Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/48—Arrangements for providing different damping effects at different parts of the stroke
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/50—Special means providing automatic damping adjustment, i.e. self-adjustment of damping by particular sliding movements of a valve element, other than flexions or displacement of valve discs; Special means providing self-adjustment of spring characteristics
  • F16F9/516—Special means providing automatic damping adjustment, i.e. self-adjustment of damping by particular sliding movements of a valve element, other than flexions or displacement of valve discs; Special means providing self-adjustment of spring characteristics resulting in the damping effects during contraction being different from the damping effects during extension, i.e. responsive to the direction of movement

Definitions

• This invention relates to a damper and, more particularly, to a damper suitably used as a shock absorber or front fork on the suspension of a bicycle, motorcycle, automobile or other vehicle.
• Dampers shock absorbers, MacPherson struts, front forks, etc.
• Dampers typically comprise a closed hydraulic cylinder with an internal piston connected to a central piston rod, which reciprocates within the cylinder to produce damping forces.
• damping forces created by a damper have a major influence on the overall dynamic performance of a vehicle.
• a wide range of dynamic conditions are encountered during typical vehicle motion over various surfaces and terrain features.
• these features and conditions include large and small bumps, sharp-edged bumps and round-edged bumps, close-spaced bumps and widespaced bumps, stutter bumps and gradual undulating bumps, and so forth.
• conditions include vehicle acceleration and deceleration modes, uphill and downhill travel modes, as well as turning modes .
• damping forces are dynamic modulation of damping forces based on sensing and reacting to internal conditions, common to most conventional dampers, wherein damping forces generally increase as the velocity of the piston increases (there are, however, wide variations in the force-vs-velocity curve shapes and force levels found in various dampers calibrated for specific applications and conditions).
• a damper which includes a conventional cylinder and a piston rod with an attached first piston which divides the interior of the cylinder into two chambers. Fluid flow through the first piston is controlled by an adjoining, pressure-sealed second piston which is driven by pressure differentials to move relative to the first piston. Motion of the second piston relative to the first piston blocks or unblocks flow passages in the first piston, thus creating the compression damping forces produced.
• One drawback of this construction is that it produces a relatively "flat" force vs. velocity compression damping curve (a "blow-off type of damping characteristic), which can be difficult to tune for specific applications and conditions.
• the present invention was developed to provide an improved damper which provides automatic modulation of damping forces based on sensing and reacting to internally-generated or externally-generated conditions, and that avoids the above and other drawbacks of the known prior art.
• One aspect of a preferred embodiment of the present invention is to provide a damper that generates a compression damping rate that is modulated in accordance with an internally-generated pressure.
• An example of an internally-generated pressure is the air or nitrogen pressure found in the wide-variety of conventional "DeCarbon-type" pressurized dampers as have been known in the art for 40 years (reference U.S. patent 3,101,131 to DeCarbon, issued in 1963).
• Another aspect of a preferred embodiment of the present invention is to provide a damper that generates a compression damping rate that is modulated in accordance with an externally-generated pressure.
• An example of an externally-generated pressure would be the pressure that could be created at an end fitting of a compressed external coil-over spring.
• Another aspect of a preferred embodiment of the present invention is to provide a damper that generates a compression damping rate that is modulated in accordance with an independently-regulated pressure.
• An example of an independently-regulated pressure would be a pressure source controlled by computer and supplied to the shock absorber.
• the computer could utilize input from various sensors on the vehicle (for example sensors monitoring vehicle speed and acceleration, as well as the relative positions and velocities of the sprung and unsprung masses) and continuously regulate the pressure supplied to the shock absorber in accordance with a pre-determined algorithm.
• Another aspect of a preferred embodiment of the present invention is to provide a damper that enables the advantages disclosed to be directly utilized in conjunction with a wide variety of known piston constructions with known characteristics and damping curves, as are known and established in the art for various applications, without substantial alteration to these known piston constructions. Additionally, an aspect is to enable said damper to also utilize the external adjustment features of these known prior art dampers, generally without alteration or re-engineering of said external adjustment features.
• Another aspect of a preferred embodiment of the present invention is to provide a damper where the disclosed damping features can be quickly and easily tuned and adjusted by simply rotating one or more readily-accessible external knobs or levers, hi the context of mountain biking applications, for example, those prior-art methods that require an air pressure pump and gauge to alter damping characteristics create a significant interruption in the ride, and thus typically are not done during a ride.
• turning an external knob (or knobs) as described according to the present invention is quick and easy and thus can be done in a routine "on-the-fly" manner frequently during the ride. Since terrain and trail conditions constantly change, this greatly benefits the rider by enabling him/her to continuously select the best damping characteristics for the current situation.
• a preferred embodiment achieves these aspects by providing the disclosed valving structures directly adjoining, or within, a fixed partition member in the damper that partitions a portion of the damper interior into two liquid chambers.
• the disclosed valving structures specifically do not directly adjoin, or comprise part of, the main damping piston connected to the piston rod of the damper.
• the disclosed valving structures react as a function of internal or external pressures to provide damping forces by restricting fluid flow in one direction through the fixed partition member.
