Patent Description:
In one aspect, a bolster spring for a vehicle suspension is provided as claimed in claim <NUM>.

Exemplary embodiments of the invention are described herein with reference to the drawings, wherein like parts are designated by like reference numerals, and wherein:.

<FIG> provide various views of vehicle suspension <NUM>. Vehicle suspension <NUM> is designed to support longitudinally extending vehicle frame rails (not shown) which can be of various types that are positioned above laterally extending vehicle axles. As will be appreciated by those skilled in the art, components of vehicle suspension <NUM> are duplicated on each side of the vehicle as shown in <FIG>. It will also be appreciated that vehicle wheels may be mounted to the ends of the vehicle axles in a known manner. Further, it will be appreciated that the vehicle frame rails may be connected by one or more vehicle frame cross members.

Those skilled in the art will further understand that a suspension, arranged in accordance with the suspension <NUM> and the components thereof, alternatively may be attached to frame rails of a trailer (for example, a trailer that connects to a semi-tractor). The frame rails of a trailer may comprise frame rails such as those described above or another type of frame rail.

For purposes of this description, unless specifically described otherwise, hereinafter, "vehicle" refers to a vehicle or a trailer. In this way, for example, a vehicle frame refers to a vehicle frame or a trailer frame. Furthermore, for purposes of this description, the left side of a vehicle refers to a side of the vehicle on an observer's left-hand side when the observer faces the back of the vehicle, and the right side of the vehicle refers to a side of the vehicle on an observer's right-hand side when the observer faces the back of the vehicle. Furthermore still, for purposes of this description, "outboard" refers to a position further away from a center line, running from the front to the back of a vehicle, relative to "inboard" which refers to a position closer to that same center line.

<FIG> is a perspective view of an outboard side of vehicle suspension <NUM> having a frame attachment portion <NUM> that is adapted for attachment to a vehicle frame or frame rail with a plurality of mounting holes <NUM>. Frame attachment portion <NUM> includes outer gussets <NUM> and <NUM> and central flange <NUM> that provide additional strength and rigidity to the vehicle suspension <NUM>. Frame attachment portion <NUM> is attached to saddle <NUM>. Bolster springs <NUM> and <NUM> are provided that each have a top attached bolster spring mounts <NUM> and <NUM> extending from an outboard side of saddle <NUM> and a bottom attached to walls of bolster spring mount 107b positioned on equalizing beam <NUM>. Equalizing beam <NUM> has a beam hub <NUM> on a first end and a beam hub <NUM> on a second end. Beam hub <NUM> includes a bar pin <NUM> adapted for attachment to a first axle (not shown) and beam hub <NUM> includes a bar pin <NUM> adapted for attachment to a second axle (not shown).

A pair of shock absorbers <NUM> and <NUM> each have one end mounted to the equalizing beam <NUM> and another end mounted to saddle <NUM> on the inboard side of vehicle suspension <NUM>. In some applications, shock absorbers may not be used. A load cushion <NUM> is mounted to load cushion mount <NUM> extending from saddle <NUM> and load cushion <NUM> is positioned beneath saddle <NUM> and positioned inwardly from and generally above bolster springs <NUM> and <NUM>. A first rebound strap <NUM> is mounted to load cushion mount <NUM>, and a second rebound strap is mounted to load cushion mount <NUM> (shown in <FIG>). A bracket <NUM> having U-shaped ends that are used to mount rebound straps <NUM> may be positioned between the load cushion and the load cushion mounts <NUM> and <NUM>. In addition, shims of varying thickness may positioned between the load cushion <NUM> and bracket <NUM> to change the ride characteristics of the vehicle suspension <NUM>.

<FIG> includes a second vehicle suspension 50a that is a mirror image of vehicle suspension <NUM>, and may be positioned on an opposite side of a vehicle frame. Accordingly, <FIG> provides a perspective view of the inboard side of vehicle suspension 50a. Vehicle suspension 50a includes a frame attachment portion 62a that is adapted for attachment to a vehicle frame or frame rail with a plurality of mounting holes 63a. Frame attachment 62a further includes outer gussets 66a and 68a that along with a central flange provide additional strength and rigidity to the vehicle suspension 50a. Frame attachment portion 62a is attached to saddle 60a. Bolster springs 71a and 73a are provided that each have a top attached to bolster spring spring mounts extending from the inboard side of saddle 60a and a bottom attached to bolster spring mount 107a positioned on equalizing beam 100a. Equalizing beam 100a has a beam hub 102a on a first end and a beam hub 104a on a second end. Beam hub 102a includes a bar pin 110a adapted for attachment to a second axle (not shown) and beam hub 104a includes a bar pin 112a adapted for attachment to a first axle (not shown).

A pair of shock absorbers 120a and 122a each have one end mounted to the inboard side of equalizing beam 100a and another end mounted to the inboard side of saddle 60a. A load cushion is mounted to load cushion mount 92a extending from saddle 60a. A rebound strap 80a is mounted to load cushion mount 92a.

<FIG> provides a front view of the outboard side of vehicle suspension <NUM> and <FIG> and <FIG> provide views of the inboard side of vehicle suspension <NUM>. In <FIG>, load cushion <NUM> is shown mounted to load cushion mount <NUM> extending from saddle <NUM>. Bolster springs <NUM> and <NUM> are mounted to bolster springs mounts <NUM> and <NUM> outwardly extending from outboard wall <NUM> of saddle <NUM>, and also to bolster spring mount 107b on the outboard side of the equalizing beam <NUM>. As shown in <FIG>, bolster springs <NUM> and <NUM> are mounted to bolster spring mounts <NUM> and <NUM> extending from inboard wall <NUM> of saddle <NUM> and to walls of bolster spring mount 107a positioned on the inboard side of the equalizing beam <NUM>. The configuration of bolster springs <NUM>-<NUM> results in a balanced, split bolster spring arrangement where one pair of bolster springs <NUM> and <NUM> is positioned on the outboard side of equalizing beam <NUM> and one pair of bolster springs <NUM> and <NUM> is positioned on the inboard side of equalizing beam <NUM>.

