End member assembly and gas spring assembly comprising the same
By using polymer injection molding to form end components, the high cost and sealing problems of multi-part end components in gas spring assemblies have been solved, achieving low-cost and efficient fluid sealing connections and improving the comfort and performance of the suspension system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FIRESTONE INDUSTRIAL PRODUCTS COMPANY LLC
- Filing Date
- 2022-05-03
- Publication Date
- 2026-07-10
Smart Images
Figure CN117242277B_ABST
Abstract
Description
Background Technology
[0001] This disclosure broadly relates to the field of gas spring devices, and more specifically, to end member assemblies for gas spring assemblies. An end member assembly may include two end member sections. In some cases, one end member section may be injection molded or otherwise formed on or around the other end member section from a polymer material, such that the two end member sections are permanently assembled to each other. Such end member assemblies may optionally include a plurality of interlaced annular ribs that substantially inhibit axial displacement of the two end member sections relative to each other. Gas spring assemblies including one or more such end member assemblies are also included. In some cases, such gas spring assemblies may be co-assembled with a damper assembly to form a gas spring and damper assembly. Additionally, vehicle suspension systems including one or more such gas spring assemblies (and / or gas spring and damper assemblies) are included.
[0002] The subject matter of this disclosure is specifically suited for applications and uses with wheeled vehicles, and will be shown and described herein with reference to this. However, it should be understood that the subject matter of this disclosure can also be used in other applications and environments, and the particular uses shown and described herein are merely exemplary. For example, the subject matter of this disclosure can be used in conjunction with gas spring assemblies for non-wheeled vehicles, support structures, height adjustment systems, and actuators associated with industrial machinery and its components and / or other such equipment. Therefore, the subject matter of this disclosure is not intended to limit its use in relation to suspension systems for wheeled vehicles.
[0003] Most types and categories of wheeled motor vehicles include sprung mass (such as, for example, the body or chassis) and unsprung mass (such as, for example, two or more axles or other wheel-jointing components with a suspension system therebetween). Typically, a suspension system includes multiple springs and multiple damping devices, which together allow the sprung and unsprung masses of the vehicle to move relative to each other in a controlled manner. Movement of sprung and unsprung masses toward each other is generally referred to in the art as bump motion, while movement of sprung and unsprung masses away from each other is generally referred to in the art as bounce motion.
[0004] Typically, multiple spring devices are used to accommodate the forces and loads associated with the operation and use of a vehicle. Multiple damping devices operatively dissipate the energy associated with undesirable inputs and movements of the sprung mass (such as road surface inputs, for example, occurring during dynamic vehicle operation). In many cases, damping devices can be known-constructed hydraulic dampers filled with fluid (e.g., conventional shock absorbers or shock struts). However, in other cases, damping devices can be of a type and kind that utilizes gaseous fluids rather than liquids as the working medium.
[0005] In many applications involving vehicle suspension systems, it is desirable to utilize spring elements with the lowest possible spring stiffness because using spring elements with lower spring stiffness provides improved ride quality and comfort compared to spring elements with higher spring stiffness. That is, it should be well understood in the art that the use of spring elements with higher spring stiffness (i.e., springs with greater stiffness) transfers a larger amount of road input to the sprung mass of the vehicle, and this generally results in a bumpier and less comfortable ride. Conversely, the use of spring elements with lower spring stiffness (i.e., softer and more compliant springs) transfers a smaller amount of road input to the sprung mass, and therefore provides a more comfortable ride.
[0006] In some cases, the spring mechanism of a vehicle suspension system will include a spring that uses pressurized gas as the working medium of the mechanism. Typically, the spring stiffness of a gas spring can be reduced by increasing the volume of compressed gas associated with its operation, thereby improving ride comfort. This is usually achieved using an end member that defines an additional chamber, cavity, or volume filled with pressurized gas in fluid communication with the main spring chamber of the gas spring. However, manufacturing this type of end member as a single, integral component can be challenging. Therefore, in many cases, such end members are assembled from multiple components fixed together, forming a substantially fluid-sealed joint between them.
[0007] Unfortunately, many current assembly techniques used to manufacture such multi-component end members suffer from high manufacturing costs, likely due to the handling and installation of seals and / or components during the joining process. Furthermore, in some cases, creating and maintaining a robust and substantially fluid-tight joint between components is challenging and can sometimes lead to undesirable losses of compressed gas or a decline in other performance characteristics of the resulting assembly. Therefore, it is believed that the development of structures that can help overcome the aforementioned and / or other drawbacks associated with known end member assemblies, and / or otherwise advance the field of vehicle suspension systems and / or their components, is desirable. Summary of the Invention
[0008] An example of an end member assembly according to the subject matter of this disclosure may have a longitudinal axis and be dimensionally designed to be fixed to an associated flexible spring member. The end member assembly may extend axially from a first end to a second end. The end member assembly may include a first end member component having a first component wall extending circumferentially around the longitudinal axis. A second end member component may include a second component wall formed as a monolithic mass that extends continuously and uninterruptedly (i.e., indefinitely) around the periphery of the first end member component, such that the second end member component is permanently attached to the first end member component.
[0009] In some cases, the first component wall may include an end wall portion oriented transversely to the longitudinal axis and a side wall portion extending axially from the end wall portion. The second component wall may extend continuously around the side wall portion of the first component wall and extend axially co-extended along the side wall portion of the first component wall.
[0010] In some cases, the first component wall may include a first plurality of annular ribs arranged axially spaced apart from each other. Alternatively, the second component wall may include a second plurality of annular ribs arranged axially spaced apart from each other. In the case of including both the first plurality of annular ribs and the second plurality of annular ribs, one of the second plurality of annular ribs may be axially disposed between adjacent annular ribs of the first plurality of annular ribs, such that the first plurality of annular ribs and the second plurality of annular ribs are axially staggered.
[0011] In some cases, the sidewall portion of the first component wall may include an inner surface portion and an outer surface portion, with the first plurality of annular ribs protruding radially outward along the outer surface portion.
[0012] In some cases, the end member assembly may include a third end member component that is at least partially embedded within the first end member component.
[0013] An example of a gas spring assembly according to the subject matter of this disclosure may have a longitudinal axis and may include a flexible spring member extending circumferentially about the longitudinal axis and longitudinally between opposing first and second ends, such that a spring chamber is at least partially defined between the first and second ends. A first end member assembly according to any one or more of the preceding paragraphs is operatively fixed to the first end of the flexible spring member, such that a substantially fluid-tight connection is formed therebetween. A second end member is operatively fixed to the second end of the flexible spring member, such that a substantially fluid-tight connection is formed therebetween.
