BACKGROUND OF THE INVENTION Suspension systems for vehicles improve the handling and control of the vehicle by absorbing energy associated with uneven terrain due to bumps, depressions, obstacles, and other such features. Various forms of hydraulic suspension systems have been designed to meet the handling and control requirements of the rider. These systems typically consist of an arrangement of two telescoping tubes, two chambers for holding a viscous fluid, seals for keeping the viscous fluid within the chambers, a damper assembly which separates the two chambers, and a damper valve which regulates the flow of the fluid from one chamber to the other.

In a typical arrangement, an outer tube is fastened to the damper assembly at a point on the upper portion of the vehicle and fits over a lower inner tube which is coupled to a wheel of the vehicle. The tubes are arranged to allow them to slide axially in a telescoping fashion in relation to each other. The tubes encompass two chambers which hold a viscous fluid. Seals surround the upper and lower portions of the chambers to keep the fluid within the chambers.

When the vehicle passes over a bump, the outer tube slides axially in a telescoping fashion on the inner tube in compression and rebound. The viscous fluid flows from the lower chamber through the damper valve to the upper chamber to dampen the outer tube's downward or compression motion with respect to the inner tube. During the subsequent rebound motion, the outer tube slides in an upward motion with respect to the inner tube. In the rebound motion, the viscous fluid flows in the opposite direction through the damper valve to dampen the upward motion between the outer tube and the inner tube.

Hydraulic suspension systems exhibit a typical dampening performance. If a small input compressive force is slowly and continuously applied to the system, the viscous fluid will flow through the damper opening and the outer and inner tubes will move axially with respect to each other. Conversely, if a large input compressive force is applied suddenly to

the system, the viscous fluid will not be able to flow through the opening fast enough to allow a rapid relative movement of the two tubes. Accordingly, hydraulic suspension systems exhibit more resistance to large, sudden forces than to small, slow forces.

While hydraulic suspension systems typically exhibit the dampening performance described above, the actual dampening performance of a particular suspension system is a function of the physical characteristics of that system. The amount of resistance exhibited by the hydraulic suspension system depends on the rate at which the viscous fluid can flow through the damper valve from the lower chamber to the upper chamber. A suspension system will exhibit less dampening or resistance in response to a bump if the viscous fluid is permitted to flow more easily through the damper valve. Thus, a hydraulic suspension system with a larger opening between the two chambers will offer less than another system which has a smaller opening.

The prior art has examples of hydraulic suspension systems with telescoping tubes with added features which enable the system to modify the damping performance of the device to a limited degree. In some situations, such as sprinting, up hill travel and for road rides to a trail, it is often desired to temporarily deactivate or reduce the damping performance of the suspension. When the suspension is completely deactivated, the fluid flow from the lower chamber to the upper chamber is cut off such that the outer tube cannot move in relation to the inner tube. When the suspension has reduced damping performance, the outer tube moves more slowly than when the system is fully active. Changing the suspension from active to inactive is done, for example by adjusting the position of the damper valve. In the prior art this adjustment is performed using a rotatable dial located on top of the outer tube.

It is desirable to provide a front suspension system for two wheeled vehicles, and particularly for lightweight bicycles or motorcycles, which can be easily activated and deactivated by the rider.

SUMMARY OF THE INVENTION The present invention allows a rider of a two-wheeled vehicle to easily and instantaneously change the dampening performance of the suspension system from active to inactive in accordance with his or her preference.

The present invention also allows a rider to control the suspension without moving their hands from the preferred riding position.

These and other objects of the present invention are achieved by providing a responsive suspension system comprising a damper having a pair of telescoping outer and inner tubes, a motor associated with these tubes, a switch for the rider to activate, a damper controller arranged to react to actuation of the switch, and a movable valve operatively engaged to the motor for providing damping or not in response to the damper controller and in accordance with the operator's preferences.

More particularly, the damper has a fluid chamber associated with one of the outer and inner tubes and a lockout piston associated with the other of the outer and inner tubes for dividing the fluid chamber into a lower portion and an upper portion. The lockout piston includes a plurality of apertures for flowing the fluid between the portions of the fluid chamber. The valve is located within the hollow interior of the lockout piston. More preferably, the lockout piston includes two apertures one in fluid communication with each of the fluid chamber portions.

In the open position, the valve is unaligned with either of the apertures and the fluid can readily flow between the portions of the fluid chamber. Thus, the lockout piston is active. In this position, the lockout piston preferably provides substantially no dampening when bumps are encountered so that the outer tube can move relative to the inner tube.

However, a second piston, such as a shimmed piston, is provided to control the damping force when the lockout piston is active. In the closed position, the valve is aligned with at least one of the apertures so that fluid cannot flow between the portions of the fluid chamber. Thus, the lockout piston is inactive. In this position, the lockout piston does not allow any movement of the outer tube to the inner tube.

In a preferred embodiment, the motor is located external to the fluid chamber and is coupled to the valve so that upon actuation of the switch the motor moves the valve between the open position and the closed position. In this embodiment, the valve preferably slides between the open and closed positions.

In another embodiment, the fluid chamber is contained within a self-contained cartridge that is coupled to the inner or outer tubes, and the cartridge further includes an air chamber.

In yet another embodiment, the valve and lockout piston are configured so that the valve rotates between the open and closed positions.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of a bicycle according to the present invention.

Fig. 2 is a perspective view illustrating a preferred form of suspension fork according to the present invention.

Fig. 3 is a side view of the suspension fork of Fig. 2 partially cut away to show a dampening cartridge of the present invention.

Fig. 4 is an enlarged, perspective view of a telescoping assembly of the suspension assembly of Fig. 3.

Fig. 5 is an exploded, front view of the suspension assembly of Fig. 4 in the fully extended position.

