Bicycle suspension assembly with inertia valve and blow-off
View Patent ↗A bicycle suspension assembly having an inertia valve is described. A blow-off valve that permits fluid flow through the suspension assembly when the fluid pressure in the suspension assembly exceeds a predetermined threshold may be included.
1. A bicycle, comprising:
a frame;
a pedal crank assembly coupled to the frame and configured to be driven by rider-induced pedaling forces;
a wheel, and
a suspension assembly operably interposed between the frame and the wheel, the suspension assembly comprising:
a damper, the damper comprising a damper tube containing damping fluid and a piston rod supporting a piston in sliding engagement with the damper tube, the piston and the damper tube at least partially defining a compression chamber of the damper, wherein the piston rod occupies an increasing volume of the damper tube during compression movement of the suspension assembly, the damper additionally comprising an inertia valve including an inertia mass, the inertia mass normally biased to a closed position wherein the inertia mass is adjacent an opening to the compression chamber such that fluid flow through the opening is inhibited, and the inertia mass is movable to an open position wherein the inertia mass is not adjacent the opening such that fluid flow through the opening is not inhibited and the inertia mass having a passage formed therethrough;
a spring configured to apply a force to the suspension assembly tending to extend the piston rod relative to the damper tube;
wherein the inertia valve is configured such that the inertia mass remains in the closed position in response to the rider-induced pedaling forces applied to the frame and wherein the inertia valve is configured such that the inertia mass moves toward the open position in response to a terrain-induced force above a predetermined threshold applied to the wheel;
a blow-off valve configured to substantially inhibit fluid flow from the damper tube through the blow-off valve in response to a fluid pressure in the damper tube below a predetermined pressure threshold, and to permit fluid flow from the damper tube through the blow-off valve in response to a fluid pressure in the damper tube above the predetermined pressure threshold;
wherein the predetermined pressure threshold is configured to be above a level induced by the rider pedaling forces applied to the frame;
a reservoir chamber configured to accommodate fluid displaced by the increasing volume of the piston rod during a compression movement of the suspension assembly, wherein the damper additionally comprises a check valve configured to allow fluid flow from the inertia mass passage to the reservoir chamber and restrict fluid flow from the reservoir chamber to the inertia mass passage; and
a pocket configured to receive the inertia mass in the open position, wherein a clearance is defined between the inertia mass and the pocket and the clearance is configured to provide restricted fluid communication between the reservoir chamber and the pocket.
2. The bicycle of claim 1 wherein the damper further includes a separating barrier, movable in response to the fluid displaced, separating the reservoir chamber from a gas chamber.
3. The bicycle of claim 2 wherein the separating barrier is a floating piston.
4. The bicycle of claim 1 wherein the spring comprises a gas spring containing pressurized gas.
5. The bicycle of claim 1 wherein the piston includes at least one fluid flow passage.
6. The bicycle of claim 1 wherein the inertia valve further comprises a valve shaft, surrounded by the inertia mass and guiding sliding motion of the inertia mass, the valve shaft defining at least a portion of a fluid flow path from the compression chamber to the opening.
7. The bicycle of claim 6 wherein the valve shaft defines the opening.
8. The bicycle of claim 7 wherein, with the inertia mass in the open position, fluid displaced by the increasing volume of the piston rod during a compression movement of the suspension assembly exits the opening in a direction that is outward and away from the centerline of the valve shaft.
9. The bicycle of claim 1 , wherein the inertia valve is not associated with the piston.
10. The bicycle of claim 1 , wherein the blow-off valve is not associated with the piston.
11. The bicycle of claim 1 , wherein the piston rod is associated with a portion of the damper that is coupled to the frame.
12. The bicycle of claim 1 wherein the predetermined force threshold produces an acceleration of the wheel of between 0.2 G's and 2.0 G's.
13. The bicycle of claim 1 wherein the predetermined force threshold produces an acceleration of the wheel of between 0.3 G's and 1.6 G's.
14. The bicycle of claim 1 wherein the predetermined force threshold produces an acceleration of the wheel of between 0.4 G's and 1.2 G's.
15. The bicycle of claim 1 wherein the damper further comprises an adjustment mechanism associated with the piston rod, the adjustment mechanism permitting external adjustment of a damping characteristic of the damper.
16. The bicycle of claim 15 wherein the externally adjustable damping characteristic is rebound damping.
17. The bicycle of claim 1 wherein the upward location of the inertia mass in the closed position is limited by a stop.