[0014] An example of a gas spring and damper assembly according to the subject matter of this disclosure may include a gas spring assembly and a damper assembly as described in the foregoing paragraphs, wherein the gas spring assembly is configured to co-extend axially with at least a portion of the damper assembly.
[0015] An example of a suspension system according to the subject matter of this disclosure may include a compressed gas system comprising a compressed gas source and a control device. According to either of the foregoing paragraphs, the suspension system may also include at least one gas spring assembly and / or at least one gas spring and damper assembly. The at least one gas spring assembly and / or the at least one gas spring and damper assembly may be arranged in fluid communication with the compressed gas source via the control device, such that compressed gas can be selectively delivered into and out of the spring chamber.
[0016] An example of a method for manufacturing an end member assembly according to the subject matter of this disclosure may include injecting a first amount of polymer material into a first mold cavity at least partially defined by first and second first mold sections to form a first end member component having a longitudinal axis. The method may further include injecting a second amount of polymer material into a second mold cavity at least partially defined by the first end member component and a third mold section, the first end member component being supported on at least one of the first and second mold sections, thereby molding a second end member component that extends continuously and uninterruptedly (i.e., indefinitely) around the periphery of the first end member component, such that the second end member component is permanently attached to the first end member component. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of an example of a suspension system of a vehicle that includes one or more air spring assemblies according to the subject matter of this disclosure.
[0018] Figure 2 This is a side view of an example of a gas spring and damper assembly that includes an exemplary gas spring assembly according to the subject matter of this disclosure.
[0019] Figure 3 yes Figure 2 Top plan view of an exemplary gas spring and damper assembly.
[0020] Figure 4 It is along Figure 3 The line 4-4 in the middle is cut off Figure 2 and Figure 3 An enlarged side view of an exemplary gas spring and damper assembly.
[0021] Figure 5 It is along Figure 3 The line 5-5 is cut off. Figures 2 to 4 A cross-sectional side view of an exemplary gas spring and damper assembly.
[0022] Figure 6 It is along Figure 4 The line 6-6 in the middle is cut off Figures 2 to 5 A top cross-sectional view of an exemplary gas spring and damper assembly.
[0023] Figure 7 yes Figures 2 to 6 Exemplary gas spring and damper assembly in Figure 5 A magnified view of the part marked as detail 7.
[0024] Figure 8 This is a top perspective view of an example end component assembly according to the subject matter of this disclosure, such as, for example Figures 2 to 7 The end component assembly shown.
[0025] Figure 9 yes Figures 2 to 8 The top plan view of the exemplary end component assembly.
[0026] Figure 10 It is along Figure 9 The line 10-10 is cut off Figures 2 to 9 A cross-sectional side view of an exemplary end component assembly.
[0027] Figure 11 It is supported in the first mold cavity formed by multiple mold sections before another end component is formed. Figures 2 to 10 A cross-sectional side view of an end member component.
[0028] Figure 12 yes Figure 11 A cross-sectional side view showing an end member component that is at least partially embedded within another end member component, the other end member component being constructed by... Figure 11 Some of the mold sections are removed and one and / or another end member is left in place in one or more remaining mold sections to form a shape. Figure 11 Inside the first mold cavity.
[0029] Figure 13 yes Figure 12 A cross-sectional side view shows one end member component and another end member component held in situ on a remaining mold section and disposed within a second mold cavity, which is formed by an additional mold section surrounding the one end member component and the other end member component for in-situ manufacturing of yet another end member component around the one end member component and / or the other end member component.
[0030] Figure 14 yes Figures 8 to 13 An exploded cross-sectional side view of an end member assembly, having one end member component, another end member component, and yet another end member component before being assembled with yet another end member component. Detailed Implementation
[0031] Turning now to the accompanying drawings, it should be understood that the illustrations are examples intended to illustrate the subject matter of this disclosure, and such examples are not intended to be limiting. Furthermore, it should be understood that the drawings are not drawn to scale, and portions of particular features and / or elements may be exaggerated for clarity and / or ease of understanding.
[0032] Figure 1An example of a suspension system 100 operatively disposed between sprung mass (such as, for example, the associated vehicle body BDY) and unsprung mass (such as, for example, the associated wheel WHL of the associated vehicle VHC and / or the associated suspension component SCP). It should be understood that any one or more components of the suspension system may be operatively connected between the sprung and unsprung mass of the associated vehicle in any suitable manner. The suspension system includes one or more gas spring assemblies according to the subject matter of this disclosure and one or more damper assemblies operatively connected between the sprung and unsprung mass, and together allow the sprung and unsprung mass of the associated vehicle to move relative to each other in a controlled manner, as discussed above.
[0033] Depending on the desired performance characteristics and / or other factors, in some cases, one or more gas spring assemblies may be supplied and installed separately from one or more damper assemblies. Alternatively or additionally, the gas spring assembly may be assembled with the damper assembly such that at least a portion of the gas spring assembly co-extends axially with the damper assembly to form a so-called gas spring and damper assembly. It should be understood that gas spring assemblies and their components according to the subject matter of this disclosure have been shown and described herein with particular reference to gas spring and damper assemblies. However, it should be recognized and understood that such configurations are optional, and the gas spring assemblies (and their components and assemblies) according to the subject matter of this disclosure are not intended to be limited to use in gas spring and damper assemblies.
[0034] like Figure 1 As shown, the suspension system 100 may include a plurality of gas spring assemblies 102 operatively connected between the sprung and unsprung masses of the vehicle. Additionally, the suspension system 100 may include a plurality of damper assemblies 104 operatively connected between the sprung and unsprung masses of the vehicle. Depending on desired performance characteristics and / or other factors, the suspension system may include any suitable number of one or more gas spring assemblies and one or more damper assemblies. Furthermore, the one or more gas spring assemblies and one or more damper assemblies may be operatively connected to, along, or otherwise between the sprung and unsprung masses in any suitable manner. As a non-limiting example, the gas spring assemblies 102 and damper assemblies 104 may optionally be operatively connected in an axially co-existing arrangement to form one or more gas spring and damper assemblies 106, which may then be operatively connected as a unit to, along, or otherwise between the sprung and unsprung masses.
