Steering damper

Abstract

The described steering damper systems comprise a steering jack and a damping valve assembly fluidly coupled thereto. The damping valve assembly comprises a main valve, energy storage member(s), force and blow-off valves. A main valve shuttle is moveable between a neutral open, first and second closed positions. The shuttle is biased to the neutral, open position while the damping fluid velocity from the steering jack is below a first predetermined threshold velocity, enabling fluid flow through both the main and force valves, providing a first damping level and a first resistive force to movement of the steering jack's piston and acceleration of the vehicle steering actuator. When the damping fluid velocity reaches or exceeds the first predetermined threshold, damping fluid flows through the force valve (and not through the main valve), providing a second damping level and second resistive force greater than the first damping level and first resistive force.

Description

STEERING DAMPERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority from United States Provisional Patent Application Number 63 / 754,916 filed on February 6, 2025, the entire contents of which are incorporated by reference.TECHNICAL FIELD

[0002] This disclosure relates to vehicle damper systems, and more particularly to vehicle steering damper systems.BACKGROUND

[0003] In racing vehicles, collisions are frequent as drivers push the limits of performance. In an open-wheeled racing vehicle, a collision involving the front wheels can cause a rapid reaction through the steering system and to the steering wheel or other vehicle steering actuator. The speed at which the steering wheel rotates or moves during this type of collision is much higher than the normal turning speed generated by the driver. This reaction through the steering wheel can cause injuries to the driver’s hands during a collision. It would be beneficial to have a system on the vehicle that limits the acceleration of the vehicle steering actuator as a safety system.SUMMARY

[0004] According to some embodiments, there is provided a steering damping system comprising a steering jack and a damping valve assembly. The steering jack is configured to operatively couple to a vehicle steering actuator. The steering jack comprises a piston. The damping valve assembly is fluidly coupled to the steering jack and comprises a main valve, at least one energy storage member, a force valve and a blow-off valve. The main valve has a valve body, a valve bore in said valve body, at least two port openings in the valve body and a shuttle moveably disposed within the valve bore. The shuttle is moveable between at least three positions comprising: a neutral, open position in which the at least two port openings are in fluid communication with the steering jack; a first closed position in which the shuttle moves to restrictfluid flow through one of the at least two port openings; and. a second closed position in which the shuttle moves to restrict fluid flow through another of the at least two port openings. The at least one energy storage member is operatively coupled to the shuttle and is biased to maintain the shuttle in the neutral, open position while a velocity of a damping fluid from the steering jack is below a first predetermined threshold velocity. The force valve is in fluid communication with the steering jack and the at least two port openings. The blow-off valve is in fluid communication with the steering jack and at least one of the at least two port openings. When the velocity of the damping fluid from the steering jack is below the first predetermined threshold velocity, the shuttle is in the neutral, open position and damping fluid is enabled to flow through both the main valve and the force valve before returning to the steering jack, thereby providing a first damping level and a first resistive force to movement of the piston and, in turn, to acceleration of the vehicle steering actuator. When the velocity of the damping fluid from the steering jack reaches or exceeds the first predetermined threshold velocity, the shuttle moves to one of the first closed position and the second closed position, and the damping fluid flows through the force valve, without flowing through the main valve, before returning to the steering jack, providing a second damping level greater than the first damping level and a second resistive force greater than the first resistive force being applied to the piston of the steering jack to counter acceleration of the vehicle steering actuator. The steering jack and damping valve assembly are further configured to fluidly couple to a damping fluid reservoir. According to some embodiments, the first resistive force is about 40 N.

[0005] According to some embodiments, when the velocity of the damping fluid from the steering jack reaches or exceeds a second predetermined threshold velocity greater than the first predetermined threshold velocity, the damping fluid is enabled to flow through both the force valve and the blow-off valve without flowing through the main valve, providing a third damping level between the first and second damping levels and a third resistive force between the first and second resistive forces to the piston of the steering jack to counter acceleration of the vehicle steering actuator.

[0006] According to some embodiments, the force valve comprises a bleed orifice which is in fluid communication with the main valve when the shuttle is in each of the neutral, open position, the first closed position and the second closed position.

[0007] According to some embodiments, the force valve comprises a needle valve.

[0008] According to some embodiments, the force valve is configured such that flow of the damping fluid therethrough is adjustable.

[0009] According to some embodiments, the at least one energy storage member comprises one or more of a return spring and an elastomeric member. According to some embodiments, the return spring is a conical spring.

[0010] According to some embodiments, the at least one energy storage member comprises two energy storage members coupled to opposing ends of the shuttle.

[0011] According to some embodiments, the at least one energy storage member is pre-loaded.

[0012] According to some embodiments, the steering damper system further comprises at least one check valve in fluid communication with one or more of the steering jack, the main valve, the force valve and the blow-off valve.