• FIG. 1 is a sectional front view of a prior-art embodiment of a pressurized damper unit.
• FIG. 2 is a sectional front view of the prior-art damper of FIG. 1 modified in accordance with a preferred embodiment of the present invention.
• FIG. 3 is an enlarged partial sectional front view of the damper of FIG. 2, showing the added structure of this embodiment of the present invention.
• FIG. 4 is a sectional front view of the prior-art damper of FIG. 1 modified in accordance with a second preferred embodiment of the present invention.
• FIG. 5 is an enlarged partial sectional front view of the damper of FIG. 4, showing the added structure of this embodiment of the present invention.
• FIG. 6 is a sectional view of the damper of FIG. 5, taken through section A-A of FIG. 5.
• FIG. 7 is a sectional front view of the damper of FIG. 4, showing shaft displacement fluid flow through the fixed partition member during an extension stroke of the damper.
• FIG. 8 is a sectional front view of the damper of FIG. 4, showing shaft displacement fluid flow through the intensifier valve during a compression stroke of the damper.
• FIG. 9 is a sectional front view of the damper of FIG. 4 modified in accordance with a third preferred embodiment of the present invention, with the intensifier valve structure moved to the upper end of the damper cylinder, with a remote reservoir assembly added, and with the floating piston re-located from the damper cylinder to the reservoir cylinder.
• FIG. 10 is a sectional front view of the prior-art damper of FIG. 1, modified in accordance with a fourth preferred embodiment of the present invention, with the upper eyelet replaced by a piggyback eyelet with an attached reservoir cylinder, with the floating piston re-located from the damper cylinder to the reservoir cylinder, and with the intensifier assembly located in the upper end of the reservoir cylinder.
• FIG. 11 is an enlarged partial sectional front view of the damper of FIG. 10, showing the added structure of this embodiment of the present invention.
• FIG. 12 is a sectional front view of the damper of FIG. 10, showing this embodiment with the addition of an external intensifler adjusting screw.
• FIG. 13 is an enlarged partial sectional front view of the damper of FIG. 12.
• FIG. 14 is a sectional front view of the damper of FIG. 10, with a fifth preferred embodiment of the present invention located in the upper end of the reservoir cylinder.
• FIG. 15 is an enlarged partial sectional front view of the damper of FIG. 14.
• FIG. 16 is a sectional front view of the damper of FIG. 10, with a sixth preferred embodiment of the present invention located in the upper end of the reservoir cylinder.
• FIG. 17 is an enlarged partial sectional front view of the damper of FIG. 16.
• FIG. 18 is a sectional front view of the prior-art damper of FIG. 1 modified in accordance with a seventh preferred embodiment of the present invention.
• FIG. 19 is an enlarged partial sectional front view of the damper of FIG. 18, showing the added structure of this embodiment of the present invention.
• FIG. 2OA is a sectional front view of the prior-art damper of FIG. 1 modified in accordance with an eighth preferred embodiment of the present invention.
• FIG. 2OB is an alternate version of the damper of FIG. 2OA with modified structure to provide a first alternate shape to the compression damping characteristic produced by an embodiment of the present invention.
• FIG. 2OC is an alternate version of the damper of FIG. 2OA with modified structure to provide a second alternate shape to the compression damping characteristic produced by an embodiment of the present invention.
• FIG. 21 is an enlarged partial sectional front view of the damper of FIG. 2OA, showing the added structure of this embodiment of the present invention.
• FIG. 22 is a sectional front view of the prior-art damper of FIG. 1, modified in accordance with a ninth preferred embodiment of the present invention, including elimination of the floating piston.
• FIG. 23 is an enlarged partial sectional front view of the damper of FIG. 22, showing the added structure of this embodiment of the present invention.
• FIG. 24 is a sectional front view of the prior-art damper of FIG. 1 , modified in accordance with a tenth preferred embodiment of the present invention, including elimination of the floating piston and addition of an intensifier preload spring.
• FIG. 25 is an enlarged partial sectional front view of the damper of FIG. 24, showing the added structure of this embodiment of the present invention.
• FIG. 26 is a sectional view of the damper of FIG. 25, taken through section A-A of FIG. 25.
• FIG. 27 is an enlarged partial sectional front view of the damper of FIG. 24, modified in accordance with an eleventh preferred embodiment of the present invention, including elimination of the intensifier preload spring and addition of an intensifier open-bias spring.
• FIG. 28 is a sectional front view of an air-sprung bicycle shock absorber, modified in accordance with a twelfth preferred embodiment of the present invention.
• FIG. 29 is a sectional front view of the prior-art damper of FIG. 1, modified in accordance with a thirteenth preferred embodiment of the present invention.
• FIG. 30 a sectional front view of the prior-art damper of FIG. 1 modified in accordance with a fourteenth preferred embodiment of the present invention.
• FIG. 31 is an enlarged partial sectional front view of the damper of FIG. 30, showing the specific structure of this embodiment of the present invention.
• FIG. 32 is a sectional front view of a modified version of the damper of FIG. 30, incorporating a fifteenth preferred embodiment of the present invention.
