Patent Application
20120211963
The present invention is related to a leaf spring assembly, and in particular, to an adjustable leaf spring assembly having a leaf spring in combination with a movable block that is attached to a frame.
Leaf springs are used in suspension systems for motor vehicles such as small utility vehicles, trucks, and the like. A pair of leaf springs can support a vehicle frame over an axle and absorb at least part of the vibrations experienced by the axle during traveling over rough roads. In addition, the leaf springs can provide a cost-effective suspension for vehicles carrying heavy loads.
Leaf springs generally have a linear load deflection curve or spring rate and as such are not adjustable when the vehicle is subjected to different road conditions, cargo weights, and the like. As such, a leaf spring suspension system can result in less than desired driver comfort when conditions such as road conditions and cargo weight fall outside of a range(s) used to “set up” the suspension system. Therefore, a suspension apparatus or system that uses leaf springs and affords adjustment of a leaf spring spring rate would be desirable.
The present invention provides a suspension apparatus having a primary leaf spring and a secondary leaf spring. The primary leaf spring has a pair of spaced-apart ends that are attached to a frame and the secondary leaf spring has a pair of spaced-apart ends that are unattached to the frame. In addition, the secondary leaf spring is located between the primary leaf spring and the frame. A movable block is also included and can be attached to the frame and be located proximate to one of the pair of unattached ends of the secondary leaf spring. The movable block is operable to be moved closer to and further away from the proximate unattached end and thereby change a spring rate of the secondary spring after a load has been applied to the frame and the secondary leaf spring has contacted the movable block. Stated differently, the movable block can have a first position and a second position that afford for the secondary leaf spring to have a first spring rate and a second spring rate, respectively.
In some instances, the movable block can be bolted to the frame using one or more of a plurality of apertures within the frame, the plurality of apertures located such that the movable block can be bolted to the frame at the first position and the second position. In other instances, a rotatable cam can be included and be in contact with the movable block, the rotatable cam operable to rotate and move the movable block closer to and further away from the one proximate unattached end of the secondary spring. In still other instances, a mechanical screw in contact with the movable block can be included, the mechanical screw operable to rotate and move the movable block closer to and further away from the one proximate unattached end of the secondary spring. In still yet another instance, an air bladder in contact with or part of the movable block can be included, the air bladder operable to expand, contract, and move the movable block closer to and further away from the one proximate unattached end of the secondary leaf spring.
The suspension apparatus can include a stationary block that is attached to the frame and is proximate to another of the pair of spaced-apart unattached ends of the secondary leaf spring. In the alternative, the movable block can be a first movable block and a second movable block proximate to the another spaced-apart unattached end of the secondary spring can be included. It is appreciated that the second movable block is operable to be moved closer to and further away from the another unattached end and thus change the spring rate of the secondary spring after the load has been applied to the frame and the secondary leaf spring has contacted the first movable block and the second movable block.
A process for changing a spring rate for a suspension apparatus is also included, the process including providing a suspension apparatus as described above and then providing a load onto the frame. The load compresses the primary leaf spring until the movable block contacts the proximate unattached end of the secondary leaf spring, the secondary leaf spring having a first spring rate when the movable block is in the first position and a second spring rate when the movable block is in the second position.
The present invention provides a suspension apparatus that includes a leaf spring assembly for a motor vehicle. As such, the present invention has utility as a component for a motor vehicle.
The suspension apparatus can include a primary leaf spring and a secondary leaf spring. The primary leaf spring has a pair of spaced-apart ends that are attached to a frame as is known to those skilled in the art. The secondary leaf spring can be located between the primary leaf spring and the frame and also have a pair of spaced-apart unattached ends. Attached to the frame and proximate to one of the unattached ends of the secondary leaf spring can be a movable block that is operable to move towards or away from the one unattached end. The movable block can be movably attached to the frame using any number of attachment mechanisms that afford for the block to be located in a first position and a second position, for example and for illustrative purposes only, a bolt and aperture attachment mechanism, a rotatable cam mechanism, a mechanical screw mechanism, an air bladder mechanism, and the like.
Upon applying a load onto the frame, the primary spring can compress such that the one unattached end of the secondary leaf spring approaches and comes into contact with the movable block. When the movable block is in the first position, the secondary leaf spring can have a first spring rate and when the movable block is in the second position, the secondary spring can have a second spring rate. In this manner, a user of the suspension apparatus can alter the spring rate of the secondary leaf spring, and the spring rate of an overall suspension system, in order to provide improved performance, comfort, and the like.
Turning now to the figures,
A pair of blocks B can be fixedly attached to the frame F and located proximate to the first end 210 and the second end 220. Upon application of a load upon the frame F, the primary leaf spring 100 can be compressed in such a manner that the secondary leaf spring 200 moves toward the blocks B, and if the load is large or great enough, the first end 210 and the second end 220 can come into contact with the blocks B. As such, the frame F can accommodate normal or light loads using just the primary leaf spring 100, but incorporate the use of the secondary leaf spring 200 when heavier loads are applied to the frame.
Referring now to
The movable block 250 can have a spring surface 252 that can come into contact with the first end 210 or the second end 220 depending on the location of the block 250 and the amount of load applied to the frame F. In addition, with the movable block 250 operable to be attached to the frame F at a position that is either closer to or further away from the unattached end of the secondary leaf spring 200, the amount of load required to engage the secondary spring 200 can be altered. It is appreciated that by moving the blocks 250 closer to and further away from the first end 210 and/or the second end 220, the spring rate of the secondary spring 200 for a given load applied to the frame F can be changed.
Referring now to
Referring now to
A process for changing the spring rate of the secondary leaf spring 200 can include providing the frame F and one or more of the embodiments shown in
It is appreciated that the primary leaf spring 100 and the secondary leaf spring 200 can be attached to an axle 300, for example using a U-shaped threaded fastener 310, a bolt 312, and a fastening plate 320. It is also appreciated that other attachment mechanisms can be used to attach the primary leaf spring 100 and the secondary leaf spring 200 to the frame F and/or to another load-bearing component such as the axle 300. In addition, the leaf spring assembly does not have to be part of a motor vehicle and can be used as part of any machine, apparatus, etc. that is subjected to a load and vibration force(s).
The frame, leaf springs and blocks can be made from any material known to those skilled in the art that provide desired mechanical properties for such components, illustratively including metals, alloys, plastics, elastomers, ceramics and the like. The invention is not restricted to the illustrative embodiments described above and the embodiments are not intended as limitations on the scope of the invention. Methods, processes, apparatus, compositions, and the like described herein are exemplary and not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art. As such, the scope of the invention is defined by the scope of the claims.
