Patent Application
20110266764
1. Technical Field
The invention relates to suspension systems for vehicles, such as trailers and trucks. More particularly, the invention relates to a suspension assembly having an air spring. Even more particularly, the invention relates to a more compact air spring suspension assembly with the air spring located between frame rails of a vehicle to provide a lower center of gravity than traditional suspension systems.
2. Background Information
Truck or trailer suspension systems should be as safe, durable, and as economical as possible. Often these characteristics conflict and compete, thus necessitating a compromise of one characteristic against another characteristic, which often results in a suspension system being less than ideal. For example, safety considerations dictate that the suspension be sufficiently rigid in its various planes to maintain the vehicle's line of travel. However, safety also necessitates that the suspension be sufficiently flexible or resilient to allow (i.e. take up) deflections caused by articulation forces experienced during operation of the vehicle. Durability includes the ability to resist degeneration (damage) which occurs from the deflections. Durability conflicts with economical cost involved in achieving safety and durability.
One type of suspension, the trailing arm suspension, has a variety of undesirable characteristics. For example, trailing arm suspensions are brake reactive. That is, when a vehicle's brakes are applied, the suspension will tend to compress thereby reducing the suspension's effectiveness. Similarly, when the brakes are applied as the vehicle moves in reverse, the suspension will tend to rise up, and pivot about the single trailing arm pivot, again reducing the suspension's effectiveness. Further, most trailing arm suspensions suffer from dock walk because they move toward or away from the loading dock as the suspension moves up or down with the brakes locked. This movement is caused from air draining off the air springs, or as a result of loads added to or removed from the vehicle, or the temperature changes that occur as the trailer remains parked by the dock. Dock walk occurs primarily because of rotation of the beam, axle and tire assembly when the brakes are locked. As the suspension travels vertically with the brakes locked it rotates the tires causing the tires to move the vehicle horizontally. If the trailer is positioned adjacent a dock, it causes the trailer to move toward or away from the dock as a result of the movement or rotation about the single pivot point. Therefore, a better suspension system is needed.
One or more preferred embodiments that illustrate the best mode(s) are set forth in the drawings and in the following description. The appended claims particularly and distinctly point out and set forth the invention. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various example methods, and other example embodiments of various aspects of the invention. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. One of ordinary skill in the art will appreciate that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements may not be drawn to scale.
The same reference numbers in different drawings refer to the same component.
In
The trailer 2 has a front 10 and a back 11 (
A pair of the improved suspension assemblies is mounted to a respective frame rail 4 generally adjacent a wheel 6. Notice that a significant portion of the suspension assembly 1 is located adjacent to and generally between top surface 51 and bottom surface 52 of a frame rail 4. In contrast to earlier suspension assemblies, a signification portion of the preferred embodiment of the suspension assembly 1 is above the bottom surface 52 of the frame rail 4, as shown in
The preferred embodiment of the suspension assembly 5 as best shown in
In the preferred embodiment, the suspension assembly 5 is rigidly attached to the trailer 2 by bolting and/or welding the support beam 31 to the frame rails 4. The frame mount assembly 7 can be attached to the trailer 2 by other ways as understood by those of ordinary skill in the art. In the preferred embodiment, the support beam 31 is a generally square piece of steel with four flat surfaces; however, the support beam 31 can be round or other shapes in alternative embodiments. The support beam 31 is hollowed steel (not solid) in the preferred embodiment. However, in other embodiments the support beam 31 may be made of solid steel or other materials or filled with other materials. When the support beam 31 is of sufficient strength, it unifies independent suspension assemblies 5 and does not rely on the trailer frame for bending strength. Because the support beam 31 is attached to the frame rail 4 it does not travel up and down with the wheel 6 as do traditional axles.
The air spring housing 30 is preferably, generally box shaped with a flat horizontal tope wall having a top 33, a slanted back wall 36 and two side walls 34. These walls help define an air spring mounting chamber 35. The air spring housing 30 and air spring mounting chamber 35 are generally between the top surface 51 and the bottom surface 52 of the frame rail 4. The two side walls 34 straddle and are in contact with the upper surface 50 and a second side surface 53 of the support beam 31 and may be welded to these two surfaces of the support beam 31 at these contacts. The slanted back wall 36 may contact the support beam 31 at a bottom edge wall 36 and may be welded to the support beam 31 at this contact. The components used to form the frame mount assembly 7 are metal and of sufficient thickness so that the suspension assembly 5 is sufficiently rigid and durable.
First pivot mount 40 and second pivot mount 41 are formed on an upper surface 50 of the support beam 31. The pivot mounts 40, 41 are rigidly secured to beam 31 and are formed to allow the swing arm assembly 17 to pivot about a swing arm assembly pivot axis 100 that is above the bottom surface 52 of the frame rail 4 as shown in
The second pivot mount 41 is best seen in
The swing arm assembly 17 includes a rigid swing arm 19, a rigid swing arm beam 20, a rigid air spring support 18 and a rigid spindle arm 21. These components are each fabricated out of one or more pieces of metal so that when they are assembled, the swing arm assembly 17 is sturdy and rigid. When the swing arm assembly 17 is pivotally attached to the frame mount assembly 7, the suspension assembly 5 is durable and able to support the weight of a fully loaded trailer 2.