Fig. 6 is an enlarged cross-sectional view showing details of portions of the cartridge of Fig. 5.

Fig. 7 is an enlarged, cross-sectional view showing details of portions of an alternative embodiment of a spool for the cartridge of Fig. 6.

Fig. 8 is a plan view of a second embodiment of a bicycle according to the according to the present invention.

Fig. 9 is a diagrammatic axial cross-sectional view of an alternative embodiment of the dampening cartridge of the present invention.

Fig. 10 is a partial cross-sectional view of another embodiment of the suspension for use on the bicycle of Fig. 8.

Fig. 11 is a partial cross-sectional view of yet another embodiment of the suspension for use on the bicycle of Fig. 8.

Fig. 12 is a cross-sectional view of another embodiment of the suspension for use on the bicycle of Figs. 1-3.

Fig. 13 is a partial, front perspective view of third embodiment of a bicycle according to the present invention.

Fig. 14 is an enlarged, rear perspective view of a portion of the bicycle shown in Fig. 13.

Fig. 15 is an enlarged, plan view of a telescoping assembly of the suspension assembly of Fig. 13.

Fig. 16 is a cross-sectional view of the telescoping assembly taken along the line 16- 16 of Fig. 15.

Fig. 17 is an enlarged cross-sectional view showing details of portions of the cartridge of Fig. 16.

Fig. 18 is an enlarged cross-sectional view showing details of portions of the cartridge of Fig. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENT Fig. 1 shows the responsive front suspension system 100 and/or rear suspension system 102 of the present invention, installed on a bicycle 110. This system is particularly useful for bicycles and motorcycles. Referring to Fig. 2, the front suspension system 100 is comprised of two outer tubes 120 that are secured to a steering tube 130. The steering tube 130 is rotatably secured to the head tube 135 of the bicycle. A top bracket 140 and a bottom bracket 150 are used to secure the outer tubes 120 to the steering tube 130. Handle bars 155 are fixed to the upper end of the steering tube 130.

The suspension system 100 is further comprised of a unitary front fork 160 for rotatably supporting a front wheel 175 of the bicycle. The unitary front fork 160 is tubular to provide torsional and bending stiffness.

Inner tubes 170 are arranged in a telescoping fashion with respect to the outer tubes 120. The lower ends of the inner tubes 170 are fixed to the front fork 160. A plurality of flats 180 on the outer surface of the inner tubes 170, a plurality of flats on the inner surface of the outer tubes 120 and sets of needle bearings disposed therebetween prevent relative rotational movement between the tubes 120 and 170.

Turning to Fig. 3, as will be discussed in more detail below, in this embodiment, only one dampening cartridge 190 is required to be disposed in one of the outer and inner tubes 120,170 and has an elastomeric member 200 and coil spring 205 in series. However, the elastomeric member and coil spring can be removed. The other outer tube 120 and inner tube 170 only has the elastomeric member 200 or the coil spring 205 therein. The elastomeric member 200 and coil spring 205 can be replaced with mechanical air shocks, whose structure is familiar to those skilled in the art. This creates a suspension system

where the spring and damping elements are in parallel, which provides greater travel for the suspension system. This configuration is particularly suit for the suspension systems shown in Figs. 1,2, and 8.

The fork 160 is configured and attached to the inner tube 170 such that a longitudinally extending axis L of the inner and outer tubes 170 and 120 will intersect or approximately intersect the attachment point for the front wheel, i. e., the axle brackets 240.

In order to accomplish this, the fork 160 is comprised of a lower end 160a and an upper end or bridge section 160b. The upper end 160b is forwardly offset from the lower end 160a.

The lower end of the inner tube 170 is secured to the upper end 160b of the front fork 160 approximately half way down the front fork 160. In the preferred embodiment, the fork upper end 160b is bent forward by an angle 0 from the axis L of the lower end 160a and the inner and outer tubes 170 and 180. The angle @ is preferably about 15 to 45 degrees and, most preferably, about 22 degrees. Thus, the upper end 160b is forwardly disposed from the lower end 160a and the outer tubes 120 by a distance D and can clear the outer tubes 120 and the bottom bracket 150, which enables the suspension system 100 to have greater travel.

Referring to Fig. 1, as subsequently explained, a damper controller 210, which controls the dampening performance of the damping cartridge 190, is preferably mounted within the handle bars 155. The preferred controller is an open-loop controller, as is known by those of ordinary skill in the art.

A switch 225 is provided on the handle bars 155 of the bike. The switch is in electrical communication with the controller.

A power source, preferably a battery 230, is also preferably mounted within the handle bars 155. It supplies power to an electrical component within the damping cartridge 190, the damper controller 210, and the switch 225. The battery 230 is connected by wiring 235 to an electrical component of the damper cartridge 190, the damper controller 210, and switch 225. It is preferred that a 9-volt battery is used. Alternatively, the battery may be located in the damper controller unit. Instead of a battery, the power source may be provided by propulsion of the bicycle itself, by means of a small generator driven by one or both of the bicycle wheels.

Fig. 4 illustrates the telescoping assembly 250, which is comprised of the inner tube 170 and the outer tube 120 which are coaxially arranged. The inner tube 170 coaxially

translates within or telescopes out from the outer tube 120 along the longitudinal axis L.

Both the inner and outer tubes are essentially hollow cylinders, preferably formed from aluminum or other non-corrosive metal. A plurality of needle bearing cages between the inner and outer tubes provides for frictionless motion therebetween. In order to provide the desired preload yet avoid overloading which would cause undue friction to any telescoping motion, the assembly method may require a precise fit of the components.

As shown in Fig. 5, the inner tube 170 includes internal threads 260 on the first end thereof. The inner tube 170 has a central passage 280 of a generally circular cross section.

