US20160025179A1 - Suspension strut for a vehicle - Google Patents
Suspension strut for a vehicle Download PDFInfo
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- US20160025179A1 US20160025179A1 US14/875,426 US201514875426A US2016025179A1 US 20160025179 A1 US20160025179 A1 US 20160025179A1 US 201514875426 A US201514875426 A US 201514875426A US 2016025179 A1 US2016025179 A1 US 2016025179A1
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- valve
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- strut
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/34—Special valve constructions; Shape or construction of throttling passages
- F16F9/348—Throttling passages in the form of annular discs or other plate-like elements which may or may not have a spring action, operating in opposite directions or singly, e.g. annular discs positioned on top of the valve or piston body
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60G—VEHICLE SUSPENSION ARRANGEMENTS
- B60G13/00—Resilient suspensions characterised by arrangement, location or type of vibration dampers
- B60G13/02—Resilient suspensions characterised by arrangement, location or type of vibration dampers having dampers dissipating energy, e.g. frictionally
- B60G13/06—Resilient suspensions characterised by arrangement, location or type of vibration dampers having dampers dissipating energy, e.g. frictionally of fluid type
- B60G13/08—Resilient suspensions characterised by arrangement, location or type of vibration dampers having dampers dissipating energy, e.g. frictionally of fluid type hydraulic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60G—VEHICLE SUSPENSION ARRANGEMENTS
- B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
- B60G17/06—Characteristics of dampers, e.g. mechanical dampers
- B60G17/08—Characteristics of fluid dampers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/06—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using both gas and liquid
- F16F9/064—Units characterised by the location or shape of the expansion chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/06—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using both gas and liquid
- F16F9/066—Units characterised by the partition, baffle or like element
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/10—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using liquid only; using a fluid of which the nature is immaterial
- F16F9/14—Devices with one or more members, e.g. pistons, vanes, moving to and fro in chambers and using throttling effect
- F16F9/16—Devices with one or more members, e.g. pistons, vanes, moving to and fro in chambers and using throttling effect involving only straight-line movement of the effective parts
- F16F9/18—Devices with one or more members, e.g. pistons, vanes, moving to and fro in chambers and using throttling effect involving only straight-line movement of the effective parts with a closed cylinder and a piston separating two or more working spaces therein
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/3207—Constructional features
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/43—Filling or drainage arrangements, e.g. for supply of gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/44—Means on or in the damper for manual or non-automatic adjustment; such means combined with temperature correction
- F16F9/46—Means on or in the damper for manual or non-automatic adjustment; such means combined with temperature correction allowing control from a distance, i.e. location of means for control input being remote from site of valves, e.g. on damper external wall
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/50—Special means providing automatic damping adjustment, i.e. self-adjustment of damping by particular sliding movements of a valve element, other than flexions or displacement of valve discs; Special means providing self-adjustment of spring characteristics
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/50—Special means providing automatic damping adjustment, i.e. self-adjustment of damping by particular sliding movements of a valve element, other than flexions or displacement of valve discs; Special means providing self-adjustment of spring characteristics
- F16F9/516—Special means providing automatic damping adjustment, i.e. self-adjustment of damping by particular sliding movements of a valve element, other than flexions or displacement of valve discs; Special means providing self-adjustment of spring characteristics resulting in the damping effects during contraction being different from the damping effects during extension, i.e. responsive to the direction of movement
- F16F9/5165—Special means providing automatic damping adjustment, i.e. self-adjustment of damping by particular sliding movements of a valve element, other than flexions or displacement of valve discs; Special means providing self-adjustment of spring characteristics resulting in the damping effects during contraction being different from the damping effects during extension, i.e. responsive to the direction of movement by use of spherical valve elements or like free-moving bodies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60G—VEHICLE SUSPENSION ARRANGEMENTS
- B60G2300/00—Indexing codes relating to the type of vehicle
- B60G2300/60—Vehicles using regenerative power
Definitions
- This invention relates generally to the damper field, and more specifically to an improved suspension strut in the vehicle suspension field.
- the triple-tube type strut construction includes tube and valve arrangement that allows for fluid flow within the strut that is generally in a single direction for both the compression and rebound direction of the suspension strut, whereas both mono-tube and twin-tube type struts require fluid to flow in different directions for the compression and rebound directions.
- This single-direction property of the triple-tube type strut allows for damping control of the fluid flow within the triple-tube type strut to be localized to one general area within the strut for both compression and rebound directions.
- conventional semi-active or continuously variable damping control systems typically utilize the triple-tube type strut and a single active solenoid valve to control damping force for both the compression and rebound directions of the strut.
- triple-tube type strut dampers include many internal parts that function to tune the dampening properties of the strut and are, for this reason, quite complex. Additionally, the damping mechanisms that are utilized in such triple-tube type struts may leak, decreasing the efficiency of the damper, or may be relatively expensive. As shown in FIG. 1 (prior art), the active valve 10 in typical triple-tube type strut dampers is often mounted perpendicular to the long axis of the damper tube 12 and substantially adjacent to the base valve 14 that allows replenishment flow to the inner cavity 16 during the rebound stroke of the strut. This may allow such triple-tube type strut dampers to increase the range of travel of the suspension strut given a total strut height.
- this arrangement requires a fastening mechanism that does not benefit from the compressive forces from tube assembly and/or the vehicle.
- the fastening mechanism used to mount the active valve perpendicularly to the axis of the damper tube may become substantially costly to withstand such high pressures. Because of complexity of typical triple-tube type strut dampers, cost is relatively high and adoption of such semi-active or continuously variable damping control systems in the field is substantially impaired.
- FIG. 1 is a schematic representation of a semi-active suspension strut of the prior art.
- FIGS. 2A and 2B are schematic representations of the suspension strut of the preferred embodiments with the displacement rod and cavity piston displaced away from the valve plate and with the displacement rod and cavity piston displaced toward the valve plate, respectively.
- FIGS. 3A , 3 B, and 3 C are schematic representations of the valve plate with a passive damper valve in an orthogonal view, taken along Line A-A in FIG. 3A with the damping flow path, and taken along Line B-B in FIG. 3A with the replenishment flow path, respectively.
- FIG. 4 is a schematic representation of flow during the compression stroke.
- FIGS. 5A and 5B are schematic representations of flow during the rebound stroke of the outflow from the pressure chamber and the rebound flow into the interior cavity, respectively.
- FIGS. 6A and 6B are schematic representations of the valve plate with a variation of an actuatable damper valve with decreased damping force and increased damping force, respectively.
- FIGS. 7A , 7 B, and 7 C are a schematic representation of the valve plate with a first, second, and third variation of a regenerative damper valve, respectively.
- FIG. 8 is a schematic representation of the regenerative suspension strut system embodiment.
- FIGS. 9A and 9B are schematic representations of flow during the compression stroke for a first and a second embodiment of the regenerative suspension strut system embodiment, respectively.
- FIGS. 10A and 10B are schematic representations of flow during the rebound stroke of the outflow from the pressure chamber and the rebound flow into the interior cavity, respectively, for the regenerative suspension strut system embodiment.
- FIGS. 11A and 11B are schematic representations of the valve plate with a passive damper valve in an orthogonal view, taken along Line A-A in FIG. 3A with the damping flow path, and taken along Line B-B in FIG. 3A with the replenishment flow path, respectively.
- FIGS. 12 and 13 are schematic representations of alternative flow paths of the regenerative suspension strut system of the preferred embodiments.
- FIG. 14 is a graphical representation of the operating regions of the suspension strut and the energy that may be recovered using the regenerative suspension strut system of the preferred embodiments.
- FIGS. 15 and 16 are schematic representations of variations of the regenerative suspension system strut with a second compliant volume and a reservoir, respectively.
- the suspension strut 100 of the preferred embodiments is preferably used with a vehicle having a wheel contacting a surface under the vehicle, such as the road, and preferably functions to suspend the wheel from the vehicle while allowing compression movement of the wheel toward the vehicle and rebound movement of the wheel toward the surface.
- the suspension strut 100 preferably includes a compressible fluid 102 ; a hydraulic tube 110 including an inner tube 130 that defines an inner cavity 132 that contains a portion of the compressible fluid 102 , a secondary tube 140 that substantially envelopes the inner tube 130 and cooperates with the inner tube 130 to define an intermediary cavity 142 that contains another portion of the compressible fluid 102 and that accepts fluid flow from the inner cavity 132 through an inner flow path, and a housing tube 150 that substantially envelops the secondary tube 140 and cooperates with the secondary tube 140 to define a reservoir cavity 152 that contains another portion of the compressible fluid 102 ; a displacement rod 120 ; a cavity piston 122 coupled to the displacement rod 120 and extending into the hydraulic tube, thereby separating the inner cavity into a first volume 134 and a second volume 136 , and that includes an aperture 124 that allows flow of fluid from the first volume 134 to the second volume 136 during the compression movement of the wheel; and a valve plate 160 coupled to the end of the hydraulic tube 110 opposite the displacement rod no
- the valve plate 160 may also include an inlet/outlet valve 172 or a regeneration valve 170 that allows for additional fluid to enter the hydraulic strut 110 and/or extraneous fluid to exit the hydraulic strut 110 (for example, to increase or decrease, respectively, the suspending force provided by the suspension strut 100 ).
- the flow of fluid into and/or out of the hydraulic strut through the regeneration valve 170 and/or inlet/outlet valve 172 may be actively driven by one or more pumps, such as the digital displacement pump or motor as described in U.S. Pat. No. 5,259,738 entitled “Fluid Working Machine” and issued on 9 Nov. 1993, which is incorporated in its entirety by this reference, but may alternatively be any other suitable type of hydraulic pump.
- the hydraulic tube 110 is coupled to the body of the vehicle and the displacement rod 120 is coupled to the wheel of the vehicle, which decreases the unsprung weight of the vehicle and may be beneficial in the dynamics of the vehicle.
- the hydraulic tube 110 and the displacement rod 120 preferably cooperate to translate forces felt by the wheel into a force substantially along the long axis of the suspension strut no.
- the hydraulic tube no preferably includes a vehicle interface 114 (shown in FIG. 2 ).
- the displacement rod preferably includes a wheel interface 126 .
- the vehicle interface 114 and the wheel interface 126 are preferably non-permanent attachment interfaces, for example, an eye that allows for a bolt to couple to the body of the vehicle or the wheel, screw holes to receive coupling screws, clips, Velcro, or any other suitable removable attachment mechanism.
