Suspension system
A space-saving suspension apparatus comprising a coarse suspension device, a mechanical assembly, and a fine suspension device coupling a supported frame to a base frame at a neutral height such that forces and/or displacements of either the base frame or the supported frame result in oppositely directed forces and/or displacements of the other of the base frame and the supported frame. In some embodiments, the neutral height is adjustable.
1. A passive suspension apparatus for supporting a payload, the passive suspension apparatus comprising:
a base frame and a supported frame, the supported frame coupled to the base frame, the supported frame configured to be disposed vertically a neutral height above the base frame when a payload having a payload weight is disposed on the supported frame, the passive suspension apparatus configured to support relative displacement in a generally vertical direction between the supported frame and the base frame from a minimum height to a maximum height, the neutral height being between the minimum height and the maximum height, the supported frame being coupled to the base frame via:
a scissor linkage, the scissor linkage comprising two crossed scissor arms pivotably coupled together about a central pivot, each of the two crossed scissor arms extending from the base frame to the supported frame, the two crossed scissor arms being free to rotate relative to each other as the supported frame and the base frame move closer to and farther away from each other;
a coarse suspension device coupling the base frame to the supported frame, the coarse suspension device configured to oppose a relative displacement in the generally vertical direction between the base frame and the supported frame, the coarse suspension device being adjustable to support the payload at the neutral height;
a mechanical assembly configured to convert the relative displacement in the generally vertical direction between the base frame and the supported frame into a generally horizontal displacement; and
a fine suspension device operably coupled to the mechanical assembly to provide damping to the horizontal displacement from the mechanical assembly, the mechanical assembly and the fine suspension device coupling the base frame to the supported frame;
wherein the passive suspension apparatus comprises only passive components,
wherein a force applied to one of the base frame and the supported frame in the generally vertical direction causes a generally opposite force to be applied to the other of the base frame and the supported frame, and
wherein the damping provided by the fine suspension device and the mechanical assembly varies in a non-linear manner such that:
the amount of damping provided in response to the relative displacement in the generally vertical direction between the base frame and the supported frame is different for an upward displacement of a given amount X than for a downward displacement of the given amount X.
2. The suspension apparatus of claim 1 wherein the coarse suspension device is directly coupled to the base frame and to the supported frame.
3. The suspension apparatus of claim 1 wherein the coarse suspension device comprises one or more air springs or mechanical springs.
4. The suspension apparatus of claim 3 wherein the coarse suspension device comprises one or more air springs configured to be adjusted to a different air pressure based on the payload weight and the neutral height.
5. The suspension apparatus of claim 3 wherein the coarse suspension device further comprises one or more blocks.
6. The suspension apparatus of claim 5 wherein the one or more blocks are configured to facilitate adjusting the coarse suspension device to support the payload at the neutral height.
7. The suspension apparatus of claim 1 wherein the neutral height is closer to the maximum height than to the minimum height.
8. The suspension apparatus of claim 1 wherein the neutral height is closer to the minimum height than to the maximum height.
9. The suspension apparatus of claim 8 wherein the damping provided by the fine suspension device and the mechanical assembly vary as a function of both (a) the relative displacement in the generally vertical direction between the base frame and the supported frame, and (b) a velocity of the generally horizontal displacement from the mechanical assembly.
10. The suspension apparatus of claim 9 wherein the damping provided by the fine suspension device and the mechanical assembly increases as the relative displacement in the generally vertical direction between the base frame and the supported frame increases above and decreases below the neutral height.
11. The suspension apparatus of claim 9 wherein the damping provided by the fine suspension device and the mechanical assembly increases as the relative displacement in the generally vertical direction between the base frame and the supported frame increases above and decreases below a minimum damping height that is not equal to the neutral height.
12. The suspension apparatus of claim 10 wherein the damping provided by the fine suspension device and the mechanical assembly is greater as the relative displacement in the generally vertical direction between the base frame and the supported frame decreases below the neutral height by a given amount X than when the relative displacement in the generally vertical direction between the base frame and the supported frame increases above the neutral height by the given amount X.
13. The suspension apparatus of claim 8 wherein the neutral height is between 20% and 45% of a travel distance from the minimum height to the maximum height.
