Overmolded air strut top hat with metal reinforcement

Abstract

The present invention relates to an overmolded air spring top cover with metal reinforcement. An air spring strut assembly includes a top cover having a metal flange overmolded within a plastic overmolded housing. The metal flange carries the load of the top cover structure and the plastic overmolded housing includes complex shapes and surfaces that do not carry the load. A shock absorber and a bellows are attached to the top cover to complete the air spring strut assembly.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 261,283, filed on September 16, 2021. Technical Field

[0003] This disclosure relates to a top cap for an air spring strut, and more particularly to a top cap having an overmolded metal support feature. Background Technology

[0004] Air spring struts provide spring damping and cushioning for a motor vehicle's suspension system. An air strut comprises an air spring and an integrated shock absorber. The air spring includes a bellows sandwiched between a top cover and a lower portion attached to the shock absorber. The top cover is attached to the vehicle's frame members, and the shock absorber is attached to the suspension members. Loads encountered during vehicle operation are transferred to the vehicle's frame members through the top cover. Furthermore, the top cover includes features and complex shapes that provide attachment for the shock absorber, bellows, and other features and structures of the air strut. Therefore, the top cover needs to be formed of a material that can withstand the significant loads encountered during vehicle operation while also providing the features required for assembling the air spring strut.

[0005] The background description provided herein is for the purpose of generally presenting the context of this disclosure. The work of the currently attributed inventors, to the extent described in this background section, and in all respects of that description which at the time of filing may not be regarded as prior art, is neither expressly nor implicitly considered prior art to this disclosure. Summary of the Invention

[0006] An air spring strut for a motor vehicle according to a disclosed example embodiment includes, among other things: a shock absorber; a top cover having an overmolded metal flange extending from a plastic-overmolded housing configured for attachment to a frame member of the motor vehicle, the plastic-overmolded housing being configured to receive a damper bushing; and bellows including a first end clamped to the plastic-overmolded housing of the top cover and a second end attached to a portion of the shock absorber, the bellows defining an air-filled working space and forming rolling folds on the top cover and the shock absorber.

[0007] In a further embodiment of the aforementioned air spring strut, a plastic-coated molded housing defines a top cavity, a bottom cavity, and an opening therebetween for a piston rod of a shock absorber.

[0008] In any further embodiment of the aforementioned air spring strut, the central portion of the metal flange is disposed within the plastic-coated molded housing, between the top cavity and the bottom cavity.

[0009] In any further embodiment of the aforementioned air spring strut, the outer portion of the metal flange extends outward from the central portion and outward from the plastic-coated molded housing.

[0010] In any further embodiment of the aforementioned air spring strut, the central portion of the metal flange includes at least one opening, and the plastic material of the plastic-coated molding housing is disposed within said at least one opening for securing the metal flange within the plastic-coated molding housing.

[0011] In any further embodiment of the aforementioned air spring strut, the bottom cavity is configured to receive and retain the buffer to limit movement and absorb energy from the shock absorber.

[0012] In a further embodiment of any of the aforementioned air spring struts, the top cavity includes an integrally molded inner groove for receiving a retaining ring to secure the closure to the top cover.

[0013] In any further embodiment of the aforementioned air spring strut, the metal flange includes a plurality of outwardly extending ribs that extend outward from the plastic-coated molded housing.

[0014] In any further embodiment of the aforementioned air spring strut, the air spring strut includes at least one metal fastening member fixed to a metal flange.

[0015] In any further embodiment of the aforementioned air spring strut, the air spring strut includes a support ring partially overmolded within a plastic-coated molded housing, the support ring being formed of metal and disposed radially inside the crimping surface for the first end of the bellows.

[0016] According to another example disclosed embodiment, the top cover assembly for an air spring strut includes, among other things, an overmolded metal flange extending outward from a plastic-overmolded housing, wherein the metal flange is configured for attachment to a frame member of a motor vehicle, and the plastic-overmolded housing is configured to receive a damper bushing.

[0017] In a further embodiment of the aforementioned top cover assembly, a plastic-coated molded shell defines a top cavity, a bottom cavity, and an opening extending therebetween.

[0018] In a further embodiment of any of the aforementioned top cover assembly, the central portion of the metal flange is disposed within the plastic-coated molded housing, between the top cavity and the bottom cavity.

[0019] In a further embodiment of any of the aforementioned top cover assembly, the outer portion of the metal flange extends outward from the central portion and outward from the plastic-coated molded housing.

[0020] In a further embodiment of any of the aforementioned top cover assembly, the central portion of the metal flange includes at least one opening, and the plastic material of the plastic-coated molded housing is disposed within said at least one opening for securing the metal flange within the plastic-coated molded housing.

[0021] A method of assembling an air strut assembly according to another disclosed embodiment includes, among other things, each of the following: forming a metal flange to include attachment features configured for attachment to a frame member of a motor vehicle; forming a top cover assembly by overmolding the metal flange into a plastic-overmolded housing such that the features of the metal flange configured for attachment to the motor vehicle extend to the exterior of the plastic-overmolded housing; assembling a shock absorber assembly to the top cover assembly; and assembling a first end of a bellows to the top cover and a second end of a bellows to a portion of the shock absorber, the bellows defining an air-filled working space and forming rolling folds that roll over the top cover and the shock absorber.

[0022] In a further embodiment of the aforementioned method, forming the top cover assembly further includes partially overmolding the support ring within a plastic overmolded housing and radially inward of a press-fit portion formed of the plastic material of the plastic overmolded assembly.

[0023] In a further embodiment of any of the foregoing methods, the metal flange is formed to include rib portions extending radially outward from a central portion, wherein attachment features are disposed on these rib portions.

[0024] In a further embodiment of any of the foregoing methods, the central portion of the metal flange is formed to include at least one opening, and forming the top cover assembly includes overmolding the metal flange such that plastic material of the plastic-overmolded housing is disposed within the at least one opening for securing the metal flange within the plastic-overmolded housing.

[0025] In a further embodiment of any of the foregoing methods, assembling the shock absorber to the top cover assembly further includes assembling the damper bushing into the top cavity of the top cover, extending the piston rod of the damper through an opening in the top cover into the top cavity, and attaching the piston rod to the damper bushing.

[0026] Although the different examples have the specific components shown in the illustrations, the embodiments of this disclosure are not limited to those specific combinations. It is possible to combine some components or features from one example with features or components from another example.

[0027] These and other features disclosed herein are best understood from the following description and accompanying drawings, which are briefly described below. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of an example air spring strut embodiment.

[0029] Figure 2 This is a cross-sectional view of an example top cover assembly embodiment.

[0030] Figure 3 This is a top perspective view of an example top cover component embodiment.

[0031] Figure 4 This is a plan view of an example metal flange of the top cover assembly.

[0032] Figure 5 This is a cross-sectional view of an example metal flange.

[0033] Figure 6 This is a schematic flowchart illustrating an example method for assembling an air spring strut. Detailed Implementation

[0034] refer to Figure 1 The air spring strut 20 is shown in cross-section and is generally indicated by 20. The air spring strut 20 includes a top cover 26 having an overmolded metal flange 50 defining a connection interface with the vehicle frame. The metal flange 50 is overmolded into a plastic overmolded housing 52 of the top cover 26 to provide a single integrated part, which reduces weight while maintaining structural durability and strength.

[0035] Example air spring strut 20 includes an air spring 22 and a shock absorber 24. A bellows 28 includes a first end 32 and a second end 34. The bellows 28 provides the working volume for the air spring 22. The first end 32 of the bellows 28 is airtightly secured to a top cover 26. The second end 34 of the bellows 28 is secured to a portion of the shock absorber 24. An upper clamping ring 36 secures the first end of the bellows 28 to the top cover 26. A lower clamping ring 38 secures the second end 34 of the bellows 28 to the shock absorber 24.

[0036] In one disclosed example, the bellows 28 is embodied as a double-lobe rolling bellows. However, other bellows 28 and air spring configurations may be utilized and are within the scope and intent of this disclosure.

[0037] The piston rod 30 of the shock absorber 24 extends upward through the top cover 26 into the top cavity 56. Within the top cavity 56, the piston rod 30 is secured to the damper bushing 42 by a nut 44. The closure 46 is secured to the top cavity 56 by a retaining ring 48.

[0038] The bump buffer 40 is secured within the bottom cavity 58, which is confined within the top cover 26. An opening 64 through the top cover 26 between the top cavity 56 and the bottom cavity 58 provides open space for the piston rod 30.

[0039] refer to Figure 2 and Figure 3 And continue to refer to Figure 1 The top cover 26 includes a metal flange 50 overmolded into a plastic-coated molded housing 52. The metal flange 50 is molded into the plastic-coated molded housing 52 to define mounting features that abut against the vehicle body and / or frame and define a load path through the air spring strut 20. One or more fastening members may be attached to the metal flange 50 to facilitate mounting, depending on the vehicle-specific configuration. In one disclosed example, a threaded stud 54 is press-fitted into the metal flange 50 to facilitate mounting. Other fastening devices and structures may also be utilized and are within the scope and intent of this disclosure.

[0040] The plastic-coated molded housing 52 defines additional features that do not require the strength of the metal structure. In one disclosed example, the plastic-coated molded housing 52 defines a top cavity 56 for the damper bushing 42 and a bottom cavity 58 for the bump buffer 40.

[0041] The plastic-overmolded housing 52 further defines a press-fit support surface 62 configured to receive the first end of the bellows 28. A support ring 60 is overmolded into the plastic-overmolded housing 52 radially inward of the press-fit support surface 62 to provide structural rigidity. In one disclosed example, the support ring 60 is a continuous metal ring whose thickness and material properties provide the desired structural characteristics to maintain the hermetic seal of the bellows 28. In another disclosed example, the support ring 60 is overmolded and has an exposed inner side not covered by plastic material.

[0042] The plastic-coated molded housing 52 includes complex, irregular shapes and features that cannot be efficiently formed using metalworking techniques. The press-fit support surface 62 includes a series of grooves that provide the desired airtightness. Forming such grooves in metal castings or forgings would be time- and cost-intensive.

[0043] Furthermore, the configuration of the top cavity 56 and the bottom cavity 58 includes features that provide for the assembled air spring strut 20. The top cavity 56 includes an inner recess 78 for retaining a ring 48 for holding the closure 46 in place. The bottom cavity 58 includes an inner protrusion 75 for holding the buffer 40 in place. Machining such features from metal castings or forgings is inefficient, and therefore integrally molding such features within the plastic-coated molded housing 52 provides reduced costs and increased production efficiency.

[0044] refer to Figure 3 , Figure 4 and Figure 5 And continue to refer to Figure 2 The metal flange 50 includes a central portion 68 enclosed within a plastic-coated molded housing 52. A central opening 76 is provided to correspond to an opening 64 defined to extend through the plastic-coated molded housing 52. In one disclosed example, the metal flange 50 is disposed within the plastic-coated molded housing 52 in a central space 55 between a top cavity 56 and a bottom cavity 58.

[0045] Multiple openings 74 are provided in the central portion 68 to allow plastic flow through the metal flange 50 during overmolding. The openings 74 are arranged to provide the desired plastic flow during the overmolding process. Once the top cover 26 is completed, the cured and solidified plastic material within the openings 74 secures the metal flange within the plastic overmolding housing 52.

[0046] Rib 66 extends outward from the central portion 68 into the outer portion 78, which radially surrounds the central portion 68. Rib 66 provides increased structural stiffness to accommodate loads encountered during operation. Opening 72 is provided in the outer portion 70 to receive stud 54.

[0047] Although the example metal flange 50 is shown as a circular plate, other shapes may be utilized and are within the scope and intent of this disclosure. The metal flange 50 may have any curved or straight shape or a complex shape corresponding to a vehicle mounting structure. Furthermore, the metal flange 50 may be flat and / or curved to conform to the desired shape of the plastic-coated molded housing 52.

[0048] In one disclosed example, the metal flange 50 is formed of steel coated to inhibit corrosion. The specific steel material can be of any grade, as long as it provides the desired structural properties to transfer loads over the desired operational lifespan. Additionally, other metallic and composite materials compatible with the overmolding process may also be utilized and are within the scope and contemplation of this disclosure.

[0049] refer to Figure 6The method of assembling the air spring strut 20 is schematically shown and indicated by 80. The example process includes step 82, which involves forming a metal flange 50. The metal flange 50 can be formed using any metal forming process. In one disclosed example, the metal flange 50 is formed as a stamped part. The support ring 60 is also formed using a known metal manufacturing process.

[0050] The metal flange 50 and support ring 60 are then placed in the mold and overmolded, as schematically indicated at 84. The metal flange 50 is secured within a cavity defined by the mold, which provides the desired shape of the completed plastic overmolded housing 52. The metal flange 50 includes an opening 74 that facilitates the molding process by defining a pathway for the flow of molten plastic material. The molten plastic material flows through the opening 74 in the metal flange to improve molding consistency and efficiency. Additionally, the plastic, which solidifies and hardens within the opening 74, secures the metal flange 50 within the plastic overmolded housing 52.

[0051] Thus, the completed top cover 26 is essentially a one-piece part having both a metal flange 50, which provides features for mounting to motor vehicles and bearing loads; and a plastic-coated molded housing 52, which provides a more complex shape that does not bear loads but is essential for operation and durability. Such features include a press-fit surface 62 and features integrally included within the top cavity 56 and the bottom cavity 58.

[0052] Once the top cover 26 is completed, the shock absorber 24 is assembled to the top cover 26, as indicated by 86. The shock absorber 24 is attached by extending the piston rod 30 into the top cavity 56. The piston rod 30 is then secured to the damper bushing 42 by the nut 44, as shown. Figure 1 As best shown in the diagram. Other components are assembled into the top cover 26, including the buffer 40 and any other parts disposed within the bellows 28.

[0053] As indicated by 88, assembly is completed by attaching any additional components to the shock absorber 24 and the top cover 26. The final assembly indicated by 88 involves attaching the bellows 28 to the top cover 26 at the first end 32. Then, the second end 34 of the bellows 28 is attached to a portion of the shock absorber 24.

[0054] The metal flange 50 forming a one-piece top cover 26 and the plastic-coated molded housing 52 reduce the time and cost associated with producing the air spring strut 20. Furthermore, the disclosed top cover 26 provides weight reduction while maintaining structural characteristics and durability.

[0055] Although different non-limiting embodiments are illustrated to have specific components or steps, the embodiments disclosed herein are not limited to those specific combinations. It is possible to combine some components or features from any non-limiting embodiment with features or components from any other non-limiting embodiment.

[0056] It should be understood that similar reference numerals identify corresponding or similar elements throughout these figures. It should be understood that while specific component arrangements are disclosed and illustrated in these exemplary embodiments, other arrangements may also benefit from the teachings of this disclosure.

[0057] The foregoing description should be interpreted as illustrative and not in any limiting sense. Those skilled in the art will understand that certain modifications may be made within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.

Claims

1. An air spring strut for a motor vehicle, the air spring strut comprising: a shock absorber; a top hat including a plastic overmolded shell and a metal flange overmolded to the plastic overmolded shell, wherein the metal flange is configured for attachment to a frame member of a motor vehicle and the plastic overmolded shell defines a top cavity (56) for receiving a damper bushing (42), a bottom cavity (58) for receiving a jounce bumper (40), and an opening (64) extending therebetween for receiving a piston rod of the shock absorber, the metal flange including a central portion disposed within the plastic overmolded shell between the top cavity and the bottom cavity, an outer portion of the metal flange extending outwardly from the central portion and outwardly from the plastic overmolded shell; and a bellows including a first end clamped to the plastic overmolded shell of the top hat and a second end attached to a portion of the shock absorber, the bellows defining an air-filled working space and forming rolling convolutions that roll over the top hat and the shock absorber.

2. The air spring strut of claim 1, wherein, The central portion of the metal flange includes at least one opening, and a plastic material of the plastic overmolded shell is disposed within the at least one opening for securing the metal flange within the plastic overmolded shell.

3. The air spring strut of claim 1, wherein, The bottom cavity is configured to receive and retain a bumper to limit movement and absorb energy from the shock absorber.

4. The air spring strut of claim 1, wherein, The top cavity includes an integrally molded inner groove for receiving a retaining ring to secure a closure cap to the top hat.

5. The air spring strut of claim 1, wherein, The metal flange includes a plurality of outwardly extending ribs that extend outwardly from the plastic overmolded shell.

6. The air spring strut of claim 1, including at least one metal fastening member secured to the metal flange.

7. The air spring strut of claim 1, including a support ring partially overmolded within the plastic overmolded shell, the support ring being formed of metal and disposed radially inward of a crimp surface for the first end of the bellows.

8. A method of assembling an air spring assembly, the method comprising: forming a metal flange to include an attachment feature configured for securing to a frame member of a motor vehicle; forming a top hat assembly by overmolding the metal flange into a plastic overmolded shell such that the feature of the metal flange configured for securing to the motor vehicle extends outside of the plastic overmolded shell, the plastic overmolded shell defining a top cavity (56) for receiving a damper bushing (42), a bottom cavity (58) for receiving a jounce bumper (40), and an opening (64) extending therebetween for receiving a piston rod of a shock absorber, the metal flange including a central portion disposed within the plastic overmolded shell between the top cavity and the bottom cavity, an outer portion of the metal flange extending outwardly from the central portion and outwardly from the plastic overmolded shell; assembling a shock absorber to the top cover assembly; and assembling a first end of a bellows to the top cover and a second end of the bellows to a portion of the shock absorber, the bellows defining an air-filled working space and forming rolling convolutions that roll over the top cover and the shock absorber.

9. The method of claim 8, wherein, forming the top cover assembly further includes partially overmolding a support ring within the plastic overmolded housing and radially inward of a crimped portion, the crimped portion being formed from plastic material of the plastic overmolded housing.

10. The method of claim 9, comprising forming the metal flange to include a rib portion extending radially outward from a central portion, wherein, the attachment feature is disposed on the rib portion.

11. The method of claim 10, wherein, the central portion of the metal flange is formed to include at least one opening, and forming the top cover assembly includes overmolding the metal flange such that plastic material of the plastic overmolded housing is disposed within the at least one opening for securing the metal flange within the plastic overmolded housing.

12. The method of claim 8, wherein, assembling the shock absorber to the top cover assembly further includes assembling a damper bushing into a top cavity of the top cover, and extending a piston rod of the damper through an opening in the top cover into the top cavity, and attaching the piston rod to the damper bushing.

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