As shown in <FIG>, shock absorber <NUM> has a first end secured to mount <NUM> positioned on equaling beam <NUM> and a second end secured to mount <NUM> positioned on saddle <NUM>, and shock absorber <NUM> has a first end secured to mount <NUM> positioned on equalizing beam <NUM> and a second end secured to mount <NUM> positioned on saddle <NUM>. In other examples, the second ends of shock absorbers <NUM> and <NUM> could also be mounted to a vehicle frame or frame rail, or not used at all.

Prior vehicle suspensions employing bolster springs typically provided an acute angle, or apex angle, between the bottoms of the bolster springs of <NUM> degrees, which has become a de facto industry standard. However, as best shown in <FIG> and <FIG>, vehicle suspension <NUM> significantly departs from the de facto apex angle standard of <NUM> degrees. In particular, an apex angle α is provided that is significantly less than <NUM> degrees. In the examples shown in <FIG>, the apex angle α between the bottom of bolster springs <NUM> and <NUM> (and the apex angle between bolster springs <NUM> and <NUM>) is <NUM> degrees. While an apex angle of <NUM> degrees is preferred, the apex angle α may range between <NUM>-<NUM> degrees, or from <NUM>-<NUM> degrees, all lower than a standard apex angle of <NUM> degrees.

By reducing the apex angle α to <NUM> degrees, a number of important advantages are achieved. For example, the reduced apex angle α allows the springs to be positioned closer together, and thereby taking up less space longitudinally. In turn, a greater clearance between the vehicle tires and the bolster spring arrangement is provided, which may provide greater tire chain clearance or allow for the use of larger tires. In addition, by reducing the apex angle α, the bolster springs are put more into a shear, rather than compression. As a result, a lower primary vehicle spring rate may be achieved, while at the same time providing for increased longitudinal stiffness. The present configuration of the bolster springs with an apex angle α of <NUM> degrees has increased the longitudinal stiffness of the suspension resulting in a corresponding decrease in the longitudinal deflection to less than an inch. As a result, the reduced apex angle α has resulted in reduced axle translation along the SAE X-Axis during braking and acceleration.

Reducing the apex angle α between the bolster springs has advantageously resulted in a reduction in the primary suspension spring rate to <NUM>-<NUM> kN/mm depending upon the elastomer used to create the bolster springs. Furthermore, a secondary spring rate of the vehicle suspension when the load cushion is engaged measured at <NUM> ranges from <NUM>-<NUM> kN/mm depending upon the elastomers chosen for both the bolster springs and initial gap between the load cushion and its reaction plate. These primary and second vehicle suspension spring rates are orders of magnitude lower than traditional elastomeric suspensions and are on the same order of magnitude as parabolic <NUM>-rod suspensions.

Additionally, as discussed in more detail below with respect to <FIG>, in addition to reducing the apex angle α between the bolster springs <NUM> and <NUM>, and <NUM> and <NUM>, vehicle suspension <NUM> also incorporates a unique bolster spring mounting arrangement wherein an angled flange <NUM> on the bottom plate <NUM> of bolster spring <NUM> is directly mounted to a corresponding angled flange <NUM> on bottom plate <NUM> of bolster spring <NUM> using a pair of common fasteners for retention. Bolster springs <NUM> and <NUM> are also directly mounted to each other using a pair of common fasteners in the same manner. As used herein, the term "directly mounted" means that the flanges are mounted together using a common fastener without a portion of the equalizing beam or bolster spring mount positioned therebetween, although a gasket or spacer, or portion of a spring saddle, could be positioned therebetween and the flanges would still be "directly mounted" to each other.

Directly mounting bolster springs <NUM> and <NUM> to each other, and directly mounting bolster springs <NUM> and <NUM> to each other using common fasteners provides a number of advantages. In particular, the bolster springs may be able to be positioned even closer together because there is no portion of the equalizing beam or a bolster spring mount extending between the flanges of the bolster springs. Furthermore, using common fasteners allows the positioning of the bolster springs to be closer together than if independent fasteners were used for each bolster spring. The closer positioning of the bolster springs allows even further clearance from the tires, again providing even greater clearance for tire chains or larger tires. The end result of directly mounting the flanges of the bolster springs with common fasteners provides for the use of fewer fasteners, faster assembly, improved clearances to surrounding components (because bolster springs are closer together), as well as the creation of a mechanical joint between the mounted flanges of the bolster springs.

As known to those skilled in the art, a mechanical joint formed between two components improves retention integrity and can permit the use of smaller fasteners compared to typical bolster spring designs. A benefit of smaller fasteners is improved clearances to surrounding packages, a more weight optimized design, and improved serviceability because smaller fasteners require less torque to achieve design load as a percent of proof load. Therefore, smaller fasteners are more easily and likely to be tightened appropriately.

