Damper with externally mounted semi-active system

An automatic damper for an automobile automatic damper system which provides a compression valve operable to vary compressive damping characteristics of a damper, as well as a rebound valve operable to vary rebound damping characteristics of the damper. Use of the invention in cooperation with presently available electronic control modules and sensing algorithms provides a damper with either discrete valves or continuously variable valves for independently setting the rebound and compression damping characteristics of the damper.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates generally to hydraulic dampers, and more
 particularly to a new and improved semi-active damper with an externally
 mounted valve assembly for selectively varying stiffness of the damper in
 compression and separately selectively varying stiffness of the damper in
 rebound.
 2. Description of Related Art
 Dampers are used in conjunction with automotive suspension systems to
 absorb unwanted vibrations which occur while driving a vehicle. In order
 to absorb unwanted vibrations, dampers are generally connected between the
 body and the suspension of an automobile. A piston is located within the
 damper which is connected to the body of the automobile through a piston
 rod. Furthermore, the damper body is connected to the suspension of the
 automobile. Because the piston is able to limit the flow of damping fluid
 within the working chamber of the damper as the damper is compressed
 extended, the damper is able to produce a damping force which counteracts
 suspension system vibration which wold otherwise be transmitted from the
 suspension to the body. By further restricting the flow of damping fluid
 within the working chamber of a damper, greater damping forces are
 generated by the damper.
 In determining the optimal amount of damping that a damper should provide,
 three vehicle performance characteristics are often considered: ride
 comfort, vehicle handling and road holding ability. Ride comfort is
 typically a function of the spring constant of the vehicle's main springs,
 as well as the spring constant of the occupant's seat, the vehicle's tires
 the suspension geometry, and the damper. Vehicle handling is related to
 changes in the vehicle's attitude (i.e., pitch, yaw, and roll). To achieve
 optimum vehicle handling, relatively large damping forces are required to
 avoid excessively rapid variation in the vehicle's attitude during
 acceleration, deceleration, and cornering. Road holding ability is
 generally dependent on the amount of contact between the vehicle tires and
 the ground. In order to optimize a vehicle's road holding ability, large
 damping forces are required as a vehicle passes over irregular surfaces in
 order to prevent loss of contact between the wheels and ground for an
 excessive period of time.
 Because different driving characteristics require differing amounts of
 damping force from the damper in order to optimize its performance, it is
 often desirable to have a damper which can be adjusted to increase or
 decrease the requisite damping forces. One method for selectively changing
 a damper's damping characteristics is described in U.S. Pat. No.
 4,890,858. This reference discloses a rotary valve for use in controlling
 a damper. The damper comprises a first valve member which is disposed
 within the pressure cylinder for establishing a plurality of flow
 passages. Furthermore, the damper comprises a second valve member also
 disposed within the pressure cylinder for establishing a second plurality
 of flow passages. In addition, the damper includes an actuator for
 providing an accelerating and decelerating force to the second valve
 member. Finally, control means for controlling displacement of the second
 valve member are also disclosed.
 Because dampers which provide adjustable damping generally use a single
 valve to control the flow of damping fluid during both compression and
 rebound, a sensor is generally required to determine whether the damper is
 in compression or rebound. Not only does this provide a degree of
 difficultly in terms of sensor placement, there are also disadvantages
 with respect to the electronics which are required to generate an output
 indicative of whether the damper is in compression or rebound from the
 output of the sensor. Accordingly, these systems tend to be somewhat
 expensive.
 SUMMARY OF THE INVENTION
 The present invention relates to a damper which includes a pressure
 cylinder and a piston which is reciprocally mounted in the cylinder so as
 to define a compression chamber and rebound chamber. The compression and
 rebound chambers are operable to store damping fluid and the piston is
 movable for reciprocally varying the volumes of the compression and
 rebound chambers. The damper further includes a valve for controlling the
 flow of fluid between the compression and rebound chambers, as well as a
 reservoir for receiving damping fluid. A compression transfer tube is
 provided which allows fluid communication between the compression chamber
 and the reservoir. The damper further includes a compression valve in
 communication with the transfer tube as well as a base valve in the
 pressure cylinder in communication with the pressure chamber and the
 reservoir. Finally, the damper includes a reservoir fluid aperture in the
 reservoir for establishing fluid flow from the reservoir to the rebound
 chamber.