14. The suspension apparatus of claim 7 wherein the neutral height is between 55% and 80% of a travel distance from the minimum height to the maximum height.
15. The suspension apparatus of claim 1 wherein the mechanical assembly comprises:
a two-arm vertical linkage comprising:
an upper link arm; and
a lower link arm pivotably coupled to the upper link arm, and
a lever arm having a first end and a second end, the first end of the lever arm coupled to
an end of the two-arm vertical linkage, the second end configured to be coupled to
the fine suspension device.
16. The suspension apparatus of claim 15 wherein the first end of the lever arm is configured to rotate about a generally horizontal axis in response to movement of the two-arm vertical linkage caused by the relative displacement between the supported frame and the base frame in the generally vertical direction.
17. The suspension apparatus of claim 16 wherein the lever arm is configured to maintain a fixed angular relationship with the end of the two-arm vertical linkage coupled to the lever arm during rotation of the lever arm about the generally horizontal axis.
18. The suspension apparatus of claim 17 wherein the angular relationship maintained between the lever arm and the end of the two-arm vertical linkage comprises an angle between 15 and 165 degrees.
19. The suspension apparatus of claim 18 wherein the angular relationship maintained between the lever arm and the end of the two-arm vertical linkage comprises an angle between 30 and 90 degrees.
20. The suspension apparatus of claim 19 wherein the angle between the lever arm and the end of the two-arm vertical linkage is approximately 60 degrees.
21. The suspension apparatus of claim 1 wherein the scissor linkage being not directly coupled to the coarse suspension device and the fine suspension device results in a reduction in friction of the suspension apparatus.
22. The suspension apparatus of claim 1 wherein a displacement of the base frame in the generally vertical direction causes a displacement of the supported frame in a direction generally opposite that of the base frame.
23. The suspension apparatus of claim 22 wherein the displacement of the supported frame caused by the displacement of the base frame is approximately equal to the displacement of the base frame.
24. The suspension apparatus of claim 1 wherein the fine suspension device is pivotably coupled to one of the base frame and the supported frame.
25. A passive suspension apparatus for supporting a payload, the passive suspension apparatus comprising:
a base frame and a supported frame, the supported frame coupled to the base frame, the supported frame configured to be disposed vertically a neutral height above the base frame when a payload having a payload weight is disposed on the supported frame, the passive suspension apparatus configured to support relative displacement in a generally vertical direction between the supported frame and the base frame from a minimum height to a maximum height, the neutral height being between the minimum height and the maximum height, the supported frame being coupled to the base frame via:
a scissor linkage, the scissor linkage comprising two crossed scissor arms pivotably coupled together about a central pivot, each of the two crossed scissor arms extending from the base frame to the supported frame, the two crossed scissor arms being free to rotate relative to each other as the supported frame and the base frame move closer to and farther away from each other;
a coarse suspension device coupling the base frame to the supported frame, the coarse suspension device configured to oppose a relative displacement in the generally vertical direction between the base frame and the supported frame, the coarse suspension device being adjustable to support the payload at the neutral height;
a mechanical assembly configured to convert the relative displacement in the generally vertical direction between the base frame and the supported frame into a generally horizontal displacement; and
a fine suspension device operably coupled to the mechanical assembly to provide damping to the horizontal displacement from the mechanical assembly, the mechanical assembly and the fine suspension device coupling the base frame to the supported frame;
wherein the passive suspension apparatus comprises only passive components,
wherein a force applied to one of the base frame and the supported frame in the generally vertical direction causes a generally opposite force to be applied to the other of the base frame and the supported frame,
wherein the damping provided by the fine suspension device and the mechanical assembly vary as a function of both (a) the relative displacement in the generally vertical direction between the base frame and the supported frame, and (b) a velocity of the generally horizontal displacement from the mechanical assembly, and
wherein the damping provided by the fine suspension device and the mechanical assembly varies in a non-linear manner such that:
the amount of damping provided in response to the relative displacement in the generally vertical direction between the base frame and the supported frame is different for an upward displacement of a given amount X than for a downward displacement of the given amount X.
26. The suspension apparatus of claim 25 wherein the mechanical assembly and the fine suspension device couple the base frame to the supported frame without being coupled to the scissor linkage.
27. The suspension apparatus of claim 25 wherein the second force is generally out of phase with the first force.