Dual rate vehicle suspension system with adjustable ride height
A spring configuration comprises a cylindrical damper ( 5 ), a primary coil spring ( 9 ) with a first predetermined spring rate K1, and a secondary coil spring ( 11 ) with a second predetermined spring rate K2, the coil springs arranged about the cylindrical damper ( 5 ) in series so as to provide a total combined spring rate KT, an actuator ( 20 ) configured to compress and decompress the coil springs ( 9, 11 ), a stop ( 12 ) configured to deactivate the secondary coil spring ( 11 ) at a stop position, such that, when the system is in a first, comfort, mode, the overall suspension spring rate is defined by the series equation 1/KT=1/K1+1/K2, and when the system is in a second, handling, mode, the overall vehicle suspension spring rate is defined by the series equation KT=K1, thus selectively and switchably providing both a low rate, optimal ride comfort setting and a high rate, optimal handling lower ride height setting.
1 . A selectively switchable dual rate vehicle suspension system configured to be oriented between the unsprung mass and the sprung mass of one corner of a vehicle, comprising:
a cylindrical damper;
a primary coil spring with a first predetermined spring rate K1, and a secondary coil spring with a second predetermined spring rate K2, the coil springs both connected to a common spring abutment and arranged about the cylindrical damper in series so as to provide a total combined spring rate KT;
an actuator mounted to the damper and configured to compress and decompress the coil springs;
stop means configured to deactivate the secondary coil spring in at least one stop position;
such that, when the system is in a first mode the overall suspension spring rate is defined by the series equation 1/KT=1/K1+1/K2, and when the system is in a second mode the overall vehicle suspension spring rate is defined by the series equation 1/KT=1/K1, thus selectively and switchably providing both a low rate, optimal ride comfort setting in the first mode and a high rate, optimal handling lower ride height setting in the second mode.
2 . The suspension system of claim 1 , wherein the actuator comprises a hydraulic cylinder and a hydraulic piston.
3 . The suspension system of claim 2 , wherein the hydraulic cylinder rides on an outer wall of the cylindrical damper.
4 . The suspension system of claim 3 , wherein the stop means comprises a stop portion of the outer wall of the cylindrical damper against which a contact portion of the hydraulic cylinder abuts.
5 . The suspension system of any one of claims 1 to 4 , wherein the actuator acts on the secondary coil spring via a lower spring abutment.
6 . The suspension system of claim 1 , wherein the secondary coil spring is deactivated when decompressed.
7 . The suspension system of claim 1 , further comprising a third, maneuvering, mode wherein both the secondary coil spring and the primary coil spring are compressed beyond the first mode to increase a vehicle ride height above that in the first mode, optimal ride comfort setting.
8 . The suspension system of any one of claims 1 to 3 , wherein the actuator comprises the common spring abutment.
9 . The suspension system of claim 8 , wherein the stop means comprises a lockout means configured to hold the secondary coil spring in multiple selected stop positions.
10 . The suspension system of claim 9 , wherein the lockout means comprises valve means to inhibit flow of a hydraulic fluid in the hydraulic cylinder.
11 . The suspension system of claim 1 , further comprising a third, manoeuvering, mode wherein the secondary coil spring is decompressed and the primary coil spring is raised to increase a vehicle ride height above that in the first mode, optimal ride comfort setting.
12 . The suspension system of claim 1 , wherein the cylindrical damper provides adjustable damping to match changes in spring rate for optimal vehicle comfort and handling.