• FIG. 33 is an enlarged partial sectional front view of the damper of FIG. 32, showing the specific structure added to this embodiment of the present invention.
• FIG. 34 is an overall perspective view of the front fork of a bicycle.
• FIG. 35 is an overall sectional front view of one leg of the fork of FIG. 34, incorporating a sixteenth preferred embodiment of the present invention.
• FIG. 36 is a sectional front view of the damper assembly of the fork leg of FIG. 35.
• FIG. 37 is an enlarged partial sectional front view of the damper of FIG. 36, showing the specific structure of this embodiment of the present invention.
• the prior-art damper 100 of FIG. 1 will be described first, in order to provide a point of departure for better understanding the improvements of the present invention, which will be described further on. It is to be understood, of course, that this specific prior-art embodiment is representative only, and that the embodiments disclosed herein may be applied to other types of dampers.
• the prior-art damper 100 is comprised of an upper eyelet 110 and a lower eyelet 112 for attachment to, for example, the sprung and un-sprung portions of a vehicle (not shown).
• the lower eyelet 112 is connected to the piston rod 120 which passes through the seal head 130 and has a damping piston 140 attached at the other end.
• the damping piston 140 reciprocates in the damper cylinder 150 as the sprung and unsprung portions of the vehicle move relative to each other when, for example, the vehicle traverses uneven terrain.
• the damping piston 140 has rebound valving 141 (shown symbolically here) and compression valving 142 (also shown symbolically) for restricting fluid flow during rebound strokes (lengthening) and compression strokes (shortening).
• the valving produces damping forces that resist the imposed motion.
• Many different valving structures for example flexible stacks of disc valves covering flow ports through the damping piston 140, suitable for a variety of applications and condition, are known in the art.
• the damper cylinder 150 is sealed at one end by the seal head 130 and at the other end by the upper eyelet 110.
• a floating piston 160 is sealingly engaged, but free to reciprocate, toward the upper end of the damper cylinder 150.
• the floating piston 160 separates the hydraulic fluid 170 below it from the internally-pressurized chamber 180 above it, which contains a pressurized gas (for example, nitrogen or air).
• the Schrader valve 190 provides access to the internally-pressurized chamber 180.
• the damping piston 140 divides the total amount of hydraulic fluid 170 contained in the damper cylinder 150 into two portions: a portion above the damping piston 140, and a portion below it.
• a portion above the damping piston 140 When the damping piston 140 moves upward in the damper cylinder 150 (a compression stroke) some of the hydraulic fluid 170 above the damping piston 140 flows downward through the damping piston 140, via the compression valving 142, into the area below the damping piston 140.
• the compression valving 142 restricts this flow, creating compression damping.
• the damping piston 140 moves downward in the damper cylinder 150 (a rebound stroke) some of the hydraulic fluid 170 below the damping piston 140 must flow upward through the damping piston 140, via the rebound valving 141, into the area above the damping piston 140.
• the rebound valving 141 restricts this flow, creating rebound damping.
• FIGS. 2 and 3 additional structure in accordance with a first preferred embodiment of the present invention is shown added to the prior-art damper 100 of FIG. 1. Since the structure and function of several of the parts in FIGS. 2 and 3 are substantially identical to those in FIG. 1, the corresponding parts are designated by the same reference numbers as in FIG. 1. (This also generally applies to all other FIGS, which follow.)
• a partition 210 is secured within the bore of the damper by a partition retaining ring 211.
• This partition 210 physically divides the hydraulic fluid into one portion above the partition 210, and another portion below it.
• the partition 210 has a plurality of rebound flow ports 220 covered by a check valve 230 which is lightly biased in contact with the partition 210 by a relatively soft check valve spring 231. Additionally, the partition 210 has a central compression flow port 240 which, in the position illustrated in FIG. 3, is blocked at its upper end by the small end of an intensifier piston 250.
• the intensifier piston 250 is located within an intensifier housing 260, which can be integral with the damper cylinder 150 (as shown), or can be a separate structure sealed and retained within the bore of the damper cylinder 150. During upward movement of the intensifier piston 250 as occurs during operation (to be described in detail further on), the intensifier piston 250 is prevented from exiting the intensifier housing 260 by the intensifier retaining ring 251.
• the intensifier piston is sealingly engaged with the intensifier housing 260 at its upper (large diameter) end, as well as at its lower (smaller diameter) end.
• There is at least one vent port 270 which vents the space between the upper and lower seals of the intensifier piston 250 to outside atmospheric pressure.
• There is also at least one bi-directional flow port 280 which passes vertically through intensifier housing 260.
• the fluid must create an upward force (pressure) at the lower (small) end of the intensifier piston 250 which is sufficient to overcome the downward force (pressure) at the upper (large) end of the intensifier piston 250.
• pressure pressure
• To do so requires a pressure at the lower end of the intensifier piston 250 that is greater than the pressure at the upper end of the intensifier piston 250 by a multiple approximately equal to the ratio of the cross-sectional area of the large end of the intensifier piston 250 to the cross-sectional area of the compression flow port 240.
• the diameter of the small end of the intensifier piston 250 is only slightly greater than the diameter of the compression flow port 240.
