Patent Description:
An air spring may comprise a flexible member, such as an elastomeric sleeve that extends between a pair of plates, typically referred to as a top or bead plate and a bottom plate or piston. The elastomeric sleeve is attached to each of the top plate and the bottom plate to form an air tight seal. With the air tight seal, the elastomeric sleeve, top plate, and bottom plate form a pressurized chamber. The pressurized chamber contains a fluid, typically a gas such as air. The fluid contained in the pressurized chamber acts as a spring.

The top plate, and the bottom plate, are typically formed from a metal, such as, for example, iron or steel. The iron or steel plates, however, are exposed to the environment and suffer from corrosion, such as simple rusting or oxidation. To reduce the effect of corrosion, the metal may be treated or coated, which for example zinc, so the steel is not exposed to the environment. However, the process of attaching the plates to the sleeve often compromises the treatment or coating, which leads to reduced effectiveness of the coating and, eventually, corrosion.

One attempt to overcome the deficiencies of the prior art may be found in <CIT>, and is owned by the present application, which disclosure is incorporated herein by reference as if set out in full. <CIT> provided, among other things, preforming certain plastic parts that are assembled during the final assembly of the air spring. Another attempt to overcome the deficiencies in the prior art include German Patent Application No. <CIT>, owned by Contitech Luftfedersysteme GmbH, the disclosure of which is incorporated herein as if set out in full. The German Patent Application, similar to the United States Patent <CIT>, includes forming the top plate from multiple preformed plastic parts that are subsequently joined. <CIT> discloses air spring comprising of a piston, a top plate, a clamp ring, and a flexible member which is affixed to the piston and the top plate.

While each of the above solutions are functional in their own way, neither provides a sufficiently robust solution for all applications of air springs. However, it is desirable to increase the amount of composite parts (or plastic parts) in an air spring for durability, weight, and cost reasons to name but a few reasons. Composite and plastic are used interchangeably herein.

Thus, against this background, it would be desirable to provide an air spring where at least portions of the air spring comprise composite parts instead of metal.

This Summary, and the foregoing Background, is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter.

In some aspects of the technology, an air spring having at least one composite part is provided. The air spring will have a top plate, a flexible sleeve, and a clamp ring coupled together by an injection molded collar. The injection molded collar will be formed to hold the top plate, flexible sleeve, and clamp ring in compression to form an air tight seal. In certain embodiments, the top plate also is formed as a composite. In other embodiments, the clamp ring also is formed as a composite. In yet other embodiments, the top plate, clamp ring, and injection molded collar are all formed from composites.

In some embodiments, at least one of the clamp ring and top plate are formed with at least one of a plurality of indentations, perforations, channels, or a combination thereof. The indentations, perforations, channels, or combinations are filled with the injected plastic to facilitate the connection between the collar and the top plate and clamp ring.

In some aspect, a method of forming an air spring having at least one composite part is provided. The top plate, clamp ring, and flexible sleeve for an air spring are placed into a mold of an injection mold press. The press applies a compressive force to the top plate, clamp ring, and flexible sleeve forming an air tight seal between the top plate, clamp ring, and flexible sleeve. Plastic is injected into the mold while the press is applying the compressive force, which compressive force is held until the injected plastic cures and forms the injected mold collar. Once the injected mold collar is formed, the press is opened, and the air spring is removed. Optionally, the parts can be subsequently machine finished.

These and other aspects of the present system and method will be apparent after consideration of the Detailed Description and Figures herein.

Non-limiting and non-exhaustive embodiments of the present invention, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

The technology of the present application will now be described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the technology of the present application. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense.

The technology of the present application is described with specific reference to an air spring for a heavy-duty vehicle. However, the technology described herein may be used with applications other than those specifically described herein. Moreover, the technology of the present application will be described with relation to exemplary embodiments.

<FIG> shows a cross-section of a conventional state of the art air spring <NUM>. The conventional state of the art air spring <NUM> includes a steel bead plate <NUM>, a flexible member <NUM>, and a piston <NUM>. The flexible member includes an upper portion of the flexible member <NUM> which extends from the upper end of the flexible member <NUM> to no more than <NUM>% along the length of the flexible member <NUM> from the upper end of the flexible member <NUM> to the lower end of the flexible member <NUM>. The upper portion of the flexible member <NUM> is adapted to be affixed to the steel bead plate <NUM> to create an air tight seal. The flexible member <NUM> also includes a lower portion of the flexible member <NUM> which extends from the lower end of the flexible member <NUM> to no more than <NUM>% along the length of the flexible member <NUM> from the lower end of the flexible member <NUM> to the upper end of the flexible member <NUM>. The lower portion of the flexible member <NUM> is adapted to be affixed to the piston <NUM> to create an air tight seal. The lower portion of the flexible member <NUM> may be secured in any conventional manner, including, but not limited to, crimping the lower portion of the flexible member <NUM> to the piston <NUM> or to a conventional lower retainer or by securing a lower bead core by a lower retainer. An internal bumper may be provided for absorbing impact forces.

The steel bead plate <NUM>, the flexible member <NUM>, and the piston <NUM> define a pressurizable chamber <NUM>. The pressurizable chamber <NUM> is generally filled with a gas, such as air or nitrogen, to a pressure greater than atmospheric pressure. The gas is usually air for economic reasons. However, the pressurizable chamber can optionally be filled with an inert gas, such as nitrogen to help protect the flexible member (a rubber component) from degradation caused by oxygen or ozone. The steel bead plate <NUM> is attached to either a fixed or movable component and the piston <NUM> is attached to a corresponding fixed or movable component so that loads tending to move the steel bead plate <NUM> and the piston <NUM> towards each other will be counteracted by the pressure within the pressurizable chamber <NUM>.

As can be appreciated, the steel bead plate <NUM> is rolled or crimped at the outer radial edge such that the upper portion <NUM> of the flexible member <NUM>, i.e., the upper portion <NUM> that encompasses the retention bead (shown but not specifically referenced in <FIG>). As mentioned above, the steel bead plate <NUM> is subject to corrosion. Moreover, the crimping (or rolling) of the steel bead plate <NUM> at the outer radial edge can cause cracks, sometime microcracks, that are further any potential corrosion or oxidation of the steel bead plate <NUM>.

<FIG> shows a cross-sectional view of a top <NUM> of an air spring <NUM> consistent with the technology of the present application. The bottom of the air spring <NUM> may be consistent with known technology for air spring's and is not shown herein expect as necessary for an understanding of the technology. The air spring <NUM> includes a top plate <NUM>, a flexible sleeve <NUM>, a clamp ring <NUM>, and a collar <NUM>. The top plate <NUM>, the flexible sleeve <NUM>, the clamp ring <NUM>, and the collar <NUM> joint to form joint <NUM>, which facilitates forming an air tight seal between the top plate <NUM> and the flexible sleeve <NUM> that allows the air spring to be pressurized, as shown in <FIG>. The joint <NUM> will be explained further below with reference to <FIG>.

<FIG> shows a cross-sectional view of the joint <NUM> consistent with the technology of the present application. The joint <NUM> forms, among other things, an air tight seal <NUM> between the top plate <NUM> and the flexible sleeve <NUM>. The terminal end <NUM> of the flexible sleeve <NUM> comprises a retention bead <NUM> that contains a wire member <NUM> to facilitate structural integrity. In certain embodiments, the wire member <NUM> may be optional in view of the improvements presented by the technology of the present application.

The terminal end <NUM> of the flexible sleeve <NUM>, or the retention bead <NUM>, is captured in a cavity <NUM> formed by top plate <NUM> and a clamp ring <NUM>. As shown in this example, the top plate <NUM> does not need to be bent, but can remain a relatively flat, planar shape at the outer radial end portion <NUM>. The clamp ring <NUM> is shown as having a crescent shape but could form other shapes. The cavity <NUM> is generally circular, oval, elliptical, or the like to facilitate capture of the retention bead, but the cavity <NUM> could be alterative geometric or random shapes that accommodate the retention bead <NUM>. The annular clamp ring <NUM> has a seal end surface <NUM> that forms a gap G between a surface of the top plate <NUM> and the seal end surface <NUM>. The flexible sleeve <NUM> extends from the retention bead through the gap G. The seal end surface <NUM> engages with the flexible sleeve <NUM> and the surface of the top plate <NUM> engages with the flexible sleeve <NUM> to form an air tight seal.

The clamp ring <NUM> has a second end surface <NUM> opposite the seal end surface <NUM> that that abuts the surface of the top plate <NUM>. The clamp ring <NUM> is pressed against the top plate <NUM> and held in place by a collar <NUM> as will be explained further below. The collar <NUM> is shown with a C shape, but the shape is not limited to a C shape and, as will be clear from the below, an internal surface <NUM> of the collar <NUM> will likely be operatively shaped to coincide with an outer surface <NUM> of the clamp ring <NUM>. The collar <NUM> has a top plate engagement portion <NUM> that generally aligns with the top plate <NUM> and a clamp ring engagement portion <NUM> that generally engages the clamp ring <NUM>. The end <NUM> of the clamp ring engagement portion <NUM> is shown as squared off or with edges, but the end portion <NUM> may be rounded, blunt, or chamfered. The end portion <NUM> may, in certain embodiments, engage the flexible member <NUM> at times as the flexible member is pressurized and depressurized. The end portion <NUM> being rounded, blunt, or chamfered may reduce wear on the flexible member <NUM>.

The collar <NUM>, as will be explained with reference to <FIG>, is formed after the top plate <NUM>, flexible sleeve <NUM>, and clamp ring <NUM> are put together. The top plate <NUM>, flexible sleeve <NUM>, and clamp ring <NUM> are held in place and a press, such as an injection molding press, is applied to force the top plate <NUM> and clamp ring <NUM> together in compression such that the flexible sleeve <NUM> is compressed in the cavity <NUM>. The flexible sleeve <NUM> is compressed in the gap G to form an air tight seal. The press compresses the parts, as explained, in a mold configured for injection molding. The mold forms the collar shape around the parts and a plastic is injected into the mold and held in place at pressure until the plastic cures such that the collar <NUM> is injection molded around the top plate <NUM> and clamp ring <NUM>.

<FIG> shows an exemplary method <NUM> of forming the air spring having composite parts consistent with the technology of the present application. The exemplary method <NUM> is illustrative and shown in several discrete steps. Each of the steps, in context, may be performed in alternative orders and/or simultaneously with other steps. Additionally, certain of the steps may be combined into a single step or any of the single steps may involve multiple additional or sub steps as required. With that, the process begins at step <NUM>. The component parts of the air spring, including the top plate <NUM>, the flexible sleeve <NUM>, and the clamp ring <NUM>, are arranged in a mold in an injection mold press, step <NUM>. A force is applied to the component parts of the air spring by the injection mold press, step <NUM>.

While the press is compressing the top plate <NUM>, the flexible sleeve <NUM>, and the clamp ring <NUM> together, a plastic composite is injected into the mold, step <NUM>. The compression is maintained by the press until the plastic composite is solidified, step <NUM>. Once solidified, the press released and the air spring with the composite parts consistent with the technology of the present application is removed from the injection mold press, step <NUM>, with the collar formed by the injection molding process. Optionally, the collar may be machined to a shape, step <NUM>.

As can be appreciated, the injection mold press would form a mold with an outer shape as designed, which would typically be an annular shape, but the shape would match the shape of the air spring. The outer surface of the mold is shaped consistent with the outer surface <NUM> of the collar <NUM> as shown in <FIG>. As explained above, the inner surface of the mold will be formed, in most cases, by the surface <NUM> of the top plate <NUM> and an outward surface <NUM> of the clamp ring <NUM>. However, in certain embodiments, the inner surface of the mold may be formed in the shape consistent with the inner surface <NUM> of collar <NUM>, shown in <FIG>.

<FIG> shows a bottom elevation view of the clamp ring <NUM>. The clamp ring <NUM> is shown with indentations <NUM> or perforations <NUM>. The indentations <NUM> and perforations <NUM> are formed at least in the outward surface <NUM> of the clamp ring <NUM> to allow the injected composite flow and cure in the indentations <NUM>, perforations <NUM>, or a combination thereof. Although shown and described in this embodiment, the indentations <NUM>, perforations <NUM>, or combination thereof may be located on the assembly in a plurality of locations. The perforations <NUM> may be formed as through bores. Still with reference to <FIG>, a top elevation view of the top plate <NUM> is shown. The surface <NUM> of the top plate <NUM> may have indentations <NUM>, perforations <NUM>, or a combination thereof as well. The indentations <NUM>, perforations <NUM>, or the combination may increase the strength of the connection between the collar <NUM> and the top plate <NUM>/clamp ring <NUM>.

<FIG> shows a similar air spring <NUM> with an injection molded collar <NUM>. The air spring <NUM> includes a top plate <NUM>, a flexible sleeve <NUM>, and a clamp ring <NUM> in addition to the collar <NUM>. The top plate <NUM>, unlike the top plate <NUM> described above, is bent at a radially outer edge <NUM> to provide a downwardly extending circumferential lip <NUM>. The clamp ring <NUM> is similar to the clamp ring <NUM> described above and is shaped to form the gap G between the top plate <NUM> and the sealing surface <NUM> of the clamp ring. The outer surface <NUM> of the circumferential lip <NUM> and the outer surface <NUM> of the clamp ring <NUM> may be scarred or grooved with channels <NUM>, which correspondingly form ridges <NUM>. The channels <NUM> and ridges <NUM> are filled during the injection molding process to facilitate the grip between the molded collar <NUM> and the top plate <NUM> and clamp ring <NUM>.

Additionally, as shown in <FIG>, a reinforcing rib <NUM> may be provided in the collar <NUM> (or the molded collar <NUM> above). The reinforcing rib <NUM> may be a metal or composite of additional strength to facilitate the structural integrity of the collar <NUM> as it is exposed to vibration, shock forces, corrosive environments, a combination thereof, or the like. The reinforcing rib <NUM> may be operatively shaped similar to the collar (as shown) or have alternative shapes including straight shapes.

With reference back to <FIG>, the top plate <NUM> and the clamp ring <NUM> form a junction <NUM>. When compressed, the junction <NUM> inhibits the injected plastic from contacting the retention bead <NUM> and flexible sleeve <NUM>.

As described above, and shown in isolation in <FIG>, the top plate <NUM> and clamp ring <NUM> may have perforations <NUM> that form through holes. The through holes <NUM> provide a pathway for the plastic of the injection molded collar to contact the flexible sleeve <NUM>. Thus, the injected plastic flowing into the perforations may increase the strength of the connection, but may, in certain aspects, weaken or otherwise damage the flexible sleeve <NUM>. In certain aspect, column sleeves <NUM> may be provided providing a channel between the top plate <NUM> and the clamp ring <NUM> such that a barrier is provided between injection mold and the flexible sleeve. The injected plastic would thus flow from the collar lower part to the collar upper part through the clamp ring <NUM> and the top plate <NUM> forming a connector.

As can be appreciated, the injection molded collar <NUM>, <NUM> provides a strong connection between the top plate <NUM>, <NUM> and the clamp ring <NUM>, <NUM>. The collar <NUM>, <NUM> functions whether the top plate <NUM>, <NUM> is a metal or a composite. Similarly, the clamp ring <NUM>, <NUM> may be a metal or composite.

Claim 1:
An air spring comprising,
a top plate (<NUM>, <NUM>) having a top surface and a bottom surface opposite the top surface;
a flexible sleeve (<NUM>) having a retention bead (<NUM>) at a terminal end portion (<NUM>) of the flexible sleeve (<NUM>);
a clamp ring (<NUM>), the clamp ring (<NUM>) forming a cavity (<NUM>) with the bottom surface of the top plate (<NUM>), wherein retention bead (<NUM>) is in the cavity (<NUM>) and the flexible sleeve (<NUM>) extends from the retention bead (<NUM>) through a gap (G) formed between a seal end surface (<NUM>) of the clamp ring (<NUM>) and the bottom surface of the top plate (<NUM>); and
an injection molded collar (<NUM>) formed from an injection molded plastic, the injection molded collar (<NUM>) operatively shaped to hold the clamp ring (<NUM>) to the top plate (<NUM>) such that the retention bead (<NUM>) and the flexible sleeve (<NUM>) are compressed forming an air tight seal (<NUM>) between the top plate (<NUM>) and the retention bead (<NUM>) and the flexible sleeve (<NUM>), wherein the injection molded collar (<NUM>) is distinct from the clamp ring (<NUM>).