Method for inflating bellows accumulator

Abstract

A method of inflating a bellows accumulator of a vehicle suspension system includes providing a housing with an accumulator port and an inflation port and inserting a bellows assembly within the housing. The bellows assembly includes an annular bellows wall at least partially defining a variable volume plenum. The bellows assembly is axially extendable between a retracted position and a fully extended position. The air chamber is in fluid communication with the inflation inlet. An energy storage chamber between the housing and the bellows assembly is in fluid communication with the accumulator port. The method further includes evacuating the energy storage chamber when the bellows assembly is not in the fully extended position such that a pressure less than atmospheric pressure is obtained within the energy storage chamber, and supplying pressurized gas to the inflation port.

Description

Technical Field

[0001] The present application generally relates to the art of vehicle suspension components. More specifically, the present application describes a method of pressurizing or charging a bellows accumulator associated with a hydraulic shock absorbing system. Background Art

[0002] This section provides background information related to the present application which is not necessarily prior art.

[0003] In order to improve the ride and handling characteristics of a vehicle, it is often beneficial to equip the vehicle with a suspension system that is operable to absorb loads input to the vehicle as it travels over a road surface, turns, brakes, and accelerates. In order to dissipate the energy associated with the vehicle traveling over bumps and depressions in the road surface, shock absorbers are often connected between the vehicle body and the vehicle suspension.

[0004] The suspension system, including the shock absorbers mentioned above, not only attempts to control the reaction of each wheel end to road loads, but also strives to improve the overall handling and safety of the vehicle. Undesirable vehicle roll may occur during cornering maneuvers, and pitch may occur when the vehicle decelerates and accelerates. Roll and pitch moments may adversely affect tire adhesion, cornering performance, braking performance, and may cause discomfort to the driver and passengers.

[0005] Existing suspension systems may be equipped with mechanical torsion bars to counteract the tendency to roll or pitch. More recently, fluid control systems have been implemented to hydraulically interconnect two or more shock absorbers located on a vehicle. At least some fluid control systems are equipped with one or more accumulators. An accumulator typically includes a pressurized air chamber and an accumulator chamber that supplies and receives working fluid to a hydraulic system including the shock absorbers. Several types of accumulators have been constructed, including bladder accumulators, piston accumulators, and bellows accumulators.

[0006] In a bellows accumulator, the bellows defines an internal pressurized air chamber. The bellows can extend and contract within the housing based on the pressure of the pressurized air chamber acting on the fluid in the hydraulic system. The pressurized gas provides a positive pressure within the bellows, which will force the working fluid out of the accumulator when the fluid pressure in the accumulator chamber is less than the gas pressure in the pressurized air chamber. Typically, the accumulator is pre-assembled and filled with pressurized gas before it is installed or otherwise connected to the shock absorber or suspension system. Unfortunately, if there is a pressure differential between the charging chamber and the accumulator chamber, the bellows may be damaged before or during vehicle installation. For example, during the accumulator manufacturing process, there is a risk of bellows damage during the initial pre-charging of the accumulator. In addition, or alternatively, the bellows may undergo undesirable deformation during the process of filling the vehicle suspension system with fluid at the vehicle manufacturing site. There is a possibility of further damage to the bellows when charging the hydraulic system on the vehicle or possibly during suspension system maintenance operations. There may also be a pressure differential condition during extreme handling events of the vehicle.

[0007] The fatigue life of an undesirably deformed bellows may be significantly less than the expected life. It may therefore be advantageous to ensure that the bellows retains its proper shape and that the corrugations or folds of the bellows do not deform undesirably when the pressure inside the bellows differs significantly from the pressure outside the bellows.

[0008] Some accumulator assembly procedures may include supplying fluid to the accumulator chamber prior to assembling the accumulator to the suspension system or vehicle. Later, when or before the accumulator is attached to the vehicle, residual fluid in the accumulator chamber may leak out of the housing, causing unnecessary contamination of the workspace.

