U.S. patent application number 12/684072 was filed with the patent office on 2010-07-08 for remotely operated bypass for a suspension damper.
Invention is credited to John Marking.
Application Number | 20100170760 12/684072 |
Document ID | / |
Family ID | 42310990 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100170760 |
Kind Code |
A1 |
Marking; John |
July 8, 2010 |
Remotely Operated Bypass for a Suspension Damper
Abstract
A damper assembly with a bypass for a vehicle comprises a
pressure cylinder with a piston and piston rod for limiting the
flow rate of damping fluid as it passes from a first to a second
side of said piston. A bypass provides fluid pathway between the
first and second sides of the piston separately from the flow rate
limitation. In one aspect, the bypass is remotely controllable from
a passenger compartment of the vehicle. In another aspect, the
bypass is remotely controllable based upon one or more variable
parameters associated with the vehicle.
Inventors: |
Marking; John; (El Cajon,
CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, L.L.P.
3040 Post Oak Blvd., Suite 1500
Houston
TX
77056
US
|
Family ID: |
42310990 |
Appl. No.: |
12/684072 |
Filed: |
January 7, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61143152 |
Jan 7, 2009 |
|
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|
Current U.S.
Class: |
188/299.1 ;
280/5.515 |
Current CPC
Class: |
F16F 9/065 20130101;
F16F 9/466 20130101; B60G 17/08 20130101; F16F 9/18 20130101 |
Class at
Publication: |
188/299.1 ;
280/5.515 |
International
Class: |
F16F 9/44 20060101
F16F009/44; B60G 17/00 20060101 B60G017/00 |
Claims
1. A vehicle suspension damper comprising: a cylinder and a piston
assembly comprising a piston and piston rod; working fluid within
said cylinder; a passageway through said piston allowing and
limiting a flow rate of the working fluid through the piston in at
least one direction; a bypass having a fluid pathway between the
first and second sides of the piston; and a remotely controllable
valve for limiting the flow of fluid through the bypass.
2. The damper of claim 1, further including a control system for
moving the valve between an open and closed position form a remote
location, the control system comprising: a switch for operating the
valve; and a conduit providing communication between the switch and
valve.
3. The damper of claim 2, wherein the switch is a manually operable
switch having at least two positions.
4. The damper of claim 2, wherein the switch is located in a
passenger compartment of the vehicle.
5. The damper of claim 2, wherein the conduit is a fluid conduit
for carrying control fluid and the system includes a source of
control fluid.
6. The damper of claim 2, wherein the conduit is an electrical
conduit for carrying a control signal.
7. The damper of claim 2, wherein the valve is solenoid actuated,
the solenoid electrically connected to the conduit.
8. The damper of claim 2, wherein the conduit is a waveform for
carrying an RF signal.
9. The damper of claim 2, wherein the control system further
includes a power source.
10. The damper of claim 1, wherein the valve is disposed adjacent
the bypass and includes valve member having a first position
obstructing a flow path between the cylinder and bypass and a
second position allowing flow through the flow path.
11. The damper of claim 1, wherein the at least one direction
comprises two directions.
12. The damper of claim 2, wherein the signaling apparatus is a
transducer for measuring rod position within a damper cylinder.
13. The damper of claim 1, further comprising a second valve for
limiting flow through the bypass.
14. The damper of claim 2, wherein the switch comprises a load
transducer for sensing piston rod force.
15. The damper of claim 2, wherein the switch comprises a
transducer arranged to measure an angle associated with the
steering wheel of the vehicle.
16. The damper of claim 1, further comprising a one way valve
arranged to control flow through the piston.
17. A remotely controllable shock absorber system for a vehicle
comprising: at least two dampers associated with at least two
wheels of the vehicle, each damper comprising: a cylinder with a
piston for movement therein, the piston metering fluid in at least
one direction there though; a bypass for bypassing fluid around the
piston to decrease a dampening effect in the damper, a remotely
actuatable valve for opening and closing the bypass to the flow of
fluid; and the shock absorber system further including a switch
associated with each damper, the switch arranged to cause at least
one valve to operate based upon at least one characteristic of the
vehicle.