- the vehicle 114 and wheel interface 126 may alternatively be a substantially permanent attachment interface, for example, a welding joint.
- any other suitable interface type and arrangement of the suspension strut 100 relative to the vehicle may be used.
- the suspension strut 100 of the preferred embodiments allows the base valve as seen in typical struts to also function to dampen the fluid flow within the strut, and functions to combine the dampening mechanism (the damper valve 166 ) and the base valve into the valve plate 160 .
- This provides a substantially more compact and relatively simple construction as compared to the prior art (shown in FIG. 1 ).
- a valve plate 160 of any particular valve plate is preferably replaceable with another valve plate 160 . For example, if a first valve plate 160 malfunctions, a second valve plate 160 may be swapped in to replace the first valve plate 160 to restore function of the suspension strut 100 .
- valve plate 160 because most of the fluid control is contained within the valve plate 160 , the fluid flow within the strut may be adjusted by using different types of valve plates 160 without any substantial change to other components of the suspension strut 100 .
- a first valve plate 160 with a first set of fluid flow control and characteristics may be replaced with a second valve plate 160 with a second set of fluid flow control and characteristics relatively easily.
- the suspension strut 100 may be easily updated with alternative valve plates 160 that provide additional and/or other functions as the application of the strut 100 changes and/or as valve plate 160 designs change.
- a first valve plate 160 with a passively actuated damper valve 166 may be swapped with a second valve plate 160 with an active damper valve 166 , changing the strut 100 from a passive suspension strut to a semi-active suspension strut.
- This feature may substantially increase the versatility and adaptability of the suspension strut 100 by allowing the same suspension strut 100 to be repeatedly used even as applications (or even conditions) may change.
- the compressible fluid 102 the preferred embodiments functions to supply the suspending spring force hydraulic suspension strut.
- the compressible fluid 102 is preferably a silicone fluid that compresses about 1.5% volume at 2,000 psi, about 3% volume at 5,000 psi, and about 6% volume at 10,000 psi. Above 2,000 psi, the compressible fluid has a larger compressibility than conventional hydraulic oil.
- the compressible fluid may alternatively be any suitable fluid, with or without a silicon component that provides a larger compressibility above 2,000 psi than conventional hydraulic oil.
- the hydraulic tube 110 the preferred embodiments functions to contain compressible fluid 102 to provide damping force as the displacement rod 120 and the cavity piston 122 is displaced towards (compression stroke) and away from (rebound stroke) the valve plate 160 as the wheel of the vehicle experiences irregularities in the road, for example, as the vehicle turns or encounters bumps.
- the hydraulic tube 110 is preferably of a triple-tube construction that allows for substantially single-directional flow within the hydraulic tube 110 during both compression and rebound strokes, as shown in FIG. 4 and FIG. 5 , respectively. As shown in FIG. 4 , during the compression stroke, the displacement rod 120 and cavity piston 122 are displaced toward the valve plate 160 .
- fluid 102 flows from the first volume 134 of the internal cavity to the second volume 136 through the aperture 124 of the cavity piston 122 . Because of the displacement rod 120 that is coupled to the cavity piston 122 and occupies a portion of the volume of the second volume 136 , a portion of the fluid 102 is displaced into the intermediary cavity 142 from the internal cavity 132 through an inner flow path.
- the inner flow path fluidly couples the intermediary cavity 142 to the internal cavity 132 near or below the lowest stroke point of the cavity piston 122 , and is preferably a valve in a second valve plate, but may alternately be an aperture through the inner tube wall, connection tubing or any other fluid connection.
- the aperture 124 preferably includes an aperture valve that is preferably a one-direction valve, fluid flow from the first volume 134 into the second volume 136 is permitted and flow from the second volume 136 into the first volume 134 is prevented.
- fluid 102 is displaced from the second volume 136 into the intermediary cavity 142 (as fluid flow into the first volume 134 is prevented by the aperture valve), and follows a path substantially identical to the one described above for the compression stroke.
- the volume of the first volume 134 increases as the displacement rod 120 and cavity piston 122 are displaced away from the valve plate 160 .
- fluid 102 is directed into the first volume 134 to replenish the fluid contained in the internal cavity 132 , as shown in FIG. 5B , and fluid 102 from the reservoir cavity 152 is directed through the second fluid path 164 of the valve plate 160 into the internal cavity 132 .
- the valve plate 160 preferably includes a replenishment valve coupled to the second fluid path 164 that is preferably a one directional valve that opens when the pressure in the first volume is decreased as a result of the rebound stroke.
- Both the aperture valve and the replenishment valve preferably do not increase the pressure of the fluid flowing through, and preferably allow both sides of the valve to become substantially equal pressure when the valve is opened.
- the aperture valve and the replenishment valve may each be a check valve that allows substantially unhindered flow in one direction and prevents flow in an opposite direction.
- the aperture valve and the replenishment valve may alternatively be a butterfly valve, a ball valve, a diaphragm valve, a needle valve, or any other valve, and may be either passive or active.
- the aperture valve and replenishment valve may be of any other suitable type and arrangement.
- the housing tube 150 , secondary tube 140 , and internal tube 130 are preferably steel tubes that withstand the pressure provided by the compressible fluid during either a compression or rebound stroke.
- the fluid control is mostly contained within the valve plate 160 . This substantially decouples fluid control from the housing, secondary, and internal tubes and allows for the housing, secondary, and internal tubes to be optimized as pressure vessels that better withstand the pressures that may be present in a compressible fluid strut system. Because each vehicle (or “application”) may require different characteristics from the suspension strut 100 , the geometry of each of the housing, secondary, and internal tubes, may be tailored to each application.
- the housing, secondary, and internal tubes of any suitable geometry preferably include a valve plate interface that interfaces with the valve plate 160 .
- the valve plate interface preferably allows for the valve plate 160 to couple to any suitable geometry of the housing, secondary, and internal tubes.
- the valve plate interface may include a first end that is customized for a specific geometry of housing, secondary, and internal tubes and a second end that is adapted to the geometry of the valve plate 160 .
- the valve plate interface may be formed into the housing, secondary, and internal tubes.
- the housing, secondary, and internal tubes may each be a desired geometry for a substantial portion of the hydraulic tube no and taper into diameters that accommodate for a valve plate 160 .
- the valve plate interface may be any other suitable arrangement.
- the valve plate 160 functions to provide most of the fluid control within the suspension strut 100 .
- the valve plate 160 preferably defines a first fluid path 162 from the intermediary cavity 142 to the reservoir cavity 152 (also referred to as “damping flow” path) and a second fluid path from the reservoir cavity 152 to the first portion of the inner cavity 132 (also referred to as “replenishment flow” path), and includes a damper valve 166 that substantially affects the flow of fluid through the first fluid path 162 .
- the valve plate 160 is preferably mounted to the end of the hydraulic tube 110 opposite of the displacement rod, as shown in FIGS. 2 and 3 , but may alternatively be arranged in any other suitable location. As shown in FIGS.
- the valve plate 160 is preferably clamped onto the housing, secondary, and inner tubes using a cap 180 .
- the cap 180 may include a plurality of holes that receive bolts that function to apply pressure onto the cap 180 to clamp the valve plate 160 onto the tubes 150 , 140 , and 130 .
- the valve plate 160 may be assembled to the hydraulic tube no using any other suitable mechanism or arrangement.
- the valve plate 160 may also include a sealant, such as o-rings, that substantially seal the interface between the valve plate 160 and the housing, secondary, and inner tubes to substantially prevent fluid leakage.
- the valve plate 160 defines a first fluid path 162 between the intermediary cavity 142 and the reservoir cavity 152 .
- a damper valve 166 is coupled to the first fluid path 162 to substantially affect the flow of fluid 102 through the first fluid path 162 , providing the damping force on the fluid 102 and, subsequently, the suspension strut 100 .
- the damper valve 166 is preferably a passive valve in a first variation, a manually actuated valve in a second variation, an active valve in a third variation, or a regenerative valve in a fourth variation.
- the damper valve 166 is a passive valve.
- the passive damper valve 166 is preferably a one directional valve that allows fluid flow when the pressure difference between a first side (side closest to the intermediary cavity 142 ) and the second side (side closet to the reservoir cavity 152 ) is at a certain level.
- the damper valve 166 of the preferred embodiments is preferably a disc valve (or shim stack) where fluid deflects the disc valve in one direction when a certain pressure differential is reached between either side of the disc valve, opening the valve for fluid flow, and where the disc valve prevents fluid flow in the opposite direction.
- Disc valves which are generally robust, reliable, and consistent, are often used in a damper valve.
- valves which are generally passive damper valves
- the valve plate 160 of the preferred embodiments allows for a disc valve to be used in a triple-tube type strut architecture by, as shown in FIG.
- the damper valve 166 of the first variation may be any other suitable type of passive damper valve, such as a check valve, a ball valve, check valve, or needle valve.
- the damper valve 166 is a manually actuated valve.
- a technician may use the manually actuated valve damper valve 166 to adjust the damping characteristics of the suspension strut 100 .
- the manually actuated damper valve 166 may be a bi-state valve that allows for a high damping force state and a low damping force state, but may alternatively be variable with a plurality of degrees of damping forces.
- the disc valve exhibits damping properties that are desirable in a damper valve.
- the damper valve 166 of the second variation preferably includes a disc valve and an actuator 167 , as shown in FIGS. 6A and 6B .
- the actuator 167 of the second variation of the damper valve 166 is preferably a manual actuator.
- the actuator 167 preferably includes a piston 169 that is arranged over the disc valve that functions to provide an adjustable pressure onto the disc valve to adjust the damping force provided by the disc valve. More specifically, because fluid flow must deflect the disc valve in order to flow through the valve, by applying a pressure onto the disc valve through the piston 169 , the force necessary to deflect the disc valve increases, increasing the damping force on the fluid 102 flowing through the disc valve.
- the actuator 167 may include a screw coupled to the piston 169 that is accessible by a user.
- valve plate 160 may function to define a third fluid path 165 that directs fluid 102 from the intermediary cavity 142 to the reservoir cavity 152 , as shown in FIGS. 6A and 6B .
- the third fluid path 165 preferably passes over the top of the piston 169 , applying a fluid pressure across the top of the piston 169 .