[0035] For example, in Figure 1In the arrangement shown, the suspension system 100 includes four air spring and damper assemblies 106, one of which is positioned toward each corner of the relevant vehicle adjacent to the corresponding wheel WHL. It should be understood that any other suitable number of air spring assemblies and / or air spring and damper assemblies may be optionally used in any other configuration and / or arrangement. Figure 1 As shown, the gas spring and damper assembly 106 is supported between the suspension component SCP and the body BDY of the relevant vehicle VHC. It should be understood that the gas spring assembly 102 shown and described herein has a rolling cam configuration. However, it should be understood that other types, kinds, and / or structures of gas spring assemblies may be used interchangeably without departing from the subject matter of this disclosure.
[0036] The suspension system 100 also includes a compressed gas system 108, operatively associated with the gas spring assembly and / or the gas spring and damper assembly, for selectively supplying and transferring compressed gas (e.g., air) to and from it. Figure 1 In the exemplary arrangement shown, the compressed gas system 108 includes a compressed gas source, such as a compressor 110, for example, to generate compressed air or other gases. Control devices such as valve assembly 112 are shown, for example, in communication with the compressor 110 and can be of any suitable configuration or arrangement. In the illustrated exemplary embodiment, valve assembly 112 includes a valve block 114 having a plurality of valves 116 supported thereon. Valve assembly 112 may also optionally include a suitable venting device, such as a muffler 118, for example, to vent compressed gas from the system. Optionally, compressed gas system 108 may also include a reservoir 120 in fluid communication with the compressor 110 and / or valve assembly 112 and adapted to store compressed gas for extended periods (e.g., seconds, minutes, hours, weeks, days, months).
[0037] Valve assembly 112 is connected to the gas spring 102 and / or damper 104 of assembly 106 via a suitable gas transmission line 122. Thus, by selectively operating valve 116, compressed gas can be selectively transmitted into and / or out of the gas spring and / or damper via valve assembly 112, thereby changing or maintaining, for example, the vehicle height at one or more corners of the vehicle.
[0038] The suspension system 100 may also include a control system 124 capable of communicating with the vehicle's VHC and / or any one or more systems and / or components of the suspension system 100, such as for selectively operating and / or controlling these systems and / or components. The control system 124 may include a controller or electronic control unit (ECU) 126 communicatively coupled to the compressor 110 and / or valve assembly 112, for example via conductors or leads 128, for selectively operating and / or controlling the compressor and / or valve assembly. This selective operation and / or control may include supplying compressed gas to and discharging compressed gas from the gas spring and damper assembly 106. The controller 126 may be of any suitable type, kind, and / or configuration.
[0039] The control system 124 may optionally include one or more sensing devices 130, such as those operatively associated with the gas spring assembly and / or the gas spring and damper assembly and capable of outputting or otherwise generating data, signals, information, and / or other communications relating to one or more of the following: the height of the gas spring assembly and / or the gas spring and damper assembly; the distance between other components of the vehicle; the pressure or temperature associated with the gas spring assembly and / or the gas spring and damper assembly and / or the pressure or temperature associated with the wheels or tires or other components associated with the gas spring assembly and / or the gas spring and damper assembly; and / or acceleration, load, or other inputs acting on the gas spring assembly and / or the gas spring and damper assembly. The sensing device 130 may communicate with the ECU 126, from which the ECU may receive data, signals, information, and / or other communications. The sensing device may communicate with the ECU 126 in any suitable manner, such as, for example, through conductors or leads 132. Furthermore, it should be understood that the sensing device may be of any suitable type, kind and / or structure, and may be operated using any suitable combination of one or more operating principles and / or technologies.
[0040] Examples of suspension systems (e.g., suspension system 100) that may include gas spring assemblies according to the subject matter of this disclosure have been described, and will now be combined with Figures 2 to 7 An example describing a gas spring (or gas spring assembly) and a gas spring and damper assembly including such a gas spring assembly. Figures 2 to 7 The text shows, for example, what can correspond to... Figure 1 The gas spring (or gas spring assembly) GS1 is one of the gas springs in gas spring 102. In some cases, it may optionally include, for example, a gas spring corresponding to... Figure 1The damper (or damper assembly) DP1 of the damper 104 is a damper in the damper 104. In this case, the gas spring assembly GS1 and the damper assembly DP1 can be arranged in a mutually extending manner. In addition, the gas spring assembly and the damper assembly can be operatively fixed to each other in a suitable manner, such as, for example, as described below, to form a gas spring and damper assembly AS1, which can be suitable for use as Figure 1 One or more gas spring and damper assemblies in gas spring and damper assembly 106. The longitudinal axis AX extends longitudinally along gas spring GS1 and / or assembly AS1, as shown... Figure 5 As shown.
[0041] The damper assembly DP1 may include a damper housing 200 and a damper rod assembly 202 at least partially received within the damper housing. The damper housing 200 extends axially between housing ends 204 and 206 and includes a housing wall 208 that at least partially defines a damping chamber 210. The damper rod assembly 202 extends longitudinally between opposing ends 212, 214 and includes an elongated damper rod 216 and a damper piston 218 operatively connected along the end 214 of the damper rod assembly 202 to the elongated damper rod 216. The damper piston 218 is received within the damping chamber 210 of the damper housing 200 for reciprocating along the housing wall in a conventional manner. A quantity of damping fluid 220 may be disposed within the damping chamber 210, and the damper piston 218 may be displaced through the damping fluid to dissipate kinetic energy acting on the gas spring and the damper assembly AS1. Although the damper assembly DP1 is shown and described herein as having a conventional structure in which hydraulic fluid is included within at least a portion of the damping chamber 210, it should be recognized and understood that other types, kinds and / or structures of dampers, such as compressed gas or “air” dampers, may be used without departing from the subject matter of this disclosure.
[0042] The housing wall 208 may include a sidewall portion 222 extending longitudinally about a longitudinal axis AX from end 204 toward end 206. The housing wall 208 may form an opening (not numbered) along the housing end 204. A damper end wall 224 may extend through this opening and may be secured to or along the housing wall 218, such that a substantially fluid-tight connection is formed between them. In some cases, the housing wall 208 may include an end wall portion 226 disposed along the housing end 204, extending radially inward from the sidewall portion 222 to at least partially retain the damper end wall 224 on or at least partially along the damper housing. The damper end wall 224 may include an opening (not numbered) and an elongated damper rod 216 may extend axially outward from the damping chamber 210 through this opening in a direction opposite to the housing end 206. Additionally, the damper end wall (not numbered) may span across the end 206 of the damper housing 200, forming a substantially fluid-impermeable connection between them. The side wall portion 222 of the housing wall 208 may be included on the side wall portion 224 of the damper housing or on an outer surface portion 228 exposed radially outward along the side wall portion.