One end of the outer tube 120 includes internal threads 300. Though the inner tube 170 is shown with a round inner tubular cavity, the cavity may be square shaped and still accommodate the shock absorber cartridge. Similarly, the outer tube 120 may comprise a square shaped inner cavity, and in such an embodiment, the inner tube 170 is also preferably comprised of a square tube shape to facilitate the bearing cages.

The damping cartridge 190 is preferably comprised of damping elements integrated into a single self-contained cartridge housing 310. The damping cartridge further includes an upper piston shaft 320 and lower piston shaft 330 coupled by an annular piston 340.

These shafts 320,330 and piston 340 are housed within the housing 310. These shafts and the piston are hollow tubular members and preferably have identical diameters. The piston 340 contains a spool damper valve 350, and the upper piston shaft contains a motor mount 360 and motor 370 (as shown in Fig. 6).

The self-contained cartridge 190 further includes a top cap 380, an intermediate cap 390, and an end cap 400. The top cap 380 has external threads 410 to couple with the outer tube 120 threads 300. The top cap 380 also has an internal bore 420 into which the upper end of the upper piston shaft 320 is coupled, preferably by a press fit.

As shown in Figs. 5 and 6, the intermediate cap 390 caps the upper end of the housing 310 and has threads 430 to couple with the threads 260 of the inner tube 170. The end cap 400 caps the lower end of the housing 310. Thus, the cartridge 190 can be easily installed and removed from the inner and outer tubes 170,120 as a unit and provides dampening to restrain the translational movement therebetween.

The end cap 400 is configured to slideably receive the lower piston shaft 330 therein. The lower end of the lower piston shaft 330 has a piston 435 coupled thereto. As shown in Fig. 3, the piston 435 engages the springs 200 and 205. The piston 340 includes

a flange 440 integrally formed on a circumferential portion thereof. The flange 440 divides the housing 310 into two chambers, an upper chamber 450 and a lower chamber 460. Both chambers 450 and 460 hold a viscous liquid such as SAE 5 weight oil. A seal 470 formed between the housing 310 and the intermediate cap 390 confines the viscous liquid within the upper chamber 450.

The two chambers 450,460 are separated by a first O-ring 480 which occupies the flange 440 in the piston 340. The O-ring seal 480 prevents oil leakage between the upper and lower chambers 450,460.

The piston 340 further includes a pair of longitudinally spaced first and second openings 490 and 500, and rebound channels 510. The first or upper opening 490 is positioned above the flange 440, while the second or lower opening 500 is positioned below the flange. Openings 490,500 communicate with chambers 450,460, respectively.

The channels 510 longitudinally extend from one side of the flange 440 to the other.

The channels 510 have openings 520 below the flange. A second O-ring seal 530 surrounds the openings 520 and is disposed in a groove to prevent its lateral movement. The channels 510 provide an ancillary pathway for rebound fluid flow, as discussed below.

The substantially cylindrical spool valve 350 is a two-position valve that comprises a primary pathway for oil flow between chambers 450,460. The primary pathway is now described. The spool valve 350 is provided with a pair of slotted, longitudinally extending grooves, one groove 535 is shown. The grooves are formed on the outer surface of the spool valve. The grooves 535 are circumferentially spaced 180° apart. The grooves 535 can be aligned with the upper openings 490 in the piston connect shaft, and have a length at least equal to the width from one opening 490 to the other opening 500. Referring to Fig. 7, the spool valve 350'can be modified so that it is hollow with a first pair of openings 535', and a second pair of openings 540'being circular in shape. The openings in each pair are spaced circumferentially 180° apart. The first pair of openings 535'can be aligned with the upper opening 490. The second pair of openings 540'can be aligned with the lower opening 500.

Turning again to Fig. 6, the spool valve 350 also includes an index groove 550 in the stepped upper portion of the spool valve. The index groove 550 circumferentially extends 90°. The upper piston shaft 320 also includes an index pin 560, which radially extends inwardly to be received within the index groove 550.

Spool valve 350 further includes drive shaft 570 extending from the upper end thereof along the longitudinal axis L. The drive shaft 570 is integrally formed with the spool valve 350, but it can also be formed separately and pressed or bonded in place.

The motor mount 360 is fixed to the upper end of the piston connect shaft 340. The motor mount is tubular and receives the motor 370 therein. The motor mount supports the motor so that a rotatable drive shaft 580 of the motor is concentric with the spool valve drive shaft 570. The motor mount 360 also acts to prevent movement of the motor 530.

The motor mount 360 has two circumferentially spaced openings 600 formed therein for assisting in loading the fluid into the upper piston shaft 320, and bleeding air out of the system. The motor mount 360 can be formed integrally with the piston connect shaft 340.

The motor is mounted within the fluid chamber.

A coupling 575 operatively engages the motor drive shaft 580 to the spool drive shaft 570 such that the motor controls the spool valve 350 which, in turn, controls the flow of viscous liquid between the two chambers 450,460. The motor rotates the motor drive shaft 580 about the longitudinal axis L, which, through the coupling, rotates the spool drive shaft 570 and spool valve 350 about the longitudinal axis L. The motor 370 is activated by the damper controller 210 via control lines 235.

The upper end of the upper piston shaft 320 also includes an annular member 630 for retaining a seal 640 therein to seal the fluid within the interior of the upper piston shaft.

A threaded tubular member 650 is disposed centrally through the annular member 630 for receiving the control lines 235. To ensure the sealing of the upper piston shaft 320 potting compound 660 is used around the tubular member 650. There is also fluid within the interior of the lower shaft and piston connect shaft.

As described further below, damper controller 210 selectively turns the motor 370 on and off such that the motor shaft 580 is driven in a predetermined direction based on the polarity of the signal from the damper controller 210. The magnitude and/or duration of this signal controls the speed of the motor and the length of travel, which will be the same for each actuation.