- the actuator 167 of this variation preferably includes a fluid flow valve 163 that is manually actuated, for example, a needle valve, which is coupled to the third fluid path 165 downstream of the piston 169 .
- a fluid flow valve 163 that is manually actuated, for example, a needle valve, which is coupled to the third fluid path 165 downstream of the piston 169 .
- the damper valve 166 is an active valve, allowing the suspension strut 100 to function as a semi-active suspension strut.
- the active damper valve 166 may be a bi-state valve that allows for a high damping force state and a low damping force state, but may alternatively be variable with a plurality of degrees of damping forces.
- the active valve variation of the damper valve 166 is preferably used to provide substantially instantaneous adjustments of the damping force provided by the suspension strut 100 , preferably during use in a vehicle while the vehicle is in motion, for an example, if a bump in the road is detected or if the vehicle makes a sudden turn.
- the suspension strut 100 may also be used with an active control suspension system, which may function to actively change the suspending force provided by the suspension strut 100 by increasing or decreasing the amount of fluid 102 contained within the suspension strut 100 .
- Vehicle dynamics may be controlled on more than one level by combining a semi-active suspension strut 100 with an active control suspension system, providing a vehicle that can substantially quickly adapt to a vast variety of driving conditions.
- the active damper valve 166 is substantially similar to the manual damper valve 166 as described above.
- the active damper valve 166 preferably also includes a disc valve and an actuator 167 , as shown in FIGS. 6A and 6B .
- the actuator 167 of the third variation of the damper valve 166 is preferably an active actuator that may be electronically actuated, for example, by a processor or remotely by a user.
- the active actuator 167 preferably also includes a piston 169 that is arranged over the disc valve that functions to provide an adjustable pressure onto the disc valve to adjust the damping force provided by the disc valve.
- a first variation of the actuator 167 of the active damper valve 166 is substantially similar to the first variation of the actuator 167 of the manually actuated damper valve 166 .
- the actuator 167 of the active damper valve 166 of the first variation includes a motor that is coupled to a screw that functions to raise or lower the piston 169 away from or towards the disc valve, adjusting the damping force provided by the disc valve.
- a second variation of the actuator 167 of the active damper valve 166 is substantially similar to the second variation of the actuator 167 of the manually actuated damper valve 166 .
- the valve plate 160 functions to define a third fluid path 165 that directs fluid 102 from the intermediary cavity 142 to the reservoir cavity 152 to provide pressure across the top of the piston 169 , thus adjusting the pressure provided by the piston onto the disc valve and adjusting the damping force provided by the disc valve.
- the actuator 167 of the active damper valve 166 of the second variation includes a fluid flow valve 163 that is active, for example, a pilot valve that is actuated by a solenoid or any other suitable type of actuated fluid valve, coupled to the third fluid flow path 165 downstream of the piston 169 .
- the fluid flow valve 163 functions provide control of the fluid flow through the third fluid path 165 substantially identical to the manual fluid flow valve 163 .
- the stiffness of the damper valve may be electronically controlled by using materials that exhibit different strain properties with the application of heat or electricity, or by using electromagnets.
- the active damper valve 166 may be of any other suitable arrangement.
- the damper valve 166 is a regenerative valve, as shown in FIG. 7 .
- the damper valve 166 may be either passive or active. As fluid flow is damped, a significant amount of energy is dissipated. In conventional dampers, the energy is dissipated as heat and substantially wasted.
- the damper valve 166 of the fourth variation provides a method and means to harness the energy, in particular, to convert the energy into electrical energy.
- the damper valve 166 may include an impeller that is coupled to a motor. As fluid flows past the impeller, the impeller is caused to spin, and the energy used to spin the impeller is used to generate electricity in the generator.
- the fluid 102 is damped as a result because of the work used to spin the impeller.
- the work required to spin the impeller is substantially constant at all times.
- increasing the electrical generation required from the generator may increase the work required to spin the impeller, increasing the damping of the fluid 102 (examples shown in FIGS. 7B and 7C ).
- any other variation of a damper valve 166 that is regenerative may be used.
- the first, second, and third variations all preferably utilize a similar construction that includes a disc valve. Because of this feature, it is conceivable that the same housing for the valve plate 160 may be used with different variations of the damper valve 166 , allowing a valve plate 160 that was outfitted with a passive damper valve 166 to be upgraded to an active damper valve 166 with the same housing for the valve plate 160 .
- the valve plate 160 preferably includes one of the above variations of damper valve 166 , but may alternatively include any number or suitable combinations of the above variations.
- the regenerative damper valve 166 of the fourth variation may be combined with the passive damper valve 166 of the first variation. More specifically, the valve plate 160 of this variation may also include both an impeller/generator assembly and a disc valve that cooperate to provide two fluid flow paths in situations with substantially high volume of fluid flow that a regenerative valve alone may not be able to accommodate. Additionally, because the regenerative valve includes a substantial number of moving parts, the regenerative valve may fail and prevent fluid from flowing through. By allowing a second path for fluid flow, the suspension strut 100 may continue to function.
- valve plate 160 may be any other suitable variation.
- the suspension strut 100 of the preferred embodiments preferably allows for different valve plates 160 to be used with the same hydraulic tube body, meaning a suspension strut 100 that originally used a valve plate 160 with a damper valve 166 of the first variation may be exchanged with a valve plate 160 with a damper valve 166 of the second, third, or fourth variation, allowing the suspension strut 100 to function differently without substantial changes to any other component of the suspension strut 100 .
- the suspension strut system 100 may additionally include a regenerative valve and a pump, fluidly coupled to the first fluid path 134 , to form a regenerative suspension strut 101 .
- the regenerative suspension strut 101 functions to regenerate energy from fluid flow within the strut, and is preferably also operable in non-regenerative modes.
- the regenerative suspension system 101 may additionally include a third flow path 165 (“regenerative fluid path” or “pump path”), to which the regenerative valve and pump are coupled, wherein the third flow path fluidly couples the intermediary cavity to the reservoir cavity through the valve plate, preferably in parallel with the first flow path 134 , more preferably sharing an inlet and an outlet with the first flow path 134 .
- regenerative fluid path or “pump path”
- the regenerative suspension strut system 101 preferably operates in a first mode that provides a damping force substantially internally within the suspension strut 100 by directing the displaced compressible fluid 102 to a damper valve 166 and a second mode that provides a damping force substantially external to the suspension strut 100 by directing the flow of compressible fluid 102 into the pump 190 to drive the pump 190 and recover energy.
- the force required to drive the pump 190 provides the damping force.
- the regenerative suspension strut system 101 may include a third mode where the damping force is provided both through the damper valve 166 and by directing flow of compressible fluid into the pump 190 and/or a fourth mode where the pump 190 pumps fluid 102 back into the suspension strut 100 .
- the damper valve 166 and the regeneration valve 170 may be thought of as operating in parallel such that fluid flow from the strut 100 may flow to either valve depending on the state of the valve.
- the damper valve 166 and the regeneration valve 170 may be the same physical valve with multiple modes to function to direct fluid into the pump 190 , to dampen fluid 102 , and/or to both direct fluid into the pump 170 and to dampen the fluid 102 .
- the damper valve 166 is preferably of the type of valve where the failure mode still provides substantial damping force (for example, for a damper valve 166 that is a shim stack valve that increases damping force with increasing stiffness, the shim stack preferably fails in a semi-stiff orientation) to the suspension strut 100 .
- the damper valve 166 and the regeneration valve 170 may be used.
- the flow pattern of the regenerative suspension strut 101 during the compression stroke is preferably substantially similar to that described above.
- the displacement rod 120 and cavity piston 122 are displaced toward the valve plate 160 .
- fluid 102 flows from the first volume 134 of the internal cavity to the second volume 136 through the aperture 124 of the cavity piston 122 .
- the displacement rod 120 that occupies a portion of the volume of the second volume 136 and is coupled to the cavity piston 122 , the volume available for the displaced compressible fluid 102 to occupy is less in the second volume 136 than in the first volume 134 , and the pressure of the fluid within the second volume 136 increases.
- a portion of the fluid 102 may be displaced into the intermediary cavity 142 from the internal cavity 132 and, from the intermediary cavity 142 , the fluid flows through the first and/or third fluid path 162 of the valve plate 160 .
- the compressible fluid 102 is then directed to the damper valve 166 to apply a damping force on the compressible fluid 102 (shown in FIG. 8 ).
- the fluid 102 is directed through the regeneration valve 170 to the pump 190 to drive the pump 190 and to recover energy.
- the fluid 102 is directed to both the damper valve 166 and the regeneration valve 170 (shown in FIGS. 9 and 11A ).
- any other suitable arrangement of the flow during the compression stroke may be used.
- the flow pattern of the rebound stroke is substantially similar to that described above.
- the displacement rod 120 and cavity piston 122 are displaced away from the valve plate 160 .
- the aperture 124 preferably includes an aperture valve that is preferably a one-direction valve that only allows fluid flow from the first volume 134 into the second volume 136 and not from the second volume 136 to the first volume 134 .
- the fluid pressure within the second volume 136 is again increased and follows a path substantially identical to the one described above for the compression stroke, potentially further driving the pump 190 to recover energy during the rebound stroke.
- Fluid 102 is directed into the first volume 134 from a compliant volume 191 (as shown in FIG.
- This compliant volume 191 may be the reservoir cavity 152 , such that fluid 102 from the reservoir cavity 152 is directed through the second fluid path 164 of the valve plate 160 into the internal cavity 132 , as shown in FIG. 10 .
- the valve plate 160 preferably includes a replenishment valve coupled to the second fluid path 164 that is preferably a one-directional valve that opens when the pressure in the first volume is decreased as a result of the rebound stroke.
- the regenerative suspension strut system 101 may function to direct the compressible fluid 102 to only the damper valve 166 (the first mode), only the regeneration valve 170 (the second mode), or to both the damper valve 166 and the regeneration valve 170 (the third mode).
- the regenerative suspension strut system 101 may include a processor that determines the mode depending on the use scenario, the user preferences, and/or any other suitable factor. In a first example, directing fluid through the regeneration valve 170 and into the pump 160 to drive the pump may provide a substantially slower damping response than directing fluid into the damper valve 166 .
- the processor when the processor detects a maneuver of the vehicle that requires a faster suspension response, for example, during a fast turn or a substantial bump in the road, the processor may select to operate in the first mode.
