U.S. patent application number 09/916093 was filed with the patent office on 2001-11-22 for position-sensitive shock absorber.
This patent application is currently assigned to Fox Factory, Inc.. Invention is credited to Brewer, Douglas E., Fox, Robert C. JR., Marking, John.
Application Number | 20010042663 09/916093 |
Document ID | / |
Family ID | 27380026 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042663 |
Kind Code |
A1 |
Marking, John ; et
al. |
November 22, 2001 |
Position-sensitive shock absorber
Abstract
The present invention is directed to shock absorbers, including
position-sensitive shock absorbers (2) in which the
position-sensitive damping can be different during compression and
rebound strokes, and shock absorbers (60) with damping adjusters
(80, 118) which vary the damping provided during compression and
rebound strokes. The position-sensitive shock absorber includes a
cylinder (4) within which a piston (122) is movably mounted for
movement between the first and second ends of the cylinder. Bypass
openings (24-32) open into the cylinder interior (6) at axially
spaced-apart positions. The bypass openings are coupled by a bypass
channel (38). A flow valve (40, 42) may be positioned along the
bypass channel permitting fluid flow from the first opening to the
second opening and restricting fluid flow from the second opening
to the first opening. A pressurized gas container (18) may be
fluidly coupled to the cylinder interior with a movable barrier
(14) separating the pressurized gas container and the cylinder
interior.
Inventors: |
Marking, John; (EI Cajon,
CA) ; Brewer, Douglas E.; (Sunnyvale, CA) ;
Fox, Robert C. JR.; (Los Gatos, CA) |
Correspondence
Address: |
HAYNES BEFFEL & WOLFELD LLP
P O BOX 366
HALF MOON BAY
CA
94019
US
|
Assignee: |
Fox Factory, Inc.
130 Hangar Way
Watsonville
CA
95076
|
Family ID: |
27380026 |
Appl. No.: |
09/916093 |
Filed: |
July 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09916093 |
Jul 26, 2001 |
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09422867 |
Oct 21, 1999 |
|
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|
6296092 |
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60106028 |
Oct 28, 1998 |
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60106380 |
Oct 29, 1998 |
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Current U.S.
Class: |
188/266 ;
188/282.1 |
Current CPC
Class: |
F16F 9/3235 20130101;
F16F 9/43 20130101; F16F 9/067 20130101; F16F 9/48 20130101; F16F
9/0209 20130101; F16F 9/34 20130101 |
Class at
Publication: |
188/266 ;
188/282.1 |
International
Class: |
F16F 009/12; F16D
057/00 |
Claims
What is claimed is:
1. A position-sensitive shock absorber comprising: a cylinder
having an interior, first and second ends and defining an axis; a
piston movably mounted within the cylinder for movement between the
first and second ends; first and second bypass openings opening
into the cylinder interior at first and second axially spaced-apart
positions; a bypass channel fluidly coupling the first and second
bypass openings; and a flow valve along the bypass channel
permitting fluid flow from the first opening to the second opening
and restricting fluid flow from the second opening to the first
opening.
2. The shock absorber according to claim 1 wherein the piston is a
vented piston.
3. The shock absorber according to claim 1 further comprising a
third bypass opening opening into the cylinder interior at a third
position, the third bypass opening fluidly coupled to the bypass
channel.
4. The shock absorber according to claim 1 wherein the third bypass
opening is positioned axially spaced-apart from and between the
second and first bypass openings.
5. The shock absorber according to claim 1 further comprising means
for selectively sealing said first bypass opening.
6. The shock absorber according to claim 1 further comprising a
first bypass opening closing member movable between a covering
position, at least substantially sealing the first bypass opening,
and an uncovering position, spaced-apart from the first bypass
opening.
7. The shock absorber according to claim 6 further comprising an
electromagnet element located to selectively move the closing
member between the covering and uncovering positions.
8. The shock absorber according to claim 6 wherein the closing
member is in the form of a ring having first and second ends, and
further comprising latching magnets at the first and second
ends.
9. The shock absorber according to claim 6 further comprising a
biasing element biasing the closing member to a chosen one of the
covering and uncovering positions.
10. The shock absorber according to claim 9 wherein the closing
member has a mass and the biasing element has a biasing force, said
mass and biasing force comprising inertia means for causing the
closing member to overcome the biasing force and thus move between
said covering and uncovering positions when closing member is
subjected to a selected acceleration.
11. The shock absorber according to claim 9 wherein the biasing
element comprises a spring.