[0009] Therefore, there is a need for an improved method of charging a bellows accumulator that ensures simple assembly and reliable operation. Summary of the invention

[0010] The present application provides a method for inflating a bellows accumulator of a vehicle suspension system, comprising: providing a housing having an accumulator port and a charging port, and inserting a bellows assembly into the housing. The bellows assembly includes an annular bellows wall that at least partially defines an air chamber with a variable volume. The bellows assembly can extend axially between a retracted position and a fully extended position. The air chamber is arranged to be in fluid communication with the charging port. An accumulator chamber is provided between the housing and the bellows assembly, and the accumulator chamber is in fluid communication with the accumulator port. The method also includes: evacuating the accumulator chamber when the bellows assembly is not in a fully extended position so that a pressure less than atmospheric pressure is obtained in the accumulator chamber, and supplying pressurized gas to the charging port.

[0011] In another arrangement, the present application provides a method for charging a bellows accumulator for a vehicle suspension system, comprising: providing a housing and providing a bellows assembly, the bellows assembly including a plate and an annular bellows wall defining a variable volume air chamber. The plate is axially movable between a first position and a second position. The method includes: providing an accumulator chamber in fluid communication with the bellows assembly, and providing a valve in fluid communication with the accumulator chamber. When the plate is not in the second position, the valve is in an open state, and when the plate is in the second position, the valve is in a closed state. The method also includes: applying a vacuum to the accumulator chamber when the valve is in the open state, and filling the air chamber with pressurized gas so that the air chamber contains pressurized gas when the vacuum is applied to the accumulator chamber.

[0012] In some embodiments, the air chamber is filled with pressurized gas when the plate is in the second position.

[0013] In some embodiments, the air chamber is filled with pressurized gas when the plate is not in the second position.

[0014] In some embodiments, the methods provided herein further include maintaining the plate in a position other than the second position when the vacuum is applied so that the valve remains in an open state.

[0015] In some embodiments, the plate is held in a position other than the second position by positioning a lift pin within the accumulator port and engaging the bellows assembly.

[0016] In some embodiments, the method provided herein further includes retracting the lift pin from the accumulator port after a predetermined vacuum value is reached in the accumulator chamber.

[0017] In some embodiments, the method provided herein further includes retracting the lift pin from the accumulator port after charging the gas chamber with the pressurized gas.

[0018] In some embodiments, the suspension assembly further includes a shock absorber, and the method provided in the present application further includes connecting a bellows accumulator to the shock absorber fluid, and using pressurized gas in the bellows accumulator to apply pressure to the fluid in the shock absorber.

[0019] Other applicable fields of the present application will become apparent from the detailed description, claims and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present application can be more fully understood from the detailed description and accompanying drawings, in which: Figure 1 is a schematic diagram showing a vehicle having an exemplary suspension system of the present application; Figure 2is a schematic diagram of a portion of an exemplary suspension system including a shock absorber, a hydraulic conduit, and an exemplary accumulator; Figure 3 is a perspective view of an exemplary bellows accumulator constructed according to the teachings of the present application; Figure 4 yes Figure 3 An exploded perspective view of a bellows accumulator is shown; Figure 5 yes Figure 3 A cross-sectional view taken along line 5-5 is shown; and 6a, 6b, 6c and 6d illustrate a method of charging a bellows accumulator according to the teachings of the present application.

[0021] In the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0022] The present application relates generally to suspension systems for motor vehicles equipped with accumulators and, more particularly, to a method of charging a bellows accumulator.

[0023] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. Exemplary embodiments are provided to make the present application more detailed and to fully convey the scope of the present application to those skilled in the art. In order to provide a comprehensive understanding of the embodiments of the present application, many specific details are listed, such as examples of specific parts, devices and methods. It is apparent to those skilled in the art that, without adopting specific details, exemplary embodiments can be embodied in a variety of different forms, and these specific details should not be construed as limiting the scope of the present application. In some exemplary embodiments, well-known processes, well-known device structures and well-known technologies are not described in detail.

[0024] The terms used herein are only used to describe specific example embodiments and are not restrictive. The singular forms "one", "an" and "the" used herein also include plural forms unless the context clearly indicates otherwise. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or increase of one or more other features, integers, steps, operations, elements, parts and / or groups thereof. The method steps, processes and operations described herein should not be understood to be necessarily performed in the specific order discussed or described, unless the execution order is specifically specified. It should also be understood that other steps or alternative steps may also be used.

