Patent Description:
Current shock absorption technologies include fluid dampers that vary the amount of damping force provided to a sprung mass of a system by channeling fluid through various passageways and valves to constrict fluid flow, increase pressures, and bypass damping fluid chambers. Various damping characteristic curves may result from tuning the sizes and locations of orifices and the stiffness of valve shims.

Current fluid dampers are constructed of uniform damper tubes, damper pistons, piston shafts, seals, wear bands, and bearings that engage one another frictionally. The surface treatment is uniform along the length of the inner surface of the damper tube and the outer surface of the piston shaft. The damper pistons, seals, wear bands, and bearings engage the damper tube and piston shaft and include both a static friction and a kinetic friction. Both frictions depend upon the surface to surface interaction between the piston (or piston wear band) and the damper tube or between the shaft and a seal and/or bearing surface.

<CIT> discloses narrowing the diameter of a cylinder of a damper at certain points along a stroke length in order to improve efficiency of damping, and suppressing or avoiding auto-oscillation and resonance.

According to some embodiments of the present invention there is provided a fluid damper shock absorber, comprising:.

In some embodiments, the fourth surface is a shaft guide.

In other embodiments, the fourth surface is the interior surface.

In some embodiments, the fourth surface is a shaft seal.

In some embodiments the damper piston includes a wear band around an outer circumference of the damper piston, the piston surface including an exterior surface of the wear band.

In some embodiments, the surface treatments include at least one of a coating, vibro-rolled, a chemically etched, an abrasive machined, a honed, a reactive ion etched, a high energy chemical plasma etched, a photolithographic deposited, an abrasive jet machined, an excimer laser beam machined, a vibro-mechanical textured, a laser surface textured, an electro-plated, an evaporative deposited surface, and a polyelectrolyte coating treatment.

In some embodiments, the different surface treatment has a second coefficient of friction with the piston surface that is less than the first coefficient of friction.

In some embodiments, the shock absorber includes a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the piston surface that is less than the second coefficient of friction.

In some embodiments, the shock absorber includes a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the piston surface that is greater than the second coefficient of friction.

Optionally, compression and rebound tuning of the first surface treatment results in two different coefficients of static friction and two different coefficients of kinetic friction for the first surface treatment: both including a compression direction coefficient and a rebound direction coefficient.

Optionally, compression and rebound tuning of the second surface treatment results in two different coefficients of static friction and two different coefficients of kinetic friction for the second surface treatment: both including a compression direction coefficient and a rebound direction coefficient.

According to another aspect of the present invention there is provided a vehicle comprising a fluid damper shock absorber as set out above. The fluid damper shock absorber of the present invention may be useful on any vehicle that uses shock absorbers for example, but not limited to boats (e.g. hull suspension), planes, trucks, cars, motorcycles, bicycles, all-terrain vehicles, side by sides and snowmobiles. The fluid damper shock absorber of the present invention may also be useful on dampers used in other applications such as heavy equipment mounting dampers, gun buffers, etc..

Aspects of the present invention are illustrated by way of example, and not by way of limitation, in the accompanying drawings, wherein:.

The description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention is to be practiced. Each embodiment described in this disclosure is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous over other embodiments. In some instances, well known methods, procedures, objects, and the like have not been described in detail as not to unnecessarily obscure aspects of the present disclosure.

The architecture described herein takes advantage of frictional forces and reduces the number of complex fluid flow solutions found in today's hydraulic dampers. One embodiment creates different zones within the damper where frictional forces between the engaging surfaces of the hydraulic damper vary. At least two different zones, utilize various surface treatment techniques to achieve micro-textured surfaces that exhibit varying coefficients of friction (static and kinetic). The surface treatments are applied to the inner surface of the damper tube's working chamber, to the outer surface of the piston shaft, or a combination thereof.

For example, in one embodiment, a middle portion of the damper tube could be treated to achieve a first surface treatment to drastically reduce breakaway friction forces when the damper has been stationary for a prolonged period. This middle portion would be the "ride zone" in which the damper piston most often travels. A first adjacent portion just above the middle portion is treated to achieve a second surface treatment that provides a higher kinetic friction force. This first adjacent portion will experience faster damper piston velocities that the middle portion from severe compression events. In one embodiment, portions at the top and bottom of the damper tube are also treated to achieve a third surface treatment to further increase kinetic friction and create a "virtual" bottom out or top out system that slows the damper piston substantially as full compression or extension occurs.

