CN117529618A

CN117529618A - Accumulator with reinforcing structure

Info

Publication number: CN117529618A
Application number: CN202280043551.9A
Authority: CN
Inventors: J·A·M·奥布莱恩; L·华纳
Original assignee: Advanced Energy Storage Co ltd
Current assignee: Advanced Energy Storage Co ltd
Priority date: 2021-05-13
Filing date: 2022-05-13
Publication date: 2024-02-06

Abstract

An accumulator assembly, comprising: a first cylindrical housing; a second cylindrical housing coaxially positioned within the first cylindrical housing, wherein a cylindrical space is formed between the first and second cylindrical housings, the space defining a gas volume; a first end cap and a second end cap attached to and closing the distal ends of both the first cylindrical housing and the second cylindrical housing, each end cap having four radially outwardly extending sides defining reinforcing support flanges, wherein each reinforcing support flange includes a reinforcing element engagement surface; and a stiffening element extending around each of the two opposing support flanges such that the stiffening element engagement surface defines a channel for the stiffening element, wherein the stiffening element holds the first end cap and the second end cap to the axial ends of both the inner housing and the outer housing.

Description

Accumulator with reinforcing structure

Cross Reference to Related Applications

The present application claims the benefit of U.S. provisional application Ser. Nos. 63/188,008, filed on day 13 5 of 2021, and 63/220,767, filed on day 12 of 7 of 2021, the disclosures of which are incorporated herein by reference.

Background

The present invention relates generally to pressurized fluid storage devices and, in particular, to pressurized accumulators having structural reinforcement elements to allow storage of fluid under high pressure.

It is well known that accumulators store fluid (particularly fluid that is considered incompressible) under pressure for controlled release. The pressure is generated by compressing a spring element, in particular a fluid spring element, which provides stored energy to drive the fluid to do work. It is known to provide an external clamping mechanism consisting of a rod to add structural support to the end cap for containing pressurized contents, such as the accumulator device described in us patent 7,661,442. While these structural reinforcements provide axial strength, they tend to increase the weight of the accumulator system and require the end cap to be sized larger than necessary in order to accommodate the connector. Accordingly, there is a need to provide an end cap restraint structure that is lightweight and compact in order to improve packaging and space utilization.

Disclosure of Invention

The present invention relates generally to pressurized fluid, gas or gas-liquid storage devices (gas over fluid storage devices), and in particular to pressurized accumulators having structural reinforcement elements to allow storage of fluid at high pressure.

The accumulator assembly includes: a first cylindrical housing; a second cylindrical housing coaxially positioned within the first cylindrical housing, wherein a cylindrical space is formed between the first and second cylindrical housings, the space defining a gas volume; a first end cap and a second end cap attached to and closing the distal ends of both the first cylindrical housing and the second cylindrical housing, each end cap having four radially outwardly extending sides defining reinforcing support flanges, wherein each reinforcing support flange includes a reinforcing element engagement surface; and a stiffening element extending around each of the two opposing support flanges such that the stiffening element engagement surface defines a channel for the stiffening element, wherein the stiffening element holds the first end cap and the second end cap to the axial ends of both the inner housing and the outer housing.

Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of an exemplary hydraulic circuit within which an enhanced accumulator according to the present disclosure may be used.

Fig. 2 is a perspective view of a reinforced accumulator according to the present invention.

Fig. 3 is an enlarged perspective view of an end cap and reinforcement structure of the reinforced accumulator of fig. 2.

Fig. 4 is a cross-sectional view taken along line 4-4 of fig. 2.

Fig. 5A is a cross-sectional view taken along line 5A-5A of fig. 2.

Fig. 5B is an enlarged cross-sectional view of the reinforced accumulator of fig. 5A.

Fig. 6 is an alternative perspective view of the reinforced accumulator shown in fig. 2-5B.

Detailed Description

Referring now to the drawings, FIG. 1 shows an exemplary hydraulic circuit with multiple accumulators as disclosed in International application PCT/US2021/023664, the disclosure of which is incorporated herein by reference in its entirety. In fig. 1, a schematic diagram of a hydraulic unit is shown generally at 26 and includes one or more hydraulic circuits. In the illustrated embodiment, a plurality of accumulators 22 are connected to the bridge 12 through accumulator output lines 22c. Each of the accumulators 22 is connected to an output line 22c through an output regulator 28. Regulator 28 is configured to control any of fluid flow rate, pressure, and/or flow direction. The regulator 28 may be based on demandIs activated individually, as a cascade output from each accumulator, or as a group. The pressurized chamber of each accumulator 22 is filled with a compressible medium, such as an inert gas (e.g., nitrogen (N) ₂ ) Any suitable gas may be used). The pressurized chamber of each accumulator 22 is connected to a vent line 30 for the purpose of regulating or eliminating the pressure level of the gas. The vent line 30 may be regulated by one or more relief valves 32, 34. Alternatively, each accumulator may have a relief valve connected from the pressurized chamber to the vent line 30.