[0043] The elongated damper rod 216 may protrude outward from the damper end wall 224, such that the end 212 of the damper rod assembly is exposed outward from the damper housing and can be accessed from the outside relative to the damper housing. For example, a connection structure 230 (such as multiple threads) may be provided on or along the elongated rod for directly or indirectly operatively connecting the gas spring and damper assembly 200 to an associated vehicle structure, a component of the gas spring assembly GS1, or other components of the gas spring and damper assembly AS1.
[0044] It should be understood that the gas spring and damper assembly AS1 can be operably connected between the sprung and unsprung masses of the relevant vehicle (or other structure) in any suitable manner. For example, one end of the assembly can be operably connected to the relevant sprung mass, while the other end of the assembly is positioned towards and operably connected to the relevant unsprung mass. Figure 2 and Figure 4 As shown, for example, end 212 of the damper rod assembly 202 may be connected to the first structural component or the upper structural component USC (such as, for example...). Figure 1The gas spring assembly GS1 is operatively engaged (directly or indirectly) with the associated vehicle body (BDY) and can be secured to the component in any suitable manner. As a non-limiting example, the gas spring assembly GS1 may include an end member or end member assembly 300 that can be secured to the upper structural member USC, and one or more other components of the gas spring assembly and / or one or more components of the damper assembly DS1 are operatively connected to the end member or end member assembly. Additionally or alternatively, the gas spring assembly GS1 and / or the damper assembly DP1 may be secured to the second structural member or lower structural member LSC. Figure 2 (such as, for example) Figure 1 It is fixed on or along the associated suspension components (SCP) and can be fixed to it in any suitable manner.
[0045] The gas spring assembly GS1 may include a flexible spring member 400 that extends circumferentially about an axis AX and is substantially fluid-tightly secured between opposing end members (or end member assemblies) such that a spring chamber 402 is at least partially defined therebetween. The flexible spring member 400 may extend axially from end 404 to end 406 and is operatively connected between opposing end members (or end member assemblies) in any suitable manner. As a non-limiting example, end 404 of the flexible spring member 400 may be secured to end member assembly 300. Additionally, end 212 of the damper rod assembly 202 may optionally be operatively connected to end member assembly 300. The gas spring assembly GS1 may also include an end member assembly EM1 supported on or along the damper housing 200. The end member assembly EM1 may extend axially from end ED1 to end ED2, and the end 406 of the flexible spring member 400 is secured to or along the end ED1 of the end member assembly EM1 in any substantially fluid-tight or other suitable manner. Additionally, it should be understood that the end member assembly EM1 can be operatively supported on or along the damper housing 200 in a suitable manner, such as as described below.
[0046] As a non-limiting example, the end member assembly EM1 may be supported on or along end 204 of the damper housing 200. In a suitable arrangement, axial forces and loads between the end member assembly EM1 and the damper housing 200 are at least partially transferred (directly or indirectly) to the housing wall 208. As a non-limiting example, such axial forces and / or loads are transferred (directly or indirectly) to, from, and / or between the end member assembly EM1 and the damper housing 200 via end wall portions 226 engaging with end ED1 along end ED1. In this way, the end member assembly EM1 may be suspended from end ED1 by the damper housing 200 or otherwise axially supported along end ED1. In some cases, end ED2 of the end member assembly may optionally be substantially unsupported by the damper housing in the axial direction. In some cases, the damper housing 200 may be adapted to provide radial support to the end ED2 of the end member assembly EM1, such as as described below.
[0047] As a non-limiting example, the damper assembly DP1 may include a support wall or support wall portion 232 extending radially outward from the outer peripheral edge 234 along the damper housing. The support wall portion 232 may include a surface portion 236 facing the end 204 of the damper housing 200 and a surface portion 238 facing the end 206 of the damper housing. The support wall portion 232 can be supported on or along the damper housing in any suitable manner, such as, for example, through one or more flow material joints 240. In some cases, a radial spacer or bushing 242 may be supported on or along the support wall portion 232 and arranged radially between the outer surface portion 228 of the housing wall 208 and the end ED2 of the end member assembly EM1. In a preferred arrangement, the radial spacer 242 slidably engages at least one of the outer surface portion of the housing wall and the corresponding surface portion of the end member assembly EM1. In some cases, the sealing device 244 can be supported on the radial spacer 242 between the outer surface portion 228 of the housing wall 208 and the end ED2 of the end member assembly EM1, spatially related to the supporting wall portion 232, such as, for example... Figure 5 As shown. However, it should be understood that other constructions and / or arrangements may be used alternatively without departing from the subject matter of this disclosure.
[0048] It should be understood that the flexible spring member 400 can have any suitable size, shape, structure, and / or construction. Furthermore, the flexible spring member can be of any type and / or kind, such as a rolling cam type or a spiral bellows type structure. The flexible spring member 400 in... Figures 5 to 7The diagram illustrates a flexible wall 408, which can be formed in any suitable manner from any suitable material or combination of materials. For example, the flexible wall may comprise one or more fabric-reinforced elastomeric posts or layers and / or one or more unreinforced elastomeric posts or layers. Typically, one or more fabric-reinforced elastomeric posts and one or more unreinforced elastomeric posts are used together and formed from common elastomeric materials such as synthetic rubber, natural rubber, or thermoplastic elastomers. However, in other cases, combinations of two or more different materials, two or more compounds of similar materials, or two or more grades of the same material may be used.
[0049] As indicated above, the flexible wall 408 may extend generally longitudinally between opposite ends 404 and 406. Additionally, the flexible wall 408 may include an outer surface 410 and an inner surface 412, the inner surface at least partially defining the spring chamber 402 of the gas spring assembly GS1. The flexible wall 408 may include an outer or inner tire cord layer (not identified) at least partially forming the outer surface 410. The flexible wall 408 may also include an inner or inner tire cord layer (not identified) at least partially forming the inner surface 412. In some cases, the flexible wall 408 may also include one or more reinforcing posts (not shown) disposed between the outer surface 410 and the inner surface 412. The one or more reinforcing posts may have any suitable structure and / or configuration. For example, the one or more reinforcing posts may include one or more filament materials of one or more lengths at least partially embedded therein. Furthermore, it should be understood that, if present, the one or more filament materials of one or more lengths may be oriented in any suitable manner. As an example, a flexible wall may include at least one layer or cord of filament material of various lengths oriented at an oblique angle and at least one layer or cord of filament material of various lengths oriented at the same but opposite oblique angle.