12. The shock absorber according to claim 1 wherein the flow valve
is a check valve, including a movable check valve element,
preventing any substantial fluid flow from the second opening to
the first opening.
13. The shock absorber according to claim 2 wherein the check valve
element has a chosen stiffness and the bypass channel has a chosen
minimum cross-sectional area.
14. The shock absorber according to claim 13 wherein the check
valve element comprises a generally semicircular check valve
element having an effective spring length, the chosen stiffness
chosen corresponding to the effective spring length.
15. The shock absorber according to claim 2 further comprising
means for at least partially restricting movement of the check
valve element.
16. The shock absorber according to claim 15 wherein the movement
restricting means comprises at least one of a rotatable cylinder
and a remotely actuated solenoid valve.
17. The shock absorber according to claim 1 further comprising: a
pressurized gas container fluidly coupled to the cylinder interior;
and a movable barrier separating the pressurized gas container and
the cylinder interior.
18. The shock absorber according to claim 17 further comprising a
compression damping adjuster comprising: a flow controller situated
between the piston and the movable barrier, the flow controller
having a first flow path permitting substantially free fluid flow
in a rebound direction from the movable barrier towards the piston,
the flow controller having a second flow path for fluid flow in a
compression direction; and an adjustable position flow restrictor
situated along the second flow path to adjust the restriction to
fluid flow in the damping direction.
19. The shock absorber according to claim 1 further comprising: a
shaft having an inner end secured to the piston and an outer end
extending out past the first end of the cylinder; and a shaft seal
assembly fluidly sealing the axially-movable shaft and the first
end of the cylinder.
20. The shock absorber according to claim 19 further comprising a
spring element coupling the shaft and the cylinder.
21. The shock absorber according to claim 20 wherein the spring
element comprises a coil compression spring.
22. The shock absorber according to claim 19 further comprising a
rebound damping adjuster, the rebound damping adjuster comprising a
rebound flow path through the piston and a rebound flow restricting
element movable between first and second positions to vary the
restriction to rebound fluid flow along the rebound flow path.
23. The shock absorber according to claim 22 wherein the shaft is a
hollow shaft and the rebound flow restricting element comprises: a
rod housed within the hollow shaft, the rod having an inner end at
the rebound flow path and an outer end; a rod position adjuster
mounted to the shaft and engaging the rod so to adjust the axial
position of the rod along the hollow shaft.
24. A position-sensitive shock absorber comprising: a cylinder
having an interior, first and second ends and defining an axis; a
piston movably mounted within the cylinder for movement between the
first and second ends; first and second bypass openings opening
into the cylinder interior at first and second axially spaced-apart
positions; a bypass channel fluidly coupling the first and second
bypass openings; a pressurized gas container fluidly coupled to the
cylinder interior; a movable barrier separating the pressurized gas
container and the cylinder interior; a shaft having an inner end
secured to the piston and an outer end extending out past the first
end of the cylinder; a shaft seal assembly fluidly sealing the
axially-movable shaft and the first end of the cylinder; and a
spring element coupling the shaft and the cylinder.
25. The shock absorber according to claim 24 wherein the piston is
a vented piston.
26. The shock absorber according to claim 24 further comprising a
flow valve along the bypass channel permitting fluid flow from the
first opening to the second opening and restricting fluid flow from
the second opening to the first opening.
27. The shock absorber according to claim 26 wherein the flow valve
is a check valve, including a movable check valve element,
preventing any substantial fluid flow from the second opening to
the first opening.
28. The shock absorber according to claim 24 further comprising: a
compression damping adjuster comprising: a flow controller situated
between the piston and the movable barrier, the flow controller
having a first flow path permitting substantially free fluid flow
in a rebound direction from the movable barrier towards the piston,
the flow controller having a second flow path for fluid flow in a
compression direction; and an adjustable position flow restrictor
situated along the second flow path to adjust the restriction to
fluid flow in the damping direction; a rebound damping adjuster,
the rebound damping adjuster comprising: a rebound flow path
through the piston and a rebound flow restricting element movable
to vary the restriction to rebound fluid flow along the rebound
flow path; wherein the shaft is a hollow shaft and the rebound flow
restricting element comprises: a rod housed within the hollow
shaft, the rod having an inner end at the rebound flow path and an
outer end; and a rod position adjuster mounted to the shaft and
engaging the rod so to adjust the axial position of the rod along
the hollow shaft.
