US 6,149,142 AGranted

Pneumatic vehicle suspension system with variable spring stiffness

AssigneePACCAR Inc

InventorRoger P. Penzotti

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Abstract

A pneumatic suspension system for a vehicle providing minimum pneumatic spring stiffness to minimize frame beaming in the vehicle frame. In one embodiment of the invention, the pneumatic suspension system has a first pneumatic spring connected to a first axle and to the frame. A second pneumatic spring is connected to the second axle and to the frame. The first and second pneumatic springs contain pneumatic fluid. A conduit containing pneumatic fluid is in fluid communication with the first and second pneumatic springs. The conduit allows the fluid to move between the first and second pneumatic springs. The pneumatic fluid in the conduit has a fluid resonant frequency. The first and second pneumatic springs and the conduit define a system having a variable stiffness dependent upon an input vibration frequency. The input vibration frequency is a predetermined fraction of the fluid resonant frequency. The pneumatic conduit is sized so the predetermined fraction of the fluid resonant frequency corresponds to the frame beaming frequency, thereby providing minimum stiffness of the system at the frame beaming frequency.

Claims21

Dependent claims

A pneumatic suspension system for a vehicle, first and second axles and a frame, the vehicle frame having a frame beaming frequency, comprising:

a first pneumatic spring connected to the first axle and the frame and being subjected to input vibrations from the first axle, the first pneumatic spring containing pneumatic fluid;
a second pneumatic spring connected to the second axle and the frame, the second pneumatic spring containing the pneumatic fluid;
and
a pneumatic conduit in fluid communication with the first and second pneumatic springs, the pneumatic conduit containing the pneumatic fluid therein and being configured to allow the pneumatic fluid to move between the first and second pneumatic springs, the pneumatic fluid in the pneumatic conduit having a resonant frequency in the range of approximately 8.5 to 17.5 Hertz, inclusive, and the first and second pneumatic springs and the conduit define a system having a variable stiffness with a minimum spring stiffness when the input vibration has a frequency substantially corresponding to the frame beaming frequency, and wherein the first pneumatic spring has an internal volume, and the pneumatic conduit has a length and a cross-sectional area, the pneumatic conduit being shaped and sized so the resonant frequency of the pneumatic fluid therein is approximately equal to
251.multidot.(A/(V.multidot.L)).sup.1/2, wherein:
A=cross sectional area of the pneumatic conduit;
V=internal volume of the first pneumatic springs;
and
L=length of the pneumatic conduit, where the units of measure are in feet.

6 more elements

A pneumatic suspension system for a vehicle, the vehicle having a frame with a frame beaming frequency, comprising:

a first pneumatic spring connected to the frame, the first pneumatic spring having a pneumatic fluid therein, the first pneumatic spring being positionable to receive an input vibration with a frequency,
a second pneumatic spring connected to the frame, the second pneumatic spring having the pneumatic fluid therein;
and
a pneumatic conduit in fluid communication with the first and second pneumatic springs, the pneumatic conduit having the pneumatic fluid therein and being configured to allow the pneumatic fluid to move between the first and second pneumatic springs, the pneumatic fluid in the pneumatic conduit having a fluid resonant frequency, the first and second pneumatic springs and the conduit define a system having a variable stiffness wherein the stiffness is dependent upon the frequency of the input vibration, the input vibration frequency being a fraction of the fluid resonant frequency, the pneumatic conduit being sized so the fraction of the fluid resonant frequency substantially corresponds to the beaming frequency, and the system has a minimum stiffness when the frequency of the input vibration substantially corresponds to the fraction of the fluid resonant frequency, and wherein the first pneumatic spring has an internal volume and the pneumatic conduit has a length and a cross-sectional area. the pneumatic conduit being shaped and sized so the fluid resonant frequency of the pneumatic fluid is approximately equal to
251.multidot.(A/(V.multidot.L)).sup.1/2, wherein:
A=cross sectional area of the pneumatic conduit;
V=volume of the first pneumatic spring;
and
L=length of the pneumatic conduit,
where units of measure are in feet.

7 more elements

A pneumatic suspension system for a vehicle, the vehicle having a frame with a frame beaming frequency and first and second axles, comprising:

a first pneumatic spring having a pneumatic fluid therein and being connected to the first axle and the frame;
a second pneumatic spring having the pneumatic fluid therein and being connected to the second axle and the frame;
a pneumatic conduit in fluid communication with the first and second pneumatic springs to define a system, the pneumatic conduit having the pneumatic fluid therein and adapted to allow the pneumatic fluid to move between the first and second pneumatic springs, the pneumatic fluid in the pneumatic conduit having a fluid resonant frequency, wherein the system has a variable stiffness with the stiffness being dependent upon a frequency of an input vibration applied to first axle, first and second pneumatic springs and the pneumatic conduit being sized so the system has a minimum stiffness when the frequency of the input vibration substantially corresponds to the beaming frequency, and wherein the first pneumatic spring has an internal volume. and the pneumatic conduit has a length and a cross-sectional area, the pneumatic conduit being shaped and sized so the fluid resonant frequency of the pneumatic fluid is approximately equal to
251.multidot.(A/(V.multidot.L)).sup.1/2,wherein:
A=cross sectional area of the pneumatic conduit;
V=volume of the first pneumatic spring;
and
L=length of the pneumatic conduit.
where units of measure are in feet.

6 more elements

Dependencies are inferred from the claim text.