- a user may select to operate in the first mode because of the increased responsiveness of the suspension system. For example, the user may plan on driving quickly on mountain roads that include a substantial number of turns.
- the user may know that the road ahead contains a substantial amount of irregularities, for example, an unpaved road. Because of the high number of irregularities, the instances in which energy may be recovered from the suspension system may be high and the user may select the second mode.
- the user may select a “fuel economy” mode, which instructs the processor to put a preference on utilizing the second mode.
- the user does not instruct a particular mode to operate in, but instructs the processor to prioritize one mode over another and allows the processor to determine the appropriate mode based on the driving scenario.
- the processor may select to operate in the fourth mode for increased flexibility where flow is directed to both the damper valve 166 and the regeneration valve 170 .
- the processor may function to determine the percentage of fluid that is directed to the damper valve 166 and to the regeneration valve 170 .
- the amount of damping force that is provided by the pump 190 may be an amount that is determined by the characteristic of the pump 190 (such as the initial starting pressure necessary).
- the processor may determine to route more fluid to the damper valve 166 .
- the processor may determine a desired amount of damping force and evaluate a percentage flow combination between the damper valve 166 and pump 160 to achieve the desired damping force.
- the processor may detect that the pump 190 is malfunctioning and may determine to direct all fluid flow into the damper valve 166 .
- any other suitable selection of the operation modes of the regenerative suspension strut system 101 may be used.
- the pressure in the compressible fluid 102 used to drive the pump 190 is used to direct fluid 102 back into the first volume 134 to replenish the volume in the first volume 134 during the rebound stroke.
- the pressure at which fluid 102 is directed back into the first volume 134 is preferably substantially less than the pressure of the fluid 102 used to drive the pump 190 , which results in a net positive energy recovery in the regenerative suspension strut system 101 .
- the rate and/or pressure at which the fluid 102 is directed back into the first volume 134 during the rebound stroke is preferably actively controlled to increase energy efficiency.
- the rate and/or pressure at which the fluid 102 is displaced from the second volume 126 is preferably also actively controlled to balance with the pressure of fluid injected into the first volume 124 .
- the rebound stroke is passive and is substantially dependent on the type of road irregularity, for example, the shape of the bump on the road. In other words, energy that could have been captured from the compression of the suspension due to the bump in the road is used in the uncontrolled retraction of the suspension after the bump.
- the pump 190 may be directly coupled to the first volume 134 , wherein the valve plate further includes a fourth flow path coupling the pump outlet to the first volume 134 and a second replenishment valve, disposed within the fourth flow path, that allows one-way fluid flow from the pump to the first volume 134 .
- the pump 190 and damper valve 166 may also function to provide a retractive force on the regenerative suspension strut 101 100 .
- Typical suspension struts are configured to provide a force to suspend the vehicle, or, in other words, a force to extend the strut, and compresses only when there is an external force such as a bump or a turn, and typically do not provide a force to compress the strut, or a retractive force.
- An active suspension utilizing a single acting cylinder actuator may change the height of the strut, but cannot provide a retractive force unless the strut is fully extended.
- the regenerative suspension strut system 101 is able to provide such a retractive force.
- fluid flow from the first volume 134 to the second volume 136 results in an increased pressure within the second volume 136 , which is relieved when the fluid 102 is forced through the damper valve 166 and/or pump 190 and damped.
- an imbalance between the flow rate out through the damper valve 166 and/or the pump 190 and flow rate into the second volume 136 is present, the pressure within the volume of fluid contained within the second volume 136 cannot be relieved, and a force to push the cavity piston 122 back towards the valve plate 160 is present, providing a retractive force.
- Varying the amount of fluid that is bled through the damper valve 166 and/or directed to pump 190 may control this retractive force. This may be particularly useful if a particular position of the strut that is shorter than the fully extended is desired.
- An additional retractive force may be achieved by driving the pump 190 to pump fluid into the second volume 136 , as shown by the dashed line 4 a in FIG. 14 .
- the retractive force may be decreased to substantially zero and/or a force to extend the suspension strut 100 may result.
- This pull force may be used to relatively quickly restore the height of the triple tube strut 100 or for any other suitable use.
- any other suitable method to produce a retractive force in the suspension strut 100 may be used.
- the regenerative suspension strut system 101 of the preferred embodiments functions to recover a substantial amount of energy used to operate the triple tube strut 100 .
- the X-axis of FIG. 14 represents displacement frequency seen in the suspension strut 100 , for example, from irregularities in the road while the Y-axis represents the force that the suspension strut provides on the vehicle, in other words, the suspending force.
- Curve 1 represents the equilibrium position of the triple tube strut 100 , which changes depending the weight of the vehicle, the payload of the vehicle, or any other suitable parameter.
- Curve 2 represents the force preferably provided by the regenerative suspension strut system 101 to the vehicle (for example, through a suspension strut 100 of the triple tube strut construction), in other words, the operating region of the suspension strut 100
- Curve 4 represents the retractive force provided by the suspension strut 100 , as described above.
- the shaded region 3 describes the operating region of the suspension strut from which energy may be recovered, in particular, the energy from irregularities on the road.
- Portion 3 A represents the region of irregularities that require suspension response speeds that may be provided by the pump 190 while
- Portion 3 B cross-hatched
- represents the region of irregularities that require a faster response for example, when the damper valve 166 is used to provide the damping force.
- the regenerative suspension strut system 101 of the preferred embodiments may also include a second compliant volume 192 that is preferably isolated from the system when fluid 102 is actively directed to the pump 190 and may be connected when fluid 102 is not directed to the pump 190 .
- the second compliant volume 192 receives fluid 102 from damper valve 166 to alleviate the pressure of the fluid 102 that would otherwise be used to drive the pump 190 .
- the suspension strut 100 may be operated at higher pressures when fluid is actively directed to the pump 190 because increased pressure in the fluid 102 is substantially quickly alleviated through the pump 190 .
- the pressure within the triple tube strut 100 may be too high for passive operation (e.g., the strut 100 may be too stiff) and fluid may then be directed to the second compliant volume 192 to decrease the pressure within the suspension strut 100 .
- This embodiment preferably utilizes the third variation of the damper valve 166 (such as that shown in FIG. 7B ), but may alternately utilize any variation of the damper valve 166 as described above.
- any other suitable arrangement of the fluid flow to allow both internal damping through the damper valve 166 and external damping through the pump 190 may be used.
- the pump 190 may function to direct fluid back into the suspension strut 100 to replenish flow within the suspension strut 100 .
- the regenerative suspension strut system 101 may include a reservoir 194 , as shown in FIG. 16 , from which the suspension strut 100 may draw fluid 102 to replenish the fluid 102 within the suspension strut 100 .
- the suspension strut 100 may function substantially similarly to a pump that pumps fluid 102 at substantially high pressures during the compression stroke into the pump 190 to drive the pump 190 and recover energy, and to draw fluid from the reservoir 194 at a substantially lower pressure during the rebound stroke.
- the pump 190 functions to dampen fluid flow to provide a damping force and during the rebound stroke, the reservoir 190 provides fluid at a lower pressure than the fluid used to drive the pump 190 to recover energy, satisfying the pressure relationships for energy recovery as described above.
- the regeneration valve 170 preferably directs fluid 102 during the compression stroke from the suspension strut 100 into the pump 190 and preferably directs fluid 102 from the reservoir 194 into the suspension strut 100 from the reservoir 194 .
- This variation of the regenerative suspension strut system 101 is preferably otherwise substantially similar to the variations as described above.
Abstract
A hydraulic strut system that damps vehicle vibration and includes a compressible fluid, a strut, and a valve plate. The strut includes three concentric tubes defining an inner cavity, an intermediary cavity, and an outer reservoir cavity, the inner cavity and intermediary cavity being fluidly coupled, wherein the inner cavity receives a piston that divides the inner cavity into a first volume and a second volume, the piston having an aperture that allows one way flow from the first volume to the second volume. The valve plate is removably coupled to the strut, and includes a first fluid path that allows one-way fluid flow from the intermediary cavity to the reservoir cavity, the first fluid path including a damping valve that damps fluid flowing therethrough; and a second fluid path that allows one-way fluid flow from the reservoir cavity to the inner cavity, the second fluid path further including a replenishment valve.
Description
- This application is a continuation of co-pending U.S. patent application Ser. No. 14/029,139, filed 17 Sep. 2013, which is a continuation of U.S. patent application Ser. No. 13/176,720, filed 5 Jul. 2011, which claims the benefit of U.S. Provisional Application Nos. 61/361,493 filed 5 Jul. 2010 and 61/423,573 filed 15 Dec. 2010, all of which are both incorporated in their entirety by this reference.
- This application is related to U.S. Pat. Nos. 6,811,167 and 6,988,599, which are both incorporated in their entirety by this reference.
- This invention relates generally to the damper field, and more specifically to an improved suspension strut in the vehicle suspension field.
- There are a variety of dampers in automotive suspensions, including a mono-tube type strut, a twin-tube type strut, and a triple-tube type strut. Within each variation, there are variations with valve arrangement and fluid management. The triple-tube type strut construction includes tube and valve arrangement that allows for fluid flow within the strut that is generally in a single direction for both the compression and rebound direction of the suspension strut, whereas both mono-tube and twin-tube type struts require fluid to flow in different directions for the compression and rebound directions. This single-direction property of the triple-tube type strut allows for damping control of the fluid flow within the triple-tube type strut to be localized to one general area within the strut for both compression and rebound directions. As a result, conventional semi-active or continuously variable damping control systems typically utilize the triple-tube type strut and a single active solenoid valve to control damping force for both the compression and rebound directions of the strut.
- Conventional triple-tube type strut dampers include many internal parts that function to tune the dampening properties of the strut and are, for this reason, quite complex. Additionally, the damping mechanisms that are utilized in such triple-tube type struts may leak, decreasing the efficiency of the damper, or may be relatively expensive. As shown in
FIG. 1 (prior art), theactive valve 10 in typical triple-tube type strut dampers is often mounted perpendicular to the long axis of thedamper tube 12 and substantially adjacent to thebase valve 14 that allows replenishment flow to theinner cavity 16 during the rebound stroke of the strut. This may allow such triple-tube type strut dampers to increase the range of travel of the suspension strut given a total strut height. However, this arrangement requires a fastening mechanism that does not benefit from the compressive forces from tube assembly and/or the vehicle. In semi-active or continuously variable damping control systems that utilize compressible fluids where the pressure within the suspension strut may increase to substantially high levels, the fastening mechanism used to mount the active valve perpendicularly to the axis of the damper tube may become substantially costly to withstand such high pressures. Because of complexity of typical triple-tube type strut dampers, cost is relatively high and adoption of such semi-active or continuously variable damping control systems in the field is substantially impaired. - Thus, there is a need in the vehicle suspension field to create an improved suspension strut. This invention provides such strut.