[0050] The flexible spring member 400 may include any feature or combination of features suitable for forming a substantially fluid-tight connection with the end member assembly 300 and / or suitable for forming a substantially fluid-tight connection with the end member assembly EM1. As a non-limiting example, the flexible spring member 400 may include an open end secured to or along the corresponding end member assembly via one or more crimping rings 414 and 416. Alternatively, a mounting bead (not shown) may be provided along either or both ends of the flexible wall. In some cases, the mounting bead (if present) may optionally include a reinforcing element, such as, for example, an endless annular bead wire. In some cases, a restraining cylinder 418 and / or other components may be arranged radially outward along the flexible wall 408. In some cases, such components can be secured to or along the flexible wall in a suitable manner, such as, for example, via one or more backing rings 420.
[0051] As mentioned above, the gas spring and damper assembly AS1 can be positioned in any suitable manner between the relevant sprung and unsprung mass of the relevant vehicle. For example, one component is operatively connected to the relevant sprung mass, while another component is positioned toward and operatively connected to the relevant unsprung mass. For example, as... Figures 2 to 4 As shown, the end member assembly 300 may include one or more fasteners 302 operable to secure the end member assembly 300 to the superstructure component USC (such as, for example...). Figure 1 The damper assembly DP1 is fixed to or along the associated vehicle body (BDY) of the superstructure component. The damper assembly DP1 can be operatively connected to the superstructure component via the end member assembly 300 and can be operatively engaged with the end member assembly in any suitable manner. For example, the damper assembly DP1 may include a bushing 246 supported on or along the end member assembly 300, and the damper rod assembly 202 is secured to the bushing, for example, by a connector 248 of the connection structure 230 engaging along the end 212 of the elongated damper rod 216. The bushing 246 can be supported on or along the end member assembly 300 and can be operatively secured to the end member assembly in any suitable manner. As a non-limiting example, the bushing 248 may be captured between the end member assembly 300 and an end cap 250, which can be secured to or along the end member assembly in a suitable manner, such as by a retaining ring 252.
[0052] It should be understood that the gas spring and damper assembly AS1 is capable of shifting between an extended state and a compressed state during normal operation. In some cases, one or more bump dampers may be included to suppress contact between one or more features and / or components of assembly AS1. For example, damper assembly DP1 may include bump damper 254 positioned within spring cavity 402 on or along elongated damper rod 216. It should be understood that bump dampers (if provided) may be supported in any suitable manner. As a non-limiting example, bump damper 254 may be supported on or along end member assembly 300 and sized to contact end ED1 of end member assembly EM1 during bumpy conditions of assembly AS1. However, it should be understood that other constructions and / or arrangements may be used alternatively.
[0053] The end member assembly EM1 is a type and kind commonly referred to as a rotary piston or piston assembly. It should be understood that, according to the subject matter of this disclosure, the end member assembly EM1 may include any suitable number of two or more components and / or portions. For example, in the arrangements shown and described herein, the end member assembly EM1 includes an end member component 500, which includes a component wall 502, which is at least partially formed of a polymer material. The end member assembly EM1 also includes an end member component 600 that extends axially along the end member component 500. The end member component 600 is formed as a monolithic material body or mass. The end member component 600 extends continuously and uninterruptedly (i.e., indefinitely) around the periphery of the end member component 500. With this configuration, the end member component 600 is permanently attached to the end member component 500 (i.e., cannot be separated without damage, destruction, or alteration of the material of at least one of the component portions). In some cases, the end member component 600 may optionally extend radially with the end member component 500 or otherwise radially engage with each other.
[0054] The end member component 600 may include a component wall 602, which is at least partially formed of a polymer material. The component wall 602 may include an outer surface portion 604 along which the rolling blade 422 of the flexible spring member 400 may be displaced when the gas spring and damper assembly AS1 is displaced between a compressed state and an extended state. It should be understood that the outer surface portion 604 may have any of a variety of different sizes, shapes, and / or configurations (e.g., an outer profile with different contours and / or combinations of shapes), such as in... Figure 13 The middle part is represented by the dashed line 604'.
[0055] Optionally, the end member assembly EM1 may include an end member component 700 that is at least partially embedded within the end member component 500. The end member assembly EM1 may optionally further include an end member component 800 that is fixed to or along the end member component 500. In some cases, the end member component 800 can be permanently attached to the end member component 600 in a spaced-apart relationship (i.e., cannot be separated without damage, destruction, or alteration of the material of at least one of the component components), but it should be understood that other constructions and / or arrangements may be alternatively used without departing from the subject matter of this disclosure. Furthermore, it should be understood that the end member components 500, 600, 700, and 800 may be formed of any suitable material or combination of materials and may include any suitable number of walls and / or wall portions or combinations of one or more walls and / or wall portions. For example, end member components 500, 600, and 800 may be formed from a combination of one or more suitable polymeric materials, such as, for example, fiber-reinforced polypropylene, fiber-reinforced polyamide, or unreinforced (i.e., relatively high-strength) thermoplastics (e.g., polyester, polyethylene, polyamide, polyether, or any combination thereof). As another example, end member component 700 may be at least partially formed from a relatively high-strength and / or rigid material, such as, for example, a metallic material. In this case, if end member component 700 is included, it can be used to reinforce or otherwise strengthen at least a portion of end member component 500.
[0056] The component wall 502 of the end member component 500 may optionally include an end wall portion 504 oriented transversely to the longitudinal axis AX and disposed toward the end ED1 of the end member assembly EM1. The component wall 502 may also include a side wall portion 506 extending axially from the end wall portion 504 toward a distal edge 508 disposed toward the end ED2 of the end member assembly. The side wall portion 506 includes an inner surface portion 510 that at least partially defines an end member chamber 512 within the end member assembly EM1. In some cases, one or more end member components of end member components 600, 700, and / or 800 may be configured to be in fluid communication with and / or at least partially define the end member chamber 512.