18. The remotely controllable shock absorber system of claim 17,
wherein the dynamic characteristic is at least two of vehicle
speed, vehicle trajectory angular acceleration, damper rod
velocity, and rod location in a damper cylinder.
19. The remotely controllable shock absorber system of claim 17,
further comprising a second valve for limiting fluid flow through
the damper.
20. The remotely controllable shock absorber system of claim 19,
wherein the second valve is remotely controllable.
21. The remotely controllable shock absorber system of claim 20
wherein the second valve controls fluid flow through the bypass.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent
application Ser. No. 61/143,152, filed Jan. 7, 2009, which is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] Embodiments of the present invention generally relate to a
damper assembly for a vehicle. More specifically, the invention
relates to a remotely operated bypass device used in conjunction
with a vehicle damper.
[0003] Vehicle suspension systems typically include a spring
component or components and a dampening component or components.
Typically, mechanical springs, like helical springs are used with
some type of viscous fluid-based dampening mechanism and the two
are mounted functionally in parallel.
SUMMARY OF THE INVENTION
[0004] The present invention generally comprises a damper assembly
having a bypass. In one aspect, the assembly comprises a cylinder
with a piston and piston rod for limiting the flow rate of damping
fluid as it passes from a first to a second portion of said
cylinder. A bypass provides fluid pathway between the first and
second portions of the cylinder and may be independent of, or in
conjunction with, the aforementioned flow rate limitation. In one
aspect, the bypass is remotely controllable from a passenger
compartment of the vehicle. In another aspect, the bypass is
remotely controllable based upon one or more variable parameters
associated with the vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] So that the manner in which the above recited features can
be understood in detail, a more particular description may be had
by reference to embodiments, some of which are illustrated in the
appended drawings. It is to be noted, however, that the appended
drawings illustrate only typical embodiments of this invention and
are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0006] FIG. 1 is a section view showing a suspension damping unit
with a remotely operable bypass, the bypass in a closed
position.
[0007] FIG. 2 is a section view showing the suspension damping unit
of FIG. 1 with the bypass in an open position.
[0008] FIG. 3 is a schematic diagram showing a control arrangement
for a remotely operated bypass.
[0009] FIG. 4 is a schematic diagram showing another control
arrangement for a remotely operated bypass.
[0010] FIG. 5 is a graph showing possible operational
characteristics of the arrangement of FIG. 4.
DETAILED DESCRIPTION
[0011] As used herein, the terms "down" "up" "downward" upward"
"lower" "upper" and other directional references are relative and
are used for reference only. FIGS. 1 and 2 are section views of a
suspension damping unit 100. The damper includes a cylinder portion
102 with a rod 107 and a piston 105. Typically, the fluid meters,
from one side to the other side of piston 105, by passing through
flow paths 110, 112 formed in the piston 105. In the embodiment
shown, shims 115, 116 are used to partially obstruct the flow paths
110, 112 in each direction. By selecting shims 115, 116 having
certain desired stiffness characteristics, the dampening effects
can be increased or decreased and dampening rates can be different
between the compression and rebound strokes of the piston 105. For
example, shims 115 are configured to meter rebound flow from the
rebound portion 103 of the cylinder 102 to the compression portion
104 of the cylinder 102. Shims 116, on the other hand, are
configured to meter compression flow from the compression portion
of the cylinder to the rebound portion. In one embodiment, shims
116 are not included on the rebound portion side leaving the piston
essentially "locked out" in the compression stroke without some
means of flow bypass. Note that piston apertures (not shown) may be
included in planes other than those shown (e.g. other than
apertures used by paths 110 and 112) and further that such
apertures may, or may not, be subject to the shims 115, 116 as
shown (because for example, the shims 115, 116 may be clover-shaped
or have some other non-circular shape).