29. A shock absorber comprising: a cylinder having an interior,
first and second ends and defining an axis; a piston movably
mounted within the cylinder for movement between the first and
second ends; a pressurized gas container fluidly coupled to the
cylinder interior; a movable barrier separating the pressurized gas
container and the cylinder interior; a shaft having an inner end
secured to the piston and an outer end extending out past the first
end of the cylinder; and a compression damping adjuster comprising:
a flow controller situated between the piston and the movable
barrier, the flow controller having a first flow path permitting
substantially free fluid flow in a rebound direction from the
movable barrier towards the piston, the flow controller having a
second flow path for fluid flow in a compression direction; and an
adjustable position flow restrictor situated along the second flow
path to adjust the restriction to fluid flow in the damping
direction.
30. A shock absorber comprising: a cylinder having an interior,
first and second ends and defining an axis; a piston movably
mounted within the cylinder for movement between the first and
second ends; a pressurized gas container fluidly coupled to the
cylinder interior; a movable barrier separating the pressurized gas
container and the cylinder interior; a shaft having an inner end
secured to the piston and an outer end extending out past the first
end of the cylinder; and a rebound damping adjuster, the rebound
damping adjuster comprising: a rebound flow path through the piston
and a rebound flow restricting element movable to vary the
restriction to rebound fluid flow along the rebound flow path;
wherein the shaft is a hollow shaft and the rebound flow
restricting element comprises: a rod housed within the hollow
shaft, the rod having an inner end at the rebound flow path and an
outer end; and a rod position adjuster mounted to the shaft and
engaging the rod so to adjust the axial position of the rod along
the hollow shaft.
31. A shock absorber comprising: a cylinder having an interior,
first and second ends and defining an axis; a piston movably
mounted within the cylinder for movement between the first and
second ends; a pressurized gas container fluidly coupled to the
cylinder interior; a movable barrier separating the pressurized gas
container and the cylinder interior; a shaft having an inner end
secured to the piston and an outer end extending out past the first
end of the cylinder; a compression damping adjuster comprising: a
flow controller situated between the piston and the movable
barrier, the flow controller having a first flow path permitting
substantially free fluid flow in a rebound direction from the
movable barrier towards the piston, the flow controller having a
second flow path for fluid flow in a compression direction; and an
adjustable position flow restrictor situated along the second flow
path to adjust the restriction to fluid flow in the damping
direction; a rebound damping adjuster, the rebound damping adjuster
comprising: a rebound flow path through the piston and a rebound
flow restricting element movable to vary the restriction to rebound
fluid flow along the rebound flow path; wherein the shaft is a
hollow shaft and the rebound flow restricting element comprises: a
rod housed within the hollow shaft, the rod having an inner end at
the rebound flow path and an outer end; and a rod position adjuster
mounted to the shaft and engaging the rod so to adjust the axial
position of the rod along the hollow shaft.
32. A method for modifying the front forks of a wheeled vehicle
comprising: selecting a position-sensitive shock absorber
comprising: a cylinder having an interior, first and second ends
and defining an axis; a piston movably mounted within the cylinder
for movement between the first and second ends; first and second
bypass openings opening into the cylinder interior at first and
second axially spaced-apart positions; a bypass channel fluidly
coupling the first and second bypass openings; a pressurized gas
container fluidly coupled to the cylinder interior; a movable
barrier separating the pressurized gas container and the cylinder
interior; a shaft having an inner end secured to the piston and an
outer end extending out past the first end of the cylinder; a shaft
seal assembly fluidly sealing the axially-movable shaft and the
first end of the cylinder; and a spring element coupling the shaft
and the cylinder; removing any existing shock-absorbing components
from within the telescoping front forks of a wheeled vehicle, the
front forks being telescopic tubular members; and mounting said
position-sensitive shock absorber within each telescopic front
fork.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the following
provisional patent applications: 60/106,028, filed Oct. 28, 1998
and 60/106,380, filed Oct. 29, 1998.
BACKGROUND OF THE INVENTION
[0002] Many types of suspensions and supports include a spring and
a damping device to help isolate that supported from the support
structure or surface. For example, automotive vehicles commonly use
separate springs and simple shock absorbers to support the vehicle
frame on the axle assemblies. Simple shock absorbers are typically
oil-filled cylinders within which a vented piston is mounted. The
piston is connected to a shaft which extends out of one end of the
cylinder. The outer end of the shaft is mounted to one point on the
vehicle and the other end of the cylinder is mounted to another
point on the vehicle in parallel with the suspension spring. Thus,
simple shock absorbers only provide damping and not support.