 Accordingly, the primary object of the present invention is to provide a
 semiactive damper for use in an automatic damping system of a vehicle
 which can be controlled by individually dedicated or shared electronic
 control modules. In this regard, a related object of the present invention
 is to provide a simplified and lower cost semiactively adjustable damper
 in which adaptive external valves allow for independent adjustable setting
 of the damper damping in rebound and compression.
 A further object of the present invention is to provide a semi-active
 damper in which a pair of separate dedicated valving systems are utilized
 to soften damper damping in rebound and compression, which simplifies the
 damper while still providing an automatic damper system in which the rate
 of damping fluid flow between upper and lower portions of a working
 chamber may be controlled with a relatively high degree of accuracy. A
 related object of the present invention is to provide a semi-active
 damping system in which detection of rebound-compression transitions for
 each damper are not required which eliminates the need for a position
 sensor to sense the transition, yet still allows for achievement of
 separately tailored compression and rebound characteristics.
 Further objects, features and advantages of this invention are to provide a
 damper which can be easily and readily adjusted automatically and
 semi-actively to optimize damping characteristics, with separate discrete
 or continuously variable external valves achieving separate damping
 settings in rebound and compression, and which has a long service life and
 is rugged, durable, reliable, of simplified design and of relatively
 economical manufacture and assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 The following description of the preferred embodiment of the present
 invention is merely exemplary in nature and is in no way intended to limit
 the invention or its application or uses.
 Referring now to FIG. 1, a plurality of four dampers 10 according to the
 preferred embodiment of the present invention are shown. Each damper 10 is
 depicted in operative association with a diagrammatic representation of a
 conventional automobile 12. Automobile 12 provides a rear suspension
 system 14 having a transversely extending rear axle assembly (not shown)
 adapted to operatively support the vehicle's rear wheels 16. The rear axle
 assembly is operatively connected to the automobile 12 by means of a pair
 of dampers 10 as well as by helical coil springs 18. Similarly, automobile
 12 has a front suspension system 20 including a transversely extending
 front axle assembly (not shown) which operatively supports the front
 wheels 22. The front axle assembly is operatively connected to the
 automobile 12 by means of a second pair of dampers 10 and by the helical
 coil springs 24. The dampers 10 serve to damp the relative movement of the
 unsprung portion (i.e., the front and rear suspension systems 20 and 14)
 and the sprung portion (i.e., the body 26) of the automobile 12. While the
 automobile 12 has been depicted as a passenger car, the damper 10 may be
 used with other types of automotive vehicles or in other types of vehicles
 or system applications. Furthermore the term "damper" as used herein will
 refer to dampers in general and will include shock absorbers and McPherson
 struts.
 In order to automatically adjust the dampers 10 of this invention, an
 electronic control module 28 is electrically connected to the dampers. As
 depicted in FIG. 1, each damper 10 is provided with a dedicated electronic
 control module 28. Each control module 28 is used for controlling
 operation of each damper 10 in order to provide appropriate damping
 characteristics during compression and rebound resulting from movement of
 the body 26 of the automobile 12. While the present invention is being
 illustrated with dedicated control modules 28, it is within the scope of
 the present invention to utilize a single control module communicating
 with each damper 10. Various techniques are known in the art for
 implementing electronic control modules in conjunction with dampers in
 order to regulate damping characteristics of a damper through variation of
 fluid flow valves in the damper.
 As a general rule, it is desirable to have soft damping when the frequency
 of movement of the body 26 of the automobile 12 in the vicinity of damper
 10 is less than a first specified frequency as well as when it is above a
 specified frequency. It is also generally desirable to have firm damping
 only when the acceleration of body 26 of automobile 12 in the range of the
 damper 10 exceeds a preselected value even when the frequency of the
 acceleration is between the first and second specified frequencies.
 Furthermore, it is generally desirable to separately adjust between soft
 and firm damping for the rebound mode and for the compression mode, which
 means the transition between rebound and compression modes must be
 detected in order to selectively switch parameters in order to achieve the
 desired optimal rebound and compression performance stiffness parameters
 during each mode. By designing a damper which has separate valving for the
 rebound mode and the compression mode, the electronic control module 28
 can be used to generate an electronic control signal for separately and
 concurrently setting desirable compression and rebound damping
 characteristic of the damper 10 to which it is connected.
 Referring to FIG. 2, to retain the damper 10 to an automotive vehicle 12,
 the damper 10 includes an upper end fitting 30 and a lower end fitting 32.