-
FIG. 1 is a schematic representation of a semi-active suspension strut of the prior art. -
FIGS. 2A and 2B are schematic representations of the suspension strut of the preferred embodiments with the displacement rod and cavity piston displaced away from the valve plate and with the displacement rod and cavity piston displaced toward the valve plate, respectively. -
FIGS. 3A , 3B, and 3C are schematic representations of the valve plate with a passive damper valve in an orthogonal view, taken along Line A-A inFIG. 3A with the damping flow path, and taken along Line B-B inFIG. 3A with the replenishment flow path, respectively. -
FIG. 4 is a schematic representation of flow during the compression stroke. -
FIGS. 5A and 5B are schematic representations of flow during the rebound stroke of the outflow from the pressure chamber and the rebound flow into the interior cavity, respectively. -
FIGS. 6A and 6B are schematic representations of the valve plate with a variation of an actuatable damper valve with decreased damping force and increased damping force, respectively. -
FIGS. 7A , 7B, and 7C are a schematic representation of the valve plate with a first, second, and third variation of a regenerative damper valve, respectively. -
FIG. 8 is a schematic representation of the regenerative suspension strut system embodiment. -
FIGS. 9A and 9B are schematic representations of flow during the compression stroke for a first and a second embodiment of the regenerative suspension strut system embodiment, respectively. -
FIGS. 10A and 10B are schematic representations of flow during the rebound stroke of the outflow from the pressure chamber and the rebound flow into the interior cavity, respectively, for the regenerative suspension strut system embodiment. -
FIGS. 11A and 11B are schematic representations of the valve plate with a passive damper valve in an orthogonal view, taken along Line A-A inFIG. 3A with the damping flow path, and taken along Line B-B inFIG. 3A with the replenishment flow path, respectively. -
FIGS. 12 and 13 are schematic representations of alternative flow paths of the regenerative suspension strut system of the preferred embodiments. -
FIG. 14 is a graphical representation of the operating regions of the suspension strut and the energy that may be recovered using the regenerative suspension strut system of the preferred embodiments. -
FIGS. 15 and 16 are schematic representations of variations of the regenerative suspension system strut with a second compliant volume and a reservoir, respectively. - The following description of the preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention.
- As shown in
FIGS. 2 and 3 , thesuspension strut 100 of the preferred embodiments is preferably used with a vehicle having a wheel contacting a surface under the vehicle, such as the road, and preferably functions to suspend the wheel from the vehicle while allowing compression movement of the wheel toward the vehicle and rebound movement of the wheel toward the surface. Thesuspension strut 100 preferably includes acompressible fluid 102; ahydraulic tube 110 including aninner tube 130 that defines aninner cavity 132 that contains a portion of thecompressible fluid 102, asecondary tube 140 that substantially envelopes theinner tube 130 and cooperates with theinner tube 130 to define anintermediary cavity 142 that contains another portion of thecompressible fluid 102 and that accepts fluid flow from theinner cavity 132 through an inner flow path, and ahousing tube 150 that substantially envelops thesecondary tube 140 and cooperates with thesecondary tube 140 to define areservoir cavity 152 that contains another portion of thecompressible fluid 102; adisplacement rod 120; acavity piston 122 coupled to thedisplacement rod 120 and extending into the hydraulic tube, thereby separating the inner cavity into afirst volume 134 and asecond volume 136, and that includes anaperture 124 that allows flow of fluid from thefirst volume 134 to thesecond volume 136 during the compression movement of the wheel; and avalve plate 160 coupled to the end of thehydraulic tube 110 opposite the displacement rod no that defines afirst fluid path 162 from theintermediary cavity 142 to the reservoir cavity 152 (also referred to as “damping flow” path) and a second fluid path from thereservoir cavity 152 to the first volume 134 (also referred to as “replenishment flow” path), and includes adamper valve 166 that substantially affects the flow of fluid through thefirst fluid path 162. Thevalve plate 160 may also include an inlet/outlet valve 172 or aregeneration valve 170 that allows for additional fluid to enter thehydraulic strut 110 and/or extraneous fluid to exit the hydraulic strut 110 (for example, to increase or decrease, respectively, the suspending force provided by the suspension strut 100). The flow of fluid into and/or out of the hydraulic strut through theregeneration valve 170 and/or inlet/outlet valve 172 may be actively driven by one or more pumps, such as the digital displacement pump or motor as described in U.S. Pat. No. 5,259,738 entitled “Fluid Working Machine” and issued on 9 Nov. 1993, which is incorporated in its entirety by this reference, but may alternatively be any other suitable type of hydraulic pump. - In the preferred embodiments, the
hydraulic tube 110 is coupled to the body of the vehicle and thedisplacement rod 120 is coupled to the wheel of the vehicle, which decreases the unsprung weight of the vehicle and may be beneficial in the dynamics of the vehicle. Thehydraulic tube 110 and thedisplacement rod 120 preferably cooperate to translate forces felt by the wheel into a force substantially along the long axis of the suspension strut no. The hydraulic tube no preferably includes a vehicle interface 114 (shown inFIG. 2 ). Similarly, the displacement rod preferably includes awheel interface 126. The vehicle interface 114 and thewheel interface 126 are preferably non-permanent attachment interfaces, for example, an eye that allows for a bolt to couple to the body of the vehicle or the wheel, screw holes to receive coupling screws, clips, Velcro, or any other suitable removable attachment mechanism. However the vehicle 114 andwheel interface 126 may alternatively be a substantially permanent attachment interface, for example, a welding joint. However, any other suitable interface type and arrangement of thesuspension strut 100 relative to the vehicle may be used. - The
suspension strut 100 of the preferred embodiments allows the base valve as seen in typical struts to also function to dampen the fluid flow within the strut, and functions to combine the dampening mechanism (the damper valve 166) and the base valve into thevalve plate 160. This provides a substantially more compact and relatively simple construction as compared to the prior art (shown inFIG. 1 ). When desired, avalve plate 160 of any particular valve plate is preferably replaceable with anothervalve plate 160. For example, if afirst valve plate 160 malfunctions, asecond valve plate 160 may be swapped in to replace thefirst valve plate 160 to restore function of thesuspension strut 100. Similarly, because most of the fluid control is contained within thevalve plate 160, the fluid flow within the strut may be adjusted by using different types ofvalve plates 160 without any substantial change to other components of thesuspension strut 100. For example, afirst valve plate 160 with a first set of fluid flow control and characteristics may be replaced with asecond valve plate 160 with a second set of fluid flow control and characteristics relatively easily. Additionally, by placing most of the fluid control within aremovable valve plate 160, thesuspension strut 100 may be easily updated withalternative valve plates 160 that provide additional and/or other functions as the application of thestrut 100 changes and/or asvalve plate 160 designs change. For example, afirst valve plate 160 with a passively actuateddamper valve 166 may be swapped with asecond valve plate 160 with anactive damper valve 166, changing thestrut 100 from a passive suspension strut to a semi-active suspension strut. This feature may substantially increase the versatility and adaptability of thesuspension strut 100 by allowing thesame suspension strut 100 to be repeatedly used even as applications (or even conditions) may change. - The
compressible fluid 102 the preferred embodiments functions to supply the suspending spring force hydraulic suspension strut. Thecompressible fluid 102 is preferably a silicone fluid that compresses about 1.5% volume at 2,000 psi, about 3% volume at 5,000 psi, and about 6% volume at 10,000 psi. Above 2,000 psi, the compressible fluid has a larger compressibility than conventional hydraulic oil. The compressible fluid, however, may alternatively be any suitable fluid, with or without a silicon component that provides a larger compressibility above 2,000 psi than conventional hydraulic oil. - The
hydraulic tube 110 the preferred embodiments functions to containcompressible fluid 102 to provide damping force as thedisplacement rod 120 and thecavity piston 122 is displaced towards (compression stroke) and away from (rebound stroke) thevalve plate 160 as the wheel of the vehicle experiences irregularities in the road, for example, as the vehicle turns or encounters bumps. Thehydraulic tube 110 is preferably of a triple-tube construction that allows for substantially single-directional flow within thehydraulic tube 110 during both compression and rebound strokes, as shown inFIG. 4 andFIG. 5 , respectively. As shown inFIG. 4 , during the compression stroke, thedisplacement rod 120 andcavity piston 122 are displaced toward thevalve plate 160. Thus, fluid 102 flows from thefirst volume 134 of the internal cavity to thesecond volume 136 through theaperture 124 of thecavity piston 122. Because of thedisplacement rod 120 that is coupled to thecavity piston 122 and occupies a portion of the volume of thesecond volume 136, a portion of the fluid 102 is displaced into theintermediary cavity 142 from theinternal cavity 132 through an inner flow path. The inner flow path fluidly couples theintermediary cavity 142 to theinternal cavity 132 near or below the lowest stroke point of thecavity piston 122, and is preferably a valve in a second valve plate, but may alternately be an aperture through the inner tube wall, connection tubing or any other fluid connection. From theintermediary cavity 142, the fluid flows through the firstfluid path 162 of thevalve plate 160 to thereservoir cavity 152. As the fluid 102 flows through the firstfluid path 162, the fluid 102 flows throughdamper valve 166, which provides a damping force to the fluid 102 and, subsequently, to thesuspension strut 100. As shown inFIG. 5A , during the rebound stroke, thedisplacement rod 120 andcavity piston 122 are displaced away from thevalve plate 160. Theaperture 124 preferably includes an aperture valve that is preferably a one-direction valve, fluid flow from thefirst volume 134 into thesecond volume 136 is permitted and flow from thesecond volume 136 into thefirst volume 134 is prevented. Thus, as thesecond volume 136 is decreased during the rebound stroke, fluid 102 is displaced from thesecond volume 136 into the intermediary cavity 142 (as fluid flow into thefirst volume 134 is prevented by the aperture valve), and follows a path substantially identical to the one described above for the compression stroke. Concurrently, the volume of thefirst volume 134 increases as thedisplacement rod 120 andcavity piston 122 are displaced away from thevalve plate 160. To prevent aeration,fluid 102 is directed into thefirst volume 134 to replenish the fluid contained in theinternal cavity 132, as shown inFIG. 5B , and fluid 102 from thereservoir cavity 152 is directed through the secondfluid path 164 of thevalve plate 160 into theinternal cavity 132. Thevalve plate 160 preferably includes a replenishment valve coupled to the secondfluid path 164 that is preferably a one directional valve that opens when the pressure in the first volume is decreased as a result of the rebound stroke. Both the aperture valve and the replenishment valve preferably do not increase the pressure of the fluid flowing through, and preferably allow both sides of the valve to become substantially equal pressure when the valve is opened. For example, the aperture valve and the replenishment valve may each be a check valve that allows substantially unhindered flow in one direction and prevents flow in an opposite direction. The aperture valve and the replenishment valve may alternatively be a butterfly valve, a ball valve, a diaphragm valve, a needle valve, or any other valve, and may be either passive or active. However, the aperture valve and replenishment valve may be of any other suitable type and arrangement. - The
