Land vehicles – Wheeled – Running gear
Reexamination Certificate
2002-06-17
2004-05-25
Ark, Darren W. (Department: 3643)
Land vehicles
Wheeled
Running gear
Reexamination Certificate
active
06739608
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a suspension system of a vehicle. A suspension system of a vehicle being considered, for the purposes of this disclosure, to be a group of components engaged to and supported by either the ground or one or more support structure(s) and also engaged to and supporting one or more suspended structure(s). Additionally, a suspension system of a vehicle comprises one or more spring(s) that support the weight of the suspended structure(s) engaged to the suspension system. The spring(s) of a suspension system of a vehicle support the weight of the one or more suspended structure(s) that are engaged to the suspension system in a cushioned manner by flexing and allowing the suspended structure to move relative to the support structure(s) or ground, which support the suspension system, when the vertical accelerations of the suspended structure and/or the support structure change and/or when the loading of the suspended structure is changed. For instance, when a load is dropped upon the suspended structure or when a vehicle in motion travels over uneven terrain, the springs of the suspension system flex and transmit forces between the suspended structure and the support structure or ground that are much less than the impact forces that would be transmitted between the suspended structure and the support structure or the ground if the suspended structure were supported by components of greater stiffness than the springs of the suspension system. By supporting the suspended structure in such a cushioned manner, the springs of a suspension system of a vehicle provide for more gentle support of the suspended structure and occupants or cargo supported thereby. Such gentle support can result in longer life of the suspended structure, decreased incidence of damage to cargo supported by the suspended structure, and increased comfort for occupants supported by the suspended structure.
Known suspension systems of vehicles utilize a number of different types of springs to support the weight of suspended structures. One common type of spring that is used in known suspension systems of vehicles to support the weight of suspended structures is a leaf spring. Leaf springs are elongated members that are used as a flexible beam to support the weight of a suspended structure. Each leaf spring of a suspension system of a vehicle has a plurality of mounting portions one or more of which is/are support mounting-portions that are engaged directly or indirectly to and directly or indirectly support at least a part of the weight of the suspended structure. One or more of the mounting portions of each of the leaf springs is/are supported mounting-portion(s) that is/are disposed at points distant from the one or more support mounting-portion(s) and that is/are engaged directly or indirectly to and are directly or indirectly supported by spring-support components. The spring-support components that a supported mounting-portion of a spring of a suspension system may be part of the support structure that supports the suspension system or may be part of the suspension system itself. The portions of each leaf spring that are disposed between each support mounting-portion and each supported mounting-portion function as a beam to support the loads applied at the support mounting-portion. When the loads at each support mounting-portion change, the magnitude of the bending of the portion of the leaf spring between that support mounting-portion and the nearest supported mounting-portion changes in proportion to the change in the load at the support mounting-portion. Leaf springs can be used in a suspension system of a vehicle to provide a simple, cost-effective, and easy to design suspension system as compared to suspension systems that include only springs of types other than leaf springs for supporting the weight of the suspended structure. A suspension system of a vehicle with leaf springs can provide such benefits because many designs of leaf springs are strong enough in all directions perpendicular to their longitudinal axis and also along their longitudinal axis to provide full location of the suspended structure they support without assistance from other structural components acting in parallel to them. In other words, in addition to providing full support for the suspended structure in vertical directions, leaf springs of a suspension system of a vehicle are capable of providing full support for the suspended structure in lateral and longitudinal directions. The use of only leaf springs in a vehicle's suspension system to support the weight of the suspended structure does, however, have disadvantages as compared to the use of other types of springs for supporting the weight of the suspended structure. Leaf springs generally have greater weight than other types of springs with equivalent weight carrying capabilities. Due to a combination of factors which include weight carrying requirements, limitations in the length of leaf springs due to space constraints on a vehicle, and fatigue strength of the leaf springs, the use of leaf springs as opposed to other types of springs in a vehicle suspension system often requires greater spring rates of the leaf springs than would be necessary for other types of springs if employed. The greater spring rates that are often necessitated in a suspension system of a vehicle as a result of the use of leaf springs in lieu of other types of springs can result in a harsher ride for the occupants and cargo of the vehicle and reduced life of the suspended structure supported by the leaf springs. Additionally, many known designs of suspension systems of vehicles include leaf-spring packs, which include multiple leaf springs stacked upon one another to provide the requisite load carrying ability. One disadvantage of the use of such leaf-spring packs is that friction between each of the leaf springs and those positioned above and below it causes hysteresis in the reaction of the leaf-spring pack to changing loads. The hysteresis in leaf-spring packs results in the same negative consequences for suspension systems that utilize them as those negative consequences associated with increased spring rates.
Another type of spring that it is known to employ in suspension systems of vehicles to support suspended structures thereof is a pneumatic spring. Pneumatic springs comprise an expandable and contractable gas-compression chamber within which a gas, which is usually simply air, is compressed when the gas-compression chamber is contracted and within which the gas is expanded when the gas-compression chamber is expanded. Like leaf springs, pneumatic springs have two or more mounting portions. One or more of the mounting portions of a pneumatic spring of a suspension system of a vehicle is/are supported mounting-portions that are engaged directly or indirectly to and are supported directly or indirectly by spring-support components which may be components of the support structure that supports the suspension system or components of the suspension system itself. One or more of the mounting portions of a pneumatic spring of a suspension system of a vehicle is/are support mounting-portions that are engaged directly or indirectly to and support directly or indirectly the suspended structure that is supported by the suspension system. Gas pressure of the gas in the gas-compression chamber of a pneumatic spring directly or indirectly supports the support mounting-portions of the pneumatic spring. The components of a pneumatic spring that define its gas-compression chamber automatically move and/or elastically deform to positions and/or shapes that effect a volume of the gas-compression chamber at which the gas contained therein has a pressure that will just support the load applied to the support mounting-portion of the pneumatic spring. Pneumatic springs have little or no hysteresis, especially as compared to leaf-spring packs. Due to the relatively low hysteresis of pneumatic springs, the use of pneumatic springs in a suspension system of
Korson James
Warinner Derek K.
Ark Darren W.
Calfa Jeffrey P.
International Truck Intellectual Property Company, LLC
Lukasik Susan L.
Sullivan Dennis Kelly
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