 The upper end fitting 30 extends through an upper cap portion 34 and is
 connected to a vehicle body structure, such as a shock tower (not shown).
 Similarly, the lower end fitting 32 is connected to the damper 10 adjacent
 a lower cap portion 36 so as to secure the damper 10 to one of the
 suspension systems 14 and 20. As will be appreciated by those skilled in
 the art, other suitable means may be used to secure the damper, or
 dampers, 10 to the automotive vehicle 12.
 As shown in FIG. 2, the damper 10 of this invention comprises an elongated
 tubular pressure cylinder 38 defining a damping fluid-containing working
 chamber 40, and disposed within the chamber 40 is a reciprocal piston 42.
 The reciprocal piston 42 is secured to one end of an axially extending
 piston post 44 which is in turn secured to one end of an axially extending
 piston rod 46. Alternatively, the piston 42 can be secured directly to one
 end of piston rod 46. Preferably, the piston 42 carries an annular
 TEFLON.TM. sleeve 48 which is trapped on the outer circumference of the
 piston to permit movement of the piston with respect to the pressure
 cylinder 38 without generating undue frictional forces. Additionally, the
 piston 42 is further provided with a bi-directional flow valve 43 which
 allows regulated flow of damping fluid from one side of the piston to the
 other, or alternatively, is provided with at least a pair of
 uni-directional flow valves arranged on piston 42 for opposite-directional
 fluid flow therethrough. Further variations of piston valves are presently
 known in the art which include spring biased valves with valve seats which
 provide fluid flow in a regulated manner above a threshold pressure, or
 alternatively, metering pins and orifices which variably regulate fluid
 flow depending on exerted pressure therethrough. A further explanation of
 the construction and operation of pistons and piston valves is disclosed
 in U.S. Pat. No. 4,113,072, which is hereby incorporated by reference.
 A base valve 50 is located within the lower end of the pressure cylinder 38
 and is used to control the flow of damping fluid between the working
 chamber 40 and an annular fluid reservoir 52. The annular fluid reservoir
 52 is defined as the space between the outer periphery of a compression
 transfer tube 54, a circumferential interface ring 56, and a rebound
 transfer tube 58 and the inner periphery of a reservoir tube 60 forming
 the exterior surface of the damper 10. Preferably, the operation of base
 valve 50 is similar to the operation of the base valve shown in U.S. Pat.
 No. 3,757,910, which is hereby incorporated by reference. However, other
 types of base valves may be used.
 In addition to receiving the upper and lower cap portions 34 and 36,
 reservoir tube 60 of damper 10 may support a spring base flange 62 such
 that flange 62 is received circumferentially about tube 60 where it is
 welded. Additionally, a support collar 64 is received circumferentially
 about the piston rod 46 where it exits through upper cap portion 34 such
 that the collar 64 is retained atop the upper cap portion 34. The spring
 base flange 62 receives a bottom end of a helical coil spring 18 (as
 depicted in FIG. 1) which is circumferentially carried about the top end
 of the damper 10. Likewise, a spring cap (not shown) is received on the
 top of spring 18 such that a hole in the cap mates with a collar 68 formed
 on piston rod 46 and abuts with a corresponding shoulder 70 onto which it
 is trapped by threading a nut (not shown) onto threaded end 66. The spring
 cap is first loaded onto the threaded end 66 before loading end 66 into a
 receiving hole formed in vehicle body shock tower (not shown), such that a
 nut is threaded onto end 66 which traps the shock tower and spring cap to
 the end of the piston rod 46. Vehicle loads produced between the vehicle
 shock tower on the piston rod 46 react against loads imparted by lower end
 fitting 32 which is affixed to a vehicle wheel such that compression
 therebetween counteracts forces produced by a coil spring 18. In its
 assembly configuration, the spring acts in a compressive mode to space
 apart base flange 62 from the spring cap on the end of the piston rod 46.
 Finally, the apertures 72 and 74 are provided through reservoir tube 60,
 on opposite sides, such that each receives a compression valve 76 and a
 rebound valve 78, respectively. The compression valve 76 and rebound valve
 78 fluidly communicate with a circumferential interface ring 56 against
 which they are sealingly retained. Preferably, each aperture 72 and 74 is
 circumferentially welded to a valve housing of each valve 76 and 78.