housing tube 150,secondary tube 140, andinternal tube 130 are preferably steel tubes that withstand the pressure provided by the compressible fluid during either a compression or rebound stroke. In thesuspension strut 100 of the preferred embodiments, the fluid control is mostly contained within thevalve plate 160. This substantially decouples fluid control from the housing, secondary, and internal tubes and allows for the housing, secondary, and internal tubes to be optimized as pressure vessels that better withstand the pressures that may be present in a compressible fluid strut system. Because each vehicle (or “application”) may require different characteristics from thesuspension strut 100, the geometry of each of the housing, secondary, and internal tubes, may be tailored to each application. The housing, secondary, and internal tubes of any suitable geometry preferably include a valve plate interface that interfaces with thevalve plate 160. The valve plate interface preferably allows for thevalve plate 160 to couple to any suitable geometry of the housing, secondary, and internal tubes. The valve plate interface may include a first end that is customized for a specific geometry of housing, secondary, and internal tubes and a second end that is adapted to the geometry of thevalve plate 160. Alternatively, the valve plate interface may be formed into the housing, secondary, and internal tubes. For example, the housing, secondary, and internal tubes may each be a desired geometry for a substantial portion of the hydraulic tube no and taper into diameters that accommodate for avalve plate 160. However, the valve plate interface may be any other suitable arrangement. - As described above, the
valve plate 160 functions to provide most of the fluid control within thesuspension strut 100. Thevalve plate 160 preferably defines a firstfluid path 162 from theintermediary cavity 142 to the reservoir cavity 152 (also referred to as “damping flow” path) and a second fluid path from thereservoir cavity 152 to the first portion of the inner cavity 132 (also referred to as “replenishment flow” path), and includes adamper valve 166 that substantially affects the flow of fluid through the firstfluid path 162. Thevalve plate 160 is preferably mounted to the end of thehydraulic tube 110 opposite of the displacement rod, as shown inFIGS. 2 and 3 , but may alternatively be arranged in any other suitable location. As shown inFIGS. 2A , 2B, and 3A, thevalve plate 160 is preferably clamped onto the housing, secondary, and inner tubes using acap 180. Thecap 180 may include a plurality of holes that receive bolts that function to apply pressure onto thecap 180 to clamp thevalve plate 160 onto thetubes valve plate 160 may be assembled to the hydraulic tube no using any other suitable mechanism or arrangement. Thevalve plate 160 may also include a sealant, such as o-rings, that substantially seal the interface between thevalve plate 160 and the housing, secondary, and inner tubes to substantially prevent fluid leakage. - As shown in
FIG. 3B , thevalve plate 160 defines a firstfluid path 162 between theintermediary cavity 142 and thereservoir cavity 152. Adamper valve 166 is coupled to the firstfluid path 162 to substantially affect the flow offluid 102 through the firstfluid path 162, providing the damping force on the fluid 102 and, subsequently, thesuspension strut 100. Thedamper valve 166 is preferably a passive valve in a first variation, a manually actuated valve in a second variation, an active valve in a third variation, or a regenerative valve in a fourth variation. - In the first variation, the
damper valve 166 is a passive valve. Thepassive damper valve 166 is preferably a one directional valve that allows fluid flow when the pressure difference between a first side (side closest to the intermediary cavity 142) and the second side (side closet to the reservoir cavity 152) is at a certain level. Thedamper valve 166 of the preferred embodiments is preferably a disc valve (or shim stack) where fluid deflects the disc valve in one direction when a certain pressure differential is reached between either side of the disc valve, opening the valve for fluid flow, and where the disc valve prevents fluid flow in the opposite direction. Disc valves, which are generally robust, reliable, and consistent, are often used in a damper valve. Because typical semi-active or continuously variable damping control systems require active damper valves, however, disc valves (which are generally passive damper valves) are typically not used in triple-tube type strut architectures. Further, because of the fluid flow paths in such systems, it is difficult-to-impossible to apply a disc valve within a conventional semi-active or continuously variable damping control systems that utilize the triple-tube type strut. Thevalve plate 160 of the preferred embodiments, however, allows for a disc valve to be used in a triple-tube type strut architecture by, as shown inFIG. 3B , defining a firstfluid path 162 that directs fluid flow in a flow direction suitable for a disc valve from theintermediary cavity 142 and directs flow from the disc valve to thereservoir cavity 152. Additionally, as will be described later, the same disc valve may be converted into a manually actuated or active arrangement. However, thedamper valve 166 of the first variation may be any other suitable type of passive damper valve, such as a check valve, a ball valve, check valve, or needle valve. - In the second variation, the
damper valve 166 is a manually actuated valve. As an example, a technician may use the manually actuatedvalve damper valve 166 to adjust the damping characteristics of thesuspension strut 100. The manually actuateddamper valve 166 may be a bi-state valve that allows for a high damping force state and a low damping force state, but may alternatively be variable with a plurality of degrees of damping forces. As mentioned above, the disc valve exhibits damping properties that are desirable in a damper valve. Thus, thedamper valve 166 of the second variation preferably includes a disc valve and anactuator 167, as shown inFIGS. 6A and 6B . Theactuator 167 of the second variation of thedamper valve 166 is preferably a manual actuator. Theactuator 167 preferably includes apiston 169 that is arranged over the disc valve that functions to provide an adjustable pressure onto the disc valve to adjust the damping force provided by the disc valve. More specifically, because fluid flow must deflect the disc valve in order to flow through the valve, by applying a pressure onto the disc valve through thepiston 169, the force necessary to deflect the disc valve increases, increasing the damping force on the fluid 102 flowing through the disc valve. In a first version of theactuator 167 of the manually actuateddamper valve 166, theactuator 167 may include a screw coupled to thepiston 169 that is accessible by a user. To adjust the damping force provided by the disc valve, a user may tighten the screw to push thepiston 169 towards disc valve. In a second version of the manually actuateddamper valve 166, thevalve plate 160 may function to define a thirdfluid path 165 that directs fluid 102 from theintermediary cavity 142 to thereservoir cavity 152, as shown inFIGS. 6A and 6B . The thirdfluid path 165 preferably passes over the top of thepiston 169, applying a fluid pressure across the top of thepiston 169. Because damping force is preferably applied to the fluid 102 that flows from theintermediary cavity 142 to thereservoir cavity 152, a portion of the already existing flow between theintermediary cavity 142 and thereservoir cavity 152 may be relatively easily directed across thepiston 169 when a damping force is desired. Theactuator 167 of this variation preferably includes afluid flow valve 163 that is manually actuated, for example, a needle valve, which is coupled to the thirdfluid path 165 downstream of thepiston 169. By adjusting the rate of fluid flow through the thirdfluid path 165, the pressure provided by the fluid 102 onto thepiston 169 may be adjusted. As shown inFIG. 6B , when thefluid valve 163 is closed, fluid flows into the thirdfluid path 165, but cannot flow into thereservoir cavity 152, resulting in increasedfluid 102 pressure onto thepiston 169, and subsequently, increased damping force provided by thedamper valve 166. As shown inFIG. 6A , when thefluid valve 163 is open and fluid flows through the thirdfluid path 165 into thereservoir cavity 152, the pressure applied by thepiston 169 is low, as the pressures in the first 134 and third 165 flow paths are substantially equivalent. However, the manually actuateddamper valve 166 may be of any other suitable arrangement. - In the third variation, the
damper valve 166 is an active valve, allowing thesuspension strut 100 to function as a semi-active suspension strut. Theactive damper valve 166 may be a bi-state valve that allows for a high damping force state and a low damping force state, but may alternatively be variable with a plurality of degrees of damping forces. The active valve variation of thedamper valve 166 is preferably used to provide substantially instantaneous adjustments of the damping force provided by thesuspension strut 100, preferably during use in a vehicle while the vehicle is in motion, for an example, if a bump in the road is detected or if the vehicle makes a sudden turn. As mentioned above, thesuspension strut 100 may also be used with an active control suspension system, which may function to actively change the suspending force provided by thesuspension strut 100 by increasing or decreasing the amount offluid 102 contained within thesuspension strut 100. Vehicle dynamics may be controlled on more than one level by combining asemi-active suspension strut 100 with an active control suspension system, providing a vehicle that can substantially quickly adapt to a vast variety of driving conditions. Theactive damper valve 166 is substantially similar to themanual damper valve 166 as described above. Theactive damper valve 166 preferably also includes a disc valve and anactuator 167, as shown inFIGS. 6A and 6B . Theactuator 167 of the third variation of thedamper valve 166 is preferably an active actuator that may be electronically actuated, for example, by a processor or remotely by a user. Theactive actuator 167 preferably also includes apiston 169 that is arranged over the disc valve that functions to provide an adjustable pressure onto the disc valve to adjust the damping force provided by the disc valve. A first variation of theactuator 167 of theactive damper valve 166 is substantially similar to the first variation of theactuator 167 of the manually actuateddamper valve 166. Theactuator 167 of theactive damper valve 166 of the first variation includes a motor that is coupled to a screw that functions to raise or lower thepiston 169 away from or towards the disc valve, adjusting the damping force provided by the disc valve. A second variation of theactuator 167 of theactive damper valve 166 is substantially similar to the second variation of theactuator 167 of the manually actuateddamper valve 166. Thevalve plate 160 functions to define a thirdfluid path 165 that directs fluid 102 from theintermediary cavity 142 to thereservoir cavity 152 to provide pressure across the top of thepiston 169, thus adjusting the pressure provided by the piston onto the disc valve and adjusting the damping force provided by the disc valve. Theactuator 167 of theactive damper valve 166 of the second variation includes afluid flow valve 163 that is active, for example, a pilot valve that is actuated by a solenoid or any other suitable type of actuated fluid valve, coupled to the thirdfluid flow path 165 downstream of thepiston 169. Thefluid flow valve 163 functions provide control of the fluid flow through the thirdfluid path 165 substantially identical to the manualfluid flow valve 163. In a third variation, the stiffness of the damper valve may be electronically controlled by using materials that exhibit different strain properties with the application of heat or electricity, or by using electromagnets. However, theactive damper valve 166 may be of any other suitable arrangement. - In the fourth variation, the