The motor 370 controls the dampening performance of the damper 190 by moving the spool valve 350 with respect to the piston connect shaft 340 to adjust the alignment between the openings 540 and slotted grooves 535 of the spool valve 350 and the corresponding openings 500,490 of the piston connect shaft 340.

If the grooves 535 are not aligned with the openings 500,490 of the piston connect shaft, then the spool valve 350 is in a closed position. In the closed position, the suspension system is deactivated. This is because the oil, or other viscous liquid, cannot pass through from the lower chamber 460 to the upper chamber 450 when a bump is experienced. As a result, the outer tube 120 cannot move downward with respect to the inner tube 170.

Conversely, if the grooves 535 are aligned with the openings 500,490 of the piston 340, then spool valve 350 is in an open position. In the open position, the suspension system is activated and a small damping force results. When a bump is encountered and the spool valve is in the open position, the oil in the lower chamber 460 enters into the interior of the piston 340 through the lower opening 500, flows through the grooves 535 in the spool valve 350 and out into the upper chamber 450 through the upper opening 490. And the outer tube 120 is free to move with respect to the inner tube 170.

Referring to Figs. 3 and 5, downward movement of the outer tube 120 also causes the upper piston shaft 320, piston 340, lower piston shaft 330, and piston 435 to move downwardly. The piston 340 passes fluid through the spool valve 350 between the chambers 460,450. Thus, allows the piston 435 to compress the springs 200 and 205 and provide the dampening effect of the shock absorber system.

Thus, the grooves 535 of the spool valve 350 and the openings 500,490 of the piston connect shaft 340 form a primary pathway for conveying the viscous fluid between the two chambers 460,450. The viscous liquid flows from the lower chamber 460 to the upper chamber 450 during compression of the damper 190, i. e., the"downward stroke."The liquid flows in the opposite direction during rebound of the damper after a bump, i. e., during the"upward stroke."A 90 ° rotation of the spool valve is preferably used to change it between the open position and the closed position. In the embodiment shown in Fig. 7, the compression and rebound flow pass through the interior, of the spool valve using the openings 535'and 540'therein.

Referring to Figs. 1 and 6, in response to the rider actuating the switch 225, an actuation signal is generated that is input into the damper controller 210. The damper controller 210 sends a control signal to the motor 370, to adjust the position of the spool valve 350. The motor rotates the spool valve 90° in a first direction, which changes the spool valve between the open and closed positions. Upon receiving another actuation signal from the switch, the damper controller sends another control signal to the motor to drive the

motor 90 ° in a second, opposite direction, again, changing the spool between the open and closed positions. The index pin 560 and groove 550 act as a mechanical stop for the motor rotation and prevent the motor 370 from over rotating the spool valve 350 in either direction. The actuation of the valve is almost instantaneous requiring less than about 1 second, and preferably about 0.5 seconds.

The ancillary pathway is discussed next. Regardless of the fluid pressure in the lower chamber 460 it cannot overcome the second seal 530, and cause oil to flow through the channel 510 into the upper chamber 450. Any force applied by the liquid to the seal 530 from the lower chamber 460 urges the seal 530 into the opening 520, preventing the aforementioned flow. However, if fluid pressure in the upper chamber 450 is large enough, the fluid applies a force to the second seal 530 which urges it away from the channel opening 520. This allows the fluid to flow slowly from the upper chamber 450 to the lower chamber 460 through the channel 510. This auxiliary flow allows the outer tube rebound oil to rise slowly if the suspension is locked during a compression stroke. Also, both pathways may be used during rebound when a bump is encountered by the suspension system.

In the preferred embodiment, the damper valve 350 will have a body diameter of about 0.3 to 0.4 inches. The entire assembly will operate at a maximum ambient temperature of 130 degrees fahrenheit and consume less than 1.0 watt of power at voltages ranging from 3.0 volts to 12.0 volts. Other operating specifications include a minimum operating frequency of between 300-500 Hz, a maximum flow rate of 0.4 GPM at 1000 psi, a maximum leakage of 0.02 GPM at 1000 psi, and a minimum relief pressure of 500 psi.

The design of the damper, and particularly the circumferential holes in the piston 340, allows one to use a low weight motor 370 to control the damper valve 350. In the preferred embodiment, the motor 370 is a bi-directional brushless DC motor with planetary gears (SPH50003), available from RMB. The SPH50003 consists of a brushless motor in line with multiple gear stages. The gears are planetary reduction gears with a predetermined transmission rate of 1: 125. Thus, for every 125 motor rotations the drive shaft rotates once.

The SPH50003 has a very fast response time due to the transmission rate, and is compact.

Since the interior of the entire cartridge including the inside of the upper piston shaft and lower piston shaft is full of oil, the motor is submerged in oil and a less powerful motor can

be used. This oil also allows minimal friction between the spool valve and the piston connect shaft.

A dampening cartridge similar to that discussed above can also be used to provide electronic dampening to the rear suspension 102 (as shown in Fig. 1) of a bicycle. The rear suspension can be activated by the same switch as the front suspension or by a separate switch.

Referring to Figs. 8 and 9, there is shown a bicycle with the suspension system 800 mounted in a head tube 820. A switch 225'is disposed on the hand grip portion of the handle bars. The bicycle front wheel 175 is mounted on the lower ends of front fork 810 that extend outwardly and then downwardly from either side of a fork upper end 811. The front fork is telescopically supported by the head tube 820 of the bicycle frame. An outer tube 840 is rotatably mounted within the head tube 820 on upper and lower headset roller bearings 822,824 that are housed within shoulders in respective upper and lower head tube collars 823,825. An inner tube 890 is coaxially and telescopically mounted within the outer tube 840 with needle bearings 830 interposed between the inner tube 890 and the outer tube 840 to provide a low-friction telescoping mechanism.