Thus, the damper can operate with far fewer valve architectures and even be simplified to only a main piston valve or base valve configuration. In one embodiment, the system is used in conjunction with existing technologies to provide more uniform response from the damper. The surfaces are treated in a fashion to alter the frictional force based on temperature (increased damping from friction forces for example as the fluid temperature increase and/or cavitation begins).

In one embodiment, the fluid damper shock absorber includes a damper tube, a damper piston, a piston shaft, and at least two different surface treatments. The damper tube includes an interior surface. The damper piston includes a piston surface that engages the interior surface. The piston shaft couples with the damper piston and includes a shaft surface that engages a fourth surface. The at least two different surface treatments are disposed on at least one of the interior surface and the shaft surface and create a corresponding plurality of coefficients of friction with at least one of the piston surface and the fourth surface respectively.

In other features, the fourth surface is a shaft guide surface, the interior surface of the damper tube, or a shaft seal surface. In other features, the damper piston includes a wear band around an outer circumference of the damper piston and the piston surface includes an exterior surface of the wear band.

In yet other features, the surface treatments include at least one of a coating, a vibro-rolled, a chemically etched, an abrasive machined, a honed, a reactive ion etched, a high energy chemical plasma etched, a photolithographic deposited, an abrasive jet machined, an excimer laser beam machined, a vibro-mechanical textured, a laser surface textured, an electro-plated, an evaporative deposited surface and a polyelectrolyte coating treatment.

In yet other features, the surface treatments include a first surface treatment at a first end of the interior surface of the damper tube having a first coefficient of friction with the piston surface. In other features, the surface treatments include a second surface treatment adjacent the first surface treatment having a second coefficient of friction with the piston surface that is less than the first coefficient of friction. In still other features, the surface treatments include a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the piston surface that is less than the second coefficient of friction. In yet other features, the surface treatments include a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the piston surface that is greater than the second coefficient of friction.

Another exemplary fluid damper shock absorber includes a damper tube, a damper piston, a first surface treatment, and a second surface treatment. The damper tube includes an interior surface. The damper piston includes a piston surface that engages the interior surface. The first surface treatment is disposed at a first end of the interior surface of the damper tube and includes a first coefficient of friction with the piston surface. The second surface treatment is disposed adjacent the first surface treatment and includes a second coefficient of friction with the piston surface that is less than the first coefficient of friction.

In other features, the damper piston includes a wear band around an outer circumference of the damper piston and the piston surface includes an exterior surface of the wear band.

In yet other features, the surface treatments include a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the piston surface that is less than the second coefficient of friction. In still other features, the surface treatments include a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the piston surface that is greater than the second coefficient of friction.

In yet other features, the surface treatments include at least one of a coating, a vibro-rolled, a chemically etched, an abrasive machined, a honed, a reactive ion etched, a high energy chemical plasma etched, a photolithographic deposited, an abrasive jet machined, an excimer laser beam machined, a vibro-mechanical textured, a laser surface textured, an electro-plated, an evaporative deposited surface and a polyelectrolyte coating.

Another exemplary fluid damper shock absorber includes a damper tube, a damper piston, a piston shaft, a first surface treatment, and a second surface treatment. The damper tube includes an interior surface. The damper piston includes a piston surface that engages the interior surface. The piston shaft couples with the damper piston and includes a shaft surface that engages a fourth surface. The first surface treatment is disposed at a first end of the piston shaft and includes a first coefficient of friction with the fourth surface. The second surface treatment is disposed adjacent the first surface treatment and includes a second coefficient of friction with the fourth surface that is less than the first coefficient of friction.

In yet other features, the surface treatments include a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the fourth surface that is less than the second coefficient of friction. In still other features, the surface treatments include a third surface treatment adjacent the second surface treatment having a third coefficient of friction with the fourth surface that is greater than the second coefficient of friction.

