulators. Some hydraulic accumulators have only one opening and therefore may only utilize one end closing arrangement. 
     The housing  102  comprises an outside wall  103 . In some embodiments the outside wall  103  is cylindrical. The housing  102  comprises a first interior wall  140  and a second interior wall portion  144  with a housing step wall  142  between the first interior wall  140  and the second interior wall portions  144 ,  152 . The second interior wall portion comprises an inner portion  144  and an outer portion  152 . The second interior wall portion is located closer to an end  109  of the accumulator  100  as compared to the first interior wall  140 . The housing step wall extends about the entire inner circumference of the housing. In some embodiments, the housing step wall is perpendicular to the first interior wall  140  and the inner second interior wall portion  144 . 
     The end cap  110  comprises an outer/front face  120  and an opposite inter face  122 . The inter face faces the interior and the piston  104 . Between the inner and outer face of the end cap is a first peripheral surface  128  and a second peripheral surface  124  with an end cap step wall  126  there between. The first peripheral surface  128  comprises to gasket recesses  131  and  133 , each comprising a gasket or O-ring  130 ,  132  respectively. In some embodiments, the first and second peripheral surfaces  128 ,  124  do not comprise threads for securing the end cap to the housing. In some embodiments, the first and second peripheral surfaces  128 ,  124  are flat. In some embodiments, the first and second peripheral surfaces  128 ,  124  are substantially smooth. The end cap step wall extends about the entire circumference of the end cap. In some embodiments, the housing step wall is perpendicular to a first peripheral surface  128  and a second peripheral surface  124 . 
     When the segmented ring  112 , and the pilot ring  114  are removed or not otherwise present, the end cap can be moved in the direction A or B as shown in  FIG. 4 . The end cap can be removed from the housing by pulling the end cap in the direction A. However, the housing step wall  142  limits the extent to which the end cap be moved in the direction B. Further movement in the direction B is prohibited by contact between the end cap step wall  126  and the housing step wall  142 . When then the end cap step wall is suit against the housing step wall, the second peripheral surface  124  is in surface-to-surface contact with the second interior wall portion  144  of the housing and the first peripheral surface  128  is in surface-to-surface contact with a portion of the first interior wall  140 , except for the gasket recesses  131 ,  133 , as shown in  FIG. 4 . 
     To prevent the end cap  110  from moving in that direction A, out of the housing, a stop ring, such as the segmented ring  112 , is placed in a ring recess  145  in the second interior wall portion  144 ,  152  between the inner portion  144  and the outer portion  152 . The ring recess has a first wall  146 , a second wall  148 , and a third wall  150 . In some embodiments, the walls  146 , 148 ,  150  of the ring recess  145  form a partial rectangle, as shown in  FIG. 4 , with two 90-degree angle corners. In some embodiments, the ring recess  145  is shaped to receive square, quadrilateral, round, oval, triangle or other cross-section shaped segmented rings. 
     The segmented ring  112  is configured to fit in the ring recess  145  to prevent the end cap from moving in the direction as shown in  FIG. 4  and being removed or dislodged from the housing step wall  142 . The segmented ring  112  has an outer surface  113 , an inner surface  117 , a rear surface  119 , and a front surface  115 . The outer surface  113  of the segmented ring is configured to mate in surface to surface contact with the second wall  148  of the ring recess  145 . The rear surface  119  of the segmented ring is prohibited from moving in the direction B by contact with the first wall  146  of the ring recess  145 . The front surface  115  is prohibited from moving in the direction A by contact with the third wall  150  of the ring recess  145 . The end cap  110  is prohibited from moving in the direction A when the segmented ring  112  is in the ring recess  145  so that the front surface  120  of the end cap  110  is prevented from moving in the direction A by contact with a portion of the rear surface  119  of the segmented ring. Outward pressure and force from the end cap in the direction A is transferred by the segmented ring to the housing at the ring recess. 
     To secure the segmented ring  112  in the ring recess  145  a pilot ring  114  is installed. The pilot ring  114  comprises a front surface  170 , a rear surface  174 , a first outer surface  172 , a pilot ring step wall  166 , a second outer surface  164 , and an inner surface  168 . The rear surface  174  is configured to be placed against the front surface  120  of the end cap. The pilot ring is held against the end cap by pilot ring fasteners  160 , such as bolts. The fasteners  160  extend through pilot ring fastener openings  161 . The pilot ring fastener openings have a countersink  162  to receive the head of the fastener  160 . The pilot ring fastener openings  161  are aligned with fastener end cap openings  163 . The fastener end cap openings may be threaded to receive a threaded shaft (not shown) of the fastener  160 . 
     When the pilot ring is secured to the end cap with the fasteners  160 , the segmented ring is prohibited from moving in the direction C of  FIG. 4  by the second outer surface  164 , and is prohibited from moving in the direction A by the pilot ring step wall  166  and third wall  150  of the ring recess, and is prohibited from moving in the direction B by the front surface  120  of the end cap and the first wall  146  of the ring recess, and is prohibited from moving in the direction D by the second wall  148  of the ring recess. In some embodiments, there are tolerances that allow the segmented ring to move slightly within the boundaries just described. The first outer surface  172  has a larger circumference than the second outer surface. The pilot ring step wall  166  connects the first outer surface  172  to the second outer surface  164 . In some embodiments, the pilot ring step wall  166  is perpendicular to the first outer surface  172  and the second outer surface  164 . The first outer surface  172  has a rectangular gasket recess for receiving a pilot ring circumferential gasket  154  or o-ring. The rear surface  174  also has a rectangular gasket recess for receiving a pilot ring rear gasket  156 . 
     The segmented ring  112  has a plurality of segments. In one embodiment, the segmented ring  112  has four segments  180 ,  182 ,  184 ,  186  as shown in  FIGS. 5-9 . The segmented ring may be made by taking a ring and making two longitudinal cuts offset in opposite direction from a central vertical diameter line of the ring. In some embodiments, the segments can be equal in arc length. In some embodiments, the opposite segments  180  and  182  are equal in arc length and opposite segments  184  and  186  are equal in arc length, but segments  180  and  184  are not equal in arc length. A first end  184   a  of one segment, such as segment  184  is configured to mate with a second end  182   b  of the next segment, such as segment  182  as shown in  FIG. 7 . 
       FIGS. 8 and 9  demonstrate one method of installing the segmented ring. In  FIG. 9  the segments  180 ,  182  are installed. Segment  180  is installed a long install path  190 . Install pass  190  provides that segment  180  is moved first towards the face of the end cap then is slid leftward toward the interior wall of the housing into the ring recess  145 . Likewise segment  182  is moved a long install path  192  and a similar, mirror image fashion to that of install path  190 . The next steps as shown in  FIG. 8  where the remaining segments  184 ,  186  are installed along install paths  194 ,  196 . Segment  184  is first moved towards the face of the end cap then is slid upward toward the interior wall of the housing into the ring recess  145 . Segment  186  is first moved towards the face of the end cap then is slid downward toward the interior wall of the housing into the ring recess  145 . 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.