[0057] Optionally, component wall 502 may also include an inner sidewall portion 514 extending axially from along end wall portion 504 toward distal edge 516. If an inner sidewall portion 514 is included, it may be disposed radially inside sidewall portion 506 such that a gap or space 518 is radially included between them. In some cases, multiple longitudinal ribs 520 may project radially inward from along inner sidewall portion 514, such as being sized to, for example, abut against outer surface portion 228 of housing wall 208 in the assembled state of gas spring and damper assembly AS1. Multiple annular grooves 522 may be provided on or along sidewall portion 506, such as being sized to, for example, receiveably engage end 406 of flexible spring member 400 together with crimp ring 416.
[0058] The component wall 502 may optionally include a plurality of annular ribs 524 extending about a longitudinal axis AX and projecting radially outward to rib end surfaces 526. If annular ribs 524 are included, they are arranged axially spaced apart from each other along the sidewall portion 506 such that a plurality of rib root surfaces 528 are arranged along the sidewall portion, with one of the rib root surfaces 528 disposed between adjacent annular ribs 524.
[0059] Component wall 502 may optionally include an attachment wall portion 530 disposed toward the distal edge 508. The attachment wall portion 530 may be sized to cooperatively engage end component component 800 (if included) so as to permanently attach (i.e., not to be separated without damage, destruction or alteration of the material of at least one of the component portions) end component components 500 and 800.
[0060] The component wall 602 of the end member component 600 may include a sidewall portion 606, and an outer surface portion 604 and / or 604' is at least partially defined on or along the sidewall portion. The sidewall portion 606 may include a distal edge 608 disposed toward the end wall portion 504 of the end member component 500 and / or a distal edge 610 disposed toward the distal edge 508 of the end member component 500.
[0061] As described above, the end member component 600 extends continuously and uninterruptedly (i.e., indefinitely) around the periphery of the end member component 500. That is, in a preferred arrangement, the end member component is free from (i.e., has no) longitudinally extending edges or margins that could form joints along the length of the component wall. In this case, the end member component 600 is permanently attached to the end member component 500 (i.e., cannot be separated without damage, destruction, or alteration of the material of at least one of the component components). In some cases, the end member component 600 may radially co-extend with the end member component 500 or otherwise radially engage with it.
[0062] In a preferred arrangement, the component wall 602 is formed in situ or otherwise from a polymer material together with the end member component 500. In this configuration, the component wall 602 may be formed as an endless wall extending circumferentially around the end member component 500. If the end member component 500 includes annular ribs 524, the component wall 602 may be injection molded or otherwise formed to include a plurality of annular ribs 612 extending around the longitudinal axis AX. If annular ribs 612 are included, they may project radially inward toward the rib root surface portion 528 to substantially fill the space between adjacent annular ribs of the annular rib 524. In this way, the annular ribs 524 and 612 are staggered relative to each other in the axial direction. This configuration substantially inhibits axial movement between the end member components 500 and 600.
[0063] If an end member component 700 is included, the end member component may include a component wall 702, which may include an end wall portion 704 oriented transversely to the longitudinal axis AX. The component wall 702 may also include a side wall portion 706 extending axially from along the end wall portion 704 toward a distal edge 708. The component wall 702 may also include a plurality of openings or channels 710 extending through the end wall portion 704.
[0064] In a preferred arrangement, the end member component 700 is at least partially embedded within the component wall 502 of the end member component 500. In this arrangement, an opening or channel 710 extends through and through the component wall 702, such that the opening 710 is configured to be in fluid communication with the end member chamber 512, for example, through the gap 518 between the side wall portion 506 and the inner side wall portion 514. In this way, during operation and use of the assembly AS1, the spring chamber 402 and the end member chamber 512 are configured to be in fluid communication through the opening 710. Additionally, in this configuration, during bumpy conditions (when the bump buffer 254 abuts against the end wall portion 504 of the end member component 500), the opening 710 can remain open and in fluid communication between the spring chamber 402 and the end member chamber 512. Furthermore, in a preferred arrangement, the side wall portion 706 may be axially co-extended with the annular groove 522 of the component wall 502.
[0065] End member 800 may include a component wall 802 extending circumferentially around a longitudinal axis AX, and a side wall portion 804 extending axially between an attachment wall portion 806 and a sealing wall portion 808 disposed opposite to the attachment wall portion 806. The side wall portion 804 may extend axially along an outer surface portion 228 of the housing wall 208. The attachment wall portion 806 is dimensioned to cooperate with the attachment wall portion 530 to permanently attach (i.e., not detachable without damage, destruction, or alteration of the material of at least one of the component portions) end member components 500 and 800, as described above. The sealing wall portion 808 is radially outwardly spaced from the side wall portion 804 and is dimensioned to at least partially receive a radial spacer 244 and / or a sealing device 246.
[0066] In a preferred arrangement, the component wall 502 of the end member component 500 may be manufactured or otherwise formed within the mold cavity CV1 of the injection mold, which includes multiple mold sections, such as, for example, in Figure 11 The end member 700 is represented by mold sections MS1, MS2, MS3, and MS4. In a preferred arrangement, the end member 700 may optionally be positioned within the cavity CV1 prior to injection molding or otherwise forming the component wall 502 of the end member 500. As a non-limiting example, the component wall 702 may be captured on or along one or more mold sections (e.g., between mold sections MS1 and MS2) to hold the end member 700 in proper position within the cavity CV1. The component wall 502 may then be injection molded or otherwise formed from a suitable polymeric material or combination of polymeric materials, such as, for example, fiber-reinforced polypropylene, fiber-reinforced polyamide, or unreinforced (i.e., relatively high-strength) thermoplastic (e.g., polyester, polyethylene, polyamide, polyether, or any combination thereof), to at least partially embed the end member 700 within the component wall 502 of the end member 500, such as... Figure 12 As shown.