[0003] Another type of shock absorber, which is the type commonly
used with motorcycles, off-road vehicles, competition automotive
vehicles and off-road bicycles, combines both the suspension
function and the shock absorbing function in one unit. This second
type of shock absorber commonly uses a spring unit to provide the
suspension function coupled with a damping unit to provide the
damping function. Conventional shock absorber designs commonly
incorporate an external coil spring, an internal air spring, or an
internal bladder to provide the suspension function.
[0004] Typical shock absorbers (also referred to as shocks) provide
two kinds of damping: compression damping ("CD"), and rebound
damping ("RD"). One refers to damping force created during "inward"
travel of the shaft (shortening of the shock), the other refers to
force created during "outward" travel of the shaft (lengthening of
the shock). Generally, but not always--depending on linkage
connecting shock to vehicle, RD applies during outward motion and
CD applies during inward motion. Some shocks are externally
adjustable by the user to provide for RD and/or CD adjustment.
[0005] Piston-type shock absorbers can be designed to provide the
same amount of damping on both the compression stroke and the
rebound stroke. Alternatively, the fluid passageways through the
vented, damping piston can be designed so that the restriction to
fluid flow through the damping piston during the compression stroke
is different than the restriction to fluid flow during the rebound
stroke. In this case the damping during the entire compression
stroke is different than the damping during the entire rebound
stroke.
[0006] Another type of damping is called position-sensitive
damping. Position-sensitive damping is typically achieved by the
combination of conventional vented piston damping, with the oil
flowing through the damping piston, plus damping provided by the
passage of oil around the damping piston through a bypass chamber
or channel, which permits oil to bypass the piston during a portion
of the piston stroke. The bypass channel thus permits lesser
damping over the portion of the stroke during which some fluid
flows around the piston through the bypass channel. Therefore, the
shock can have different damping characteristics along different
segments of the stroke. This is beneficial to the user because a
single set of shocks can provide smooth damping for less aggressive
riding and firm damping for aggressive riding without making any
adjustments during the ride. For example, the shocks can provide
reduced damping in the mid-stroke zone, where the shock is most
active in, for example, trail riding or other less aggressive
riding. If the rider starts riding more aggressively, or hits a
large bump, causing the shock to compress deeper into the stroke,
the bypass damping then becomes available and the shock relies on
the conventional piston damping. This type of shock absorber has
been available for many years. For example, a position-sensitive
shock absorber has been sold by Fox Factory, Inc. of San Jose,
Calif. since about 1987. U.S. Pat. No. 5,178,239 illustrates
another example of a position-sensitive shock absorber. The
position-sensitive damping action of the bypass channel is
available during both the compression and rebound strokes.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to shock absorbers,
including position-sensitive shock absorbers in which the
position-sensitive damping can be different during compression and
rebound strokes, and shock absorbers with damping adjusters which
vary the damping provided during compression and rebound
strokes.
[0008] The position-sensitive shock absorber includes a cylinder
within which a piston is movably mounted for movement between the
first and second ends of the cylinder. First and second bypass
openings open into the cylinder interior at axially spaced-apart
positions. The bypass openings are coupled by a bypass channel. A
flow valve is positioned along the bypass channel permitting fluid
flow from the first opening to the second opening and restricting
fluid flow from the second opening to the first opening. The first
bypass opening may be selectively sealed by, for example, a movable
closing member which is used to selectively cover or uncover the
bypass opening. This selective sealing can be through the use of
electromagnetic energy. Alternatively, the closing member can be
biased to either cover or uncover the opening, the closing member
overcoming the biasing force when a shock absorber is accelerated
to an appropriate degree. The flow valve may also be a check
valve.
[0009] Another aspect of the invention is directed to a
position-sensitive shock absorber with a piston movably mounted
within the cylinder for movement between the first and second ends
of the cylinder. First and second bypass openings, coupled by a
bypass channel, open into the cylinder interior. A pressurized gas
container is fluidly coupled to the cylinder interior. A movable
barrier separates the pressurized gas container from the cylinder
interior. A shaft, having an inner end secured to the piston and an
outer end extending out past the first end of the cylinder, is
sealed by a shaft seal assembly. A spring element couples the shaft
and the cylinder. This invention is also directed to a method for
modifying the front forks in which any existing shock-absorbing
components are removed from within the telescoping front forks of a
wheeled vehicle and the above-described position-sensitive shock
absorber is mounted within each telescoping front fork.