[0025] When an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged to, connected to, or coupled to another element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may be no intermediate elements or layers. Other words used to describe the relationship between elements should also be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0026] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms may only be used to distinguish an element, component, region, layer or part from another region, layer or part. Unless the context clearly states, the "first", "second" and other numerical terms used herein do not mean order or sequence. Therefore, the first element, component, region, layer or part discussed below may be referred to as the second element, component, region, layer or part without departing from the teachings of the exemplary embodiments.

[0027] For ease of description, spatially relative terms such as "inside", "outside", "below", "beneath", "lower", "above", "upper", etc. may be used herein to describe the relationship between one element or feature and another element or feature shown in the figure. In addition to the orientations described in the figures, spatially relative terms may also include different orientations of the device in use or operation. For example, if the device in the figure is turned over, other elements or features described as "below" or "below" will be placed "above" the other elements or features. Therefore, the example term "below" can include both "above" and "below" orientations. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein can be interpreted accordingly.

[0028] Figure 1An exemplary vehicle 10 is shown including a suspension system 12 and a vehicle body 14. The suspension system 12 includes shock absorbers 20 and coil springs 22. The shock absorbers 20 may be semi-active, with the level of damping being controlled by an electronic control unit 25. The electronic control unit 25 receives information from sensors (not shown), such as acceleration, displacement, steering angle, brake application, and vehicle speed. Alternatively, it should be understood that the shock absorbers 20 may be selectively fluidly interconnected to one another with a network of fluid lines and valves (not shown). The network of fluid lines and valves controls the function of the shock absorbers to handle inputs to the vehicle that attempt to cause rollover, pitching, or other undesirable motions.

[0029] Reference Figure 2 , the exemplary shock absorber 20 includes a shock absorber housing 28, a piston rod 30, and a piston 32 mounted on the piston rod 30. The piston 32 is arranged to be slidably engaged with the interior of the shock absorber housing 28, so that the piston 32 divides the shock absorber housing into a compression chamber 34 and a rebound chamber 36. The piston 32 is a closed piston with no fluid flow path defined within or by its structure. In addition, there are no other fluid flow paths in the shock absorber housing 28, so that there is no fluid communication between the compression chamber and the rebound chamber of the shock absorber except through an external hydraulic circuit (not shown) via the rebound chamber port 40 and the compression chamber port 42 in the shock absorber housing 28.

[0030] The accumulator 50 is arranged in fluid communication with the compression chamber port 42. The accumulator 50 may alternatively be positioned in fluid communication with the rebound chamber port 40 or with a hydraulic line coupled to either of the ports 40, 42. The accumulator 50 defines a variable fluid volume that increases and decreases depending on the fluid pressure within the compression chamber port 42.

[0031] Reference Figures 3 to 5 The accumulator 50 is configured as a bellows accumulator. The accumulator 50 includes an accumulator port 52 and an accumulator chamber 54. It should be understood that the accumulator 50 can be located at any number of physical locations on the vehicle as long as fluid communication occurs between the accumulator chamber 54 of the accumulator 50 and the shock absorber port, hydraulic line or valve of the suspension system. In one example, the accumulator 50 is directly fixed to the base of the shock absorber housing (not shown).

[0032] The accumulator chamber 54 contains the same working fluid as the working fluid contained in the shock absorber 20 and flows through the hydraulic circuits of the suspension system. In addition, the accumulator 50 also includes a pressurized gas chamber 56, which is defined by and contained in a bellows assembly 58 located within the housing 60 of the accumulator 50. After completing the pre-charging process described in more detail below, the pressurized gas chamber 56 is filled with pressurized gas, sealed, and fluidly isolated (i.e., separated) from the accumulator chamber 54. In the example shown, the accumulator chamber 54 is longitudinally positioned between the pressurized gas chamber 56 and the accumulator port 52. However, it should be understood that the accumulator 50 can be designed with the accumulator chamber 54 in an alternative location, such as between the pressurized gas chamber 56 and another portion of the structural component, shock absorber, or housing 60.