[0067] Further reference Figure 12 End member component 500, together with end member component 700 at least partially embedded within end member wall 502, is shown in situ within mold sections MS1 and MS2, where mold sections MS3 and MS4 are removed to expose at least a portion of component wall 502. Figure 13In this arrangement, mold sections MS5 and MS6 are introduced, which at least partially define a mold cavity CV2 surrounding at least a portion of the component wall 502. The component wall 602 can then be injection molded or otherwise formed from a suitable polymeric material or combination of polymeric materials, such as, for example, fiber-reinforced polypropylene, fiber-reinforced polyamide, or unreinforced (i.e., relatively high-strength) thermoplastic (e.g., polyester, polyethylene, polyamide, polyether, or any combination thereof), such that the end member component 600 extends circumferentially around the end member component 500 and is permanently attached (i.e., cannot be separated without damage, destruction, or alteration of the material of at least one of the component parts) to the end member component. In this arrangement, annular ribs 612 may optionally flow into and substantially fill the space between adjacent annular ribs 524 (if included), such that annular ribs 612 and 524 are staggered relative to each other in the axial direction. If end member component 800 is included, this end member component may optionally be supplied separately and assembled together with end member components 500, 600 and 700, such as in Figure 14 The arrow ASM indicates this. It should be understood that end member component 800 can be permanently attached to the combination of end member components 500, 600, and 700 in any suitable manner, such as, for example, via a flow material joint JNT. Figure 5 ).
[0068] As used herein with reference to certain features, elements, components, and / or structures, numerical ordinal numbers (e.g., first, second, third, fourth, etc.) may be used to indicate different individual features, elements, components, and / or structures among a plurality of others, or to otherwise identify certain features, elements, components, and / or structures, and do not imply any order or sequence unless expressly specified by the language of the claims. Furthermore, the terms “lateral,” etc., are interpreted broadly. For this reason, the term “lateral,” etc., may include a wide range of angular orientations, including but not limited to approximately perpendicular angular orientations. Additionally, the terms “circumferential,” “circumferentially,” etc., may be interpreted broadly, and they may include, but are not limited to, circular shapes and / or constructions. In this respect, the terms “circumferential,” “circumferentially,” etc., may be synonymous with terms such as “peripheral,” “outer periphery,” etc.
[0069] Furthermore, the phrase "flowing material joint," as used herein, can be interpreted to include any joint or connection in which a liquid or other flowable material (e.g., molten metal or a combination of molten metals) is arranged or otherwise presented between adjacent components to form a fixed and substantially fluid-impermeable connection therebetween. Examples of processes that can be used to form such flowing material joints include, but are not limited to, welding, brazing, and soldering processes. In such cases, one or more metallic materials and / or alloys may be used to form such flowing material joints, in addition to any material derived from the components themselves. Another example of a process that can be used to form flowing material joints includes applying, depositing, or otherwise presenting an adhesive between adjacent components to form a fixed and substantially fluid-impermeable connection therebetween. In such cases, it should be understood that any suitable adhesive material or combination of materials may be used, such as, for example, one-component and / or two-component epoxy resins.
[0070] Furthermore, the term "gas" as used herein refers to any gaseous or mist-like fluid in a broad sense. Most commonly, air is used as the working medium for gas spring devices such as those described herein, as well as suspension systems and other components. However, it should be understood that any suitable gaseous fluid can be used.
[0071] It should be recognized that the embodiments shown and described herein illustrate many different features and / or components, and no single embodiment is explicitly shown and described as including all such features and components. Therefore, it should be understood that the subject matter of this disclosure is intended to cover any and all combinations of the different features and components shown and described herein, and that any suitable arrangement of features and components may be used without limitation in any combination. Therefore, it should be clearly understood that, whether specifically embodied herein or not, any such combination of features and / or components is intended to be supported by the claims in this disclosure. To assist the Patent Office and any reader of this application and any resulting patent for interpreting the appended claims, the applicant does not intend for any claim or any element of the appended claims to invoke 35 U.SC112(f), unless the terms “means for…” or “steps for…” are expressly used in a particular claim.
[0072] Therefore, although the subject matter of this disclosure has been described with reference to the above embodiments and considerable emphasis has been placed on the structure and structured interrelationships between the component parts of the disclosed embodiments herein, it should be understood that other embodiments can be constructed and many changes can be made to the illustrated and described embodiments without departing from the principles of the invention. Clearly, modifications and alterations will be made to other aspects after reading and understanding the foregoing detailed descriptions. Therefore, it should be clearly understood that the above descriptive issues are to be interpreted merely as illustrative of the subject matter of this disclosure and not as limiting. For this reason, it is intended that the subject matter of this disclosure be understood to include all such variations and modifications.
Claims
1. An end member assembly having a longitudinal axis and dimensioned to receptively engage an associated flexible spring member, the end member assembly extending axially from a first end toward a second end, and the end member assembly comprising: A first end member component includes a first component wall formed of a first number of polymer materials, the first component wall extending circumferentially around the longitudinal axis, the first component wall including a first end wall portion oriented transversely to the longitudinal axis and disposed toward a first end of the end member assembly, the first component wall including a first side wall portion extending axially from along the first end wall portion toward a distal edge disposed toward a second end of the end member assembly, the first side wall portion including an inner surface portion and a plurality of first annular ribs extending radially outward to a plurality of rib end surface portions, the plurality of first annular ribs being disposed axially spaced apart from each other along the first side wall portion of the first component wall; and A second end member extends axially along the first end member. The second end member includes a second member wall formed of a second number of polymer materials. The second member wall is formed as a continuous and uninterrupted integral mass extending around the first end member, such that the second end member has no longitudinally extending edges or margins that could form a joint along the second member wall. Thus, the second end member is permanently attached to the first end member. The second member wall includes an outer surface having a plurality of second annular ribs arranged axially spaced from each other. Each of the plurality of second annular ribs is axially disposed between adjacent first annular ribs, such that the plurality of first annular ribs and the plurality of second annular ribs are axially staggered, thereby substantially inhibiting axial movement of the first end member and the second end member relative to each other.
2. The end member assembly of claim 1, wherein the first member wall includes at least one inner sidewall portion extending radially inward from along the first sidewall portion and axially from along the first end wall portion to a distal edge, such that a gap is provided therebetween.
3. The end member assembly of claim 1, wherein the inner surface portion of the first sidewall portion of the first member wall at least partially defines an end member chamber within the end member assembly.
4. The end member assembly of claim 1, further comprising a third end member component, the third end member component being at least partially embedded within the first component wall of the first end member component.
5. The end member assembly of claim 4, wherein the end member assembly includes an end member chamber, and the third end member component includes a third component wall having an end wall portion and a plurality of channels, the end wall portion being at least partially embedded within the end wall portion of the first component wall, the plurality of channels extending through the end wall portion of the third component wall and through the first component wall, such that the plurality of channels are in fluid communication with the end member chamber.