A lower collar 845 is attached to the outer tube 840 by a threaded connection 845a, and an extensible bellows boot 815 is secured between the lower collar 845 and the fork upper end 811. The boot 815 readily extends and contracts lengthwise with the motion of the suspension and keeps debris and dust from entering the internal mechanisms of the system.

The lower end of the inner tube 890 is received by and affixed to the fork upper end 811 and extends upwardly and telescopically into the lower portion of the outer tube 840.

Spring support of the relative motion of the inner and outer tubes is provided by an elongated elastomeric spring or coil spring element 884 that is received within the lower portion of the inner tube 890. The elastomeric spring element 884 is compressed between a piston 882 and a bottom cap 886, which closes the bottom end of the inner tube 890. The bottom cap 886 is held in place in the lower end of the inner tube 890 by a clip 888 which is received in an internal annular groove. The tubes 840 and 890 are preferably circular in cross-section but may be square or some other suitable shape.

The piston 882 is integral with the lower end of a lower piston shaft 880 that extends upwardly telescopically through the tubes and is positioned concentrically within the tubes

840 and 890. The lower piston shaft is joined to the upper piston shaft 881 via piston 876.

The upper end of the upper piston shaft is coupled to a top cap 850. The top cap 850 is affixed to the outer tube 840 by a threaded connection 852 and has a pair of holes 853 which allow insertion of an appropriate tool to assist in tightening or removing the cap 850.

A preload system may be incorporated into this system as known in the art. The elastomeric spring element 884 operates primarily as a spring. According to the present invention, damping that is actuatable"on the fly"is incorporated into the telescoping motion. In a preferred embodiment, such damping is provided by a hydraulic damping unit 870. The damping unit 870 is received above the elastomeric spring 884 and is provided by a piston/cylinder, the cylinder forming a hydraulic chamber 871 that is annular and is defined internally by the lower piston shaft 880 which is a moving wall for the annular chamber, and externally by a cylinder member 872. The cylinder is threadably coupled to the inner tube 890.

A lower end cap 877 is suitably affixed, such as by a rolled joint, to the lower end of the cylinder member 872 and is sealed to the lower shaft 880 by a seal. Similarly, an upper end cap 878 is affixed to the upper end of the cylinder member 872 and sealed to the upper piston shaft 881 by a seal. Accordingly, the volume of the annular chamber of the damping unit remains constant throughout the range of motion of the piston 876 within the annular chamber. The chamber 871 is filled with a suitable hydraulic liquid such as oil, and the piston has associated with it openings a spool valve 891, and a motor 892, as discussed above.

The shock absorber also includes a top-out cushioning bumper 879 of elastomeric material positioned between the piston 876 and the end cap 878 to provide a cushioning effect during top-out, cushioning the system during rebound after large impacts. The bumper is a ring and may be made of any suitable elastomeric material.

Fig. 10 illustrates an alternative embodiment of a suspension system. The suspension system comprises an inner tube 909 that is fixed at its lower end to front fork 906 so that the inner tube can move vertically with the wheel. The inner tube 909 is received within outer tube 910 and can slide therein by virtue of slide bearings 911 provided between the outer surface of an annular block 912 screwed to the top of the inner tube 909 and the inner surface of outer tube 910. The outer tube 910 is received within the head tube (not shown in Fig. 10) and connects at the top with the handle bars in any conventional

manner. At the bottom of the outer tube are projecting lugs 913 having threaded bores 914 for connection to a steering linkage.

The inner tube is divided into a pneumatic chamber 915 and a hydraulic chamber 916. These two chambers are divided from each other by means of a free piston 917 sealed by an 0-ring 918.

The pneumatic chamber 915 is defined by the lower face of piston 917 and the upper face of a plug 919 fitted to the bottom of the suspension which includes a screw-threaded valve 952. The pneumatic chamber is charged with a pressurized gas, preferably an inert gas such as nitrogen. The pressure of the gas can be pre-set to take account of the varying loads for which the suspension system is designed.

The hydraulic chamber 916 above piston 917 contains hydraulic fluid and is divided into two portions by a fixed piston 920. Piston 920 is fixed to the lower end of a hollow piston tube 921, the upper end of which is fixed to a top cap 922 fitted in the top of the outer tube 910. Sliding seals, such as 0-rings, 923, permit the inner tube to move axially relative to the piston 920 and piston tube 921. The two sides of the piston 920 communicate via a needle valve comprising a valve rod 924 and a valve seat 925. The upper end of the valve rod 924 is coupled to a motor drive shaft 926 of a motor 927 within the piston tube 911 such that rotation of the motor drive shaft 926 causes the valve rod 924 to move relative to the seat 925 to vary the valve opening. A spring 928 is provided between free piston 917 and fixed piston 920 to provide additional load carrying capacity.

The ratio of pneumatic to spring pressure is selected to optimize overall suspension linearity. The ratio of minimum gas chamber volume to maximum determines the rising rate characteristic of the suspension system.

When the bicycle is ridden over rough terrain, or otherwise experiences a vertically directed shock, the inner tube 909 moves vertically relative to the outer tube 910 and the fixed piston 920. This relative movement is, however, limited by the rate at which the in- compressible hydraulic fluid can flow from one side of the piston 920 to the other. For example, if the inner tube 909 moves upwardly fluid must flow from below piston 920 to above it. This flow rate, and thus the degree of damping provided by the suspension, is controlled by the opening of the needle valve. If the needle valve is fully open, fluid can flow relatively easily and a low degree of damping for the rider is provided: the suspension is soft. If the needle valve is closed, the suspension becomes substantially ineffective and

no damping is experienced by the rider, the bicycle assuming the ride characteristics of a conventional bicycle. It will be appreciated that control of the degree of damping is simply affected by varying the opening of the needle valve by actuating the motor by a switch on the handle bars and damper controller as discussed above. The motor moves the valve between the open and closed positions.