[0033] The bellows assembly 58 is expandable and compressible in the axial direction within the housing 60 of the accumulator 50 , so that the volumes of the accumulator chamber 54 and the pressurized air chamber 56 can increase or decrease as the fluid pressure within the accumulator chamber 54 changes.

[0034] The pressurized gas within the pressurized gas chamber 56 of the accumulator 50 is used to apply a positive pressure within the accumulator 50, which forces the fluid to flow out of the accumulator chamber 54 when the fluid pressure at the accumulator port 52 is less than the gas pressure within the pressurized gas chamber 56. In other words, the volume of the pressurized gas chamber 56 will increase and the volume of the accumulator chamber 54 will decrease until the pressures between the accumulator chamber 54 and the pressurized gas chamber 56 are equal. Conversely, when the fluid pressure at the accumulator port 52 increases, the fluid flows into the accumulator chamber 54, causing the volume of the accumulator chamber 54 to increase and the volume of the pressurized gas chamber 56 to decrease until the pressures are equal.

[0035] The housing 60 of the accumulator 50 is generally cylindrical and extends in an annular shape about the accumulator axis A. The housing 60 of the accumulator 50 includes an open end 62 that abuts a crown 63 at a distal end 64 of the accumulator 50. The crown 63 is sealed and fixed to the housing 60. A cover 66 is sealed and fixed to the crown 63. The cover 66 includes a charging port 68 and a plurality of mounting holes 69. The cover 66 is generally arranged along a transverse plane that is substantially perpendicular to the accumulator axis A. Therefore, the cover 66 of the accumulator 50 generally closes the distal end 64 of the housing 60 except for the opening provided by the charging port 68 at the distal end 64.

[0036] Although other configurations are possible, the housing 60 of the accumulator 50 may be made of metal and include an integral end wall 70 formed integrally with the housing 60. The end wall 70 extends generally transversely relative to the accumulator axis A. A threaded nipple 72 extends axially from the end wall 70 and includes the accumulator port 52. The threaded nipple 72 may be externally threaded to provide for mounting of the accumulator 50. The hole 69 may be used as a drive socket for a tool (not shown) to secure the threaded nipple 72 to any suitable structure. Other geometric features, such as a hexagon on the cover 66 and a milled slot or flat on the housing 60, may be provided in place of or in addition to the hole 69 to apply torque to the housing 60 and the threaded nipple 72. In addition, it is also contemplated that alternative mounting arrangements, such as threaded holes or axially extending studs, may be provided on the housing 60, such as at the end wall 70.

[0037] The bellows assembly 58 of the accumulator 50 is arranged in a sliding / sliding fit within the housing 60 and has an annular bellows wall 74 that extends coaxially about the accumulator axis A and axially between the cover 66 and the plate 76 of the bellows assembly 58. The plate 76 of the bellows assembly 58 has a disc shape and an outer diameter that is fixed to the annular bellows wall 74. A centering ring 77 may be used to align the annular bellows wall 74 along the accumulator axis A within the housing 60. The centering ring 77 minimizes the possibility of the bellows assembly 58 contacting the inner surface 88 of the housing 60. The cover 66 includes an annular flange 78 that is fixed to the annular bellows wall 74 at the distal end 64. The annular bellows wall 74, the cover 66 of the bellows assembly 58, and the plate 76 cooperate to define the pressurized air chamber 56 within the accumulator 50. Annular bellows wall 74 has a corrugated shape, which allows bellows assembly 58 to expand and contract in length (ie, the distance between cover 66 and plate 76 of bellows assembly 58 may increase or decrease) depending on the pressure differential between accumulator chamber 54 and pressurized gas chamber 56 .

[0038] like Figure 5 As best shown, the end wall 70 includes a groove 80 that receives a seal 82. The plate 76 and the seal 82 form a valve 83 that is normally open when the plate 76 is not in the fully extended position. When the bellows assembly 58 is in the fully extended position, the plate 76 engages the seal 82 to operate the valve 83 in a closed state and define a vacuum chamber 84 (FIG. 6c) defined by the outer surface 86 of the annular bellows wall 74, the inner surface 88 of the housing 60, the inner surface 90 of the crown 63, and the annular flange 78.