Referring to <FIG>, a cross-sectional perspective view of a shock absorber including uniform engaging surfaces is shown in accordance with an embodiment. In one embodiment, an exemplary fluid damper shock absorber <NUM> includes a damper portion and an integrated gas spring portion. The damper portion includes a damper tube <NUM>, a gas spring tube <NUM>, damper piston <NUM>, and a piston shaft <NUM>. The damper tube <NUM> is filled with a damper fluid. The damper tube <NUM> is sealed at a first end by a gas spring piston <NUM> which together with gas spring tube <NUM> and first end cap <NUM> forms a gas spring chamber <NUM> filled with a gas such as air or nitrogen. The damper tube <NUM> is further sealed at a second end by a second end cap <NUM> to fully enclose the damper fluid. A floating piston <NUM> is disposed between the damper piston <NUM> and the second end cap <NUM> to form a pressurized gas chamber <NUM>. The damper piston <NUM> divides the interior portion of the damper tube <NUM> into a rebound chamber <NUM> and a compression chamber <NUM>. An interior surface <NUM> of the damper tube <NUM> engages with the damper piston <NUM> or in some embodiments, a wear band <NUM> as the piston shaft <NUM> is forced back and forth along its linear axis, compressing and extending the shock absorber <NUM> in response to applied forces from, for example an unsprung mass such as a wheel traveling along a road surface.

Referring now to <FIG>, a cross-sectional perspective view of the shock absorber including a plurality of surface treatments on an interior surface of a damper tube is shown in accordance with an embodiment. In one embodiment, the shock absorber <NUM> further includes surface treatments such as surface micro texturing, coatings, or platings on the interior surface <NUM> of the damper tube <NUM>. For example, the interior surface <NUM> includes a first surface treatment <NUM> along a middle portion of the damper tube <NUM> corresponding to a "ride zone" of an associated vehicle on which the shock absorber <NUM> is installed. The interior surface <NUM> includes a second surface treatment <NUM> along a first adjacent portion next to the middle portion of the damper tube <NUM> corresponding to an increased damping zone of the associated vehicle. The interior surface <NUM> includes a third surface treatment <NUM> along an end portion next to the adjacent portion of the damper tube <NUM> corresponding to a heavy damping zone of the associated vehicle. Each surface treatment <NUM>-<NUM> is mirrored on the opposite side of the damper piston <NUM>. Surface treatments is developed for various damping needs along the entire length of the damper tube <NUM> in both the rebound chamber <NUM> and the compression chamber <NUM>.

Referring now to <FIG>, cross-sectional views of another shock absorber including a plurality of surface treatments on an interior surface of a damper tube in a compressed position and an extended position respectively are shown in accordance with an embodiment. In one embodiment, shock absorber <NUM> includes a damper portion without the gas spring portion of shock absorber <NUM>. Similarly, to shock absorber <NUM>, the damper tube <NUM> includes multiple surface treatments <NUM>, <NUM>, and <NUM>. In <FIG>, the shock absorber <NUM> is shown in a fully compressed or "bottomed out" position in which the damper piston <NUM> or the wear band <NUM> engages with the third surface treatment <NUM> on the interior surface <NUM>. In <FIG>, the shock absorber <NUM> is shown in a fully extended or "topped out" position in which the damper piston <NUM> or the wear band <NUM> engages with the third surface treatment <NUM> on the interior surface <NUM>. In use, the damper piston <NUM> or the wear band <NUM> will engage with each of the surface treatments. Each surface treatment provides two different frictional forces - static friction and dynamic friction. Each surface treatment provides two different coefficients of friction depending on the direction of movement of the damper piston <NUM>.

Referring now to <FIG>, a block diagram <NUM> of a shock absorber (such as shock absorber <NUM> or shock absorber <NUM>) including a plurality of regions for tuning coefficients of friction between mating surfaces is shown in accordance with an embodiment. In one embodiment, <FIG> illustrates at least three regions for tuning coefficient of friction between surfaces. A first region <NUM> includes mating surfaces of the damper piston <NUM> or wear band <NUM> and the interior surface <NUM> of the damper tube <NUM>. A second region <NUM> includes mating surfaces of the piston shaft <NUM> and a shaft guide <NUM> or a shaft seal <NUM>. A third region includes mating surfaces of the floating piston <NUM> or a seal surrounding the floating piston and another interior surface <NUM> of a reservoir <NUM>. Alternatively, the interior surface <NUM> is an interior surface of the pressurized gas chamber <NUM>. Each of the regions <NUM>, <NUM>, and <NUM> includes one or more coefficient of static friction µs and more or more coefficient of kinetic friction µk.

