Patent Application
20170043638
The present invention is related to a leaf spring, and in particular to a leaf spring with a vibration dampening pad that dampens high frequency vibration generated from a powertrain and transmitted to an interior of a vehicle.
Vehicles such as trucks, trailers, and the like that use leaf springs as part of a suspension system are known. In addition, some of these vehicles have a powertrain that includes a transmission, differential, etc. that affords for power generated by an internal combustion engine to be transmitted to wheels of the vehicle such that the vehicle can move along a surface. Such powertrains typically include a plurality of gears, belts, and the like, which upon operation of the vehicle can result in the generation of vibration. In addition, since the drivetrain is typically mechanically coupled to the remainder of the vehicle, the vibration can be transmitted to other components thereof such as a frame of the vehicle and an interior compartment of the vehicle.
One example of a powertrain vibration can occur when a pickup truck is driving along a highway at speeds such as 40 miles per hour, 50 miles per hour, 60 miles per hour, etc. In addition, the vibration can be a high frequency vibration that is transmitted through one or more axles of the pickup truck, one or more leaf springs that couple the axle to a frame of the pickup truck, to the frame, and then into an interior, sometimes known as a cab. Furthermore, the high frequency vibration can be present at a volume such that an occupant of the pickup truck can hear a high pitch noise or tone. Therefore, a leaf spring that affords for the dampening of the high pitch noise to a level such that the occupant no longer hears this high pitch tone would be desirable.
A leaf spring for a vehicle is provided. The vehicle can have a drivetrain, also known as a powertrain, that generates a high frequency vibration that is transmitted into an interior compartment of the vehicle. In addition, the high frequency vibration has a volume that is objectionable to an occupant during operation of the vehicle.
The vehicle has a leaf spring that couples an axle of the drivetrain to a frame of the vehicle. The leaf spring has a primary leaf and a secondary leaf that extends along and underneath the primary leaf. The primary leaf and the secondary leaf are mechanically coupled to the axle of the vehicle at a generally central location of the leaf spring.
The leaf spring also includes a tip liner insert that is spaced apart from the central location of the leaf spring and is located between the primary leaf and the secondary leaf. The tip liner insert can be present in order to reduce friction between the primary leaf and the secondary leaf during operation of the vehicle. A high frequency dampener is also included and is spaced apart from the tip liner insert and located between the primary leaf and the secondary leaf. In addition, the tip liner insert is located between the high frequency dampener and the center location of the leaf spring. Stated differently, the high frequency dampener is located outwardly from the tip liner insert. Furthermore, the high frequency dampener reduces the volume of the high frequency vibration that is present in the interior to a level that is not objectionable and/or noticeable to the occupant during operation of the vehicle.
The primary leaf and the secondary leaf each have a front end and a rear end that face a front and a rear of the vehicle, respectively. In addition, the high frequency dampener is located between the primary leaf and secondary leaf front ends and the tip liner insert. The high frequency dampener can be attached to the secondary leaf and not be attached to the primary leaf. The high frequency dampener can be attached to the secondary leaf with a fastener such as a threaded fastener, an adhesive, a snap fastener, an interference fit type of fastener, a hook-and-loop fastener, etc. In some instances, the fastener is a snap fastener with a shaft and the secondary leaf has an aperture therethrough that is dimensioned for the shaft to slide therethrough. In this manner, a leaf spring that dampens or isolates high frequency vibration from a powertrain of the vehicle such that it is not heard by an occupant within an interior of the vehicle is provided.
A leaf spring for a vehicle is provided. The leaf spring affords for dampening of a high frequency vibration that is produced by a drivetrain and transmitted into an interior of the vehicle. In some instances, the leaf spring dampens the high frequency vibration using a high frequency dampener that is located between a pair of leafs of the leaf spring and spaced outwardly from a tip liner insert that is also located between the pair of leafs.