[0012] A reservoir 125 is in fluid communication with the damper
cylinder 102 for receiving and supplying damping fluid as the
piston rod 107 moves in and out of the cylinder. The reservoir
includes a cylinder portion 128 in fluid communication with the
damper cylinder 102. The reservoir also includes a floating piston
130 with a volume of gas on a backside ("blind end" side) of it,
the gas being compressible as the reservoir cylinder 128 fills with
fluid due to movement of the damper rod 107 and piston 105 into the
damper cylinder 102. Certain features of reservoir type dampers are
shown and described in U.S. Pat. No. 7,374,028, which is
incorporated herein, in its entirety, by reference. The upper
portion of the rod 107 is supplied with a bushing set 109 for
connecting to a portion of a vehicle wheel suspension linkage. In
another embodiment, not shown, the upper portion of the rod 107
(opposite the piston) may be supplied with an eyelet to be mounted
to one part of the vehicle, while the lower part of the housing
shown with an eyelet 108 is attached to another portion of the
vehicle, such as the frame, that moves independently of the first
part. A spring member (not shown) is usually mounted to act between
the same portions of the vehicle as the damper. As the rod 107 and
piston 105 move into cylinder 102 (during compression), the damping
fluid slows the movement of the two portions of the vehicle
relative to each other due to the incompressible fluid moving
through the shimmed paths 110, 112 (past shims 116) provided in the
piston 105 and/or through the metered bypass 150, as will be
described herein. As the rod 107 and piston 105 move out of the
cylinder 102 (during extension or "rebound") fluid meters again
through shimmed paths 110 and 112 and the flow rate and
corresponding rebound rate is controlled by the shims 115.
[0013] In one embodiment as shown in the Figures, a bypass assembly
150 is designed to permit damping fluid to travel from a first side
of the piston to the other side without traversing shimmed flow
paths 110, 112 that may otherwise be traversed in a compression
stroke of the damper. In FIG. 1, the bypass 150 is shown in a
closed position (e.g. a valve 170 obstructs fluid passage through
entry way 160) and in FIG. 2 the bypass is shown in an open
position (e.g. valve 170 is open and fluid may flow through passage
160). In FIG. 2, the piston is shown moving downward in a
compression stroke, the movement shown by arrow 157. The bypass
includes a cylindrical body 155 that communicates with the damper
cylinder 102 through entry 160 and exit 165 pathways. In FIG. 2,
with the bypass open, the flow of fluid through the bypass is shown
by arrow 156. In one embodiment an entry valve 170 is located at
the entry pathway 160 with a valve member 175 sealingly disposed
and axially movable within the valve body. A needle-type check
valve 180, allowing flow in direction 156 and checking flow in the
opposite direction, is located proximate exit pathway 165. The
needle valve sets flow resistance through the bypass 150 during
compression and restricts fluid from entering the bypass cylinder
150 during a rebound stroke of the damper piston 105. In one
embodiment the needle valve 180 is spring loaded and biased closed.
The initial compression force of the biasing spring 182 is adjusted
via adjuster 183 thereby allowing a user to preset the needle valve
opening pressure and hence the compression damping fluid flow rate
(hence damping rate) through the bypass. The biasing force of the
needle valve spring 182 is overcome by fluid pressure in the
cylinder 155 causing the needle valve 180 to open during a
compression stroke.
[0014] The entry pathway 160 and entry valve 170 in the embodiments
shown in FIGS. 1 and 2, are located towards a lower end of the
damper cylinder 102. In one embodiment, as selected by design, the
bypass will not operate after the piston 105 passes the entry
pathway 160 near the end of a compression stroke. This "position
sensitive" feature ensures increased dampening will be in effect
near the end of the compression stoke to help prevent the piston
from approaching a "bottomed out" position (e.g. impact) in the
cylinder 102. In some instances, multiple bypasses are used with a
single damper and the entry pathways for each may be staggered
axially along the length of the damper cylinder in order to provide
an ever-increasing amount of dampening (and less bypass) as the
piston moves through its compression stroke and towards the bottom
of the damping cylinder. Certain bypass damper features are
described and shown in U.S. Pat. Nos. 6,296,092 and 6,415,895, each
of which are incorporated herein, in its entirety, by
reference.
[0015] In one embodiment the bypass 150, as shown in FIGS. 1 and 2,
includes a fluid (e.g. hydraulic or pneumatic) fitting 201 disposed
at an end of the entry valve body 170. The fluid fitting 201 is
intended to carry a control signal in the form of fluid pressure to
the valve member 175 in order to move the valve 170 from an open to
a closed position. In one embodiment, valve member 175 is biased
open by an annular spring 171 located between an upper end of the
valve member 175 and the lower axial end face of tube 155.