[0010] A further aspect of the invention is directed to a shock
absorber including a cylinder with a piston movably mounted within
the cylinder. A pressurized gas container is fluidly coupled to the
cylinder interior and a movable barrier separates the pressurized
gas container and the cylinder interior. A shaft has an inner end
secured to the piston and an outer extending out past the first end
of the cylinder. This shock absorber includes one or both of the
following compression damping adjuster and/or rebound damping
adjuster. The compressing damping adjuster includes a flow
controller having a first path permitting substantially free fluid
flow in a rebound direction from the movable barrier towards the
piston and second flow path for fluid flow in a compression
direction. The compression damping adjuster also includes an
adjustable position flow restrictor situated along the second flow
path to adjust the restriction to fluid flow in the damping
direction. The rebound damping adjuster includes a rebound flow
path through the piston and a rebound flow-restricting element
movable to vary the restriction to rebound fluid flow along the
rebound flow path. The shaft is a hollow shaft and the rebound
flow-restricting element includes a rod housed within the hollow
shaft. A rod position adjuster is mounted to the shaft and engages
the rod so to adjust the axial position of the rod along the hollow
shaft.
[0011] Other features and advantages of the invention will appear
from the following description in which the preferred embodiments
have been set forth in detail in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a side cross-sectional view of a
position-sensitive shock absorber made according to the invention
with the piston in a rest position prior to beginning the
compression stroke;
[0013] FIG. 2 shows the shock absorber of FIG. 1 at the beginning
of a compression stroke;
[0014] FIG. 3 shows the shock absorber of FIG. 2 further along the
compression stroke;
[0015] FIG. 4 illustrates the shock absorber of FIG. 3 as it
approaches the end of its compression stroke;
[0016] FIG. 5 is an enlarged cross-sectional view of a central
portion of the cylinder and bypass cylinder of the shock absorber
of FIG. 1 illustrating the expandable bands acting as check valves
covering two different bypass openings;
[0017] FIG. 5A illustrates an alternative embodiment of the
structure of FIG. 5 in which rings are positioned within the bypass
channel to cover or uncover bypass openings under the influence of
a pair of electromagnetic coils, both of the sets of bypass
openings being uncovered;
[0018] FIG. 5B illustrates the structure of FIG. 5A with one of the
sets of bypass openings covered and one uncovered;
[0019] FIG. 5C shows a further alternative embodiment of the
structure of FIG. 5A in which the rings are spring-biased to either
cover or uncover the bypass openings so that only upon sufficient
acceleration of the shock will the ring deflect the spring
sufficiently to either cover or uncover the associated bypass
openings;
[0020] FIG. 6 is overall view of a suspension-type shock
absorber;
[0021] FIGS. 6A-6C are enlarged cross-sectional views of the
left-hand, middle and right-hand portions of the shock absorber of
FIG. 6;
[0022] FIG. 7 is an enlarged view of the flow controller of FIG.
6C; and
[0023] FIG. 8 is an enlarged view of the vented piston of FIG.
6B.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] FIGS. 1-5 illustrate one aspect of the present invention
directed to a position-sensitive shock absorber 2 including a
cylinder 4 having an interior 6, first and second ends 8, 10 and
defining an axis 12. A floating piston 14 divides interior 6 into a
damping fluid chamber 16 and a gas chamber 18. Gas chamber 18 can
be pressurized through a pressurization port 20. Gas chamber 18 and
floating piston 14 accommodate the volume of oil or other damping
fluid within chamber 16 displaced by the movement of shaft 19 into
chamber 16. The compression of the gas within gas chamber 18 is
suggested by arrows 21A-21D in FIGS. 1-4.
[0025] A vented piston 22 is movably mounted within the cylinder
for moving between the first and second ends of the cylinder. A
number of axially separated bypass openings 24, 26, 28, 30, 32 are
formed through the cylinder. A bypass cylinder 36 surrounds
cylinder 4 and defines a cylindrical bypass channel 38. Bypass
openings 24, 26 and 32 are always open and fluidly couple the
damping fluid chamber and the bypass channel to permit some damping
fluid to bypass the vented damping piston 22 when the piston is
positioned between these bypass openings thus reducing the damping
during this portion of the stroke. See FIG. 2. Bypass openings 28,
30 are covered by expandable bands 40, 42 positioned within annular
grooves 44, 46 formed in the outer surface of cylinder 4. See also
FIG. 5. Bands 40, 42 act as check valve elements which permit fluid
flow from the damping fluid chamber to the bypass channel but
restricts, and typically prevents, fluid flow in the opposite
direction. Thus, the shock absorber will exhibit different damping
characteristics along the same segment of the stroke depending upon
whether the stroke is the compression stroke or the rebound
stroke.