 Reciprocating motion of the piston 42 and the piston rod 46 within the
 pressure cylinder 38 is axially guided by sliding contact of annular
 TEFLON sleeve 48 within the pressure cylinder 28 at one end, and by
 sliding and sealing reciprocation of the piston rod 46 through a rod guide
 80 which is supported by the upper cap portion 34 to seal the top end of
 the damper 10, and slidably seal the piston rod as it exits therethrough.
 Various configurations for rod guides which incorporate single and
 multiple circumferential seals are well known in the art for sealing and
 seating the ends of dampers.
 Reciprocation of the piston 42 within the work chamber 40 formed inside
 pressure cylinder 38 partitions the work chamber to define a variable
 volume compression chamber 82 and a variable volume rebound chamber 84.
 Damping fluid is provided in both the compression chamber 82 and the
 rebound chamber 84.
 A rebound transfer volume 86 is formed between the exterior surface of the
 pressure cylinder 38 and the interior surface of the rebound transfer tube
 58, and is further defined at either end by the rod guide 80 and the
 circumferential interface ring 56, respectively, with which they seal. A
 rebound connection opening 88 is formed in the pressure cylinder 38
 proximate the rod guide 80 which provides damping fluid flow between the
 rebound transfer volume 86 and the rebound chamber 84. If desired, opening
 88 can be formed in rod guide 80. Additionally, the rebound transfer
 volume 86 communicates through rebound transfer tube 58 with rebound valve
 78.
 A compression transfer volume 90 is formed between the exterior surface of
 the pressure cylinder 38 and the interior surface of the compression
 transfer tube 54, and is further defined at either end by base valve 50
 and circumferential inner face ring 56, respectively, with which they
 seal. A compression connection opening 92 is formed in the pressure
 cylinder 38 proximate the base valve 50 which provides damping fluid flow
 between the compression transfer volume 90 and the compression chamber 82.
 Additionally, the compression transfer volume 90 communicates through the
 compression transfer tube 54 with the compression valve 76.
 The base valve 50 mates within the pressure cylinder 38 at one end as a
 decreased diameter shoulder 94 on the valve 50 is received within pressure
 cylinder 38 where it substantially circumferentially seals therebetween,
 and an annular face 96 on the valve 50 seats against both ends of pressure
 cylinder 38 and compression transfer tube 54 such that a seal is formed
 therebetween which cooperates in defining the compression transfer volume
 90. Preferably, the base valve 50 is circumferentially welded to the end
 of the compression transfer tube 54. Preferably, the base valve 50 is
 provided with a fluid aperture 98 which controllably regulates a
 bidirectional fluid flow between the compression chamber 82 and the fluid
 reservoir 52. Various other forms of base valves are presently known in
 the art for providing bidirectional flow in the bottom of a damper.
 As shown in FIG. 3, the compression valve 76 and rebound valve 78 sealingly
 fasten to the reservoir tube 60 such that they extend through apertures 72
 and 74, respectively, and abut and seal in fluid communication with fluid
 ports provided in circumferential interface ring 56. The compression valve
 76 has a solenoid 102 in electrical communication through a flex cable 104
 with the accompanying electronic control module 28 which selectively
 electrically sends signals to engage and disengage the solenoid which
 opens and closes the compression valve 76. By electrically activating the
 solenoid 102, the compression valve 76 is opened which provides a flow of
 damping fluid from the compression transfer volume 90 into the annular
 fluid reservoir 52 in response to compressive motion of piston 42 toward
 the compression chamber 82. Likewise, the rebound valve 78 has a solenoid
 106 in electrical communication through a flex cable 108 with the same
 electronic control module 28 which selectively electrically activates and
 deactivates the solenoid to close and open, respectively, the rebound
 valve 78. As a consequence, when rebound valve 78 is opened by activating
 solenoid 106, fluid flows from rebound transfer volume 86 into a
 compression transfer volume 90 in response to rebound motion of the piston
 42 towards the rebound chamber 78.
 It is to be understood that opening of the compression valve 76 and the
 rebound valve 78 through activation of the solenoid 102 and activation of
 the solenoid 106, respectively, produces supplemental fluid flow between
 the compression chamber 82 and the reservoir 52, and between the rebound
 chamber and the compression chamber. Primary fluid flow between the
 compression chamber 82 and the rebound chamber 84 is provided by damping
 fluid which flows through the piston aperture 43. By closing the
 compression valve 76, the stiffness of the damper 10 during compression is
 increased. Likewise, by closing the rebound valve 78, the rebound
 stiffness of the damper 10 is decreased. Through either discrete
 fluctuation of the valve 76 and 78, or continuously variable actuation of
 such valves, fluid flow between the compression chamber 82 and rebound
 chamber 84 can be tailored to provide adjustable stiffness of the damper
 10 in an independent manner for both pressure cycles and rebound cycles.