• the annular contact area between these parts is relatively quite small, and it can be said that, for flow through the compression flow port 240, a pressure is required at the lower end of the intensifier piston 250 that is greater than the pressure at the upper end of the intensifier piston 250 by a multiple approximately equal to the ratio of the area of its large end divided by the area of its small end.
• the damping piston 140 has several large thru-holes and no restrictive valving (note that, actually, the preferred embodiments of the present invention generally do incorporate restrictive valving on the damping piston 140 which does create compression damping forces), hi other words, for purposes of clarity in describing the basic principles of the present embodiment, it is assumed here that the damping piston 140 itself creates no compression damping forces.
• the 400 psi pressure created at the small end of the intensifier piston 250 acts uniformly throughout all portions of damper cylinder 150 below the intensifier piston 250. Acting on the 0.2 square inch cross-sectional area of the piston rod 120, it creates an 80-pound "dynamic nose force".
• the present embodiment produces a "position-sensitive" compression damping effect, with the compression damping force increasing as the piston rod 120 and the damping piston 140 move further into the the damper cylinder 150.
• the extent and degree of this position-sensitive effect is influenced by the pre-set volume of the internally-pressurized chamber 180 above the floating piston 160, relative to the diameter and maximum available travel of the piston rod 120. If the pre-set volume of the internally-pressurized chamber 180 is relatively large, the position-sensitive effect is reduced. If the pre-set volume is relatively small, the position-sensitive effect is increased.
• FIGS. 4, 5, and 6, show another preferred embodiment of the present invention.
• This embodiment differs from the previous embodiment of FIGS. 2 and 3 primarily due to an alternate configuration of the intensifier piston 255, as best seen in FIG. 5.
• the intensifier piston 255 of FIG. 5 has an intensifier piston compression flow port 256 which passes through its center.
• Another difference is the addition of an intensifier bleed screw 257 instead of the vent port 270 in FIG. 3.
• the intensifier retaining ring 258 utilized here differs in form, but not function, from the previous intensifier retaining ring 251 of FIG. 3, Similarly, the check valve 235, the check valve spring 236, and the rebound flow port 222 as shown in FIG. 5 all differ in form, but not function, from the equivalent features illustrated in FIG. 3.
• FIG. 5 One practical advantage of the embodiment of FIG. 5 as compared with the embodiment of FIG. 3 is that it combines the functions of both the partition 210 and the intensifier housing 260 of FIG. 3 into one component, the partition 262 of FIG. 5. This reduces total part count and cost of the damper unit,
• FIG. 7 illustrates the shaft displacement rebound fluid flow 270 that occurs through the structure of FIG. 5 during a rebound stroke of the damper.
• FIG. 8 illustrates the shaft displacement compression fluid flow 271 that occurs during a compression stroke of the damper.
• FIG. 9 shows another preferred embodiment of the present invention. This embodiment is similar to the previous embodiment shown in FIGS. 4, 5, 6, 7, and 8, except that a remote reservoir assembly 310 has been added. Also, the intensifier assembly 330 has been moved upward to the upper end of the damper cylinder 150.
• the remote reservoir assembly 310 is connected to the main damper cylinder assembly 320 by an hydraulic hose 340.
• the remote reservoir assembly 310 includes a reservoir end fitting 312, a reservoir cylinder 314, a floating piston 160, and a reservoir cap 316.
• FIGS. 10 and 11 show a preferred embodiment of the present invention comprising a piggyback eyelet 410 with an attached reservoir cylinder 314 containing a floating piston 160 and an intensifier assembly 420.
• the function of the partition 421, the check valve 422, the check valve spring 423, and the rebound flow port 424 of this embodiment are similar to the corresponding structures of the previous embodiment shown in FIG. 3.
• the compression flow port 425 in the partition 421 provides a compression flow path for fluid from the damper cylinder 150 to an upward-facing annular area of the intensifier piston 426. Due to the piston seal 427 and the vent 428 provided, the two other upward-facing areas of the intensifier piston 426 are at atmospheric pressure (considered zero pressure for purposes of this description).
• the large area of the bottom face of the intensifier piston 426 is subjected to the pressure within the internally-pressurized chamber 180 below the floating piston 160.
• the intensifier piston 426 is fitted with an intensifier retaining ring 429 to ensure that it remains within the partition 421 during assembly and other possible conditions.
• the intensifier piston 426 under static conditions the intensifier piston 426 is urged upward by the pressure on its bottom face into firm, sealing contact with the partition 421.
• the intensifier piston 426 remains in firm sealing contact with the partition 421 unless the fluid pressure from the compression flow port 425 exerted downward against the upward-facing annular area 430 of the intensifier piston 426 creates sufficient force to overcome the upward force exerted by pressure on the bottom face of the intensifier piston 426.
• pressure in the compression flow port 425 equals a multiple of the pressure in the internally-pressurized chamber 180; said multiple being approximately equal to the ratio of the area of the bottom face of the intensifier piston 426 to the area of the upward-facing annular area 430 of the intensifier piston 426.
• the increased pressure that is required to urge the intensifier piston 426 downward, to permit flow of the displaced fluid acts on the cross-sectional area of the piston rod 120, thus creating a compression damping force.