Referring now to <FIG>, a block diagram of a shock absorber illustrating a plurality of surface treatments for creating a plurality of coefficients of friction between mating surfaces a first region is shown in accordance with an embodiment. In one embodiment, the damper tube <NUM> includes three different surface treatments <NUM>, <NUM>, and <NUM>. The piston shaft <NUM> includes a substantially uniform surface. Together, the first regions <NUM> include coefficient of frictions µ<NUM>, µ<NUM>, and µ<NUM> respectively and for both static and kinetic friction. Here, the wear band <NUM> engages the various surface treatments <NUM>-<NUM>.

With reference now to <FIG>, a block diagram of a shock absorber illustrating a plurality of surface treatments for creating a plurality of coefficients of friction between mating surfaces in a second region is shown in accordance with an embodiment. In one embodiment, the damper tube <NUM> includes a substantially uniform surface while the piston shaft <NUM> includes various surface treatments <NUM>-<NUM>. Together, second regions <NUM> include coefficient of frictions µ<NUM>, µ<NUM>, and µ<NUM> respectively and for both static and kinetic friction. In some examples, both the damper tube <NUM> and the piston shaft <NUM> include surface treatments <NUM>-<NUM>. Although not shown, the third region <NUM> will likewise include surface treatments <NUM>-<NUM> between the floating piston <NUM> and interior surface <NUM> and are combined with surface treatments on the interior surface <NUM> of the damper tube and/or with surface treatments on the piston shaft <NUM>.

The surface treatments <NUM>-<NUM> are formed throughout the circumference and along a predetermined length of the interior surface <NUM> of the damper tube <NUM> forming cylindrical sections. Alternatively, the surface treatments <NUM>-<NUM> are formed along portions of the circumference and along a predetermine length of the interior surface <NUM> forming partial cylindrical sections. Any number of patterns is used to form the surface treatments <NUM>-<NUM> including helical, striped, and the like to achieve the desired level of friction for a given position of the damper piston <NUM> within the damper tube <NUM>.

Examples of surface treatments which are used to create the surface treatments <NUM>-<NUM> include but are not limited to coatings, vibro-rolling, chemical etching, abrasive machining, honing to generate micro-grooves, reactive ion etching (RIE), high energy chemical plasma, photolithographic techniques, abrasive jet machining (AJM), excimer laser beam machining (LBM), vibro-mechanical texturing (VMT), laser surface texturing (LST), electro-plating, electric-field-induced polyelectrolyte coatings, and evaporative deposition.

Referring now to <FIG>, a block diagram of a shock absorber illustrating a variable surface treatment for creating a plurality of coefficients of friction between mating surfaces is shown in accordance with an embodiment. In one embodiment, <FIG> includes a damper piston <NUM> that is selectively charged with a variable voltage. The damper piston <NUM> or a wear band <NUM> disposed about the circumference of the damper piston <NUM> engages the interior surface <NUM> of the damper tube <NUM>. At least one of the interior surface <NUM>, the damper piston <NUM>, and the wear band <NUM> includes the surface treatment <NUM> which includes a polyelectrolyte coating. Electricity is applied to the damper piston <NUM> via leads <NUM>. A variable voltage V is applied to the damper piston <NUM> using alternating current. As the voltage is varied, the coefficient of friction of the engaging interior surface <NUM> and damper piston <NUM> or wear band <NUM> varies. The voltage is set by a user to one or more predetermined values. Each of the predetermined values corresponds to a desired level of friction.

A control system is provided to regulate the variable voltage V based on various parameters associated with vehicle operation or shock absorber characteristics. For example, a controller <NUM> receives a plurality of signals from sensors <NUM> including a temperature T associated with operation of the shock absorber, a cavitation measurement C, piston velocity PV, piston position PP, a vehicle speed VS, or other signals. In one embodiment, the controller <NUM> is integral with another controller such as a vehicle master controller or engine control unit (ECU). Alternately, in one embodiment, the controller <NUM> is a standalone unit. The controller <NUM> controls voltages for one or more shock absorbers. The controller <NUM> is linked to one or more other vehicle controllers via a CAN bus or other vehicle network communications.