Fig. 11 illustrates an embodiment very similar to that of Fig. 10 and thus like parts will not be described again. In this embodiment, the valve rod 953 is coupled to the motor drive shaft 926 of the motor 927 within the piston tube 921 and fixed piston 930. Piston 930 is provided with upper and lower extending portions 931,932 that do not extend radially completely to the walls of the inner tube. Instead, portions 931,932 are provided with circumferentially arranged holes 933 that form matching pairs in the two portions. The valve rod 953 is provided with an axial groove 934 and communication of fluid between the two sides of the piston is achieved by rotating the valve rod 953 so that the groove 934 connects a pair of said holes 933. When the valve rod is positioned such that no holes are connected by the groove, no hydraulic flow is provided. This is the closed position. The motor 927 through the drive shaft 926 opens and closes the valve as discussed above. This embodiment is preferred because the motor does not have to overcome any force on the valve during the compression stroke.

It will be appreciated that as the inner tube 909 of the embodiments of Figs. 10 and 11 moves into outer tube 910, the valve rods 924,953 effectively extends further into the hydraulic chamber. Since the hydraulic fluid is incompressible this is only possible since the gas chamber 915 can be reduced in volume accordingly to compensate for the change in volume of the hydraulic chamber caused by the valve rod. The pneumatic chamber 915 could however, be provided elsewhere, e. g., within the hydraulic chamber, or could be omitted if an alternative form of volume compensating means were provided.

Turning now to Fig. 12, another embodiment of the suspension 1000 is shown which includes spring and damping elements integrated into a single cartridge housing 1005. The suspension 1000 can be easily installed and removed from the inner and outer tubes 170 and 120 (as shown in Figs. 1-3) and provides resiliency and dampening to restrain the translational movement therebetween and dampens shocks. The suspension system 1000 is configured with an air spring 1010 and hydraulic damper 1015 in series and is particularly suited for the suspension systems shown in Figs. 1 and 3.

The suspension system 1000 further includes a piston shaft 1020 connected to a piston 1025 at one end for dividing the fluid in the chamber into a first chamber 1040 and a second chamber 1042 and a top cap 1030 at the other end for securing the piston shaft to the outer tube (not shown). The suspension also has an internal piston shaft 1022 that is coupled to a dial 1032 at a top end and extends to the piston 1025. The piston 1025 includes a plurality of apertures 1027 around the circumference for allowing flow from one side of the piston to the other. Preferably, these apertures 1027 are shimmed to provide little, if any, restriction to compression stroke flow and restricted rebound flow. The piston 1025 further includes a central aperture 1028 and valve seat 1029. The internal piston shaft 1022 extends to the valve seat 1029. The dial 1030 rotates the internal piston shaft 1022 to move the shaft and control the rebound flow through the valve 1029.

A fixed bulkhead 1035 further divides the hydraulic fluid damper 1015 into the first chamber 1040 and a lower third chamber 1045. Both chambers contain a viscous fluid such as oil. The bulkhead 1035 includes features similar to the piston 340 (shown in Fig. 6) such as upper and lower openings for compression flow between the upper and lower chambers, a motor 1050, and spool 1055, as described above. The bulkhead 1035 also has a plurality of apertures for allowing unrestricted rebound flow from the lower chamber 1045 to the upper chamber 1040.

A lower piston 1060 separates the air spring 1010 from the hydraulic damper 1015.

The lower piston 1060 is a floating piston, which moves within the housing 1005.

If the spool 1055 is in the open position, as the piston shaft 1020 moves into the cartridge housing 1005 (i. e., compression stroke) it moves the upper piston 1025 toward the bulkhead 1035. The oil flows from the upper chamber 1040 to the lower chamber 1045 causing the lower piston 1060 to move toward the closed end 1065 of the cartridge. This compresses the air spring 1010. Compression of the air spring provides the resiliency effect of the system.

If the spool 1055 is in the closed position, the oil cannot flow from the upper chamber 1040 to the lower chamber 1045 and the piston shaft 1020 cannot move. Thus, the bulkhead 1035 through the spool 1055 controls the compression flow. The motor 1050 rotates the spool 1055 between the open position and the closed position, as discussed above.

During the rebound stroke, the compressed air pushes the oil, unrestricted, through the bulkhead 1035. This pushes the piston 1025 upward, flowing oil from the second chamber 1042 to the first chamber 1040. The location of the inner piston shaft 1022 controls the rebound flow of oil from the second chamber 1042 to the first chamber 1040 as discussed above.

Figs. 13 and 14 show another embodiment of a bicycle 2000 including a single- sided fork suspension 2002. The single-sided fork suspension 2002 has an outer tube 2004, an inner tube 2006, and a steering tube 2008. The inner tube 2006 is arranged in a telescoping fashion with respect to the outer tube 2004 as discussed above.

Recirculating bearings are located between the outer and inner tubes. The details of this and various other single-sided and dual-sided forks that can be used with the present invention are disclosed in U. S. Patent Application No. filed January 22, 1999, and entitled"Vehicle Suspension Fork", which is incorporated by reference herein in its entirety.

The outer tube 2004 is connected to the steering tube 2008 via an upper bracket 2010 and a lower bracket 2012. Inner and outer telescoping tubes 2004,2006 are offset laterally from the steer tube 2008, which preferably has a steering axis 2014 that extends through the wheel 2016. Thus, the wheel is disposed laterally below the steer tube 2008.