 In the case of fluid flow from the compression chamber 82 through the
 compression valve 76 and into the rebound chamber 84, it is to be
 understood that the damping fluid travels a circuitous path. Damping fluid
 compressed in the compression chamber 82 is passed through the base valve
 50 which empties into the fluid reservoir 52. Concurrently, damping fluid
 in compression chamber 82 exits through the compression connection opening
 92 into the compression transfer volume 90 where it passes through the
 compression valve 76, while in an open position, into the reservoir 52.
 Further transfer of fluid from the reservoir 52 is provided through a
 reservoir fluid aperture 110 (FIG. 1) which is formed in the rod guide 80
 for transferring fluid from the reservoir 52 into the rebound chamber 84.
 Furthermore, the rebound chamber 84 communicates with the rebound transfer
 volume through the rebound connection opening 88 such that fluid
 compressed in the rebound chamber is transferred through rebound transfer
 volume 86 through the rebound valve 78, when in an open position, and into
 the annular fluid reservoir 52 which further transfers fluid through the
 compression connection opening 92 into the compression volume 82.
 As shown in FIGS. 3 and 4, the solenoid 102 has an axially extendable and
 retractable core 112. The core 112 is formed from a ball 114 biased by a
 spring 116 and a sealing plate 118. When deactuated, the core 112 moves
 towards a seat 120 sealing off fluid flow through the center bore of seat
 120 with the ball 114 in a first stage. Fluid flow continues through the
 seat 120 due to a plurality of bleed holes 121 circumferentially spaced
 around the central bore of the seat 120. In a second stage, the sealing
 plate 118 seals against the seat 120 to seal off the bleed holes 121
 extending through the seat 120. The two stage sealing described above
 reduces the water-hammer effect of closing compression valve 76. A check
 valve 122 prevents back flow from reservoir 52 to compression transfer
 volume 90.
 As shown in FIG. 4, compression valve 76 is depicted with reference arrows
 showing flow of damper fluid through the valve while it is in an open
 position. Fluid is delivered from the compression transfer volume 90
 through the compression valve 76 and into the fluid reservoir 52 via flow
 ports in the circumferential interface ring 56 which is mated with a valve
 collar 129 to the assembly of solenoid 102 to form the compression valve
 76. Fluid leaving the compression transfer volume 90 enters a radial port
 124 which opens into a circumferential upstream well 128 in the collar 129
 where damping fluid is passed through a bleed disc 126 into a
 circumferential downstream well 130 to transfer through the center bore of
 seat 120 while solenoid 102 is energized. The upstream well 128 and the
 downstream well 130 are integrally formed within the collar 129. Likewise,
 the bleed disc 126 is seated in the ring between the upstream and
 downstream wells. The seat 120 is carried in a receiving bore 136
 interjacent the upstream well 128, and fluid flows through a central
 aperture 138 in the bleed disc 126 where it is delivered to the center
 bore of seat 120. Upon energizing the solenoid 102, fluid flows past check
 valve 122 into a spring port 132 which supports the check valve 122, where
 damping fluid is further delivered through an exit port 134 into the
 reservoir 52.
 As further shown in FIGS. 3 and 4, the solenoid 106 is energized such that
 a core 140 having an end mounted plunger ball 142 is retracted from a flow
 orifice 144 and a plunger seat 146 through which flow is provided, thus
 opening the rebound valve 78. The rebound valve 78 is provided in sealing
 abutment against flow passages provided in the circumferential interface
 ring 56 by welding the solenoid 106 outer housing circumferentially to
 aperture 74. As a result, a flowpath is provided from the rebound transfer
 volume 86 through the interface ring 56, into and through the rebound
 valve 78, back through the interface ring 56, and out through the
 compression transfer volume 90. More particularly, damping fluid flows
 from rebound transfer volume 86 into a first radial port 148 formed in the
 interface ring 56 which empties into a circumferential upstream well 152,
 through a bleed disc 150 and into a circumferential downstream well 154
 where it passes through a central aperture 158 in the bleed disc 150 for
 transfer through orifice 144. The circumferential upstream and downstream
 wells 152 and 154 are provided in a valve collar 157 carried in the
 rebound valve 78 which seats and abuts with the interface ring 56 on one
 side, and abuts with the solenoid 106 on the other side, and further
 provides a receiving bore 160 for carrying plunger seat 146 therein.