[0026] FIG. 1 illustrates damping piston 34 at rest adjacent the
first end of the cylinder. The movement of the damping piston
upwardly, that is in the compression stroke, is dampened only by
the flow of damping fluid through the damping piston (see arrows 48
in FIG. 2) until the damping piston seal 50, which contacts and
seals against the interior of cylinder 4, passes bypass opening 24.
When this occurs fluid flow can be both through damping piston 34
via arrows 48 and also can bypass the damping piston through bypass
openings 28, 30, 32, along bypass channel 38 and back through
bypass openings 24, 26 as illustrated in FIG. 2. This 3/2 zone
(flow through 3 and 2 bypass openings on either side of the piston)
provides the softest (least damped) zone of the compression
stroke.
[0027] The next zone of the compression stroke is created when
piston seal 50 covers bypass opening 28 as shown in FIG. 3. This
2/2 zone of the compression stroke is still soft but not as soft as
that of FIG. 2. The 2/2 zone of FIG. 3 continues until bypass
opening 30 is covered by piston seal 50. This creates a short 1/2
zone (not illustrated) until piston seal 50 covers bypass opening
32. Continued compression stroke movement, see FIG. 4, results in a
0/0 zone--that is no fluid bypasses the damping piston.
[0028] The rebound stroke, not shown, exhibits no bypass fluid flow
(a 0/0 zone) until seal 50 passes bypass opening 32. At this point
fluid flow is out through bypass openings 24, 26, 28 (30 being
covered by seal 50) and back in through bypass opening 32 for a 3/1
zone. After seal 50 passes bypass opening 30, the bypass zone
remains 3/1 because fluid cannot flow from bypass channel 38
through opening 30. Once seal 50 covers opening 28, the bypass zone
is a 2/1 zone until seal 50 covers opening 26. With opening 26
covered but opening 24 open, the fluid can pass through openings 24
and 32 only, a 1/1 zone. Once seal 50 covers opening 24 no bypass
occurs, a 0/0 zone.
[0029] Thus, it is seen that the amount of damping fluid bypass
varies along both the compression and rebound strokes and may be
different along the same segments of the cylinder on the
compression and rebound strokes.
[0030] Bands 40, 42 can be made of spring metal, elastomeric
material or other suitable expandable material. Instead of a band
of material, bands 40, 42 could be replaced by individual flaps of
material. More than one bypass opening 24-32 could be provided at
the corresponding axial position with a single band type check
valve servicing the additional holes. An additional option is to
add more holes axially, with or without check valves, to provide
more specific zones. Conceptually, the damping piston could be
non-vented (solid) with all of the damping fluid channeled through
the bypass holes. The location, radial quantity, axial quantity,
size, check valve location and check valve stiffness would define
the damping tuning elements. While the check valves created at
openings 28, 30 may be substantially leak-proof, they may permit
some amount of leakage even when nominally closed. Additionally,
the stiffness of the check valve material can be tailored to alter
the amount of damping achieved by the valve in the open or
semi-open state. A relatively stiffer material will provide more
damping associated with the related bypass hole. The purpose is to
provide an additional damping tuning feature, thus providing a
means for optimal damping calibration.
[0031] In some situations it may be desired to add additional check
valves to reduce or even prevent bypass flow. By installing an
additional check valve in the groove at 26, rebound and compression
flow in all of the bypass zones is effectively reduced to a 1/1
zone. Installing bands at the remaining bypass holes 24 and 32
eliminates all bypass flow paths, a 0/0 zone.
[0032] It may be desired to permit user adjustment of bypass
damping. One way to do so is to permit bypass cylinder 36 to rotate
and/or reciprocate relative to cylinder 4. This movement would
cause bypass opening seals and one-way valve elements to
selectively cover and uncover various bypass openings. This would
permit some or all of the bypass openings to be completely sealed,
left completely open or provided with a check valve. The check
valves could, as described below with reference to FIGS. 5A and 5B,
be remotely adjusted through the use of solenoid valves. The
solenoid valve would be used to restrict the available movement of
the check valve. This can be done proportionally or bi-modally.