[0016] In one example, the valve 170 is moved to a closed position
and the bypass feature disabled by remote control from a simple
operator-actuated switch located in the passenger compartment of
the vehicle. In one embodiment, fluid pressure for controlling
(e.g. closing) the valve 170 is provided by the vehicle's own
source of pressurized hydraulic fluid created by, for example, the
vehicle power steering system. In one embodiment, pneumatic
pressure is used to control (e,g, close) the valve 170 where the
pneumatic pressure is generated by an on-board compressor and
accumulator system and conducted to the valve 170 via a fluid
conduit. In one embodiment, a linear electric motor (e.g.
solenoid), or other suitable electric actuator, is used to move
valve member 175 axially within valve body. A shaft of the electric
actuator (not shown) may be fixed to the valve member 175 such that
axial movement of the shaft causes axial movement of the valve
member 175. In one embodiment, the electric actuator is configured
to "push" the valve member 175 to a closed position and to "pull"
the valve member 175 to an open position depending on the direction
of the current switched through the actuator. In one embodiment,
the valve 170 is spring biased, for example, to an open position as
previously described herein, and the actuator, being switched by a
potentiometer or other suitable current or voltage modulator, moves
the valve member 175 against the biasing spring to a closed
position or to some position of desired partial closure (depending
on the operation of the switch). Such partial closure increases the
compression stiffness of the damper but does not provide the more
rigid dampening of complete bypass closure. In such electrical
embodiments, the solenoid is wired (e.g. via electrical conduit)
into the vehicle electrical system and switched to move the valve
170 as described herein.
[0017] FIG. 3 is a schematic diagram illustrating a sample circuit
400 used to provide remote control of a bypass valve using a
vehicle's power steering fluid (although any suitable fluid
pressure source may be substituted for reservoir 410 as could an
electrical current source in the case of an electrically actuated
valve member 175). As illustrated, a fluid pathway 405 having a
switch-operated valve 402 therein runs from a fluid (or current)
reservoir 410 that is kept pressurized by, in one embodiment, a
power steering pump (not shown) to a bypass valve 170 that is
operable, for example, by a user selectable dash board switch 415.
The valve 402 permits fluid to travel to the bypass valve 170,
thereby urging it to a closed position. When the switch 415 is in
the "off" position, working pressure within the damper, and/or a
biasing member such as a spring 171 (as described herein in
relation to FIGS. 1 & 2) or annular atmospheric chamber (not
shown), returns the bypass to its normally-open position.
Hydraulically actuated valving for use with additional components
is shown and described in U.S. Pat. No. 6,073,536 and that patent
is incorporated by reference herein in its entirety. While FIG. 3
is simplified and involves control of a single bypass valve, it
will be understood that the valve 402 could be plumbed to
simultaneously provide a signal to two or more bypass valves
operable with two or more vehicle dampers and/or with a single
damper having multiple bypass channels and multiple corresponding
valves (e.g. 175). Additional switches could permit individual
operation of separate damper bypass valves in individual bypass
channels, whether on separate dampers or on the same multiple
bypass damper, depending upon an operator's needs. While the
example of FIG. 3 uses fluid power for operating the bypass valve,
a variety of means are available for remotely controlling a valve.
For instance, a source of electrical power from a 12 volt battery
could be used to operate a solenoid member, thereby shifting valve
member 175 in bypass valve 170 between open and closed positions.
The signal can be either via a physical conductor or an RF signal
(or other wireless such as Bluetooth, WiFi, ANT) from a transmitter
operated by the switch 415 to a receiver operable on the bypass
valve 175.
