METHODS AND APPARATUS FOR COMBINED VARIABLE DAMPING AND VARIABLE SPRING RATE SUSPENSION
Pressure-sensitive vales are incorporated within a dampening system to permit user-adjustable tuning of a shock absorber. In one embodiment, a pressure-sensitive valve includes an isolated gas chamber having a pressure therein that is settable by a user.
This application claims benefit of U.S. provisional patent application Ser. No. 61/157,541, filed Mar. 4, 2009. This application is also a continuation-in-part of U.S. patent application Ser. No. 12/407,610, filed on Mar. 19, 2009, which claims priority to U.S. provisional patent application Ser. No. 61/038,015, filed Mar. 19, 2008. This application is also a continuation-in-part of U.S. patent application Ser. No. 12/509,258, filed on Jul. 24, 2009, which claims priority to U.S. provisional patent application Ser. No. 61/227,775, filed Jul. 22, 2009. All of these applications are herein incorporated herein, by reference, in their entireties.
BACKGROUND OF THE INVENTION1. Field of the Invention
Embodiments of the present invention generally relate to a suspension system for a vehicle. More particularly, the invention relates to a damper operable in conjunction with a pressure-sensitive valve that affects dampening characteristics of the damper.
2. Description of the Related Art
Vehicle suspension systems typically include a spring component or components and a damping component or components. Traditionally, mechanical springs, such as metal leaf or helical springs, have been used in conjunction with some type of viscous fluid based damping mechanism mounted functionally in parallel. More recently, compressed gas acting over a piston area has replaced mechanical springs as the spring component in some contemporary suspension systems. Dampers typically operate by restricting the flow of working fluid in a chamber housing to slow the movement of a piston and rod, especially during a compression stroke. Restrictions within dampers are typically preset for “average” use conditions and are not adaptable to varying conditions.
What is needed is a damper valve that operates at a user adjustable threshold and permits dampening to occur as needed or desired. Such a damper may be “tuned” to anticipate certain road conditions and/or rider conditions, especially with vehicles like bicycles or motor cycles. What is needed is a damper tuning function operating in conjunction with a gas spring to permit additional characteristics to be added to an overall suspension system for improved performance.
SUMMARY OF THE INVENTIONEmbodiments of the invention generally relate to the use of pressure-sensitive valves incorporated within a dampening system to permit adaptive damping of a shock absorber. In one embodiment, a pressure-sensitive valve includes an isolated compressible (e.g. gas filled) chamber having a pressure therein that is settable by a user. The gas in the chamber acts upon a piston surface in opposition to working fluid acting upon an opposing surface of the valve to affect the opening and closing of the valve in a damper. In one embodiment the pressure-sensitive valve is incorporated into a damper piston. In one embodiment a closed position of the valve prevents or impedes operation of the damper and with the valve in an open position; fluid is permitted to travel more freely through the piston during a compression stroke of the damper. In another embodiment the valve is disposed in a fluid path between a damper and a reservoir for working fluid. In another example, a gas spring is incorporated to operate with a pressure-sensitive valve and a gas chamber in the spring is in communication with an isolated gas chamber of the pressure-sensitive valve. In another embodiment, a pressure-sensitive valve includes a user-settable gas chamber pressure and an opposing separate compressible chamber permitting additional “tuning” of the damper for various road and/or riding conditions.
So that the manner in which the above recited features can be understood in detail, a more particular description, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
In the embodiment shown in
In one embodiment the valve assembly 150 includes an annularly-shaped member or valve member 155 including two piston surfaces 160, 170. Surface 160 is exposed to the working fluid 125 of the damper 100 while surface 170, having a relatively smaller surface area in the embodiment shown, is exposed to a source of pressurized fluid (e.g. gas) in a chamber 180. The pressurized gas acting upon surface 170 is supplied via a pathway 181 extending through the rod 115 and terminating in a user-adjustable fill valve 183 (such as for example a Schrader or Presta type gas fill valve). Chamber 180 and hence surface 170 are isolated (including by o-ring seals as shown but not numbered) from the working fluid 125 of the damper 100. In one embodiment, a constant gas pressure exerted on surface 170 biases the valve 150 to remain in a normally closed position because the pressure set in chamber 180 is higher (optionally substantially higher depending on the ratio of areas 160 and 170) than fluid pressure in a compression side 127 prior to operation of the damper (i.e. static or ambient fluid pressure).