6. The end member assembly of claim 4, wherein the third end member component includes a third member wall having a side wall portion that is at least partially embedded within the first side wall portion of the first member wall.
7. The end member assembly of claim 4, wherein the first member wall is at least partially formed of a first polymer material, and the third end member component includes a third member wall, the third member wall being at least partially formed of a metallic material and / or a second polymer material different from the first polymer material.
8. The end member assembly of claim 6, wherein the first end member component includes a plurality of annular grooves radially outwardly spaced axially from the plurality of first annular ribs, the plurality of annular grooves being sized to receptively engage an associated end of the associated flexible spring component and being axially co-located with the sidewall portion of the third component wall of the third end member component.
9. The end member assembly of claim 1, wherein the first member wall includes an end wall portion oriented transversely to the longitudinal axis.
10. The end member assembly of claim 1, further comprising a fourth end member component attached to the first end member component in a relationship axially spaced apart from the second end member component.
11. The end member assembly according to any one of claims 1 to 10, wherein the first end member component is injection molded in a first cavity formed at least partially by a plurality of first mold segments, and the second end member component is injection molded around the first end member component in a second mold cavity formed by a plurality of second mold segments, the first end member component being supported in situ on one or more of the plurality of first mold segments.
12. The end member assembly of claim 11, wherein the third end member component is supported in a first cavity at least partially formed by a plurality of first mold sections, the first end member component being injection molded in the first cavity and at least partially encapsulating the third end member component.
13. The end member assembly of claim 11, wherein the first member wall includes an inner sidewall portion disposed radially inside the sidewall portion such that an annular gap is disposed between the inner sidewall portion and the sidewall portion.
14. The end member assembly of claim 13, wherein the inner sidewall portion includes a plurality of longitudinal ribs that project radially inward in a direction away from the annular gap.
15. The end member assembly of claim 1, wherein the first and second end member components at least partially define the end member chamber within the end member assembly.
16. A gas spring assembly, the gas spring assembly comprising: A flexible spring member that extends circumferentially about a longitudinal axis and extends longitudinally between opposing first and second ends, such that a spring chamber is at least partially defined between the first and second ends. An end member, the end member being fixed across the first end of the flexible spring member; and According to any one of claims 1 to 15, the end member assembly is operatively fixed to the second end of the flexible spring member such that a substantially fluid-tight connection is formed therebetween.
17. The gas spring assembly of claim 16, wherein the flexible spring member at least partially defines a rolling cam, the rolling cam being sized to shift along the outer surface of the second component wall of the second end member when the gas spring assembly undergoes extension and compression during use.
18. A gas spring and damper assembly, the gas spring and damper assembly comprising: A damper assembly having a longitudinally extending axis and comprising: A damper housing, the damper housing including a housing wall extending axially between opposing first and second ends, the housing wall at least partially defining a damping chamber containing a quantity of damping fluid; and A damper rod assembly, the damper rod assembly including an elongated damper rod and a damper piston fixed along the elongated damper rod, the damper rod assembly being operably engaged with a damper housing for reciprocating displacement relative to the damper housing, wherein the damper piston is disposed in the damping chamber and at least a portion of the elongated damper rod protrudes axially outward from a first end of the damper housing; and The gas spring assembly according to any one of claims 16 and 17 is configured to be axially co-extended with at least a portion of the damper assembly.
19. The gas spring and damper assembly of claim 18, wherein the damper housing includes an end wall portion oriented transversely to the longitudinal axis, and the end wall portion of the first component wall of the first end member is axially supported on the end wall portion of the damper housing, and the end of the end member assembly opposite to the end wall portion is substantially unsupported by the damper housing in both axial directions.
20. The gas spring and damper assembly of claim 19, further comprising a radial bushing slidably disposed between the damper housing and the end of the end member assembly opposite the end wall portion.
21. A suspension system, the suspension system comprising: A compressed gas system, the compressed gas system including a compressed gas source and a control device; as well as At least one gas spring assembly according to claim 16 or 17, the at least one gas spring assembly being arranged in fluid communication with the compressed gas source via the control device, such that compressed gas can be selectively transmitted into and out of at least the spring chamber.
22. A method for manufacturing an end component assembly, the method comprising: A first quantity of polymer material is injected into a first mold cavity at least partially defined by first and second first mold sections to mold a first end member component having a longitudinal axis. The first end member component includes a first component wall extending circumferentially around the longitudinal axis. The first component wall includes a first end wall portion oriented transversely to the longitudinal axis and disposed toward a first end of the end member assembly. The first component wall also includes a first side wall portion extending axially from along the first end wall portion toward a distal edge disposed toward a second end of the end member assembly. The first side wall portion includes an inner surface portion and a plurality of first annular ribs extending radially outward to a plurality of rib end surface portions. The plurality of first annular ribs are disposed along the first side wall portion of the first component wall in a relationship of axial spacing from each other. as well as, A second quantity of polymer material is injected into a second mold cavity at least partially defined by the first end member and a third mold section, the first end member being supported on at least one of the first and second mold sections, thereby molding a second end member surrounding the first end member. The second end member has a second component wall that extends axially along the first end member and continuously and uninterruptedly around the first end member, such that the second end member has no longitudinally extending edge or margin that could form a joint along the second component wall, thereby permanently attaching the second end member to the first end member. The second component wall includes an outer surface having a plurality of second annular ribs arranged axially spaced from each other. Each of the plurality of second annular ribs is axially disposed between adjacent first annular ribs, such that the plurality of first annular ribs and the plurality of second annular ribs are axially staggered, thereby substantially inhibiting axial movement of the first end member and the second end member relative to each other.
23. The method of claim 22, wherein the second component wall molding the second end component around the first end component component includes forming an end component chamber at least partially between the first end component component and the second end component component within the end component assembly.
24. The method of claim 22, wherein the first component wall of molding the first end member includes molding at least one inner sidewall portion extending radially inward along the first sidewall portion and axially extending from along the first end wall portion to a distal edge, such that a gap is provided between the first sidewall portion and the distal edge.
25. The method of any one of claims 22 to 24, further comprising providing a third end member component and positioning the third end member component within the first mold cavity prior to injecting the first quantity of polymer material into the first mold cavity.
26. The method of claim 25, further comprising providing a fourth end member component and fixing the fourth end member component to the first end member component in a spaced-apart relationship with respect to the second end member component.