• FIGS. 12 and 13 show a modified version of the embodiment of FIGS. 10 and 11 which provides external adjustability of the compression damping force produced by the intensifier assembly 440.
• This modified embodiment includes an intensifier adjusting screw 441, an adjuster piston 442, and an adjuster coil spring 443.
• rotation of the intensifier adjusting screw 441 increases or decreases the preload force on the adjuster coil spring 443.
• This force is transmitted through the adjuster piston 442 as an increased or decreased pressure in the adjacent hydraulic fluid 445.
• This increased or decreased pressure is communicated to the upward-facing areas of the intensifier piston 446 with which the hydraulic fluid 445 is in contact.
• the downward force thus created on the intensifier piston 446 reduces, to a greater or lesser degree depending on the specific adjustment of the preload force on the adjuster coil spring 443, the compression fluid pressure required to cause the intensifier piston 446 to move downward to permit compression fluid flow.
• this adjustment mechanism alters the compression damping force which is experienced at the piston rod 120.
• FIGS. 14 and 15 show another preferred embodiment of the present invention.
• This embodiment utilizes an intensifier assembly 460 structure similar to that of FIGS, 2 and 3, but incorporated into the upper end of a reservoir cylinder 314 similar to that of FIGS. 10 and 11.
• the principles of operation for this embodiment are identical to those previously described for FIGS, 2 and 3.
• FIGS. 16 and 17 show yet another preferred embodiment of the present invention.
• This embodiment utilizes an intensifier assembly 510 similar to that of FIGS. 14 and 15, but, in addition, provides external adjustability via an intensifier adjuster knob 512.
• the principles of operation for this embodiment are similar to those previously described for FIGS. 14 and 15, except for operation of the adjuster structure which is described in the following.
• an external rotatable intensifier adjuster knob 512 is secured to a freely-rotating hex driver shaft 514 which includes a downwardly-projecting male hex portion which is keyed into a female hex portion of a threaded spring base 516 which rotates with it.
• the intensifier adjuster knob 512 is fitted with at least one detent ball 518 and one detent spring 519 which provide a detent function by providing audible and tactile feedback for each quarter turn (for example) adjustment of the intensifier adjuster knob 512, as well as by helping to secure it at any pre-set position.
• the threaded spring base 516 is threaded on its outside diameter to produce axial movement upon rotation. Depending on the direction of rotation of the intensifier adjuster knob 512, axial movement of the threaded spring base 516 increases or decreases the spring preload force of the intensifier adjuster spring 520.
• the basic principle of operation of the intensifier piston 522 itself can be best characterized as: in order for the intensifier piston 522 to move downward ("open"), the force(s) acting downward on the small end of the intensifier piston 522 must equal (or, actually, slightly exceed) the force(s) acting upward on the big end.
• the force acting upward on the big end of the intensifier piston 522 equals the cross-sectional area of the big end times the pressure in the internally-pressurized chamber 180.
• the small end of the intensifier piston 522 there are two forces acting downward on it.
• One force is the compression fluid flow pressure acting on the small end of the intensifier piston 522 times the cross-sectional area of the small end.
• the other force is the force exerted by the intensifier adjuster spring 520.
• a combination of parameters could be determined according to this embodiment of the present invention such that the pressure build-up in the internally-pressurized chamber 180 at some pre-determined point in the compression travel ("stroke") of the piston rod 120 exceeded the spring preload force, thus closing the intensif ⁇ er piston 522 and thus creating a compression fluid flow restriction and a compression damping effect.
• a combination of parameters could be chosen whereby the compression damping force produced varied from zero for the first portion of a compression stroke, to a finite and increasing value beyond that first portion.
• FIGS. 18 and 19 show another preferred embodiment of the present invention.
• This embodiment incorporates an intensifier piston 540 and partition assembly 550 similar in structure and function to that previously described in FIGS. 2 and 3.
• the key difference here is that, in FIGS. 18 and 19 the pressure acting on the large end of the intensifier piston 540 is supplied by an external source (not shown), not by the internally-pressurized chamber 180 as it was in previous embodiments.
• the pressure required at the small end of the intensifier piston 540 to permit compression fluid flow, and therefore the compression damping force produced depends on the external pressure supplied.
• the pressure in FIGS. 18 and 19 is supplied to the externally pressurized chamber 560 through a pressure port 562 fed by an external source (not shown) via a pressure fitting 564.
• the pressure source, and the medium contained in the externally pressurized chamber 560 can be either pneumatic or hydraulic.
• a pneumatic medium and system is preferred where simplicity and low cost are dominant factors.
• An hydraulic medium is preferred where rapid responsiveness (quick response times)
• a pressure chamber sealing head 566 is held in place by seal head retaining rings 568, and seals the upper end of the externally pressurized chamber 560.
• FIGS. 18 and 19 One advantage of the embodiment of FIGS. 18 and 19 is the remote, external controllability provided.
• a system could be designed, for example, utilizing various sensors, as are known in the art, on a vehicle. The information from these sensors, as is known in the art, could be input to an on-board computer module having a pre- established algorithm for determining, for any given combination of inputs, the amount of pressure to be applied to the externally-pressurized chamber 560, and, thus, the desired level of compression damping produced by the damper.