The steering tube 2008 is attached to handlebars 2018 and is rotatably secured to a bicycle or motorcycle frame via a head tube. Inner tube 2006 has an axle 2024 coupled thereto for rotatably supporting the wheel 2016.

Referring to Fig. 14, as subsequently explained the fork suspension further includes a damper controller 2026, which controls the dampening performance of the suspension system. The damper controller 2026 is preferably mounted within outer tube 2004 at the top thereof. The preferred controller is an open-loop controller, as is known by those of ordinary skill in the art. A switch 2028 is connected to the handle bars 2018 of the bike remote from the controller 2026. The switch 2028 is in electrical communication with the controller 2026.

A power source, preferably a battery 2030, is also preferably mounted within the outer tube at the top thereof. It supplies power to an externally mounted motor 2064 (as shown in Fig. 16), the damper controller 2026, and the switch 2028. The battery 2030 is connected by wiring 2032 to the switch 2028, the motor, and the damper controller 2026. It

is preferred that a 9-volt battery is used. Alternatively, the battery may be located in the damper controller unit. Instead of a battery, the power source may be provided by propulsion of the bicycle itself, by means of a small generator driven by one or both of the bicycle wheels.

Turning to Figs. 15-16, the suspension further includes a dampening cartridge 2034, which is preferably comprised of damping elements integrated into a single self-contained cartridge housing 2036. The damping cartridge 2034 includes an upper piston shaft 2038 and a lower piston shaft 2040 coupled by a lockout piston 2042, a shimmed piston 2044, and an internal shaft 2046. These piston shafts 2038 and 2040 and the pistons 2042,2044 are hollow tubular members and preferably have identical diameters. The lockout piston 2042 contains a moveable damper valve 2048. The outer diameter of the damper valve and the inner diameter of the lockout piston have less than about 0.0005 inches clearance so that the valve can move, but fluid cannot flow between these components.

Referring to Figs. 16 and 13, the cartridge 2034 further includes a top cap 2050, an intermediate cap 2052 and an end cap 2054. The top cap 2050 has external threads (not shown) to couple with internal threads (not shown) on the outer tube 2004. The top cap 2050 also has an internal bore 2056 into which the upper end of the upper piston shaft 2038 is received, preferably by a press fit.

The intermediate cap 2052 covers the upper end of the housing 2036 and has external threads (not shown) to couple with the internal threads (not shown) of the inner tube 2006. Thus, the threads on the upper cap and intermediate cap secure the cartridge 2034 within the outer and inner tubes. The end cap 2054 covers the lower end of the housing 2036 and has a valve 2056 there through. The cartridge 2034 is easily installed and removed from the inner and outer tubes 2004,2006 as a unit.

Referring to Fig. 16, the cartridge further includes a fixed bulkhead 2058 within the housing 2036. The intermediate cap 2052 and the bulkhead 2058 define a hydraulic chamber 2060 there between, which contains a viscous liquid such as SAE 5 weight oil. A seal formed between the housing 2036 and the intermediate cap 2052 confines the viscous liquid within the hydraulic chamber 2060 of the housing.

The bulkhead 2058 and the end cap 2054 define an air chamber 2062 therebetween, which contains air that acts as an air spring. The air pressure within the air chamber 2062 is variable by adding and removing air using the valve 2056 in the end cap.

The top cap 2050 receives the motor 2064 which has a lead screw 2066 that extends through the bore 2056 in the top cap. In the preferred embodiment, the motor 2064 is a stepper motor. For example, one recommended motor is commercially available from HIS under the name Z-series stepper motors. The lead screw 2066 converts rotational movement of the motor about a longitudinal axis L into longitudinal movement along the axis L. The lead screw 2066 is coupled to the upper end of a connecting rod 2068 that extends through the center of the upper shaft 2038. The connecting rod 2068 extends through the intermediate cap 2052 and into the center of the lockout piston 2042, where the lower end of the connecting rod is coupled to the valve spool 2048.

Referring to Fig. 17, the lockout piston 2042 includes a flange 2070 integrally formed on a circumferential portion thereof. An upper extension 2072 extends from the upper surface of the flange 2070 and a lower extension 2074 extends from the lower surface of the flange 2070. Both of these extensions have an external circumferentially extended ridge 2076,2078, respectively. The ridges 2076,2078 mate with internal circumferentially extend grooves 2080,2082 within the upper piston shaft 2038 and the shimmed piston 2044, respectively. The ridges 2076,2078 and grooves 2080,2082 couple the lockout piston to the upper piston shaft and the shimmed piston.

The lockout piston 2042 further defines a pair of longitudinally spaced first and second openings 2084,2086. The first or upper opening 2084 is positioned above the flange 2070 in the upper extension 2072. The second or lower opening 2086 is positioned below the flange 2070 in the lower extension 2074. Each opening has a width Wo, which is about 0.100". Each opening further has a height H of about 0.315 inches and a thickness of about 0.160 inches. These dimensions allow the lockout piston to function as discussed below.

Referring again to Fig. 18, the shimmed piston 2044 includes a flange 2088 integrally formed on a circumferentical portion thereof. The flange 2088 has a plurality of longitudinally extending apertures 2090 which have shims 2091 thereon. The shims 2091 are aligned with the aperture 2090 on the upper surface of the flange 2088. The shims control the damping force by restricting compression flow during the compression stroke.

Other shims can be provided on the opposite flange surface to control flow during the rebound stroke. These types of shimmed pistons are known by those of ordinary skill in the art.

The shimmed piston 2044 further includes an upper extension 2092 that extends from the upper surface of the flange 2088. The upper extension 2092 is coupled to the lockout piston 2042 by the ridge 2078 and groove 2082 (as shown in Fig. 16). The upper extension 2092 further includes a stop surface 2094.