[0039] It may be beneficial to evacuate the accumulator chamber 54 before connecting the charging port 68 to a source of pressurized gas. As previously discussed, if there is a pressure differential between the charged chamber and the accumulator chamber, and the annular bellows wall 74 deforms undesirably rather than simply expanding and contracting as intended, damage to the bellows assembly 58 may occur. FIGS. 6a, 6b, 6c, and 6d illustrate a method of charging the accumulator 50 that applies a vacuum to the accumulator chamber 54 prior to filling the pressurized gas chamber 56 with pressurized gas to minimize the possibility of damage to the annular bellows wall 74.

[0040] The accumulator charging method starts from Figure 6a, when the accumulator 50 is assembled and the accumulator port 52 and the charging port 68 are open to the atmosphere. At this time, the plate 76 can be spaced apart from the seal 82, or it can be engaged with the seal 82.

[0041] In FIG. 6 b , the lift pin 96 is inserted into the accumulator port 52 to ensure that the plate 76 is spaced from the seal 82 and the valve 83 is in the open state. A vacuum source is provided to the accumulator port 52 so that the fluid pressure in the accumulator chamber 54 and the vacuum chamber 84 is less than atmospheric pressure by a predetermined amount. Since the charge port 68 is open to the atmosphere, the pressure in the accumulator chamber 54 and the vacuum chamber 84 is less than the atmospheric pressure in the pressurized air chamber 56. Once the predetermined vacuum amount is reached, the lift pin 96 is slowly withdrawn from the accumulator port 52. The pressure differential created by the vacuum causes the bellows assembly 58 to move toward its fully extended position and causes the valve 83 to be in the closed state. After the valve 83 is closed, the vacuum remains in the vacuum chamber 84 to cause the annular bellows wall 74 to move toward the inner surface 88 of the housing 60.

[0042] The accumulator charging process continues as shown in FIG. 6 c. Once the bellows assembly 58 is positioned as previously described, the lifting pin 96 is completely removed and a pressurized gas, such as nitrogen, is provided to the charging port 68. The pressurized gas chamber 56 now contains pressurized gas at a desired pressure. This gas charged this time is the gas contained within the accumulator during its entire life cycle. The plug 92 is positioned within the charging port 68 to maintain the required pressure and gas volume within the pressurized gas chamber 56. Based on the pressure difference between the pressurized gas within the pressurized gas chamber 56 and the air pressure that was previously in a vacuum state at the accumulator interface 52, low-pressure air is contained or otherwise trapped within the vacuum chamber 84. Since the gas pressure within the pressurized gas chamber 56 is large compared to the pressure of any gas at the accumulator port 52, the sealing engagement between the plate 76 and the seal 82 is maintained. Depending on the magnitude of the pressure differential, the additional surface area of ​​the plate 76 can engage with the seat 94 formed on the end wall 70. The seal 82 is compressed during engagement with the plate 76 to allow the plate 76 to simultaneously engage the seat 94 .

[0043] It should be understood that the process may vary slightly without departing from the scope of the present application. In particular, it is contemplated that pressurized gas is provided to the pressurized air chamber 56 after the lift pin 96 is inserted and after vacuum is applied to the accumulator port 52 but before the lift pin 96 is removed. In an alternative process, the valve 83 is opened when the pressurized gas is provided to the pressurized air chamber 56. The pressurized gas enters the pressurized air chamber 56 before the bellows assembly 58 is fully extended. The lift pin 96 is then retracted to allow the plate 76 to engage the seal 82 and close the valve 83.

[0044] 6 d , the vacuum is now removed from the accumulator port 52 so that the accumulator 50 can be installed in a suspension assembly, shipped and handled to a suspension assembly location, shipped to a vehicle assembly location, or transferred to a warehouse awaiting sale. The vacuum is maintained within the vacuum chamber 84 .

[0045] The method may also include fluidly coupling the accumulator 50 to a shock absorber (eg Figure 1 The accumulator 50 is now filled with pressurized gas and working fluid, the accumulator 50 can be operated to apply pressure to the working fluid in the first compression chamber 34 of the shock absorber 20 or any other suitable fluid chamber or conduit based on the energy stored in the pressurized gas chamber 56.