• a system of this type, utilizing an hydraulic medium could sense actual vehicle conditions and respond within milliseconds of real-time, providing enhanced dynamic performance.
• FIGS. 2OA and 21 show another preferred embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 18 and 19 except that the externally pressurized chamber 560 is directly pressurized by the spring force of the coil-over spring 570.
• the upper end of the coil-over spring 570 is supported by the spring support ring 572. Its lower end (not shown) is supported by a ring (not shown) attached to the lower eyelet (not shown, but equivalent to lower eyelet 112 in FIG. 1), in a conventional arrangement as is well-known in the art.
• the spring support ring 572 is in sealed, slidable contact with the damper cylinder 150 and the support ring housing 574.
• hydraulic fluid The space between the spring support ring 572 and the support ring housing 574, as well as the space in the externally pressurized chamber 560, is filled with hydraulic fluid. Note that this hydraulic fluid is entirely distinct and separated from the hydraulic fluid contained within the rest of the damper unit.
• FIGS. 2OA and 21 The principles of operation of the embodiment of FIGS. 2OA and 21 are similar to those described for the embodiment of FIGS. 18 and 19. The only difference is that in FIGS. 2OA and 21 the externally-supplied pressure is specifically produced by the external coil-over spring 570, rather than being from a generalized pressure source.
• the compression damping force produced by the intensif ⁇ er assembly 580 from the beginning to the end of a full-travel compression stroke, would begin at a level determined by the initial preload of the coil-over spring 570, then increase linearly with the depth of the compression stroke, according to the spring rate ("stiffness") of the coil-over spring 570. This characteristic could be described, as is known in the art, as a linearly-increasing position-sensitive compression damping curve.
• FIG. 2OB shows an alternate version of the embodiment of FIG. 2OA, including addition of a secondary spring 576 in series with the main coil-over spring 570, a dual-spring adaptor ring 577, and a travel limit retainer ring 579.
• the location of the travel limit retainer ring 579, and the spring rate of the secondary spring 576 relative to the main coil-over spring 570, is determined such that, during a compression stroke of the damper, the spring adaptor ring 577 engages the travel limit retainer ring 579 at some selected point in the travel.
• the spring adaptor ring 577 might engage the travel limit retainer ring 579 at mid-stroke (i.e., at 2-inches of travel).
• the spring force supported by the spring support ring 572 would increase linearly for the first 2-inches of travel, as the secondary spring 576 continued to compress.
• the secondary spring 576 does not compress any further (only the main coil-over spring 570 continues to compress), and thus the spring force supported by the spring support ring 572 does not increase beyond the first 2-inches of travel.
• the force supported by the spring support ring 572 produces a pressure in the externally pressurized chamber 560 that varies in direct proportion.
• this pressure multiplied by the intensifier assembly 580, proportionately increases the required pressure to unseat the small end of the intensifier piston 540 to permit compression fluid flow.
• the compression damping force produced by the intensifier assembly 580 as a function of the depth of the compression stroke has the following characteristic shape: it begins at a level determined by the initial spring preload (the force of both springs is equal until the travel limit retainer ring 579 is engaged), it then increases linearly with travel until the spring adaptor ring 577 engages the travel limit retainer ring 579 , at which point it remains constant (“flattens out") regardless of increasing travel.
• This type of compression damping characteristic is desirable for certain applications.
• FIG. 2OC shows another alternate version of the embodiment of FIG. 2OA, including addition of a secondary spring 578 in series with the main coil-over spring 570, a dual-spring adaptor ring 577, and a spring travel limit retainer ring 579.
• the location of the travel limit retainer ring 579, and the spring rate of the secondary spring 578 relative to the main coil-over spring 570 is determined such that the adaptor ring 577 is initially in engagement with the travel limit retainer ring 579.
• the secondary spring 578 has significantly more preload force than the main coil-over spring 570. Therefore, during the first portion of damper travel, only the main coil-over spring 570 compresses.
• the preload on the secondary spring 578 could be such that only the main coil-over spring 570 compresses for the first 2-inches of travel.
• the spring force supported by the spring support ring 572 would remain constant for the first 2-inches of travel.
• the embodiment of FIG. 2OC produces a characteristic shape as follows: it begins at a level determined by the initial preload of the secondary spring 578. It remains constant at that level ("flat") until the point is reached where the secondary spring 578 begins to compress further, at which point the compression damping force begins to increase linearly with travel.
• FIGS. 22 and 23 show another preferred embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 2OA and 21 except that the floating piston 160 (not included or shown in FIGS. 22 and 23), as utilized in all previous embodiments, has been entirely eliminated. This is feasible with the embodiment of FIGS. 22 and 23, since the compressed force of the coil-over spring 570 creates an internal pressure within the damper unit similar to that previously provided by the floating piston 160.