Based on the data, the controller <NUM> generates a voltage or current value to be applied to the damper piston <NUM>. For example, in colder weather and/or after a prolonged period of rest, many shock absorbers experience higher levels of friction between the damping piston <NUM> and interior surface <NUM> of the damper tube <NUM>. Hydraulic damping fluid increases in viscosity as the temperature decreases. Damper tubes also decrease in diameter as the metal contracts due to lower temperatures. These and other natural phenomenon result in reduced ride quality, harshness, unwanted noises, increased component wear, and other undesirable side effects. The control system compensates for the temperature T of the shock absorber by decreasing the coefficient of friction. For example, when the sensed or modeled temperature of the damper tube <NUM> is below a threshold temperature T1, the controller <NUM> begins to apply voltage V to decrease the coefficient of friction.

The voltage V is increased or decreased during normal temperature operation of the shock absorber as well to compensate for a variety of conditions in which increased or decreased damping forces are desired including but not limited to: steady-state high vehicle speed (highway driving), off-road situation-specific events (rough road, low vehicle speed rock crawl, jumps, landings), evasive maneuvering (rapid turning events), body roll, body pitch/heave, body yaw, and the like.

A method for selecting a plurality of surface treatments includes determining desired static breakaway forces for the damper piston <NUM> in a plurality of positions within the damper tube <NUM>, determining desired damping forces for the damper piston <NUM> in a plurality of positions within the damper tube <NUM>, determining desired damping forces for the damper piston <NUM> for piston shaft <NUM> velocity ranges, determining desired damping forces for the damper piston <NUM> for a direction of movement, and selecting a surface treatment to achieve the desired breakaway force and damping force for each of the positions, velocity ranges, and direction of movement.

For example, in a ride zone or first portion of the damper tube <NUM>, it is desirable to include a first surface treatment <NUM> with a first coefficient of static friction that is the lowest of all and a first coefficient of kinetic friction that is lowest of all. In one embodiment, the first surface treatment <NUM> is not dependent on direction of movement and will result in the same frictional forces regardless of the direction travelled by the damper piston <NUM>. Alternately, in one embodiment, the compression and rebound tuning of the first surface treatment <NUM> results in two different coefficients of static friction and two different coefficients of kinetic friction for the first surface treatment <NUM>: both including a compression direction coefficient and a rebound direction coefficient.

Similarly, the adjacent portions of the damper tube next to the first portion include a second surface treatment <NUM> with a second coefficient of static friction that is higher than the first coefficient of static friction and a second coefficient of kinetic friction that is higher than the first coefficient of kinetic friction. In one embodiment, this second surface treatment <NUM> is not dependent on direction of movement and results in the same frictional forces regardless of the direction travelled by the damper piston <NUM>. Alternately, in one embodiment, compression and rebound tuning of the second surface treatment <NUM> results in two different coefficients of static friction and two different coefficients of kinetic friction for the second surface treatment <NUM>: both including a compression direction coefficient and a rebound direction coefficient.

The end portions of the damper tube repeats the same tuning process for selecting the third surface treatment <NUM>. Any number of surface treatments is employed to provide the desired level of position-specific and piston velocity-specific damping forces.

Claim 1:
A fluid damper shock absorber, comprising:
a damper tube (<NUM>) including an interior surface (<NUM>);
a damper piston (<NUM>) including a piston surface (<NUM>) that engages the interior surface;
a piston shaft (<NUM>) coupled with the damper piston and including a shaft surface that engages a fourth surface (<NUM>,<NUM>,<NUM>); comprising
at least a first zone having a surface treatment (<NUM>) having a first coefficient of friction along the first zone and an adjacent zone (<NUM>) having a different surface treatment having a second coefficient of friction along the adjacent zone on at least one of the interior surface and the shaft surface that create a corresponding plurality of coefficients of friction with at least one of the piston surface and the fourth surface respectively, providing different zones within the shock absorber so that, in use, frictional forces vary between surfaces engaging with the different zones, characterized in that
at least one of the first and second surface treatments provides two different coefficients of friction depending on the direction of movement of the damper piston.