The shimmed piston 2044 also includes lower extension 2094 that extends from the lower surface of the flange 2088. The lower extension 2094 is coupled to the internal shaft 2046 which extends within the lower piston shaft 2040.

Referring to Figs. 16 and 18, the hydraulic chamber 2060 is divided into a plurality of chambers by the pistons 2042,2044 and bulkhead 2058. An upper hydraulic chamber 2096 extends between the intermediate cap 2052 and the lockout piston flange 2070. An intermediate hydraulic chamber 2098 extends between the lockout piston flange 2070 and the shimmed piston flange 2088. A lower hydraulic chamber 2100 extends between the shimmed piston flange 2088 and the bulkhead 2058. A plurality of O-rings 2102 are disposed within grooves in the intermediate cap 2058, the connecting rod 2068, piston flanges 2070,2088, and the internal shaft 2046 to prevent oil leakage out of the hydraulic chamber 2060 or between hydraulic chambers.

Referring to Fig. 17, the upper openings 2084 in the lockout piston is in fluid communication with the upper hydraulic chamber 2096. The lower opening 2088 in the lockout piston is in fluid communication with the intermediate hydraulic chamber 2098.

Fluid communication between the intermediate hydraulic chamber 2098 and the lower hydraulic chamber 2100 occurs through the aperture 2090 (as best shown in Fig. 18) in the shimmed piston 2044.

The substantially cylindrical valve 2048 is a two-position valve that allows a primary pathway for oil flow between the upper and intermediate hydraulic chambers. The primary pathway is now described.

The valve 2044 has an open position (as shown), where the valve is in contact with the surface 2094 and is unaligned with the openings 2084,2086. In the open position, oil can flow between the upper and intermediate chambers 2096 and 2098 via the openings through the interior of the lockout piston. This is the primary flow path. Preferably, the lockout piston has openings so large that in the open position, the lockout piston does not offer substantial resistance to fluid flow. The motor 2064 moves the connecting rod 2068 along the longitudinal axis L, which consequently moves the valve 2048 along the

longitudinal axis between the open and closed positions. The width of the valves travel path is greater than the width of lower opening 2086. For example, the valve travel path width Ws is about 0.150 inches.

Referring to Fig. 16, the lower end of the lower piston shaft 2040 extends through the bulkhead 2058, and includes an air piston 2104. The air piston 2104 includes a flange 2106 integrally formed on a circumferential portion thereof. The flange 2106 divides the air chamber 2062 into an upper air chamber 2108 and a lower air chamber 2110.

Referring to Fig. 16, damper controller 2026 selectively turns the motor 2064 on and off such that the lead screw 2066 is driven in a predetermined direction based on the polarity of the signal from the damper controller 2026. The magnitude and/or duration of this signal controls the speed of the motor and the length of travel, which will be the same for each actuation.

Referring to Figs. 13,14,16, and 17, in response to the rider actuating the switch 2028, an actuation signal is generated that is input into the damper controller 2026. The damper controller 2026 sends a control signal to the motor 2064, to adjust the position of the valve 2048. The motor slides the valve in a first direction, which moves the valve from the closed to the open position. The surface 2094 acts as a lower stop for the motor for the open position of the valve.

In the open position, the suspension system is activated and damping force is controlled by the shimmed piston 2044. When a bump is encountered and the valve 2048 is in the open position, the oil readily flows from the intermediate hydraulic chamber 2098 to the upper hydraulic chamber 2096 through the primary flow path in the lockout piston.

Since, the lockout piston offers little resistance to this flow, the outer tube 2004 is free to move with respect to the inner tube 2006. Downward movement of the outer tube 2004 causes the upper piston shaft 2038, pistons 2042,2044, lower piston shaft 2040, and piston 2104 to move downwardly. The air piston 2104 compresses the air spring 2062 resisting the downward movement of the outer tube.

During the compression stroke, as shown in Fig. 18, the shims 2091 control the flow of oil from the lower chamber 2100 through the aperture 2090 into the intermediate chamber 2098. This auxiliary flow controls the dampening force of the system and the movement of the outer tube during a compression stroke.

During the"upward stroke"or rebound, when the lockout piston is active the oil readily flows from the upper chamber to the intermediate chamber through the primary flow path. The fluid also moves from the intermediate chamber to the lower chamber through the auxiliary path of the shimmed piston. Shims on the lower surface of the shimmed piston can slow the rebound flow, which slows the upward movement of the outer tube with respect to the inner tube.

Upon receiving another actuation signal from the switch 2028, the damper controller 2026 sends another control signal to the motor 2064 to drive the motor in a second, opposite direction, moving the spool valve from the open to the closed position. The upper stop for the valve in the closed position is built into the motor. The actuation of the valve is almost instantaneous requiring less than about 1 second, and preferably about 0.5 seconds. The bike can include a light or indicator 2108 (as seen in Fig. 14) on the outer tube for indicating the damper state.

In the closed position, the suspension system is deactivated. Since the primary flow path is closed, the oil cannot pass through from the intermediate chamber 2098 to the upper chamber 2096. When a bump is experienced, the outer tube 2004 cannot move downward with respect to the inner tube 2006.

If a low battery condition is sensed by the controller, the controller causes the motor to move the valve to the open position where to lockout piston offers no resistance to fluid flow. A low battery light can be used to notify the rider of this condition.

While the above invention has been described with reference to certain preferred embodiments, it should be kept in mind that the scope of the present invention is not limited to these. Also the damping cartridge can be modified so that there is no housing and the chambers are formed by the lower tube. Any of the dampening cartridges described above can be used with the various types of front fork suspensions or the rear suspension. One skilled in the art may find variations of these preferred embodiments which, nevertheless, fall within the spirit of the present invention, whose scope is defined by the claims set forth below.