In order to open the normally closed L-valve assembly 150, a force F1 (not shown), corresponding to a pressure P1—(not shown) exerted on (e.g. multiplied by) surface area 160 (area—A1), must be greater than an opposing force F2 (not shown), corresponding to a gas pressure (P2—not shown) exerted on surface area 170 (A2—not shown). In other words F1=P1×Area 160 and F2=P2×Area 170 and the valve assembly 150 will open during a compression stroke when P1×Area 160>P2×Area 170 (i.e. when F1>F2). The areas 160 and 170 as well as the pressures P1 and P2 are selectable by design and/or in use so that the valve opening threshold can be adjusted as desired. In one embodiment, when F1 becomes greater than F2, member 155 is moved upwardly in relation to the piston body and surface 160 of the L-valve, which normally obstructs a fluid path 162 through the piston (see
In one embodiment, the damper valve 150 functions when the piston 120 and rod 115 are moved during a compression stroke. Initially, flow through the piston is blocked by the seating of surface 160 on valve seat 165 brought about by a downward force (“downward” as shown in
In addition to the simple arrangement of
In one embodiment the “blow off assembly” 200 includes three subcomponents: a check valve 205; an adjustable orifice 210 and; a normally closed, spring actuated blow-off valve 215. The check valve 205 blocks the flow of fluid from above (i.e. 127) the assembly 200 to below the assembly 200, during a compression stroke while permitting the flow of fluid through the assembly, from below to above, during a rebound stroke. The adjustable orifice 210 is provided as another metering device in lieu of or addition to the L-valve 150 to provide additional dampening during the compression stoke. In one embodiment flow through the check valve 205 is metered by shims in the flow direction (not the check direction). In one embodiment flow through the orifice 210 is metered in one or both directions by shims. In one embodiment the check valve is checked and metered by a same set of shims. The blow-off valve 215 is also a one way valve operable during the compression stroke but is biased toward a closed position by a resilient member, such as for example in this case, a spring 217. The blow-off valve is designed to operate only in the event of a relatively high pressure spike, in chamber 127, during a compression stroke of the damper that is created when a “choke” condition arises as fluid is metered through the L-valve 150 and the adjustable orifice 210. A choke condition most often arises due to fluid flow created by relatively rapid movement of the piston 120 and rod 115 in the damper housing 110.
In one embodiment, the size of orifice 210, the initial pressure in chamber 130 and the pressure P2 in chamber 180 are set (and the areas 170 and 160 are correspondingly tailored) such that upon initial movement of the suspension in compression, fluid travels from above to below assembly 200 through the orifice 210 while valve 150 remains closed. When the piston (including valve 150) has traveled sufficiently, pressure in chamber 127 is increased (due to compression of the gas in chamber 130) and valve 150 opens thereby allowing fluid to flow from below to above the piston along path 162. In one embodiment, the foregoing parameters are adjusted such that both valve 150 and orifice 210 allow fluid flow substantially simultaneously during compression. In one embodiment, blow off valve 217 is set to allow excess fluid to flow from above the assembly 200 to below when pressure in chamber 127 is increased dramatically (such “blow off” thereby reducing the pressure in chamber 127) and beyond the flow rate capabilities of other damping valve mechanisms within the damper. In one embodiment the blow off valve 217 comprises one or more shims.
In one embodiment the initial fluid pressures and piston areas are configured so that a shock, such as is shown in
The arrangement of
In certain embodiments hereof, other valves could be used instead of, or in addition to, the “L-valve.” For example, U.S. Pat. No. 5,190,126 shows a valve having a user adjustable chamber with pressurized gas. Rather than having the chamber at a location where it urges the valve to a closed position, the valve incorporates a chamber at a location that reduces, rather than increases the force needed to open the valve. The valve of the '126 patent may be adopted for use in any suitable arrangement hereof and that patent is incorporated by reference in its entirety herein.
In
In some embodiments as shown in the
The pressure-sensitive valves disclosed herein need not be incorporated in or even adjacent a damper piston but can be remotely located in any fluid path between a damper chamber and a reservoir.
In one embodiment the valve of
As shown in the description and Figures, embodiments permit pressure-sensitive valves to be incorporated into and/or used in conjunction with fluid dampers to provide various means for a user to tune a damper based on dynamic road conditions. In some embodiments, the pressure-sensitive valve is urged to a closed position to increase dampening in the shock absorber. In other instances, the valves are urged to an open position to permit fluid to flow between the compression and rebound sides of the chamber in order to decrease dampening. In some embodiments the valve is incorporated in a piston between a compression chamber and a “rebound” receiving chamber and in other embodiments the valve is incorporated between a compression chamber and a “reservoir” receiving chamber. Either of the reservoir chamber and the rebound chamber (and any other suitable chamber) enable damping by receiving working fluid from the compression chamber during a compression stroke.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims
1. A vehicle suspension damper comprising:
- a cylinder and a piston assembly comprising a piston and piston rod;
- working fluid within said damper, the damper comprising a compression chamber and a receiving chamber;
- a pressure-sensitive valve disposed in the damper between the compression chamber and the receiving chamber, the valve including: a first valve surface in communication with a pressurized gas; an opposing valve surface in communication with the working fluid.