• FIGS. 22 and 23 One advantage of the embodiment of FIGS. 22 and 23 is the complete elimination of the floating piston 160, the internally-pressurized chamber 180, and the Schrader valve 190, as included in all previous embodiments. Another advantage, shared with the embodiment of FIGS. 2OA and 21 is the linearly-increasing, position-sensitive compression damping effect produced by the intensifier assembly 590.
• the total compression damping force produced by the embodiment of FIGS. 22 and 23, as well as other embodiments of the present invention, will also include the non-linearly-increasing, non-position-sensitive compression damping forces produced by conventional compression valving at the damping piston 140.
• the overall compression damping characteristics will be a combination of those produced at the damping piston 140, plus those produced by the intensifier assembly 590.
• FIGS. 24, 25 and 26 show another preferred embodiment of the present invention.
• This embodiment is similar to the embodiment of FIGS. 22 and 23 except that an intensifier piston 610 similar to that first shown in FIGS. 4, 5 and 6 is utilized.
• Another difference is the addition of the intensifier preload spring 612.
• An optional small bleed orifice 614 permitting limited fluid flow through the intensifier piston 610 when in a closed condition, thus modifying the operative characteristics of the intensifier assembly, is included. It should be noted that the bleed orifice 614 included here, although not illustrated other embodiments, could also be incorporated in them if desired.
• FIG. 27 shows another preferred embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 24, 25 and 26 except that, rather than the previous intensifier preload spring 612 (as shown in FIG. 25), an intensifier open-bias preload spring 618 is utilized.
• the effect of the intensifier open-bias preload spring 618 is to maintain the intensifier piston 616 in an open (no flow restriction) position during the early portion (i.e., near-full-extension portion) of a compression stroke.
• the intensifier piston 616 does not tend to close until a point in the compression stroke is reached where the internal pressure generated by the coil-over spring 570 overpowers the intensifier open-bias preload spring 618.
• the intensifier assembly begins to produce a compression damping effect by requiring pressure at the small end of the intensifier piston 616 in order to keep it open.
• FIG. 28 shows a preferred embodiment of the present invention as incorporated into the FLOAT-series of air-sprung dampers as produced by FOX Racing Shox of Watsonville, California.
• an adjustable intensifier assembly 510 essentially identical to that previously shown in FIG. 17 is attached to the main damper assembly 630 by the piggyback eyelet 632.
• the pressurized air 640 for the air-sprung feature of the damper is supplied via the Schrader valve 642 as shown.
• a volume of hydraulic fluid 170 displaced by the piston rod 620 flows upward via the central port 622 in the piston rod 620, then flows to the right via a horizontal port 634 in the piggyback eyelet 632, then flows downward via an angled port 636 into the intensifier assembly 510.
• the horizontal port 634 is drilled or otherwise manufactured approximately on-axis with the Schrader valve 642.
• a press-fit sealing ball 644 is pressed into the entrance of the horizontal port 634 in order to keep the hydraulic fluid 170 and the pressurized air 640 entirely separate.
• One advantage of the embodiment of FIG. 28 is that, by providing for flow of the displaced hydraulic fluid up through the piston rod 620 to reach the intensifier assembly 510 via ports in the piggyback eyelet 632 as shown, the pressure chamber sleeve 660 can be easily and conveniently unthreaded and completely removed downward from the overall assembly for the periodic cleaning and maintenance typically required to remove foreign matter which may pass through the dynamic seals during operation and accumulate over time.
• FIG. 29 shows another preferred embodiment of the present invention.
• Two of the unique features of this embodiment, as compared with all previously-shown embodiments, are the outer sleeve 710, and the seal head check valve assembly 720.
• a third differentiating feature is the lack of compression valving (symbolic) 142 (not included or shown in FIG. 29) as shown and identified in FIG. 1, and as illustrated in all previous embodiments.
• the partition 210 and the intensifier piston 730 are similar to those previously shown and described per FIGS. 2 and 3, except for the addition of a bleed screw 257 in the intensifier piston 730 for purposes as first previously described relative to FIGS. 4 and 5. This feature is important for the embodiment of FIG. 29, since a vent port 270 (not shown or included in FIG. 29) feature such as shown in FIGS. 2 and 3 would be difficult to achieve due to the added outer sleeve 710 of FIG. 29.
• a primary advantage of the embodiment of FIG. 29 is that, since the damping piston 140 has no compression ports or valves, no hydraulic fluid flows through the damping piston 140 during a compression stroke. Therefore, the displaced fluid volume during a compression stroke is determined by the full cross-sectional area of the damping piston 140, rather than by the much smaller cross-sectional area of the piston rod 120, as in previous embodiments. One portion of the displaced fluid, a portion equal to the displaced volume of the piston rod 120, is accommodated by upward movement of the floating piston 160.
• the check valve assembly 720 opens for flow in the upward direction, allowing the fluid flow to continue and to fill the vacated annular space behind the damping piston 140 during a compression stroke. Since there is no flow through the damping piston 140 during a compression stroke, the pressure generated by the intensifier piston 730 acts on the full cross-sectional area of the damping piston 140. Thus, relatively large compression damping forces can be produced with this embodiment at significantly lower internal pressures than in previous embodiments.
• the check valve assembly 720 permits fluid flow in the upward direction only.