damper valve 166 is a regenerative valve, as shown inFIG. 7 . In this variation, thedamper valve 166 may be either passive or active. As fluid flow is damped, a significant amount of energy is dissipated. In conventional dampers, the energy is dissipated as heat and substantially wasted. Thedamper valve 166 of the fourth variation, however, provides a method and means to harness the energy, in particular, to convert the energy into electrical energy. In a first example, shown inFIG. 7A , thedamper valve 166 may include an impeller that is coupled to a motor. As fluid flows past the impeller, the impeller is caused to spin, and the energy used to spin the impeller is used to generate electricity in the generator. The fluid 102 is damped as a result because of the work used to spin the impeller. In the passive version of thedamper valve 166 of the fourth variation, the work required to spin the impeller is substantially constant at all times. In the active version of thedamper 166 of the fourth variation, increasing the electrical generation required from the generator may increase the work required to spin the impeller, increasing the damping of the fluid 102 (examples shown inFIGS. 7B and 7C ). However, any other variation of adamper valve 166 that is regenerative may be used. - As described above, the first, second, and third variations (and potentially the fourth variation) all preferably utilize a similar construction that includes a disc valve. Because of this feature, it is conceivable that the same housing for the
valve plate 160 may be used with different variations of thedamper valve 166, allowing avalve plate 160 that was outfitted with apassive damper valve 166 to be upgraded to anactive damper valve 166 with the same housing for thevalve plate 160. - The
valve plate 160 preferably includes one of the above variations ofdamper valve 166, but may alternatively include any number or suitable combinations of the above variations. For example, theregenerative damper valve 166 of the fourth variation may be combined with thepassive damper valve 166 of the first variation. More specifically, thevalve plate 160 of this variation may also include both an impeller/generator assembly and a disc valve that cooperate to provide two fluid flow paths in situations with substantially high volume of fluid flow that a regenerative valve alone may not be able to accommodate. Additionally, because the regenerative valve includes a substantial number of moving parts, the regenerative valve may fail and prevent fluid from flowing through. By allowing a second path for fluid flow, thesuspension strut 100 may continue to function. However, thevalve plate 160 may be any other suitable variation. As mentioned above, thesuspension strut 100 of the preferred embodiments preferably allows fordifferent valve plates 160 to be used with the same hydraulic tube body, meaning asuspension strut 100 that originally used avalve plate 160 with adamper valve 166 of the first variation may be exchanged with avalve plate 160 with adamper valve 166 of the second, third, or fourth variation, allowing thesuspension strut 100 to function differently without substantial changes to any other component of thesuspension strut 100. - As shown in
FIG. 8 , thesuspension strut system 100 may additionally include a regenerative valve and a pump, fluidly coupled to the firstfluid path 134, to form aregenerative suspension strut 101. Much like the fourth variation of the damper valve, theregenerative suspension strut 101 functions to regenerate energy from fluid flow within the strut, and is preferably also operable in non-regenerative modes. Theregenerative suspension system 101 may additionally include a third flow path 165 (“regenerative fluid path” or “pump path”), to which the regenerative valve and pump are coupled, wherein the third flow path fluidly couples the intermediary cavity to the reservoir cavity through the valve plate, preferably in parallel with thefirst flow path 134, more preferably sharing an inlet and an outlet with thefirst flow path 134. The regenerativesuspension strut system 101 preferably operates in a first mode that provides a damping force substantially internally within thesuspension strut 100 by directing the displacedcompressible fluid 102 to adamper valve 166 and a second mode that provides a damping force substantially external to thesuspension strut 100 by directing the flow ofcompressible fluid 102 into thepump 190 to drive thepump 190 and recover energy. In the second mode, the force required to drive thepump 190 provides the damping force. The regenerativesuspension strut system 101 may include a third mode where the damping force is provided both through thedamper valve 166 and by directing flow of compressible fluid into thepump 190 and/or a fourth mode where thepump 190 pumps fluid 102 back into thesuspension strut 100. Thedamper valve 166 and theregeneration valve 170 may be thought of as operating in parallel such that fluid flow from thestrut 100 may flow to either valve depending on the state of the valve. Alternatively, thedamper valve 166 and theregeneration valve 170 may be the same physical valve with multiple modes to function to direct fluid into thepump 190, to dampen fluid 102, and/or to both direct fluid into thepump 170 and to dampen thefluid 102. Similarly, to maintain operation ofsuspension strut 100 when the processor and/or the electronics of thedamper valve 166 and/or theregeneration valve 170 fail, thedamper valve 166 is preferably of the type of valve where the failure mode still provides substantial damping force (for example, for adamper valve 166 that is a shim stack valve that increases damping force with increasing stiffness, the shim stack preferably fails in a semi-stiff orientation) to thesuspension strut 100. However, any other suitable arrangement of thedamper valve 166 and theregeneration valve 170 may be used. - The flow pattern of the
regenerative suspension strut 101 during the compression stroke is preferably substantially similar to that described above. As shown inFIG. 9 , during the compression stroke, thedisplacement rod 120 andcavity piston 122 are displaced toward thevalve plate 160. Thus, fluid 102 flows from thefirst volume 134 of the internal cavity to thesecond volume 136 through theaperture 124 of thecavity piston 122. Because of thedisplacement rod 120 that occupies a portion of the volume of thesecond volume 136 and is coupled to thecavity piston 122, the volume available for the displacedcompressible fluid 102 to occupy is less in thesecond volume 136 than in thefirst volume 134, and the pressure of the fluid within thesecond volume 136 increases. A portion of the fluid 102 may be displaced into theintermediary cavity 142 from theinternal cavity 132 and, from theintermediary cavity 142, the fluid flows through the first and/or thirdfluid path 162 of thevalve plate 160. In the first mode, thecompressible fluid 102 is then directed to thedamper valve 166 to apply a damping force on the compressible fluid 102 (shown inFIG. 8 ). In the second mode, the fluid 102 is directed through theregeneration valve 170 to thepump 190 to drive thepump 190 and to recover energy. Alternately and/or additionally, in the third mode, the fluid 102 is directed to both thedamper valve 166 and the regeneration valve 170 (shown inFIGS. 9 and 11A ). However, any other suitable arrangement of the flow during the compression stroke may be used. - Likewise, the flow pattern of the rebound stroke is substantially similar to that described above. As shown in
FIG. 10A , during the rebound stroke, thedisplacement rod 120 andcavity piston 122 are displaced away from thevalve plate 160. Theaperture 124 preferably includes an aperture valve that is preferably a one-direction valve that only allows fluid flow from thefirst volume 134 into thesecond volume 136 and not from thesecond volume 136 to thefirst volume 134. Thus, the fluid pressure within thesecond volume 136 is again increased and follows a path substantially identical to the one described above for the compression stroke, potentially further driving thepump 190 to recover energy during the rebound stroke.Fluid 102 is directed into thefirst volume 134 from a compliant volume 191 (as shown inFIG. 8 ) to prevent aeration within thefirst volume 134 as thesuspension strut 100 extends, as shown inFIG. 10B . Thiscompliant volume 191 may be thereservoir cavity 152, such thatfluid 102 from thereservoir cavity 152 is directed through the secondfluid path 164 of thevalve plate 160 into theinternal cavity 132, as shown inFIG. 10 . Thevalve plate 160 preferably includes a replenishment valve coupled to the secondfluid path 164 that is preferably a one-directional valve that opens when the pressure in the first volume is decreased as a result of the rebound stroke. - As shown in
FIGS. 8 , 12 and 13, the regenerativesuspension strut system 101 may function to direct thecompressible fluid 102 to only the damper valve 166 (the first mode), only the regeneration valve 170 (the second mode), or to both thedamper valve 166 and the regeneration valve 170 (the third mode). The regenerativesuspension strut system 101 may include a processor that determines the mode depending on the use scenario, the user preferences, and/or any other suitable factor. In a first example, directing fluid through theregeneration valve 170 and into thepump 160 to drive the pump may provide a substantially slower damping response than directing fluid into thedamper valve 166. In this first example, when the processor detects a maneuver of the vehicle that requires a faster suspension response, for example, during a fast turn or a substantial bump in the road, the processor may select to operate in the first mode. In a second example, a user may select to operate in the first mode because of the increased responsiveness of the suspension system. For example, the user may plan on driving quickly on mountain roads that include a substantial number of turns. In a third example, the user may know that the road ahead contains a substantial amount of irregularities, for example, an unpaved road. Because of the high number of irregularities, the instances in which energy may be recovered from the suspension system may be high and the user may select the second mode. In a fourth example, the user may select a “fuel economy” mode, which instructs the processor to put a preference on utilizing the second mode. In this example, the user does not instruct a particular mode to operate in, but instructs the processor to prioritize one mode over another and allows the processor to determine the appropriate mode based on the driving scenario. In a fifth example, the processor may select to operate in the fourth mode for increased flexibility where flow is directed to both thedamper valve 166 and theregeneration valve 170. In this example, the processor may function to determine the percentage of fluid that is directed to thedamper valve 166 and to theregeneration valve 170. For example, the amount of damping force that is provided by thepump 190 may be an amount that is determined by the characteristic of the pump 190 (such as the initial starting pressure necessary). If an increased damping force is necessary, the processor may determine to route more fluid to thedamper valve 166. Similarly, the because thedamper valve 166 and thepump 160 may be thought of as providing damping force in parallel to the suspension system, the processor may determine a desired amount of damping force and evaluate a percentage flow combination between thedamper valve 166 and pump 160 to achieve the desired damping force. In a sixth example, the processor may detect that thepump 190 is malfunctioning and may determine to direct all fluid flow into thedamper valve 166. However, any other suitable selection of the operation modes of the regenerativesuspension strut system 101 may be used. - As described above, the pressure in the