[0033] The check valve can be a semicircular spring band fixed to
the body 4 at one end and covering the bypass hole at the other
end. By changing the effective stiffness of the spring element
(shorter is proportionally stiffer) the damping effect associated
with the check valve/bypass hole can be altered upon assembly or
using a rotating, reciprocation, or solenoid scheme as described
above.
[0034] FIGS. 5A and 5B illustrate the use of a pair of
axially-slidable rings 166, 168 positioned between pairs of snap
rings 170, the snap rings lying on either side of bypass opening
172, 174. FIG. 5A illustrates both openings 172, 174 being
uncovered while FIG. 5B shows openings 172 covered and openings 174
uncovered. Bypass openings 172 are surrounded by an expandable band
176. The regions between each pair of snap rings 170 are surrounded
by center tap coils 178, 180; each coil has a common ground 182 and
a pair of leads 184, 186, the ground and leads for coil 180 not
being shown in FIGS. 5A and 5B. Rings 166, 168 are made of a
ferromagnetic material so they can be attracted by a magnetic
field. Selectively energizing the appropriate lead 184, 186, which
can be done manually or automatically, creates a magnetic field and
causes the associated ring 166, 168 to shift axial position to
cover, and thus at least substantially seal, or uncover openings
172, 174. Small magnets 167, 169 are mounted to either end of rings
166, 168; magnetic attraction between magnets 167, 169 and snap
rings 170 keep rings 166, 168 in place until coils 178 are again
energized.
[0035] FIG. 5C illustrates an embodiment similar to that of FIGS.
5A and 5B with like components referred to with like reference
numerals. Rings 166A, 168A do not have magnets 167, 169, but are
lightly biased by springs 188, 190 to cover openings 172 and
uncover openings 174 as shown in FIG. 5C. The axial component of
acceleration induces rings 166A, 168A to compress springs 188, 190
via F=MA, thus, allowing the ring valve to expose or obstruct
bypass openings 172, 174. In this way the position-sensitive
feature can be tuned to have an acceleration activation component.
The feature can be used to increase or decrease compression damping
associated with the vehicle's chassis response to a bump. Instead
of compression springs 188, 190, rings 166A, 168A could be or
include magnets, which would oppose like poles of magnets carried
by cylinder 4, to bias the rings to covering or uncovering
positions.
[0036] Another aspect of the invention relates to a shock absorber
60 shown in FIGS. 6-8. Shock absorber 60 is a suspension-type shock
absorber particularly useful for supplying the suspension and shock
absorbing functions of the front forks of motorcycles, mountain
bikes and similar wheeled vehicles. While shock absorber 60 could
be used as part of the original equipment for the front forks, it
is also adapted for retrofit applications. In retrofit applications
the user would remove existing shock absorbers from within the
front forks, leaving the telescoping tubular fork housings. The
shock absorber made according to the invention could be installed
within the tubular fork housings as a sealed unit.
[0037] Shock absorber 60 includes a cylinder 62 having a first end
64 and a second end 66. A cylinder extension 68 extends from second
end 66. The combination of cylinder 62 and cylinder extension 68
defines a cylinder interior 70. Cylinder interior 70 is divided
between a damping fluid chamber 72 and a pressurized gas chamber 74
by a floating piston 76. Gas chamber 74 can be precharged with a
pressurized gas, typically nitrogen, or can be charged through a
pressurization port, not shown. Pressurized gas chamber 74 and
floating piston 76 accommodates the volume of oil or other damping
fluid within chamber 72 displaced by the movement of a shaft 78
into and out of chamber 72.
[0038] A vented piston 80 is secured to the inner end 81 of shaft
78 for movement within cylinder 62. A number of axially separated
bypass openings 82-88 are formed through cylinder 62. This portion
of cylinder 62 is surrounded by a bypass cylinder 90 which defines
a cylindrical bypass channel 92 between cylinders 62, 90. The
arrows shown in FIG. 6 illustrate the flow through the bypass
channels during a compression stroke, that is with piston 80 moving
towards floating piston 76. As suggested in FIG. 8, fluid flow
through vented piston 80 can also occur during both the compression
and rebound strokes. The variation and the flow through the various
bypass openings as piston 80 covers up and passes each of the
openings 82-88 is similar to that discussed above with regard to
shock absorber 2 and thus will not be discussed in detail. Shock
absorber 80 does not show the use of check valves or other flow
control valves to restrict flow between the bypass openings along
bypass channel 92. However, such flow control valves could be used
with the embodiment of FIGS. 6-8 just as they are used with they
embodiment of FIGS. 1-5C.