A measure, i.e. a volume, of the high frequency vibration within the interior of the vehicle without the use of the inventive leaf spring disclose herein is greater than an objectionable level for an occupant and thus can be heard by a driver or passenger riding in the vehicle. However, the inventive leaf spring reduces the high frequency vibration volume to less than the objectionable level through the use of the high frequency dampener. In this manner, the high frequency vibration volume is reduced to a level such that it is not heard by an occupant at an ‘occupant ear level’ within the interior of the vehicle. In addition, the inventive leaf spring reduces a volume of the high frequency vibration instead of shifting the frequency.
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With respect to
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The primary leaf 150, secondary leaf 160, and optional third leaf 170 can be held together and maintained in a proper position using a spring clip 156 as is known to those skilled in the art. In addition, the primary leaf 150 and secondary leaf 160 can be maintained in a proper position using a spring clip 158. It is appreciated that the spring clips assist the primary leaf in absorbing rebound vibrations from the other leafs and also prevent spreading or “fanning out” of the leafs. It is also appreciated that the leaf spring 15 has a central location 16 that is attached to the axle 212 using an axle plate 180 and one or more U-bolts 182 as is known to those skilled in the art.
Extending along and below the primary leaf 150 is the secondary leaf 160 which has a top surface 161 and a bottom surface 163. The front end 162 can have a curvature and thus serve as a military wrap as is known to those skilled in the art. The secondary leaf 160 can have an aperture 166 which affords for a shaft 192 of the tip liner insert 190 to fit therewithin. The tip liner insert 190 has a top surface 191 and a bottom surface 193 which afford for sliding movement between the primary leaf 150 and the secondary leaf 160 during operation of the leaf spring 15. The secondary leaf 160 can also have an aperture 168 which is dimensioned for a shaft 198 of the high frequency dampener 196 to slide therethrough. The high frequency dampener 196 has a top surface 197 and a bottom surface 199. However, and unlike the tip liner insert 190, the high frequency dampener 196 dampens or reduces a volume of a high frequency vibration generated from the drivetrain 200, transmitted through the leaf spring 15, to the frame 100, and into the interior 230 of the vehicle.
A distance ‘d’ between the aperture 166 for the tip liner insert shaft 192 and the aperture 168 for the high frequency dampener shaft 198 is a predefined distance and is shown for illustrative purposes only in
In one aspect disclosed herein, the high frequency dampener 196 is located outwardly from the tip liner insert 190, i.e. the high frequency dampener 196 is located further away from the axle pad 180 and/or one or more U-bolts 182 than the tip liner insert 190. Stated differently, the high frequency dampener 196 is located between the front end 152 of the primary leaf and the tip liner insert 190 and/or between the front end 162 of the secondary leaf and the tip liner insert 190. It is appreciated that the high frequency dampener 196 is attached to the secondary leaf 160 but is not attached to the primary leaf 150.
A comparison of high frequency vibration volumes for a vehicle with leaf springs that do have and do not have a high frequency dampener is shown in
The solid line labeled “Baseline” illustrates the volume of the high frequency vibration that was determined and recorded at an occupant ear level within an interior of the truck. The dotted line labeled “Adhesive-Type HFD” illustrates the volume of the high frequency vibration using a high frequency dampener according to one aspect disclosed herein. The other dotted line labeled “Tab-Type HFD” illustrates a volume for the high frequency vibration using a high frequency dampener according to another aspect disclosed herein. As shown in
It is appreciated that the high frequency dampener 196 can be made from any material known to those skilled in the art, illustratively including a polymer material and in some instances an oil-impregnated polymer material. As such, a simple, robust, and economically feasible solution to dampening high frequency vibration generated from a drivetrain of a motor vehicle is provided.
The above examples, aspects, embodiments, etc. are for illustrative purposes only and not intended to limit the scope of the invention in any way. Changes, modifications, etc. will occur to those skilled in the art and yet still fall within the scope of the invention disclosed herein. As such, it is the claims, and all equivalents thereof, which define the scope of the invention.