[0018] A remotely operable bypass like the one described above is
particularly useful with an on/off road vehicle. These vehicles can
have as much as 20'' of shock absorber travel to permit them to
negotiate rough, uneven terrain at speed with usable shock
absorbing function. In off-road applications, compliant dampening
is necessary as the vehicle relies on its long travel suspension
when encountering off-road obstacles. Operating a vehicle with very
compliant, long travel suspension on a smooth road at higher speeds
can be problematic due to the springiness/sponginess of the
suspension. Such compliance can cause reduced handling
characteristics and even loss of control. Such control issues can
be pronounced when cornering at high speed as a compliant, long
travel vehicle may tend to roll excessively. Similarly, such a
vehicle may pitch and yaw excessively during braking and
acceleration. With the remotely operated bypass "lock out"
described herein, dampening characteristics of a shock absorber can
be completely changed from a compliantly dampened "springy"
arrangement to a highly dampened and "stiffer" system ideal for
higher speeds on a smooth road. In one embodiment where compression
flow through the piston is completely blocked, closure of the
bypass 150 results in substantial "lock out" of the suspension (the
suspension is rendered essentially rigid). In one embodiment where
some compression flow is allowed through the piston (e.g. ports
110, 112 and shims 116), closure of the bypass 150 results in a
stiffer but still functional compression damper. In one embodiment,
the needle valve 180 is tuned (using adjuster 183), and the shims
116 sized, to optimize damping when the bypass 150 is open and when
bypass 150 is closed based on total anticipated driving conditions.
In one embodiment the needle valve adjuster 183 is connected to a
rotary electrical actuator so that adjustment of the needle valve4
180 may be performed remotely as disclosed herein referencing the
bypass valve 170.
[0019] In addition to, or in lieu of, the simple, switch operated
remote arrangement of FIG. 3, the remote bypass can be operated
automatically based upon one or more driving conditions. FIG. 4
shows a schematic diagram of a remote control system 500 based upon
any or all of vehicle speed, damper rod speed, and damper rod
position. One embodiment of FIG. 4 is designed to automatically
increase dampening in a shock absorber in the event a damper rod
reaches a certain velocity in its travel towards the bottom end of
a damper at a predetermined speed of the vehicle. In one embodiment
the system adds dampening (and control) in the event of rapid
operation (e.g. high rod velocity) of the damper to avoid a
bottoming out of the damper rod as well as a loss of control that
can accompany rapid compression of a shock absorber with a relative
long amount of travel. In one embodiment the system adds dampening
(e.g. closes or throttles down the bypass) in the event that the
rod velocity in compression is relatively low, but the rod
progresses past a certain point in the travel. Such configuration
aids in stabilizing the vehicle against excessive low rate
suspension movement events such as cornering roll, braking and
acceleration yaw and pitch and "g-out."
[0020] FIG. 4 illustrates, for example, a system including three
variables: rod speed, rod position and vehicle speed. Any or all of
the variables shown may be considered by processor 502 in
controlling the valve 175. Any other suitable vehicle operation
variable may be used in addition to or in lieu of the variables
515, 505, 510 such as for example piton rod compression strain,
eyelet strain, vehicle mounted accelerometer data or any other
suitable vehicle or component performance data. In one embodiment,
a suitable proximity sensor or linear coil transducer or other
electro-magnetic transducer is incorporated in the dampening
cylinder to provide a sensor to monitor the position and/or speed
of the piston (and suitable magnetic tag) with respect to the
cylinder. In one embodiment, the magnetic transducer includes a
waveguide and a magnet, such as a doughnut (toroidal) magnet that
is joined to the cylinder and oriented such that the magnetic field
generated by the magnet passes through the piston rod and the
waveguide. Electric pulses are applied to the waveguide from a
pulse generator that provides a stream of electric pulses, each of
which is also provided to a signal processing circuit for timing
purposes. When the electric pulse is applied to the waveguide a
magnetic field is formed surrounding the waveguide. Interaction of
this field with the magnetic field from the magnet causes a
torsional strain wave pulse to be launched in the waveguide in both
directions away from the magnet. A coil assembly and sensing tape
is joined to the waveguide. The strain wave causes a dynamic effect
in the permeability of the sensing tape which is biased with a
permanent magnetic field by the magnet. The dynamic effect in the
magnetic field of the coil assembly due to the strain wave pulse,
results in an output signal from the coil assembly that is provided
to the signal processing circuit along signal lines. By comparing
the time of application of a particular electric pulse and a time
of return of a sonic torsional strain wave pulse back along the
waveguide, the signal processing circuit can calculate a distance
of the magnet from the coil assembly or the relative velocity
between the waveguide and the magnet. The signal processing circuit
provides an output signal, either digital or analog, proportional
to the calculated distance and/or velocity. Such a
transducer-operated arrangement for measuring rod speed and
velocity is described in U.S. Pat. No. 5,952,823 and that patent is
incorporated by reference herein in its entirety.