[0046] During operation of a hydraulic suspension system having an accumulator 50, if the pressure present at the accumulator port 52 is so low that all of the working fluid within the accumulator chamber 54 is evacuated, the plate 76 engages the seal 82 and closes the valve 83. The working fluid is trapped within the oil chamber 84 and remains pressurized at a pressure nearly equal to that of the gas within the pressurized air chamber 56. Thus, a differential pressure condition between the pressurized air chamber 56 and the oil chamber 84 is prevented. Nearly equal pressures exist on opposite sides of the annular bellows wall 74 to prevent damage to the bellows assembly 58 during operation / life of the accumulator 50.

[0047] During the pressurized gas inflation portion of the method, the annular bellows wall 74 is prevented from being damaged by the annular bellows wall 74 being pulled toward the inner surface 88 of the housing 60 before and during the inflation step. This is important because the inflation step includes providing a relatively rapid inflow of pressurized gas to the pressurized plenum 56. Because the annular bellows wall 74 is proximate to or engages the inner surface 88 of the housing 60 before and during the inflation process step, minimal additional flexing of the bellows wall will occur, thereby avoiding damage to the bellows assembly 58.

[0048] In addition, the above discussion only discloses and describes exemplary embodiments of the present application. Those skilled in the art will readily recognize from the above discussion and the accompanying drawings and claims that various changes, modifications and variations may be made without departing from the spirit and scope of the present application as defined in the following claims.

Claims

1. A method for charging a bellows accumulator of a vehicle suspension system, the method comprising: providing a housing having an accumulator port and a charge port; inserting a bellows assembly into the housing, the bellows assembly comprising an annular bellows wall at least partially defining a variable volume air chamber, the bellows assembly being axially extendable between a retracted position and a fully extended position, the air chamber being arranged in fluid communication with the inflation port, wherein an accumulator chamber is disposed between the housing and the bellows assembly, the accumulator chamber being in fluid communication with the accumulator port; When the bellows assembly is not in the fully extended position, evacuating the energy storage chamber so that a pressure less than atmospheric pressure is obtained in the energy storage chamber; and Pressurized gas is supplied to the inflation port.

2. The method according to claim 1, further comprising: Prior to supplying pressurized gas to the inflation port, the bellows assembly is positioned toward or at the retracted position but not at the fully extended position.

3. The method according to claim 2, wherein: Positioning the bellows assembly toward or at the retracted position but not at the fully extended position includes positioning a lift pin within the accumulator port that engages the bellows assembly.

4. The method of claim 3, further comprising disengaging the lift pin from the bellows assembly after a predetermined amount of vacuum is achieved in the accumulator chamber.

5. The method of claim 3, further comprising retracting the lift pin from the accumulator port after a predetermined amount of vacuum is achieved in the accumulator chamber.

6. The method according to claim 1, wherein: Supplying pressurized gas to the inflation port creates a pressure differential between the pressurized gas chamber and the accumulator chamber, thereby urging the bellows assembly toward the fully extended position.

7. The method of claim 1 further comprising providing a seal on one of the bellows assembly and the housing, the seal engaging the other of the bellows assembly and the housing when the bellows assembly is in the fully extended position.

8. The method according to claim 1, wherein: The bellows assembly includes a plate coupled to an annular bellows wall, and the method further includes forming a seal between the plate and the housing when the bellows assembly is in the fully extended position.

9. The method according to claim 1, wherein: The suspension assembly also includes a shock absorber, and the method further includes fluidly coupling the bellows accumulator to the shock absorber and applying pressure to a fluid in the shock absorber based on the pressurized gas in the bellows accumulator.

10. The method according to claim 1, wherein: Evacuating the accumulator chamber includes connecting a vacuum source to the accumulator port.

11. The method according to claim 1, wherein: Supplying pressurized gas to the inflation port occurs when the bellows assembly is not in the fully extended position.

12. The method of claim 1 further comprising extending the bellows assembly to the fully extended position after evacuating the accumulator chamber, wherein: The bellows assembly is in the fully extended position when pressurized gas is supplied to the inflation port.

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