<FIG> is a bottom view of vehicle suspension <NUM>. From this view, the equalizing beam <NUM> is shown with beam hub104 having inboard side 104a on one end with bar pin <NUM> and with beam hub <NUM> having inboard side 102a with bar pin <NUM>. A center-plane 100c of equalizing beam <NUM> is shown offset towards inboard side 104a and inboard side 102a a distance d from a center-plane of beam hubs <NUM> and <NUM>. In this example, the center-plane is offset a distance d of <NUM> millimeters. Providing such an offset on the equalizing beam has the effect of moving the vehicle suspension towards the inboard side of the vehicle frame, thereby advantageously providing additional clearance on the outboard side of the vehicle suspension.

In <FIG>, there is a clear view of bolster spring <NUM> and bolster spring <NUM> mounted to opposing walls of bolster spring mount 107b extending from an outboard side the vehicle suspension <NUM>, as well as of bolster spring <NUM> and bolster spring <NUM> mounted to opposing walls of bolster spring mount 107a extending from the inboard side of vehicle suspension <NUM>.

<FIG> shows a top view of vehicle suspension <NUM>. In <FIG>, shock absorbers <NUM> and <NUM> can be seen secured to the inboard side of saddle using shock absorber mounts <NUM>, <NUM>, <NUM>, and <NUM>. In addition, a gap <NUM> is shown on the surface of beam hubs <NUM> and <NUM> as a result of the offset d of center-plane 100c. In <FIG>, load cushion mount <NUM> is shown extending from an outboard side of saddle <NUM> and load cushion mount <NUM> is shown extending from an inboard side of saddle <NUM>. In addition, central flange <NUM> is shown positioned on top surface <NUM> of saddle <NUM> attached to frame attachment portion <NUM>.

<FIG> is a right side view of vehicle suspension <NUM> and <FIG> is a left side view of vehicle suspension <NUM>. Beam hub <NUM> is shown with bar pin <NUM> adapted for attachment to a first axle (not shown) and beam hub <NUM> is shown with bar pin <NUM> adapted for attachment for a second axle (not shown). Frame attachment portion <NUM> with gussets <NUM> and <NUM> are shown extending above outboard wall <NUM> and inboard wall <NUM> of the saddle and load cushion mount <NUM> is shown extending from the outboard side of vehicle suspension <NUM>. Shock absorber <NUM> is shown mounted to shock absorber mount <NUM> and shock absorber <NUM> is shown mounted to shock absorber mount <NUM>. In addition, a pair of rebound straps <NUM> are shown extending from inboard and outboards sides of the vehicle suspension <NUM>. Rebound straps <NUM> serve to prevent bolster springs <NUM>-<NUM> from being overstretched and overstressed when vehicle suspension <NUM> is placed in hang or rebound, such as when a vehicle is lifted with an outrigger, hits a large pothole, or during a sudden drop when going over a steep drop in the road.

<FIG> is a close up front view of, and <FIG> is a close up perspective view of, the bolster springs <NUM> and <NUM> and load cushion <NUM> on the outboard side of vehicle suspension <NUM>. Bolster spring <NUM> is attached to bolster spring mount <NUM> on saddle <NUM> using fasteners 270b and 270c, and also attached to bolster spring mount 107a on the equalizing beam <NUM> using fastener 270a. Similarly, bolster spring <NUM> is attached to bolster spring mount <NUM> on saddle <NUM> using fasteners 272b and 272c, and also attached to bolster spring mount 107a on the equalizing beam <NUM> using fastener 272a. As illustrated in <FIG>, upwardly extending flange <NUM> of bolster spring <NUM> is directly mounted to a corresponding upwardly extending flange <NUM> of bolster spring <NUM> using common fasteners, with a portion of spring saddle <NUM> positioned therebetween. In other examples, the bolster springs flanges <NUM> may be directly mounted to each other using common fasteners without a portion of a spring saddle positioned between them. As discussed above, apex angle α is formed between the bottom plates of bolster springs <NUM> and <NUM>.

To further strengthen the bolster spring assembly, a tie-bar <NUM> is used to tie outboard bolster spring <NUM> to inboard bolster spring <NUM> (shown in <FIG> and <FIG>) and tie-bar <NUM> is used to tie inboard bolster spring <NUM> to inboard bolster spring <NUM> (shown in <FIG> and <FIG>). In this example, the tie-bar is mounted in an intermediate plate located at a midpoint between the top plate and bottom plate of the bolster spring. The midpoint is the point most susceptible to buckling, bulging, or splaying. Therefore, the tie-bar serves to react the inboard and outboard bolster springs to prevent buckling or bulging at the most vulnerable point on the bolster spring. The tie-bar therefore provides greater rigidity and strength to the bolster spring assembly.

Furthermore, by directly mounting bolster spring <NUM> to bolster spring <NUM> with common fasteners and directly mounting bolster spring <NUM> to bolster spring <NUM> with common fasteners, and by connecting bolster spring <NUM> to bolster spring <NUM> using tie-bar <NUM> and by connecting bolster spring <NUM> to bolster spring <NUM> using tie-bar <NUM>, all four bolster springs <NUM>, <NUM>, <NUM>, and <NUM> are interconnected. As a result, the present examples provide a unified, interconnected assembly of bolster springs that is more rigid and stable than if the bolster springs were not connected.

In addition, as shown in <FIG> and <FIG>, load cushion <NUM> is secured to outboard load cushion mount <NUM> (and to inboard load cushion mount <NUM> shown in <FIG>), and is positioned above reaction plate <NUM>. Rebound strap <NUM> is attached to rebound strap flange 80a and to rebound strap flange 80b. The reaction plate <NUM> is secured via attachment to rebound strap flange 80b. In this example, a bottom surface of the load cushion <NUM> is positioned a distance D above the reaction plate <NUM>. Distance D may preferably be <NUM>. Therefore, a primary spring rate is based on the bolster springs, and when the load cushion <NUM> engages the reaction plate <NUM>, a secondary spring rate that includes the load cushion <NUM> is provided. In this example, a hard stop has been included at <NUM> of travel to protect the bolster springs and load cushion from becoming overcompressed.