[0039] The position of bypass cylinder 90 along cylinder 62 can be
changed by adjusting a threaded ring 94 which engages threads 96 as
second end 66 of cylinder 62. A spacer sleeve 98 is used between
threaded ring 94 and the second end 100 of bypass cylinder 90.
[0040] Shaft 78 passes through a shaft seal assembly 102 at a first
end 64 of cylinder 62. A spacer sleeve 104 is mounted about shaft
78 is captured between shaft seal assembly 102 and a rebound spring
106. Rebound spring 106 helps to dampen the impact of excessive
rebounding of the shock by cushioning the impact of piston 80
against shaft seal assembly 102.
[0041] A coil spring 108 is captured between the first end 110 of
bypass cylinder 90 and one end 112, shown in dashed lines, of, for
example, the front forks of a motorcycle or other wheeled vehicle.
The distal end 114 of cylinder extension 68 is sealed by a threaded
cap 116 which is typically threaded to the upper end of the
vehicle's tubular fork housing.
[0042] In addition to the damping through vented piston 80 and the
position-sensitive damping provided by bypass openings 82-88, shock
absorber 60 permits the user to adjust both compression damping and
rebound damping over the entire stroke in compression and rebound.
FIG. 7 is an enlarged illustration showing a flow controller 118 at
second end 66 of cylinder 62. Flow controller 118 provides for
relatively free fluid flow along a rebound stroke flow path 120
during the rebound stroke, that is with piston 80 moving away from
piston 76 in this embodiment. However, during compression fluid
flow can pass through flow controller 118 along two different
compression stroke flow paths 122, 124. Flow along path 122 is
substantially restricted by the use of several washers 126 as
opposed to the single, easily flexed washer 128. The fluid flow
through flow controller 118 is determined by the volume of shaft 78
being extended into and retracted from damping fluid chamber 72,
which is filled with an incompressible fluid, typically oil. The
damping created by flow controller 118 is constant throughout the
entire compression stroke. Flow controller 118 also includes a
central passageway 130 having a tapered opening 132 which can be
fully or partially obstructed by the flow restricting tip 134 of an
adjustment rod 136. An adjustment screw 138 mounted to threaded cap
116 is used to adjust the axial position of rod 136 and thus the
size of the opening formed between tapered opening 132 and tip
134.
[0043] FIG. 8 illustrates fluid flows through vented piston 80
during both compression and rebound strokes. The fluid flows
through piston 80 during the compression stroke is indicated by
compression flow path 140 while the flow during the rebound stroke
and indicated by rebound flow paths 142, 144. The restriction along
rebound flow path 144 is adjustable by the user. This is achieved
by rotating a rebound damping adjustment screw 146 threadably
mounted to an outer end mounting adapter 148 which is secured to
the outer end 150 of shaft 78, typically by threads. Adjusting the
axial position of screw 146 causes the flow restricting tip 152 of
a rebound damping adjustment rod 154 to be moved into and out of
the tapered opening 156 at one end of a fluid passageway 158 formed
through the center of piston 80. As can be seen in FIG. 8,
supplemental rebound flow path 144 passes through a bleed hole 160
formed in shaft 78, passes along the channel formed between tip 152
and tapered opening 156 and out of fluid passageway 158.
[0044] During rebound, floating piston 76 will move from the dashed
line position to the solid line position of FIGS. 6 and 7. The
friction created between floating piston 76 and adjustment rod 136
will cause flow restricting tip 134 of rod 136 to be moved to the
left in FIG. 7 thus effectively sealing tapered opening 132. In
FIG. 6A there is a gap between the outer end of rod 154 and
adjustment screw 146. In practice the pressurization within gas
chamber 74 will tend to force rod 154 to the left in FIG. 6 thus
causing the outer end of the rod to engage adjustment screw 146.
Therefore, rebound flow path 144 remains open during compression as
well as rebound. However, provision of path 144 has a pronounced
effect on rebound damping but has little effect on compression
damping because of the significantly different flow rates between
the two. That is the reason why flow path 144 is considered a
rebound flow path.
[0045] In the embodiment of FIGS. 6-8 pressurized gas chamber 74 is
shown aligned with and an extension of cylinder 62. If desired it
could be positioned in other areas and could be fluidly coupled
through a flexible tube instead of a rigid connection. Also,
floating piston 76 could be replaced by a diaphragm, bellows or
other fluid force-transmitting barrier.
[0046] Any and all patents, applications, and printed publications
referred to above are incorporated by reference.
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