• the check valve assembly 720 is closed, and the fluid pressure created between the damping piston 140 and the seal head 130 cannot escape through the seal head 130. Therefore, the desired rebound damping forces are created by the damping piston 140 and the rebound valving 141.
• FIGS. 30 and 31 show another preferred embodiment of the present invention. This embodiment is somewhat similar to the previous embodiment shown in FIGS. 16 and 17, except that the intensifier assembly 750 is oriented horizontally within the piggyback eyelet 760 structure leading to the reservoir assembly 770. Besides the different location, the other key difference relative to the embodiment of FIGS. 16 and 17 is that here the intensifier adjuster spring 754 engages the large end of the intensifier piston 752, rather than the small end. The net effect of this is that, in FIGS. 30 and 31, an adjustment that increases the preload force on the intensifier adjuster spring 754 increases the compression damping force produced by the intensifier assembly 750. In contrast, in FIGS.
• FIGS. 32 and 33 show another preferred embodiment of the present invention. This embodiment differs from the previous embodiment of FIGS. 30 and 31 in two basic respects. First, the intensifier assembly 780, rather than being oriented horizontally as in the previous embodiment, is oriented at a small angle from horizontal. This provides no significant performance benefits, but is shown simply as an illustration of one of the configuration possibilities available with this embodiment which may offer easier access to the intensifier adjuster knob 512 for making adjustments to the damper as installed in a particular application.
• FIGS. 32 and 33 differs from the previous embodiment of FIGS. 30 and 31 by the addition of the compression flow bleed adjuster assembly 790.
• the basic mechanism of this assembly whereby rotation of the bleed adjuster knob 792 produces translation of the tapered bleed adjuster needle 794, is similar to the mechanism utilized in the adjustable intensifier assembly 510, as best seen and described previously relative to FIG. 17.
• the compression flow bleed adjuster assembly 790 provides independent tuning of compression bleed flow of the damper. This can be an important tuning element in many damper applications. Compression bleed flow occurs in parallel with any compression flow through the intensifier assembly 780.
• FIG. 34 shows an overall view of a front suspension fork 800 which, as is known in the art, could be used on a bicycle or motorcycle (not shown). Individual components of the suspension fork 800 are not numbered or described relative to FIG. 34, since this general construction is well-known in the art.
• FIGS. 35, 36, and 37 show a preferred embodiment of the present invention as incorporated into the suspension fork 800 of FIG.
• FIGS, 35 and 36 show a fork leg assembly 810, in part comprised of a fork crown (partial view) 812, a fork upper tube 814, a lower fork leg 816, a Schrader valve 819, air 820, and hydraulic fluid 830 filled to an approximate level 831 as shown, hi addition, the fork leg assembly 810 comprises a damper assembly 840 as shown in isolation in FIG. 36.
• the upper portion of the damper assembly 840 shown in FIG. 36 includes a piston rod 842, a damping piston 844, a damper cylinder 850 and hydraulic fluid 830, a construction as is known in the art for conventional fork damper assemblies.
• An intensifier assembly 860 in the lower portion of the damper assembly 840 shown in FIG, 36 comprises a preferred embodiment of the present invention, and is best seen in FIG. 37.
• FIG. 37 shows the intensifier assembly 860 which includes a partition 870, an intensifier housing 880, an intensifier piston 890, an intensifier preload spring 892, an adjuster rod 894, and an adjuster knob 896.
• the principles of operation of the intensifier assembly 860 of FIG. 37 are similar to those previously shown and described for previous embodiments.
• the piston rod 842 displaces a volume of the hydraulic fluid 830 in the damper cylinder 850.
• the displaced fluid must exit the damper assembly. For the structure shown in FIG. 37, this can only occur when the pressure in the hydraulic fluid 830 above the partition 870, acting on the area of the small end of the intensifier piston 890, overcomes the upward forces acting on the intensifier piston 890, thus causing the intensifier piston 890 to move downward, allowing downward fluid flow through the compression flow port 872.
• the fork leg assembly 810 of FIG. 35 can be assembled with a desired volume of air 820 at atmospheric pressure, or it can be supplied with pressurized air (or other compressible gas, such as nitrogen) via a Schrader valve 819. In either case, as a compression stroke of the suspension fork 800 proceeds, the volume of the air 820 in the fork leg assembly 810 is progressively reduced (compressed), resulting in a progressively-increasing internal pressure. This increasing internal air pressure, acting through the intensifier assembly 860, produces a progressive increase in the compression damping force of the suspension fork 800. Thus, a progressive, position-sensitive compression damping force, as it is known in the art, is produced.
• compression damping forces in the suspension fork 800 are generally also produced at the damper piston 844.
• the total compression damping characteristics produced by various embodiments of the present invention result from a combination of the compression damping forces created by valving at the damper piston (for example, 844 in FIG. 36) plus the compression damping forces resulting from pressure increases produced by the intensifier assembly (for example, 860 in FIG. 36) acting on the cross-sectional area of the piston rod (for example, 842 in FIG. 36).

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• 2004
  • 2004-11-18 WO PCT/US2004/038661 patent/WO2006054994A1/en active Application Filing
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