Hydraulic accumulator having a closing arrangement

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.

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'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.

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. 1-3show an accumulator100having an embodiment of closing arrangements106,108. The accumulator100comprises a housing102surrounding an interior space101,105, a piston104within the space105, and two end closing arrangements106,108.

The end closing arrangements106,108are identical, and therefore only closing arrangement106will be described in detail. The closing arrangement106comprises an end cap110, a segmented ring112, and a pilot ring114. The pilot ring114is recessed from the end face housing wall111. The end face housing wall has upper and lower cover fastener openings107.

The piston104divides the interior space101,105into a first chamber101and a second chamber105. The first chamber101may be fluidly coupled to a hydraulic system, such as through fluid port127, to receive pressurized hydraulic fluid. The second chamber105can be filled with an inert gas such as a nitrogen gas. The inert gas can be filled through gas port129. One or more seals135and piston rings125surround the piston to prevent hydraulic fluid and/or the inert gas from leaking across the piston between the first and second chambers. Port129may 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 port127can 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 chamber101via a pump (not shown) in fluid-communication with port127. The hydraulic fluid acts on a first side121of the piston104in the first chamber, causing the piston to move toward the second chamber105to a loaded position. As the piston moves toward the loaded position, the volume of the second chamber105is 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 side121of the piston by the pressure of the hydraulic fluid in the first chamber is substantially equal to a force exerted on a second side123of the piston104by 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 chamber101and gas in the second chamber can be subjected to high levels of pressure for a relatively long period of time. The end closing arrangements106,108close 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 chamber101decreases. When the pressure of the hydraulic fluid in the first chamber101decreases below the pressure provided by the compressed gas in the second chamber105, the gas expands and drives the piston toward the first chamber101exerting 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 chambers101,105can be swapped so that chamber101contains the gas and chamber105contains the hydraulic fluid. The end closing arrangement106,108can 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 housing102comprises an outside wall103. In some embodiments the outside wall103is cylindrical. The housing102comprises a first interior wall140and a second interior wall portion144with a housing step wall142between the first interior wall140and the second interior wall portions144,152. The second interior wall portion comprises an inner portion144and an outer portion152. The second interior wall portion is located closer to an end109of the accumulator100as compared to the first interior wall140. 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 wall140and the inner second interior wall portion144.

The end cap110comprises an outer/front face120and an opposite inter face122. The inter face faces the interior and the piston104. Between the inner and outer face of the end cap is a first peripheral surface128and a second peripheral surface124with an end cap step wall126there between. The first peripheral surface128comprises to gasket recesses131and133, each comprising a gasket or O-ring130,132respectively. In some embodiments, the first and second peripheral surfaces128,124do not comprise threads for securing the end cap to the housing. In some embodiments, the first and second peripheral surfaces128,124are flat. In some embodiments, the first and second peripheral surfaces128,124are 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 surface128and a second peripheral surface124.

When the segmented ring112, and the pilot ring114are removed or not otherwise present, the end cap can be moved in the direction A or B as shown inFIG. 4. The end cap can be removed from the housing by pulling the end cap in the direction A. However, the housing step wall142limits 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 wall126and the housing step wall142. When then the end cap step wall is suit against the housing step wall, the second peripheral surface124is in surface-to-surface contact with the second interior wall portion144of the housing and the first peripheral surface128is in surface-to-surface contact with a portion of the first interior wall140, except for the gasket recesses131,133, as shown inFIG. 4.

To prevent the end cap110from moving in that direction A, out of the housing, a stop ring, such as the segmented ring112, is placed in a ring recess145in the second interior wall portion144,152between the inner portion144and the outer portion152. The ring recess has a first wall146, a second wall148, and a third wall150. In some embodiments, the walls146,148,150of the ring recess145form a partial rectangle, as shown inFIG. 4, with two 90-degree angle corners. In some embodiments, the ring recess145is shaped to receive square, quadrilateral, round, oval, triangle or other cross-section shaped segmented rings.

The segmented ring112is configured to fit in the ring recess145to prevent the end cap from moving in the direction as shown inFIG. 4and being removed or dislodged from the housing step wall142. The segmented ring112has an outer surface113, an inner surface117, a rear surface119, and a front surface115. The outer surface113of the segmented ring is configured to mate in surface to surface contact with the second wall148of the ring recess145. The rear surface119of the segmented ring is prohibited from moving in the direction B by contact with the first wall146of the ring recess145. The front surface115is prohibited from moving in the direction A by contact with the third wall150of the ring recess145. The end cap110is prohibited from moving in the direction A when the segmented ring112is in the ring recess145so that the front surface120of the end cap110is prevented from moving in the direction A by contact with a portion of the rear surface119of 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 ring112in the ring recess145a pilot ring114is installed. The pilot ring114comprises a front surface170, a rear surface174, a first outer surface172, a pilot ring step wall166, a second outer surface164, and an inner surface168. The rear surface174is configured to be placed against the front surface120of the end cap. The pilot ring is held against the end cap by pilot ring fasteners160, such as bolts. The fasteners160extend through pilot ring fastener openings161. The pilot ring fastener openings have a countersink162to receive the head of the fastener160. The pilot ring fastener openings161are aligned with fastener end cap openings163. The fastener end cap openings may be threaded to receive a threaded shaft (not shown) of the fastener160.

When the pilot ring is secured to the end cap with the fasteners160, the segmented ring is prohibited from moving in the direction C ofFIG. 4by the second outer surface164, and is prohibited from moving in the direction A by the pilot ring step wall166and third wall150of the ring recess, and is prohibited from moving in the direction B by the front surface120of the end cap and the first wall146of the ring recess, and is prohibited from moving in the direction D by the second wall148of 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 surface172has a larger circumference than the second outer surface. The pilot ring step wall166connects the first outer surface172to the second outer surface164. In some embodiments, the pilot ring step wall166is perpendicular to the first outer surface172and the second outer surface164. The first outer surface172has a rectangular gasket recess for receiving a pilot ring circumferential gasket154or o-ring. The rear surface174also has a rectangular gasket recess for receiving a pilot ring rear gasket156.

The segmented ring112has a plurality of segments. In one embodiment, the segmented ring112has four segments180,182,184,186as shown inFIGS. 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 segments180and182are equal in arc length and opposite segments184and186are equal in arc length, but segments180and184are not equal in arc length. A first end184aof one segment, such as segment184is configured to mate with a second end182bof the next segment, such as segment182as shown inFIG. 7.

FIGS. 8 and 9demonstrate one method of installing the segmented ring. InFIG. 9the segments180,182are installed. Segment180is installed a long install path190. Install pass190provides that segment180is moved first towards the face of the end cap then is slid leftward toward the interior wall of the housing into the ring recess145. Likewise segment182is moved a long install path192and a similar, mirror image fashion to that of install path190. The next steps as shown inFIG. 8where the remaining segments184,186are installed along install paths194,196. Segment184is first moved towards the face of the end cap then is slid upward toward the interior wall of the housing into the ring recess145. Segment186is first moved towards the face of the end cap then is slid downward toward the interior wall of the housing into the ring recess145.