 Furthermore, a flow exit port 162 is provided downstream of the plunger
 seat 146 through which damping fluid exits from flow orifice 144 and
 enters a second radial port 156 provided in the interface ring 156 for
 exit to the compression transfer volume 90. As depicted in FIG. 4, the
 solenoid 106 is activated in a retracted position which provides fluid
 flow through the rebound valve 78. By de-energizing the solenoid 106, the
 rebound valve 78 is activated, axially extending core 140 and the plunger
 ball 142 to seal with the plunger seat 146 and stop flow through the
 orifice 144, thereby effectively shutting off the rebound valve 78.
 In operation, the solenoid 102 can be energized to open the compression
 valve 76 in order to provide a bypass flow of damping fluid over flow
 provided through the base valve 50, as well as the flow apertures 98
 provided in the piston 42. By energizing the solenoid 102 and opening the
 compression valve 76, the flow of damping fluid in the compression chamber
 82 is provided into the reservoir 52, via the various flow paths described
 above. By providing by-passing fluid flow in addition to fluid flow of the
 piston 42 and the base valve 50, compressive damping of the damper 10 can
 be varied. In operation, the solenoid 106 is de-energized to close rebound
 valve 78, and is energized to open the rebound valve 78. When opened, a
 by-pass flow is created for damping fluid in addition to fluid valves, or
 ports, provided in the piston 42. This by-pass flow is regulated by the
 bleed disc 150, valving or slots formed in the disc. In operation, while
 the rebound valve 78 is open, hydraulic fluid volume passing through the
 rebound valve, at low pressure after leaving the rebound valve, will
 partly fill the compression chamber 82, via the compression transfer
 volume 90. The damping fluid flows through the compression connection
 chamber 82, via the compression transfer volume 90. The damping fluid
 flows through the compression connection opening 92 which further meters
 transfer of the fluid between the compression transfer volume 90 and the
 compression chamber 82. Each of the preceding occurs during the rebound
 phase of the piston 42 in the damper 10. Furthermore, the check valve 122
 in the compression valve 76 prevents damping fluid flow from being sucked
 into the compression chamber 82 through the compression valve 76 while the
 piston 42 is in rebound. Furthermore, remaining damping fluid necessary
 for filling the compression chamber 82 is provided through the intake of
 the base valve 50 as the piston 42 is moved upward toward a rebound
 position.
 While it is apparent that the preferred embodiment illustrated above is
 well-calculated to fulfill the objects stated, it will be appreciated that
 the present invention is capable of modification, variation and change
 without departing from the scope of the invention. For example, from the
 discussion above, application of discrete valve concepts have been
 incorporated in the compression valves 76 and rebound valve 78 of the
 preferred embodiment. However, modifications are generally known in the
 art for providing variable flow orifices, such as metering pins having
 varying diameters which axially cooperate with flow orifices to provide
 annular flow paths, such that tailored flow delivery can be produced
 through each vale provide a continuously variable valve for both the
 compression and rebound phases of a damper 10. Furthermore, construction
 of a rebound transfer tube 58 which is concentric over pressure cylinder
 38 can be substituted with a transfer tube of various other design
 currently utilized with normal external valve damper systems currently
 available on the market. Likewise, the disc valving provided through bleed
 discs 126 and 150 can be replaced by spring valving systems which regulate
 fluid flow, by increased dimensions of the valve.
 In addition, various methods may be used for sensing accelerations or
 velocities of a vehicle suspension which dictate settings for tailoring
 damping characteristic in compression and rebound. For example,
 accelerometers can be provided atop each damper 10 which monitor shock
 conditions resulting from pitch, yaw, and roll, as well as interaction
 with various bumps and obstacles, such sensed signal being further
 processed by the electronic control module 28 and compared to determine
 the desired compression and rebound damping characteristics for the damper
 10. As a result, compression valve 76 and rebound valve 78 are actuated
 accordingly. In accordance, the scope of the invention is to be measured
 against the scope of the following claims.