In the preferred embodiment, the swing arm 19 may be fabricated with a first side wall 60 a second side wall 61, a top wall 64, a bottom wall 65 (not shown) and the cylindrical member 66. As shown in
In the preferred embodiment, the air spring support 18 is formed and mounted to the swing arm beam 20. The air spring support 18 is formed with a first side 67, a second side 68, and a top 69. The first and second sides 67, 68 and the top 69 may be formed by bending a piece of metal to form these components or by welding separate pieces to form these components. The first and second sides 67, 68 may have rounded ends that may be the same diameter as the swing arm beam 20. The air spring support 18 is securely attached to the swing arm beam 20 by welding or attached in another way.
A spindle arm 21 is attached to the swing arm assembly 17 at an end of the swing arm beam 20 that is axially spaced from and opposite the swing arm 19. The spindle arm 21 is formed with a first opening 74 and a second opening 78. The first and second openings 74, 78 may be round openings. The swing arm beam 20 may be projected at least partially through the first opening 74 and may be rigidly secured to the spindle arm 21 in this position. An end cap may be fastened to the end to the swing arm beam 20 to close an open area of the swing arm beam 20 when the beam is hollow as shown in
The spindle arm 21 shown in
As previously mentioned, the swing arm assembly 17 is pivotally mounted to the first pivot mount 40 and the second pivot mount 41 to rotate about the swing arm assembly pivot axis 100. The swing arm assembly 17 is pivotally mounted by passing bolts 45 through the first assembled bushing 48 and the second assembled bushing 63 in the air spring assembly 17 and securing nuts 46 to the bolts. One or more nuts 46 and one or more washers may be used to secure the swing arm assembly 17 to the frame mount assembly 7. The assembled bushings 48, 63 can be elastomeric bushings or other suitable bushings.
An air spring 57 is secured at its lower end to the air spring mount 18 by a plurality of bolts 70 (
The air spring 57 is of a usual well-known construction having a flexible outer sleeve forming an internal air chamber. The air spring 57 is shown as a double convolute air spring, but could have a single convolute or more than two convolutes. Furthermore, the air spring 57 can use various types of internal fluid for its operation, although air is the preferred fluid which is supplied to the internal fluid chamber from a compressor (not shown) usually mounted within the tractor or trailer 2 and connected to a coupling by an air supply line 95.
The manner of operation of the suspension assembly 5 is best shown in
Rebound results when energy stored in the air spring 57 as a result of a tire rolling over a bump, etc., begins to push the air spring 57 away from the compressed jounce position. Rebound may also occur when the tire falls into a pothole. During rebound, the air springs in the suspension system 1 try to return to their original heights but due to inertia in the system may travel beyond into a position which extends them to their rebound limit as generally illustrated in
After a force is encountered, eventually the force is dissipated over time throughout the suspension assemblies 5 of the trailer 2. After the force has been dissipated and there are no forces other than the weight of the trailer acting on the suspension assembly 5, the suspension assembly 5 will return to a steady state design position as shown in
The reduced length between the swing arm assembly pivot axis 100 and the spindle axis 101 will provide for a lower torque at the swing arm assembly pivot axis 100. Lowering this torque lowers stresses placed on the various components of the suspension assembly 5 as compared to prior art suspension assemblies. Lighter materials can be used to form the suspension assembly 5 because the stresses are reduced. Also, because the stresses are reduced, the chance of breakage or failure of the suspension system 5 is reduced.
The suspension assemblies 5 of the trailer 2 operate independent of one another. The independent suspension assemblies provide desired trailer stability by absorbing the various twisting and up and down or side to side movement exerted on the trailer wheels 6. The independent side-to-side absorption or compliance of the suspension assemblies 5 provides roll control for stability and diagonal compliance to allow the suspension assemblies 5 to function on uneven terrain. This allows the suspension assemblies 5 to travel over one wheel bumps or encounter diagonal bumps.
The suspension system 1 provides considerable advantages over prior art suspension systems because the length between the swing arm assembly pivot axis 100 and the spindle axis 101 is reduced. This allows the length of the swing arm assembly 17 to be reduced and allows and the air spring 57 to be positioned closer to the swing arm assembly pivot axis 100 than the prior art. When the air spring 57 is at position away from the pivot axis 100 as shown in
Example methods may be better appreciated with reference to flow diagrams. While for purposes of simplicity of explanation, the illustrated methodologies are shown and described as a series of blocks, it is to be appreciated that the methodologies are not limited by the order of the blocks, as some blocks can occur in different orders and/or concurrently with other blocks from that shown and described. Moreover, less than all the illustrated blocks may be required to implement an example methodology. Blocks may be combined or separated into multiple components. Furthermore, additional and/or alternative methodologies can employ additional, not illustrated blocks.
The method 1200 begins by producing a frame mount assembly, at 1202. The frame mount assembly is adapted for mounting a suspension assembly to a trailer or another vehicle. A swing arm assembly is produced, at 1204. The swing arm may be generally U-shaped. Two arms of the U-shaped swing arm are adapted to be pivotally attached to the frame mount assembly at a suspension pivot axis that passes through two arms forming the U-shape. The pivot axis is near the end of each of the two arms. When the suspension assembly is mounted to a trailer, the pivot axis is located above a bottom surface of a rail of the trailer. The two arms are on opposite sides of the rail when the suspension assembly is mounted to the trailer.
In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Therefore, the invention is not limited to the specific details, the representative embodiments, and illustrative examples shown and described. Thus, this application is intended to embrace alterations, modifications, and variations that fall within the scope of the appended claims.
Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. References to “the preferred embodiment”, “an embodiment”, “one example”, “an example”, and so on, indicate that the embodiment(s) or example(s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element or limitation. Furthermore, repeated use of the phrase “in the preferred embodiment” does not necessarily refer to the same embodiment, though it may.