[0021] While a transducer assembly located at the damper measures
rod speed and location, a separate wheel speed transducer for
sensing the rotational speed of a wheel about an axle includes
housing fixed to the axle and containing therein, for example, two
permanent magnets. In one embodiment the magnets are arranged such
that an elongated pole piece commonly abuts first surfaces of each
of the magnets, such surfaces being of like polarity. Two inductive
coils having flux-conductive cores axially passing therethrough
abut each of the magnets on second surfaces thereof, the second
surfaces of the magnets again being of like polarity with respect
to each other and of opposite polarity with respect to the first
surfaces. Wheel speed transducers are described in U.S. Pat. No.
3,986,118 which is incorporated herein by reference in its
entirety.
[0022] In one embodiment, as illustrated in FIG. 4, a logic unit
502 with user-definable settings receives inputs from the rod speed
510 and location 505 transducers as well as the wheel speed
transducer 515. The logic unit is user-programmable and depending
on the needs of the operator, the unit records the variables and
then if certain criteria are met, the logic circuit sends its own
signal to the bypass to either close or open (or optionally
throttle) the bypass valve 175. Thereafter, the condition of the
bypass valve is relayed back to the logic unit 502.
[0023] FIG. 5 is a graph that illustrates a possible operation of
one embodiment of the bypass assembly 500 of FIG. 4. The graph
assumes a constant vehicle speed. For a given vehicle speed, rod
position is shown on a y axis and rod velocity is shown on an x
axis. The graph illustrates the possible on/off conditions of the
bypass at combinations of relative rod position and relative rod
velocity. For example, it may be desired that the bypass is
operable (bypass "on") unless the rod is near its compressed
position and/or the rod velocity is relatively high (such as is
exemplified in FIG. 5). The on/off configurations of FIG. 5 are by
way of example only and any other suitable on/off logic based on
the variable shown or other suitable variables may be used. In one
embodiment it is desirable that the damper become relatively stiff
at relatively low rod velocities and low rod compressive strain
(corresponding for example to vehicle roll, pitch or yaw) but
remains compliant in other positions. In one embodiment the piston
rod 107 includes a "blow off" (overpressure relief valve typically
allowing overpressure flow from the compression side to the rebound
side) valve positioned in a channel coaxially disposed though the
rod 107 and communicating one side of the piston (and cylinder)
with the other side of the piston (and cylinder) independently of
the apertures 110,112 and the bypass 150.
[0024] In one embodiment, the logic shown in FIG. 4 assumes a
single damper but the logic circuit is usable with any number of
dampers or groups of dampers. For instance, the dampers on one side
of the vehicle can be acted upon while the vehicles other dampers
remain unaffected.
[0025] While the examples illustrated relate to manual operation
and automated operation based upon specific parameters, the
remotely operated bypass can be used in a variety of ways with many
different driving and road variables. In one example, the bypass is
controlled based upon vehicle speed in conjunction with the angular
location of the vehicle's steering wheel. In this manner, by
sensing the steering wheel turn severity (angle of rotation),
additional dampening can be applied to one damper or one set of
dampers on one side of the vehicle (suitable for example to
mitigate cornering roll) in the event of a sharp turn at a
relatively high speed. In another example, a transducer, such as an
accelerometer measures other aspects of the vehicle's suspension
system, like axle force and/or moments applied to various parts of
the vehicle, like steering tie rods, and directs change to the
bypass valve positioning in response thereto. In another example,
the bypass can be controlled at least in part by a pressure
transducer measuring pressure in a vehicle tire and adding
dampening characteristics to some or all of the wheels in the event
of, for example, an increased or decreased pressure reading. In
still another example, a parameter might include a gyroscopic
mechanism that monitors vehicle trajectory and identifies a
"spin-out" or other loss of control condition and adds and/or
reduces dampening to some or all of the vehicle's dampers in the
event of a loss of control to help the operator of the vehicle to
regain control.
[0026] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *