Multiple trailing arm suspension

This application relates to a suspension for an axle wherein a plurality of arms are pivotally connected to a vehicle frame, and rigidly connected to the axle.

Heavy vehicles, such as trucks, typically have an axle extending between opposed wheels, and connected to a vehicle frame through a suspension. The suspension must provide support between the axle and the vehicle, and must withstand a large number of forces.

One challenge with the design of modern heavy vehicle suspensions is that the brake torques on the axles are increasing. Federal regulations may be imposed which mandate increased brake torques to improve stopping distances. With this increase in brake torque on the axles, the suspensions that are utilized to mount the axles will need to be compatible with the higher brake torques. Current suspension design may not perform ideally during moderate to heavy braking efforts of a larger vehicle brake. A known suspension design, referred to as a “multi-link,” may be able to better withstand the higher braking forces. This design includes a number of links pivotally connected to both the axle and the vehicle frame. However, these pivotal connections increase the cost of the associated suspension due to additional bushings and connection points that are required. Further, this multi-link system is typically an air suspension that adds complexity, and which has additional cost associated with air springs and related connecting components.

The proposed solution utilizes a pair of trailing suspension arms that are pivotally attached to one of a frame and an axle, but rigidly attached to the other. This provides a simple and low cost trailing arm design, but also adds the benefits of the multi-link design in terms of brake torque reaction. In a disclosed embodiment, two arms are used on each side of the axle. The four arms are preferably utilized on the front axle, where the increased brake torque will be centered. The four front arms also provide good lateral stiffness for performance handling. The arms are preferably spring steel, and can be made thick enough that the suspension is purely mechanical. Alternatively, the arms may be reduced in section and supplemented with an air spring to achieve a desired ride performance.

In various features of a disclosed embodiment, the arms are rigidly attached to the axle, with one link is placed on a vertically upper surface, and the other is placed on a vertically lower surface of the axle. Mounting structure for rigidly securing the arms to the axle include mounting plates that can also provide connection points for various components such as a lateral support rod, and/or a shock absorber.

In another embodiment, the arms are rigidly attached to the frame, and pivotally attached to the axle.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

FIG. 1 shows a first embodiment of the present invention.

FIG. 2 shows a second embodiment of the present invention.

FIG. 3 shows a third embodiment of the present invention.

FIG. 4 shows a fourth embodiment of the present invention.

FIG. 5A shows a fifth embodiment of the present invention.

FIG. 5B shows another feature of the FIG. 5A embodiment.

A first embodiment 20 of an inventive suspension is illustrated in FIG. 1 . The suspension connects an axle 22 , which may be a front axle for a heavy vehicle, to a vehicle frame 24 . Plural trailing arms 26 and 28 are pivotally connected at 30 to the frame 24 at each lateral side. In fact, in the illustrations, frame brackets mount the arms 26 and 28 to the vehicle frame. For purposes of this application, the term “frame” would extend not only to the vehicle frame, but also to such brackets. Also, while a simple pin is shown as the pivot mount between the frame and the arms, other types of pivot arrangements such as the type known as a “bar pin” or bolted structures may be utilized. These aspects are known in the suspension art, and do not form a portion of this invention.

Arms 26 and 28 can be spring steel elements. A front end 32 of the arms 26 and 28 extends rearwardly to rear ends 34 that are rigidly mounted to the axle 22 .

In this embodiment, separate plates 38 receive bolts 36 and nuts 40 to rigidly secure the rear ends 34 on each vertical side of the axle 22 . The present invention thus achieves the ability to withstand higher braking forces due to the two separate arms 26 and 28 . However, the complexity of the prior art multi-link design, including the bushings and connections at the pivot point, is reduced. By sizing the arms 26 and 28 to be larger, they can provide all of the required suspension. As will be seen, additional suspension elements can also be incorporated, if necessary.

While the arms 26 and 28 are shown mounted on opposed vertical sides of the axle 22 , in fact, the arms could be fixed to the axle at a location vertically aligned with a side surface of the axle. In such an arrangement, the arms would have a bent end which could then be secured to the axle.

FIG. 2 shows a second embodiment 50 , which is similar to the first embodiment, other than u-bolts 52 that replace the separate bolts 36 . With this embodiment, mounting plates are not required at a lower end of the connection.

FIG. 3 shows an embodiment 60 , which is similar to the first two embodiments, however a mount structure 64 is formed on an upper mount plate 66 . The mount structure 66 mounts a lateral support rod 62 extending toward an opposed side of the vehicle, and an opposed suspension 60 .

FIG. 4 shows an embodiment 80 wherein the mounting plate 81 includes the mount structure 64 for the lateral support rod, and also a mount location 84 to receive a shock absorber 82 , shown schematically.

As further shown in FIG. 4 , an air spring mount structure 50 is illustrated in phantom. Holes 52 in the plate 81 provide a mount location for securing the air spring support 50 to the body of axle 22 . Alternatively, the air spring support 50 could be formed integrally with the axle 22 .

As shown in FIG. 5A , another embodiment 200 has an axle 202 connected to a frame 204 by arms 206 and 208 . Arms 206 and 208 are rigidly attached to the frame 204 by bolts 210 . The arms 206 and 208 are pivotally attached at 214 to a bracket 216 which is in turn welded to the axle 202 . Bars 214 pin ends of the arms 206 and 208 .

As shown in FIG. 5B , the frame 204 has a slot 220 to rigidly receive the arms 206 and 208 . A spacer 222 may be positioned between the arms 206 and 208 , and bolts 210 are tightened to secure the arms within the slot 220 .

While the present invention is disclosed and illustrated as a trailing arm suspension, the benefits of this invention would extend fully to a leading arm suspension.

As mentioned, by designing the size of the arms 26 and 28 , and by including additional suspension elements, the present invention tailors a suspension that is able to withstand the higher braking forces which are expected to be seen by heavy vehicles, and in particular the front axles. On the other hand, the prior art concern of having numerous additional mount connections is eliminated.

Although preferred embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.