In the event of a failure of an accumulator 22 or a failure of a fluid conduit, a particular accumulator 22 or any combination of accumulators 22 may be deactivated by venting pressurized gas therein. The affected accumulator 22 may be fluidly isolated by its associated regulator 28 and depressurized by a relief valve 32 or 34 connected to the affected accumulator. In the case of system maintenance activities, the vent line 30 may be used to charge the accumulator from a charging source (e.g., by a pressurized nitrogen source or by an air compressor when the inert gas is ambient air). This would allow remote use and maintenance with minimal support.

Referring to fig. 2, an accumulator according to the present invention is shown generally at 100. Accumulator 100 may be any type of pressurized fluid storage device, such as a piston accumulator; a bladder, metal bellows, or diaphragm accumulator; or a mechanical spring accumulator. The illustrated embodiment of the accumulator 100 is a coaxial accumulator. As shown in fig. 5A and 5B, the accumulator 100 includes a cylindrical inner sleeve or housing 102 within a cylindrical outer sleeve or housing 104 covered by a carbon fiber layer 106. Distal ends of both the inner housing 102 and the outer housing 104 are attached to a first end cap 108 and a second end cap 110. The illustrated housings 102, 104 may be formed of a lightweight, gas impermeable material. Materials from which the illustrated housings 102, 104 may be formed include, but are not limited to, steel, fiberglass, composite materials, and other metals. The carbon fiber layer 106 may be formed by wrapping carbon fibers around the outer housing 104. The carbon fiber layer 106 increases hoop strength, increases structural integrity, and increases gas impermeability, thereby preventing gas from the gas volume 124 (described below) from escaping to the exterior of the accumulator 100.

As shown in fig. 2, the first end cap 108 and the second end cap 110 are generally square with four radially outwardly extending sides, thereby defining a reinforcing support flange 112 that supports and orients a reinforcing element 114, as described in detail below. Each reinforcement support flange 112 includes a reinforcement element engagement surface 116 that defines a passageway for the reinforcement element 114. The reinforcement element engagement surface 116 is configured with a rounded transition 118 from a transverse orientation 120 to an axial orientation 122 relative to the axis of the coaxially disposed inner and outer shells 102, 104. As will be explained with reference to the stiffening element 114, the stiffening element engagement surface 116 directs the transition of the stiffening element 114 from an axial orientation to a transverse orientation without creating a sharp transition region.

Referring to fig. 5A, the cylindrical outer housing 104 defines an outer wall and the cylindrical inner housing 102 defines an inner wall of the gas volume 124. The interior of the cylindrical inner housing 102 defines a fluid volume 126. A piston 128 is mounted within the cylindrical inner housing 102 and is movable relative to the fluid volume 126.

The illustrated piston 128 is a substantially cup-shaped cylindrical piston having an inner surface defining an axial bore 130 extending from a first or open end 132 to a second or closed end 134 of the piston 128. The piston 128 is slidably received within the cylindrical inner housing 102. The piston 128 and the cylindrical inner housing 102 cooperate to separate the gas volume 124 from the fluid volume 126 within the cylindrical inner housing 102. A circumferential groove 136 is formed in the outer surface of the piston 128. An O-ring (not shown) is typically disposed within the groove 136 for fluid-tight sealing between the piston 128 and the inner surface of the cylindrical inner housing 102. Closed end 134 includes a preloaded check valve 138 configured to bypass overpressure. If desired, a sensor and alarm system (not shown) may be provided within the accumulator 100 to alert an operator when the check valve 138 is actuated in an overpressure condition. Thus, the check valve 138 allows bypass fluid leakage in the event of an undesirably increased fluid pressure differential within the fluid volume 126 that may cause structural damage to the inner housing 102.

In addition, at least one circumferential wear groove 139 is also formed on each side of the O-ring groove 136. A wear ring (not shown) is disposed within the groove 139 to reduce wear between the piston 128 and the inner housing 102 as the piston 128 slides within the inner housing 102 during operation of the accumulator 100.

In one embodiment, hydraulic oil is used for the fluid volume 126, but any incompressible or slightly compressible fluid may be used. As used herein, "gas" refers to a compressible material or energy storage material that forms a gas spring, and "fluid" refers to hydraulic oil or other fluid used as an energy transfer material. The gas volume 124 is in fluid communication with an open end 132 of the piston 128 and the hydraulic fluid is in fluid communication with a closed end 134 of the piston 128.

The first end cap 108 and the second end cap 110 are configured to seal the respective gas volume 124 and fluid volume 126. In the illustrated embodiment, the end cap 108 and the end cap 110 are attached to the outer housing 104 by threaded connections 143. Alternatively, end cap 108 and end cap 110 may be attached to outer housing 104 by means including, but not limited to, welding, brazing, press fitting, O-rings, and other conventional sealing means. As shown in fig. 5B, the end cap 110 includes a circumferential groove 111 formed in an outer surface of the end cap 110. An O-ring (not shown) is typically disposed within the groove 111 for fluid sealing between the end cap 110 and the inner surface of the cylindrical inner housing 102.

End cap 110 is shown with gas charge port 144 and hydraulic fluid port 146, but either end cap 108 and end cap 110 may include one or both of these ports. Advantageously, the gas charge port 144 and the hydraulic fluid port 146 are located on the end cap 110, and thus both are located at one end of the accumulator 100. The fill port 144 may include a two-way valve (not shown) and thus function as a gas inlet and as a gas outlet for safely venting gas from the gas volume 124. Similarly, the hydraulic fluid port 146 may also include a two-way valve (not shown) to regulate fluid flow into and out of the fluid volume. Alternatively, the valve may be part of a hydraulic circuit, for example as disclosed in International application PCT/US 2021/023664. The illustrated first end cap 108 includes two gas passages 148 that allow the gas volume 124 to communicate with the open end 132 of the piston 128.

In the illustrated embodiment, the reinforcing element 114 is formed from a plurality of filaments or fibrous materials that may be separate or bonded together. The filaments or fibrous materials may be formed from metallic materials such as steel cords, carbon fibers, aramid fibers, glass fibers, nanocomposite materials, or any other type of load bearing material that may be wound or formed onto the end caps 108 and 110. The reinforcing element 114 may be encapsulated with an encapsulating material (e.g., epoxy, vinyl ester) or other material that bonds the fibers together (either as pre-impregnated fibers or coated after the fibers are installed). This bonded fiber structure helps to direct the load path within the reinforcing element 114 primarily under tension, which uses the strongest load orientation of the fibers. Alternatively, the fibers may be woven tows of fibers, such as longitudinally oriented fibers and circumferentially oriented fibers.

In one embodiment of the process of forming the accumulator 100, the end caps 108 and 110 are positioned to seal the distal ends of both the inner housing 102 and the outer housing 104 and define a gas volume 124 and a fluid volume 126, respectively. Internal components such as piston 128, bladder, diaphragm, etc. are installed prior to sealing. The end caps 108 and 110 are oriented such that the axial portions of the reinforcing element engagement surface 116 of each end cap 108 and 114 are substantially in line. The fibrous material of the reinforcing member 114 is then wrapped around the reinforcing member engagement surface 116 from one end cap to the other. The reinforcing elements 114 may also be bundled with any constraining structure, such as a shaped and crimped sleeve (not shown), at least along the axial length of each reinforcing element 114 to prevent damage caused by impact loads.

Advantageously, the illustrated embodiment of the accumulator 100 relies on the stiffening element 114 to hold the end caps 108 and 110 to the axial ends of both the inner housing 102 and the outer housing 104 and to control axial stresses resulting from the pressure inside the accumulator 100 increasing beyond the pressure of the environment outside the accumulator 100. A preload is placed on the stiffening element 114 sufficient to mitigate excessive movement of the end caps 108 and 110 and maintain a barrier seal using and/or threading a sealant, a conventional seal (e.g., seal 150), or any other process that secures and seals each of the end caps 108 and 110 to the assembled inner and outer shells 102 and 104. Advantageously, the seal 150 functions to prevent gas from the gas volume 124 from escaping to the exterior of the accumulator 100.

The principles and modes of operation of the present invention have been explained and illustrated in its preferred embodiments. It must be understood, however, that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.

Claims

1. An accumulator assembly, the accumulator assembly comprising:

a first cylindrical housing;

a second cylindrical housing coaxially positioned within the first cylindrical housing, wherein a cylindrical space is formed between the first and second cylindrical housings, the space defining a gas volume;

a first end cap and a second end cap attached to and closing the distal ends of both the first cylindrical housing and the second cylindrical housing, each end cap having four radially outwardly extending sides defining reinforcing support flanges, wherein each reinforcing support flange includes a reinforcing element engagement surface; and

a stiffening element extending around each of the two opposing support flanges such that a stiffening element engagement surface defines a channel for the stiffening element, the stiffening element retaining the first and second end caps to axial ends of both the inner and outer shells.

2. The accumulator assembly of claim 1, wherein an interior of the second cylindrical housing defines a fluid volume, the accumulator assembly further comprising a piston mounted within the second cylindrical housing and movable relative to the fluid volume.

3. The accumulator assembly of claim 2, wherein the reinforcement element is further configured to control axial stress generated when pressure inside the accumulator increases beyond ambient pressure outside the accumulator.

4. The accumulator assembly of claim 2, wherein each reinforcement element engagement surface is configured with a rounded transition extending from a transverse orientation to an axial orientation, whereby the rounded transition guides the transition of the reinforcement element from the axial orientation to the transverse orientation without creating a sharp transition region.

5. The accumulator assembly of claim 2, wherein a carbon fiber layer is attached to an outer surface of the first cylindrical housing.

6. The accumulator assembly of claim 4, wherein the reinforcement element is formed of a fibrous material.

7. The accumulator assembly of claim 6, wherein the fiber material is one of a metal material, a carbon fiber, an aramid fiber, a glass fiber material, and a nanocomposite fiber.

8. The accumulator assembly of claim 2, wherein the piston includes a preloaded check valve configured as an overpressure bypass.

9. The accumulator assembly of claim 8, wherein the piston is a cup-shaped cylindrical piston having an inner surface defining an axial bore extending from an open end to a closed end of the piston, wherein the piston is slidably received within the cylindrical inner housing, and wherein the piston and the cylindrical inner housing cooperate to separate the gas volume from the fluid volume within the cylindrical inner housing.

10. The accumulator assembly of claim 9, wherein the check valve allows bypass fluid to leak when a predetermined increased fluid pressure differential occurs in the fluid volume.

11. The accumulator assembly of claim 10, further comprising a sensor and alarm system within the accumulator assembly, the sensor and alarm system configured to alert an operator when the check valve is actuated in an overpressure condition.

12. The accumulator assembly of claim 11, wherein a carbon fiber layer is attached to an outer surface of the first cylindrical housing.

13. The accumulator assembly of claim 12, wherein the carbon fiber layer is formed by wrapping carbon fibers around the first cylindrical housing, and wherein the carbon fiber layer increases hoop strength, increases structural integrity, and increases air tightness.

14. The accumulator assembly of claim 2, wherein the first end cap and the second end cap are attached to the first cylindrical housing by one of a threaded connection, welding, brazing, press fitting, and an O-ring.

15. An accumulator assembly, the accumulator assembly comprising:

a first cylindrical housing;

a second cylindrical housing coaxially positioned within the first cylindrical housing, wherein a cylindrical space is formed between the first and second cylindrical housings, the space defining a gas volume, and wherein an interior of the second cylindrical housing defines a fluid volume;

a piston mounted within the second cylindrical housing and movable relative to the fluid volume, the piston having a preloaded check valve configured as an overpressure bypass;

a carbon fiber layer attached to an outer surface of the first cylindrical housing;

a first end cap and a second end cap attached to and closing the distal ends of both the first cylindrical housing and the second cylindrical housing, each end cap having four radially outwardly extending sides defining a reinforcing support flange, wherein each reinforcing support flange comprises a reinforcing element engagement surface, and wherein the first end cap and the second end cap are attached to the first cylindrical housing by a threaded connection; and

16. The accumulator assembly of claim 15, wherein the reinforcement element is further configured to control axial stress generated when pressure inside the accumulator increases beyond ambient pressure outside the accumulator.

17. The accumulator assembly of claim 15, wherein each reinforcement element engagement surface is configured with a rounded transition extending from a transverse orientation to an axial orientation, the rounded transition thereby guiding the transition of the reinforcement element from the axial orientation to the transverse orientation without creating a sharp transition region.

18. The accumulator assembly of claim 17, wherein the fiber material is one of a metal material, a carbon fiber, an aramid fiber, a glass fiber material, and a nanocomposite fiber.

19. The accumulator assembly of claim 15, wherein the piston is a cup-shaped cylindrical piston having an inner surface defining an axial bore extending from an open end to a closed end of the piston, wherein the piston is slidably received within the cylindrical inner housing, and wherein the piston and the cylindrical inner housing cooperate to separate the gas volume from the fluid volume within the cylindrical inner housing.

20. The accumulator assembly of claim 19, wherein the check valve allows bypass fluid to leak when a predetermined increased fluid pressure differential occurs in the fluid volume.