compressible fluid 102 used to drive thepump 190. However, energy is used to direct fluid 102 back into thefirst volume 134 to replenish the volume in thefirst volume 134 during the rebound stroke. To improve the fuel economy of the vehicle, the pressure at whichfluid 102 is directed back into thefirst volume 134 is preferably substantially less than the pressure of the fluid 102 used to drive thepump 190, which results in a net positive energy recovery in the regenerativesuspension strut system 101. The rate and/or pressure at which thefluid 102 is directed back into thefirst volume 134 during the rebound stroke is preferably actively controlled to increase energy efficiency. Similarly, the rate and/or pressure at which thefluid 102 is displaced from thesecond volume 126 is preferably also actively controlled to balance with the pressure of fluid injected into thefirst volume 124. In typical suspension strut systems, the rebound stroke is passive and is substantially dependent on the type of road irregularity, for example, the shape of the bump on the road. In other words, energy that could have been captured from the compression of the suspension due to the bump in the road is used in the uncontrolled retraction of the suspension after the bump. By substantially controlling the rebound stroke through controlling the rate and/or pressure at whichfluid 102 is injected into thefirst volume 134 and/or through controlling the rate and/or pressure at whichfluid 102 is displaced from thesecond volume 136, energy recovery in the regenerativesuspension strut system 101 may be substantially improved over a typical suspension system. This control may be obtained by controlling the fluid flow rate with thepump 190, wherein thepump 190 controls fluid flow into thefirst volume 134 indirectly by controlling the fluid ingress into the reservoir cavity. Alternately, thepump 190 may be directly coupled to thefirst volume 134, wherein the valve plate further includes a fourth flow path coupling the pump outlet to thefirst volume 134 and a second replenishment valve, disposed within the fourth flow path, that allows one-way fluid flow from the pump to thefirst volume 134. - The
pump 190 anddamper valve 166 may also function to provide a retractive force on theregenerative suspension strut 101 100. Typical suspension struts are configured to provide a force to suspend the vehicle, or, in other words, a force to extend the strut, and compresses only when there is an external force such as a bump or a turn, and typically do not provide a force to compress the strut, or a retractive force. An active suspension utilizing a single acting cylinder actuator may change the height of the strut, but cannot provide a retractive force unless the strut is fully extended. By facilitating control over the compressible fluid flow to/from thesecond volume 136, the regenerativesuspension strut system 101 is able to provide such a retractive force. As shown inFIGS. 9 and 10 , fluid flow from thefirst volume 134 to thesecond volume 136 results in an increased pressure within thesecond volume 136, which is relieved when the fluid 102 is forced through thedamper valve 166 and/or pump 190 and damped. However, if an imbalance between the flow rate out through thedamper valve 166 and/or thepump 190 and flow rate into thesecond volume 136 is present, the pressure within the volume of fluid contained within thesecond volume 136 cannot be relieved, and a force to push thecavity piston 122 back towards thevalve plate 160 is present, providing a retractive force. Varying the amount of fluid that is bled through thedamper valve 166 and/or directed to pump 190 may control this retractive force. This may be particularly useful if a particular position of the strut that is shorter than the fully extended is desired. An additional retractive force may be achieved by driving thepump 190 to pump fluid into thesecond volume 136, as shown by the dashedline 4 a inFIG. 14 . Alternatively, if thepump 190 is driven to pump fluid 102 out of thesecond volume 136, the retractive force may be decreased to substantially zero and/or a force to extend thesuspension strut 100 may result. This pull force may be used to relatively quickly restore the height of thetriple tube strut 100 or for any other suitable use. However, any other suitable method to produce a retractive force in thesuspension strut 100 may be used. - As shown in
FIG. 14 , the regenerativesuspension strut system 101 of the preferred embodiments functions to recover a substantial amount of energy used to operate thetriple tube strut 100. The X-axis ofFIG. 14 represents displacement frequency seen in thesuspension strut 100, for example, from irregularities in the road while the Y-axis represents the force that the suspension strut provides on the vehicle, in other words, the suspending force.Curve 1 represents the equilibrium position of thetriple tube strut 100, which changes depending the weight of the vehicle, the payload of the vehicle, or any other suitable parameter.Curve 2 represents the force preferably provided by the regenerativesuspension strut system 101 to the vehicle (for example, through asuspension strut 100 of the triple tube strut construction), in other words, the operating region of thesuspension strut 100, andCurve 4 represents the retractive force provided by thesuspension strut 100, as described above. The shadedregion 3 describes the operating region of the suspension strut from which energy may be recovered, in particular, the energy from irregularities on the road. Portion 3A represents the region of irregularities that require suspension response speeds that may be provided by thepump 190 while Portion 3B (cross-hatched) represents the region of irregularities that require a faster response, for example, when thedamper valve 166 is used to provide the damping force. In typical driving scenarios, a majority of the irregularities encountered may require suspension response speeds that may be provided by thepump 190. As a result, a substantial portion of the energy from road irregularities may be recovered. The substantially direct linkage between thesuspension strut 100 and thepump 190 also decreases the amount of parasitic energy losses within the regenerativesuspension strut system 101, which increases the efficiency at which energy may be recovered. - As shown in
FIG. 15 , the regenerativesuspension strut system 101 of the preferred embodiments may also include a secondcompliant volume 192 that is preferably isolated from the system when fluid 102 is actively directed to thepump 190 and may be connected when fluid 102 is not directed to thepump 190. The secondcompliant volume 192 receives fluid 102 fromdamper valve 166 to alleviate the pressure of the fluid 102 that would otherwise be used to drive thepump 190. In particular, thesuspension strut 100 may be operated at higher pressures when fluid is actively directed to thepump 190 because increased pressure in the fluid 102 is substantially quickly alleviated through thepump 190. However, when fluid is not actively directed to thepump 190, the pressure within thetriple tube strut 100 may be too high for passive operation (e.g., thestrut 100 may be too stiff) and fluid may then be directed to the secondcompliant volume 192 to decrease the pressure within thesuspension strut 100. This embodiment preferably utilizes the third variation of the damper valve 166 (such as that shown inFIG. 7B ), but may alternately utilize any variation of thedamper valve 166 as described above. However, any other suitable arrangement of the fluid flow to allow both internal damping through thedamper valve 166 and external damping through thepump 190 may be used. - As described above, the
pump 190 may function to direct fluid back into thesuspension strut 100 to replenish flow within thesuspension strut 100. Alternatively, the regenerativesuspension strut system 101 may include areservoir 194, as shown inFIG. 16 , from which thesuspension strut 100 may draw fluid 102 to replenish the fluid 102 within thesuspension strut 100. In this variation, thesuspension strut 100 may function substantially similarly to a pump that pumpsfluid 102 at substantially high pressures during the compression stroke into thepump 190 to drive thepump 190 and recover energy, and to draw fluid from thereservoir 194 at a substantially lower pressure during the rebound stroke. During the compression stroke, thepump 190 functions to dampen fluid flow to provide a damping force and during the rebound stroke, thereservoir 190 provides fluid at a lower pressure than the fluid used to drive thepump 190 to recover energy, satisfying the pressure relationships for energy recovery as described above. In this variation, theregeneration valve 170 preferably directs fluid 102 during the compression stroke from thesuspension strut 100 into thepump 190 and preferably directs fluid 102 from thereservoir 194 into thesuspension strut 100 from thereservoir 194. This variation of the regenerativesuspension strut system 101 is preferably otherwise substantially similar to the variations as described above. - As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.
Claims (1)
1. A strut system comprising:
a compressible fluid;
a strut comprising:
an inner tube defining an inner cavity, the inner cavity containing a portion of the fluid;
a secondary tube disposed coaxially around the inner tube;
a housing tube disposed coaxially around the secondary tube;
an intermediary cavity defined between the inner tube and the secondary tube, the intermediary cavity containing a second portion of the fluid, wherein the intermediary cavity is fluidly coupled to the inner cavity;
a reservoir cavity defined between the secondary tube and the housing tube, the reservoir cavity containing a third portion of the fluid;
a piston, having an aperture through the piston thickness, that is disposed substantially coaxially within the inner tube, and separates the inner cavity into a first volume and a second volume, wherein the aperture allows fluid communication between the first volume and the second volume;
a one-way aperture valve within the aperture that allows fluid flow from the first volume to the second volume;
a displacement rod, coupled to the piston, that extends through the second volume;
a valve plate coupled to the strut, the valve plate including:
a damping flow path fluidly coupling the intermediary cavity to the reservoir cavity;
a replenishment flow path fluidly coupling the reservoir cavity to the inner cavity;
a damper valve within the damping flow path that damps fluid flowing therethrough; and
a one-way replenishment valve within the replenishment flow path that allows fluid flow from the reservoir cavity to the inner cavity.
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US15/784,521 US10125841B2 (en) | 2010-07-05 | 2017-10-16 | Suspension strut for a vehicle |
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US14/875,426 US20160025179A1 (en) | 2010-07-05 | 2015-10-05 | Suspension strut for a vehicle |
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US15/784,521 Expired - Fee Related US10125841B2 (en) | 2010-07-05 | 2017-10-16 | Suspension strut for a vehicle |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US20160059657A1 (en) * | 2013-05-20 | 2016-03-03 | Vilo NIUMEITOLU | Shock absorber generator |
WO2020232043A1 (en) * | 2019-05-14 | 2020-11-19 | Tenneco Automotive Operating Company Inc. | Scalable damper |
Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
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Also Published As
Publication number | Publication date |
---|---|
US20140203530A1 (en) | 2014-07-24 |
US8534687B2 (en) | 2013-09-17 |
US20180038440A1 (en) | 2018-02-08 |
WO2012006294A1 (en) | 2012-01-12 |
US9150076B2 (en) | 2015-10-06 |
US10125841B2 (en) | 2018-11-13 |
US20120001399A1 (en) | 2012-01-05 |
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