The hard stop feature is best shown in <FIG>, where fasteners 290a used to mount the load cushion <NUM> downwardly extend towards the reaction plate <NUM>. Sleeves <NUM> are positioned around the fasteners 290a and in this example fasteners 290a have a head <NUM> extending from the end of sleeves <NUM>. When load cushion <NUM> is significantly compressed, e.g. at <NUM>% compression, the heads <NUM> of fasteners 290a that contact the reaction plate <NUM> to provide a hard stop and prevent further compression of the load cushion <NUM>. In other examples, the bottom of sleeves <NUM> may be counterbored to enclose head <NUM> so that the head <NUM> does not extend from the bottom of the sleeve <NUM> and instead the bottom of the sleeve <NUM> contacts the reaction plate <NUM> to provide the hard stop. The bottom of the sleeve <NUM> has a greater surface area than head <NUM> of fasteners 290a to spread the forces upon impact with the reaction plate <NUM>. As a result of the hard stop, there is a ceiling on the amount of strain that will experienced by the bolster springs and load cushion. In this example, the rebound strap <NUM> is comprised of woven material that is advantageously removable to allow for easy repair or replacement of the rebound strap <NUM>. It should be noted that depending upon the application, the disclosed vehicle suspensions may be used without a load cushion.

The components of the vehicle suspension <NUM> shown in <FIG> may comprise cast or fabricated metal or composite material, including iron, steel, or aluminum. Frame attachment portion <NUM> and saddle <NUM>, and equalizing beam <NUM> could also be cast with any suitable castable material. Similarly, the saddle <NUM> may comprise cast or fabricated metal or composite material. Depending on the application, the metal may, for example, be nodular ductile iron (or more simply, ductile iron), steel, such as a high strength low alloy steel, or aluminum. Typically, high strength low alloy steels are a preferred material to use for the frame hanger and the saddle, although aluminum is often desired when weight considerations are of greater importance.

<FIG> are views of a bolster spring <NUM>. Bolster springs <NUM>, <NUM>, <NUM>, and <NUM> may be configured as bolster spring <NUM>. As shown in <FIG>, bolster spring <NUM> includes a base plate <NUM> and a top plate <NUM>. Bolster spring <NUM> includes an elastomeric section <NUM> between base plate <NUM> and intermediate plate <NUM>, an elastomeric section <NUM> between intermediate plate <NUM> and intermediate plate <NUM>, an elastomeric section <NUM> between intermediate plate <NUM> and intermediate plate <NUM>, and an elastomeric section <NUM> between intermediate plate <NUM> and top plate <NUM>. It should be noted that in other examples a greater or lesser number of intermediate plates can be used, including no intermediate plates.

Top plate <NUM> includes mounting holes <NUM> and <NUM> that are positioned on flanges of the top plate that extend beyond the elastomer zone with mounting hole <NUM> located on a flange on a first end of top plate <NUM> and mounting hole <NUM> located on a flange on a second end of top plate <NUM>. Such a mounting hole arrangement allows for mounting to a bolster spring mount without using studs extending from the elastomer zone. Bottom plate <NUM> includes mounting hole <NUM> that is positioned on a flange on a first end of bottom plate <NUM> that is also beyond the elastomer zone. An angled flange <NUM> extends from a second end of bottom plate <NUM>. Angled flange <NUM> includes a pair of spaced mounting holes <NUM> and <NUM> positioned beyond the elastomer zone that are adapted to be directly mounted to a corresponding angled flange of an adjacent bolster spring, as illustrated in <FIG>. Top plate <NUM> and bottom plate <NUM> advantageously extend beyond the elastomer zone, and may be formed complementary in shape with the mounting surface of a bolster spring mount to provide a larger mounting surface area, which forms a stronger mechanical joint.

As shown in <FIG>, angled flange <NUM> may extend at an angle that is one half of apex angle α, so that when directly mounted to the angled flange of an adjacent bolster spring having the same configuration, an apex angle α is formed between the bottom surfaces of the directly connected bolster springs. In addition, a tie-bar mounting extension <NUM> having a through hole <NUM> through which a tie-bar may extend is shown extending from center intermediate plate <NUM>.

<FIG> is a top view of bolster spring <NUM>. As can be seen, mounting hole <NUM> of the bottom plate <NUM> extends beyond the elastomer zone. In addition, mounting holes <NUM> and <NUM> on angled flange <NUM> extend outwardly from the bottom plate <NUM> and have a spacing that is wider than the width of the bottom plate <NUM> and the top plate <NUM>. This wide spacing of the mounting holes <NUM> and <NUM> on angled flange <NUM> advantageously provides for greater contact between the angled flange surfaces when mounted as shown in <FIG>, resulting in a stronger mechanical j oint being formed between the angled flanges of the bolster springs.

The particular configuration of the base plate <NUM>, top plate <NUM>, and intermediate plates <NUM>, <NUM>, and <NUM> of bolster spring <NUM> is illustrative only, and these components may have a variety of geometries and configurations. Thus, the bolster spring <NUM> is not required to have, but may have, the geometry shown in <FIG>. Furthermore, the use of a tie-bar may be, but is not required to be, included.

A bolster spring is typically constructed from relatively flat first and second end plates with an elastomer connected between them. This spring will then have compressive and shear rates corresponding to the chosen material, cross-section, and thickness of elastomer. In accordance with the disclosed examples, bolster spring <NUM> may be constructed of elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM> bonded to one or more of plates <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. Elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM> may comprise an elastomeric material (i.e., an elastomer) such as natural rubber, synthetic rubber, styrene butadiene, synthetic polyisoprene, butyl rubber, nitrile rubber, ethylene propylene rubber, polyacrylic rubber, high-density polyethylene, thermoplastic elastomer, a thermoplastic olefin (TPO), urethane, polyurethane, a thermoplastic polyurethane (TPU), or some other type of elastomer. In this regard and in particular, elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM> may comprise an elastomer defined as American Society of Testing and Materials (ASTM) D2000 M4AA <NUM> A13 B13 C12 F17 K11 Z1 Z2. In this case, Z1 represents natural rubber and Z2 represents a durometer selected to achieve a desired shear rate. The selected durometer may be based on a given predefined scale, such as the Shore A scale, the ASTM D2240 type A scale, or the ASTM D2240 type D scale. In a preferred example, in accordance with the Shore A scale, Z2, for example, is preferably <NUM> ± <NUM>. In another example, in accordance with the Shore A scale, Z2 is, for example, within the range of <NUM> to <NUM>. Other examples of Z2 and ranges for Z2 are also possible.

In another respect, elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM> may comprise a viscoelastomeric material that (i) has elastic characteristics when the bolster spring <NUM> is under a load within a given range and when that load is removed, and (ii) has non-elastic characteristics (for example, does not return to an original non-loaded shape) if the applied load exceeds the greatest load of the given range. The given range may extend from no load to a maximum expected load plus a given threshold. The given threshold accounts for possible overloading of bolster spring <NUM>. As an example, the viscoelastomeric material may comprise amorphous polymers, semi-crystalline polymers, and biopolymers. Other examples of the viscoelastomeric material are also possible.

In accordance with the examples, elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM> may also comprise one or more fillers. The filler(s) may optimize performance of elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM>. The fillers may include, but are not limited to, wax, oil, curing agents, and/or carbon black. Such fillers may optimize performance by improving durability and/or tuning the elastomeric sections for a given shear load and/or a given compressive load applied to the elastomeric sections. Improving durability through the use of fillers may include, for example, minimizing a temperature rise versus loading characteristic of the elastomeric sections and/or maximizing shape retention of the elastomeric sections.

Bolster spring <NUM> may be formed, for example, by inserting the plates <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> into a mold (not shown). The plates may each be coated with a coating material. As an example, the coating material may comprise a material comprising zinc and phosphate, modified with calcium. The coating material may have a coating weight of <NUM>-<NUM> milligrams per square foot. Other examples of the coating material are also possible. A bonding agent may be applied to the coated plates for bonding the plates to the elastomeric sections. As an example, the bonding agent may comprise Chemlok® manufactured by the Lord Corporation, Cary, North Carolina, USA. Other examples of the bonding agent are also possible. Applying the coating material and/or applying the bonding agent may occur prior to, during, and/or after insertion of the plates into the mold. After applying the coating material and the bonding agent, the elastomeric material (while in a pourable form) may be inserted into the mold to form the elastomeric sections.

In a preferred example any exposed portion of the plates (for example, a portion of the plates not covered by the elastomeric material) is protected against corrosion by a means other than the elastomeric material. In other examples, some exposed portions of the plates (e.g., the edges of the plates) may not be protected against corrosion, whereas any other exposed portions of the plates are protected against corrosion.

The plates <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> can be made of any of a variety of suitable materials, including, but not limited to, iron, steel, aluminum, plastic, a composite material, or some other material. The plates may be fully, or at least substantially, encapsulated in elastomer to further enhance their corrosion resistance and friction at the mating suspension members. As an example, plates <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> can comprise plates having a thickness between a range of <NUM> inches (<NUM>) to <NUM> inches (<NUM>), or more.

<FIG> are perspective views of an example load cushion <NUM> for use in vehicle suspension <NUM>. <FIG> is a side view, <FIG> is a front view, <FIG> is a bottom view, and <FIG> is a top view of load cushion <NUM>. Load cushion <NUM> shown in vehicle suspension <NUM> in <FIG> may be arranged as load cushion <NUM>.

As shown in one or more of <FIG>, load cushion <NUM> includes a top plate <NUM>, a bottom plate <NUM>, and a load cushion portion <NUM>. Top plate <NUM> includes mounting flange <NUM> with mounting hole 312a and mounting flange <NUM> with mounting hole 314a adapted for mounting to load cushion mounts <NUM> and <NUM> (shown in <FIG> and <FIG>) of vehicle suspension <NUM>. In this example, a horizontal cross section of the cushion portion <NUM> is generally square with rounded corners, although it could also be generally circular, rectangular, or conic. As shown in <FIG> and <FIG>, the bottom plate <NUM> includes holes <NUM> that are used during the molding process to provide a passage for the elastomeric material that forms the cushion portion <NUM>.

As shown in <FIG>, the load cushion portion <NUM> has a unique symmetrical shape that includes curvilinear front and rear outer surfaces <NUM> and <NUM> that taper towards the center at the midpoint between the top plate <NUM> and bottom plate <NUM> such that the narrowest thickness of the load cushion <NUM> occurs at the midpoint. Similarly, as shown in <FIG>, the load cushion portion <NUM> has a unique symmetrical shape that includes curvilinear left and right outer surfaces <NUM> and <NUM> that taper towards the center at the midpoint between the top plate <NUM> and bottom plate <NUM> such that the narrowest thickness of the load cushion <NUM> occurs at the midpoint.

Load cushion <NUM> may have a cross section where front and rear outer surfaces <NUM> and <NUM> have a negative Gaussian curvature, and similarly load cushion <NUM> may have a cross section where left and right outer surfaces <NUM> and <NUM> have a negative Gaussian curvature. In addition, load cushion portion <NUM> may be shaped as a hyperboloid. The curved outer surfaces of the load cushion portion result in a much lower elastomeric strain on the load cushion for the same deflection as compared to a linearly reduced cross-section.

The load cushion <NUM> may undergo <NUM>% compression at full jounce, or when the hard stop discussed above is reached. At this point, the cross-section of the load cushion portion <NUM> changes from a negative Gaussian curvature to a <NUM> or slightly positive Gaussian curvature. As used herein the term, <NUM> Gaussian curvature means that the outer surfaces of the cross-section are parallel, and a "slightly positive Gaussian curvature" means that the midpoint of the load cushion portion <NUM> becomes wider than the end sections, by up to <NUM> on each side of the load cushion portion.

It will be appreciated that bottom plate <NUM> is not required, and the load cushion <NUM> may have an exposed surface instead of having bottom plate <NUM>. The use of a bottom plate <NUM> does not affect in any significant way the load cushion load versus deflection curve. However, the bottom plate <NUM> may be incorporated to protect the active elastomer of the load cushion portion <NUM> from debris such as rocks that could inadvertently end up on the reaction plate that is positioned beneath the load cushion. Debris could become embedded temporarily or permanently into the elastomer and create an undesirable crack initiation site.

The bottom plate <NUM> may be encapsulated to provide for improved corrosion resistance, elimination of metal to metal contact resulting in noise reduction upon contact with the reaction plate, improved friction between the load cushion <NUM> and the reaction plate <NUM> (shown in <FIG> and <FIG>) to reduce or minimize wear between the bottom plate <NUM> and the reaction plate <NUM> during vehicle motion because relative motion is decreased or eliminated. In addition, encapsulation may be used as a service wear and replacement indicator similar to wear bars found between tire treads.

Load cushion <NUM> may have a continuously increasing spring rate as an applied load increases and a continuously decreasing spring rate as an applied load decreases, due to it generally conic shape.

The top plate <NUM> and base plate <NUM> may be constructed of any of a variety of suitable materials, including, but not limited to, iron, steel, aluminum, plastic, and a composite material. As an example, the base plate can comprise a plate having a thickness between a range of <NUM> inches (<NUM>) to <NUM> inches (<NUM>), or more. The plates can be encapsulated in elastomer and/or bonded to the load cushion portion using a bonding agent. The plate dimensions and shape can be varied to any dimension or shape desired for packaging, weight, and aesthetics. Preferably, the load cushion top plate <NUM> is dimensioned to (i) match the surface of the load cushion mount described herein, such as load cushion mounts <NUM> and <NUM>, (ii) locate mounting holes for securing the load cushion <NUM> to the load cushion mounts <NUM> and <NUM>, and (iii) minimize overall mass.

The size and dimensions of the elastomer used for the cushion portion <NUM> of load cushion <NUM> may be optimized for the vertical spring rate requirements. As noted above, the vertical spring rate for the load cushions <NUM> may continuously increase with increasing load and continuously decreases with decreasing load, defining a curvilinear shape with no discontinuities on a graph illustrating spring rate as a function of sprung load.

Preferably, load cushion portion <NUM> has a generally conic shape as it extends towards a midpoint between top plate <NUM> and bottom plate <NUM>. With this preferred shape, the vertical spring rate for the load cushion <NUM> linearly increases with increasing load and linearly decreases with decreasing load. In this regard, load cushion <NUM> is operable as a progressive spring rate load cushion. In one example, the cross section of load cushion portion <NUM> adjacent top plate <NUM> and adjacent bottom plate <NUM> is <NUM> by <NUM>. At the midpoint between the top plate <NUM> and the bottom plate <NUM> the load cushion portion <NUM> the cross section is <NUM> by <NUM>, and the height of load cushion portion <NUM> is <NUM> not including plates or wear layer encapsulation. Other example dimensions of portions of load cushion <NUM> are also possible. For a given geometry, the spring rate of load cushion <NUM> may be optimized by varying the durometer of the elastomer. By varying the durometer, a family of interchangeable progressive spring rate load cushions can be created.

It will further be appreciated that the load cushion <NUM> may be mounted with the cushion portion <NUM> extending either above or below the bottom plate <NUM>. Likewise, the load cushion <NUM> may be mounted such that the top plate <NUM> extends beneath the bottom plate <NUM>. Therefore, the use of the terms "top" and "bottom" are used simply to describe the plates <NUM> and <NUM> that are attached to the load cushion portion <NUM>, and do not in any way require that the load cushion <NUM> is mounted in any particular configuration.

<FIG> is a cross sectional inboard perspective view of vehicle suspension <NUM> taken along line 21A-21A shown in <FIG>, and <FIG> is a cross sectional inboard perspective view of vehicle suspension <NUM> taken along line 21B-21B shown in <FIG>. Frame attachment portion <NUM> with mounting holes <NUM> is shown extending upwardly from upper surface <NUM> of the saddle with central flange <NUM> and gusset <NUM>. Shock absorber <NUM> is shown mounted to inboard surface <NUM> of the saddle and rebound strap <NUM> is shown extending beneath load cushion mount <NUM>. Bolster springs <NUM> and <NUM> are shown mounted to bolster spring mounts <NUM> and <NUM> on opposite sides of equalizing beam <NUM>. Similarly, bolster springs <NUM> and <NUM> are shown mounted to bolster springs mounts <NUM> and <NUM> on opposite sides of equalizing beam <NUM>. In addition, common fastener 71b is shown directly mounting bolster spring <NUM> to bolster spring <NUM> and common fastener 70b is shown directly mounting bolster spring <NUM> to bolster spring <NUM>.

<FIG> is a cross sectional inboard perspective view of vehicle suspension <NUM> taken along line 22A-22A shown in <FIG>, and <FIG> is a cross sectional outboard perspective view of vehicle suspension <NUM> taken along line 22B-22B shown in <FIG>. Frame attachment portion <NUM> with mounting holes <NUM> is shown extending upwardly from upper surface <NUM> of the saddle with central flange <NUM> and gusset <NUM>. Shock absorber <NUM> is shown mounted to inboard surface <NUM> of the saddle and rebound straps <NUM> are shown extending on opposite sides of load cushion <NUM>. Load cushion <NUM> can be seen positioned directly above reaction plate <NUM>. Load cushion <NUM> is also shown mounted to the load cushion mounts extending from walls <NUM> and <NUM> of the saddle using fasteners 290a.

Spring saddle <NUM> is shown supporting reaction plate <NUM>. Throughhole 70d is positioned in reaction plate <NUM> to allow a fastener to extend therethrough for mounting together the angled flanges of bolster springs <NUM> and <NUM>. Similarly, throughhole 71d is positioned in reaction plate <NUM> to allow a fastener to extend therethrough for mounting together the angled flanges of bolster springs <NUM> and <NUM>.

In addition, equalizing beam <NUM> is shown having a U-shaped cross section with opposed walls 100a and 100b. A tie-bolt <NUM> having a sleeve <NUM> is used to tie the two walls 100a and 100b together. Tie-bolt <NUM> is used to relieve stress in the equalizing beam <NUM> where the bolster springs <NUM>-<NUM> are attached by "pinching" walls 100a and 100b together such that their inner surfaces contact respective end surfaces of sleeve <NUM>.

<FIG> is a cross sectional inboard perspective view of vehicle suspension <NUM> taken along line 23A-23A shown in <FIG>, and <FIG> is an outboard perspective cross sectional view of vehicle suspension <NUM> taken along line 23B-23B shown in <FIG>. Frame attachment portion <NUM> with mounting holes <NUM> is shown extending upwardly from upper surface <NUM> of the saddle with central flange <NUM> and gusset <NUM>. Shock absorber <NUM> is shown mounted to inboard surface <NUM> of the saddle and rebound straps <NUM> are shown extending on opposite sides of load cushion <NUM>. Load cushion <NUM> can be seen positioned directly above reaction plate <NUM>. Load cushion <NUM> is also shown mounted to the load cushion mounts extending from walls <NUM> and <NUM> of the saddle.

<FIG> is a perspective view of the inboard side of equalizing beam <NUM> and <FIG> is a top view of equalizing beam <NUM>. Beam hubs <NUM> and <NUM> are located on opposite ends of the equalizing beam <NUM>. Shock absorber mount <NUM> having mounting hole 106a and shock absorber mount <NUM> having mounting hole 108a are shown positioned on the inboard side of the equalizing beam <NUM>. Bolster spring mounts 107a and 107b extend from opposite sides of the center of equalizing beam <NUM>. On the inboard side, the walls of bolster spring mount 107a include mounting holes 109a and 109b that are used to mount bolster springs <NUM> and <NUM> (shown in <FIG>), and on the outboard side, the walls of bolster spring mount 107b include mounting holes 108b and 108a that are used to mount bolster springs <NUM> and <NUM> (shown in <FIG>).

The equalizing beam <NUM> is shown in an illustrative configuration. However, equalizing beam <NUM> may be constructed in any of a variety of arrangements and with a variety of configurations and/or materials.

<FIG> provides an illustration showing how bolster springs <NUM> and <NUM> may be directly mounted to each other using common fasteners. In particular, flanges <NUM> of bolster springs <NUM> and <NUM> are positioned together as shown, with spring saddle <NUM> extending therebetween, wherein a pair of common fasteners may be used to directly mount the bolster springs <NUM> and <NUM> together. Spring saddle <NUM> may be formed from a pair of bent plates having a thickness of <NUM>, such that the flanges <NUM> are positioned <NUM> apart. In addition, apex angle α is shown between the bottom surfaces of bottom plates <NUM> of bolster springs <NUM> and <NUM>.

<FIG> show various view of bolster spring <NUM>, that may be used in suspension assembly <NUM> described above. Bolster spring <NUM> includes a top plate <NUM> having mounting apertures <NUM> and <NUM>. Bolster spring <NUM> also includes a bottom plate <NUM> having mounting aperture <NUM>. Intermediate plates <NUM>, <NUM>, and <NUM> are positioned between top plate <NUM>. Elastomeric section <NUM> is positioned between bottom plate <NUM> and intermediate plate <NUM>. Elastomeric section <NUM> is positioned between intermediate plate <NUM> and intermediate plate <NUM>. Elastomeric section <NUM> is positioned between intermediate plate <NUM> and intermediate plate <NUM>. Elastomeric section <NUM> is positioned between intermediate plate <NUM> and top plate <NUM>. Elastomeric sections <NUM>, <NUM>, <NUM>, and <NUM> may be constructed in the same manner and with the same materials as described above with respect to bolster spring <NUM>. In addition, top plate <NUM>, bottom plate <NUM>, and intermediate plates <NUM>, <NUM>, and <NUM> may be constructed in the same manner and the same materials as described above with respect to bolster spring <NUM>.

Bottom plate <NUM> includes an extending section <NUM> from which upwardly extending ears <NUM> and <NUM> extend at an angle. A gap <NUM> extends between ears <NUM> and <NUM> to provide additional mounting clearance. Ear <NUM> includes a mounting aperture <NUM> and ear <NUM> includes a mounting aperture <NUM>. Ears <NUM> and <NUM> together constitute an upwardly extending flange. Intermediate plate <NUM> advantageously includes a rearwardly extending flange <NUM> that includes mounting apertures <NUM>, <NUM>, and <NUM> that are adapted for attachment to a tie-bar.

<FIG> is a bottom view of a suspension subassembly including bolster springs 400a and 400b. <FIG> is a perspective view of a suspension subassembly including bolster springs 400a and 400b, shown in <FIG>. <FIG> is another perspective view of a suspension subassembly shown in <FIG> and <FIG>, including bolster springs 400a and 400b.

Bolster springs 400a and 400b are secured to each other with tie-bar <NUM>. In particular bolts 441a and 443a are used to secure tie-bar <NUM> to rearwardly extending flange 440a with nuts 445a and 447a respectively. Similarly, bolts 441b and 443b are used to secure tie-bar <NUM> to rearwardly extending flange 440b with nuts 445b and 447b. Gap <NUM> between ears <NUM> and <NUM> (shown in <FIG>) provides clearance for the bolts to connect with the rearwardly extending flange 440a and 440b, respectively.

It will be appreciated that ears <NUM> and <NUM> of the suspension subassembly shown in <FIG> may be secured to a corresponding suspension subassembly with a common fastener in the same manner as shown in suspension <NUM> and bolster springs <NUM>.

<FIG> show alternate fasteners 443b' and 441b' that may be used to secure tie-bar <NUM> to rearwardly extending mounting flange 440b with nuts 447b and 445b, and also alternate fasteners 441a' and 443a' that may be used to secure tie-bar <NUM> to rearwardly extending mounting flange 440a with nuts 445a and 445b. Fasteners 443b', 441b', 441a', and 443a' differ from fasteners 443b, 441b, 441a, and 443a in that rather than have a nut- shaped head, fasteners 443b', 441b', 441a', and 443a' have a round, low-profile head that is much thinner than the nut-shaped head of fasteners 443b, 441b, 441a, and 443a. As a result, the low-profile head provides for additional clearance to provide for wider articulation angles that may be experienced during operation of a vehicle. The term "low-profile" means that the head has a thickness that is <NUM>% or less than the thickness of a nut shaped head. For example the nut-shaped head on an M12 bolt has a thickness of <NUM>, whereas the low-profile head on an equivalent bolt may have a thickness of <NUM>-<NUM>. The head of fasteners 443b', 441b', 441a', and 443a' is shown as round, although it could other shapes, such as square or hexagonal.

Although not required, fasteners 443b' and 441b' may have a stud that is knurled and which may be advantageously press fit into corresponding holes in rearwardly extending mounting flange 440b and a bottom of the low profile head may be drawn into engagement with surfaces <NUM> and <NUM> respectively of tie-bar <NUM> by tightening a nut onto a threaded end of the stud. Fasteners 441a' and 443b' may be configured in the same manner and press fit into corresponding rearwardly extending mounting flange 440a and drawn into engagement with surfaces of tie-bar <NUM> in the same manner. In other applications, the fasteners 443b', 441b', 441a', and 443a' may not have a knurled surface and may not be press fit into the corresponding mounting holes of rearwardly extending mounting flanges 440b, and 440a.

The current tie-bar setup shown in <FIG>, with its fastener (rearwardly extending flange <NUM>) that bolts two rate plates together is great for articulation levels up to a certain degree. In high severity applications, the bolster twists to the point where the curl plate itself (shown in bolster spring <NUM>) starts to overcome the preload on the bolt, put the bolt in bending, and stress up the curl plates to where expensive material options would be the only fix (without affected packaging).

With the tie-bar forging with the rearwardly extending flange <NUM> shown in <FIG>, the bending stiffness can be tuned in multiple directions so that in severe applications the bar itself stresses up, keeps load out of the bolts, and allows the plates to rotate relative to one another (with the forging bending and/or twisting in between). This increases integrity of the entire joint, as the <NUM> main bolt moves to <NUM> separate bolts, distributing load, and the forging stresses up instead of the rate plates.

This has the added benefit of keeping high strength steel rate plates out of the mold, which are harder to use in processing. The forging doesn't need to go in the mold and can be tuned (material and process/design wise) for different applications of the same bolster.

Claim 1:
A bolster spring (<NUM>) for a vehicle suspension comprising:
a base plate (<NUM>);
a top plate (<NUM>);
elastomeric material (<NUM>, <NUM>, <NUM>, <NUM>) positioned between the base plate (<NUM>) and the top plate (<NUM>);
a first flange (<NUM>) having a bottom mounting surface upwardly extending from a first end of the base plate (<NUM>) at an angle <NUM>/<NUM>α;
wherein
the first flange (<NUM>) comprising a pair of ears (<NUM>, <NUM>); and
one or more mounting holes (<NUM>, <NUM>) positioned in the pair of ears (<NUM>, <NUM>) in the first flange (<NUM>) adapted for attachment to a pair of ears on an upwardly extending flange on a second bolster spring; characterized in that
the one or more mounting holes (<NUM>, <NUM>) on the pair of ears (<NUM>, <NUM>) on the first flange (<NUM>) have a gap positioned therebetween.