2. The damper of claim 1, whereby;
- in a compression stroke of the piston, the valve opens permitting fluid to move from one side of the piston to the other side when a force exerted by the gas on the first valve surface is overcome by an opposing force exerted on the opposing valve surface by the working fluid.
3. The damper of claim 1, whereby:
- the valve closes, impeding movement of the fluid from one side of the piston to the other side when a force exerted by the gas on the first valve surface is overcome by an opposing force exerted on the opposing valve surface by working fluid.
4. The damper of claim 1, further including a gas spring, the gas spring having a gas filled chamber that is compressible as the rod moves in the compression stroke.
5. The damper of claim 4, whereby the gas in the gas spring is in fluid communication with the pressurized gas.
6. The suspension damper of claim 1, wherein the first valve surface has a smaller piston area than the opposing valve surface.
7. The suspension damper of claim 1, wherein the pressurized gas is user-adjustable.
8. The suspension damper of claim 7, wherein the pressurized gas is user-adjustable via a path formed in the piston rod between the first valve surface and a user-adjustable fill valve.
9. The suspension damper of claim 1, further including a gas-filled reservoir formed in a portion of the cylinder, the reservoir separated from the working fluid by a floating piston.
10. The suspension damper of claim 1, wherein the valve is normally closed impeding the flow of working fluid from moving between the sides of the piston in a compression stroke.
11. A vehicle suspension damper comprising:
- a cylinder and piston assembly comprising a piston and piston rod;
- working fluid within said cylinder;
- a valve disposed in the piston, the valve including: a first piston surface in communication with a first source of pressurized gas; a second piston surface in communication with a second source of pressurized gas; and a piston surface in communication with the working fluid, whereby the first and second piston surfaces are opposed.
12. The damper of claim 11, whereby the first source of pressurized gas is a user-adjustable source and the second, opposing source is a preset source.
13. The damper of claim 12, wherein the first source is of a higher pressure than the second source.
14. The damper of claim 11, whereby;
- in a compression stroke of the piston, the valve opens permitting fluid to move from one side of the piston to the other side when a force exerted by the gas on the first piston surface is overcome by an opposing force exerted on the opposing piston surface and an opposing force exerted on the second piston surface.
15. A vehicle suspension damper, comprising:
- a housing with working fluid, a piston and a rod designed to move into the housing in a compression stroke of the piston;
- a remotely located reservoir for housing excess fluid during the compression stroke;
- a fluid path connecting the housing and the remotely located reservoir;
- a pressure-sensitive valve located in the fluid path, the valve having at least one movable surface acted upon by a gas, the gas housed in a chamber and the chamber in fluid communication with ambient air pressure.
16. A damper for a vehicle comprising:
- a chamber with a piston and rod constructed and arranged to extend into the chamber in a compression stroke of the damper;
- a valve operable with the damper, the valve permitting and restricting operation of the damper and having a first surface formed on a movable valve member, the surface operable with a working fluid of the damper and a second surface formed on the member, the second surface operable with gas pressure whereby;
- in the compression stroke, the fluid pressure exerted on the first surface increases while the gas pressure exerted on the second surface remains constant.
17. The damper of claim 1, whereby the second surface is an opposing surface to the first surface.
18. The damper of claim 16, whereby the valve is integral to the piston.
19. A shock absorber comprising:
- a damper having a compression chamber and a piston and rod for moving into the chamber during a compression stroke;
- a valve for permitting and impeding working fluid from passing from the compression chamber of the damper to a receiving chamber of the damper, the valve having a first surface acted upon by working fluid and a second surface acted upon by a user-settable pressurized gas;
- a spring, the spring working in conjunction with the damper to affect the movement of the shock absorber during the compression stroke.
20. The shock absorber of claim 19, wherein the spring comprises a gas spring having a compressible gas chamber in fluid communication with the pressurized gas.
Type: Application
Filed: Mar 4, 2010
Publication Date: Sep 30, 2010
Inventors: Dennis K. Wootten (Scotts Valley, CA), Robert C. Fox (Los Gatos, CA), Josh Yablon (Santa Clara, CA), David M. Haugen (Pacific Grove, CA)
Application Number: 12/717,867
International Classification: B60G 17/04 (20060101); F16F 9/00 (20060101); F16F 9/34 (20060101); F16F 9/02 (20060101);