[0013] According to some embodiments, the blow-off valve is pre-loaded to a closed position. According to some embodiments, the blow-off valve comprises a blow-off energy storage member configured to provide the pre-loading. According to some embodiments, the blow-off energy storage member comprises one or more of a spring and an elastomeric member. According to some embodiments, the pre-loading of the blow-off valve is adjustable. According to some embodiments, the blow-off energy storage member is housed in a pre-load sleeve configured to apply the pre-load to the blow-off energy storage member.

[0014] According to some embodiments, the steering damper system further comprises a gas chamber operatively coupled to the damping valve assembly and wherein a pressure of gas contained therein is at least about 5 bars.

[0015] According to some embodiments, the damping fluid is a hydraulic fluid.

[0016] According to some embodiments, the vehicle steering actuator comprises a steering wheel.

[0017] According to some embodiments, there is provided a method of damping a steering velocity of a vehicle steering actuator. Damping fluid is provided from a steering jack to a main valve. When a velocity of the damping fluid from the steering jack is below a first predetermined threshold velocity: the main valve is maintained in a neutral, open position, enabling damping fluid to flow therethrough; a portion of the damping fluid is provided to a force valve; and, the damping fluid from the main valve and the portion of the damping fluid from the force valve is provided to the steering jack at a first damping level, thereby providing a first resistive force to counter movement of a piston of the steering jack and, in turn, to resist acceleration of the vehicle steering actuator. When the velocity of the damping fluid is at or above the first predetermined threshold velocity: the main valve is set to a main valve closed position, restricting fluid flow therethrough; damping fluid from the steering jack is provided to the force valve without flowing through the main valve: and, damping fluid from the force valve is returned to the steering jack, providing a second damping level higher than the first damping level and a second resistive force greater than the first resistive force to counter movement of the piston of the steering jack and resist acceleration of the vehicle steering actuator.

[0018] According to some embodiments, when the velocity of the damping fluid from the steering jack reaches or exceeds a second predetermined threshold velocity greater than the first predetermined threshold velocity, the main valve is set to the main valve closed position, a blow-off valve is opened and damping fluid is enabled to flow through both the force valve and the blow-off valve, thereby providing a third damping level between the first and second damping levels. As a result, a third resistive force between the first and second resistive forces is provided to the piston of the steering jack to resist acceleration of the vehicle steering actuator. According to some embodiments, the second predetermined threshold velocity corresponds to a predetermined damping fluid pressure.

[0019] According to some embodiments, the method further comprises adjusting an effective size of a valve orifice of the force valve to alter a flow rate of the damping fluid therethrough.

[0020] According to some embodiments, the method further comprises pre-loading a blow-off energy storage member to a closed position. According to some embodiments, the blow-off energy storage member comprises one or more of a spring and an elastomeric member. According to some embodiments, the pre-loading of the blow-off energy storage member is adjustable.

[0021] According to some embodiments, the damping fluid is a hydraulic fluid.

[0022] According to some embodiments, the method further comprises adjusting the first predetermined threshold velocity of the damping fluid from the steering jack by performing one or more of: altering a spring constant of a main valve energy storage member; and altering a pre-load of the main valve energy storage member.

[0023] According to some embodiments, a pressure of gas contained in a gas chamber operatively coupled to the main valve and the force valve is about at least 5 bars.

[0024] Further aspects of the claimed subject matter will be apparent from the following description and explanations.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a better understanding of the various embodiments described herein and to show more clearly how they may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which:

[0026] FIG. 1 depicts a schematic of a vehicle steering system having a steering damper system, according to non-limiting embodiments;

[0027] FIGS. 2A to 2C depict a steering damper system, according to non-limiting embodiments;

[0028] FIG. 3 depicts a front sectional view of a damping valve assembly, according to non-limiting embodiments:

[0029] FIG. 4 depicts a rear sectional view of the damping assembly of FIG. 3, according to non-limiting embodiments;

[0030] FIGS. 5A and 5B depict sectional views of a main valve having a shuttle in open and closed positions, according to non-limiting embodiments;

[0031] FIGS. 6A and 6B depict sectional views of a force valve having an adjustable fluid orifice, according to non-limiting embodiments;

[0032] FIGS. 7A to 7C depict section views of a blow-off valve having an adjustable pre-load in open and closed positions, according to some embodiments;

[0033] FIGS. 8A to 8C depict schematics of a steering damper system and operation thereof, according to non-limiting embodiments;

[0034] FIGS. 9A and 9B depict schematic plots of force versus velocity showing the damping characteristics of various valve configurations of a steering damper system, according to non-limiting embodiments;

[0035] FIGS. 10A and 10B depict schematic plots of force versus velocity for different force valve configurations (FIG. 10A) and blow-valve configurations (FIG. 10B), according to non-limiting embodiments;

[0036] FIG. 11A depicts a graph of force versus velocity in which a force valve is adjusted to various configurations, according to non-limiting embodiments;

[0037] FIG. 11B depicts a graph of force versus velocity in which a blow-off valve is adjusted to various configurations, according to non-limiting embodiments;

[0038] FIG. 12 depicts a gas chamber operatively coupled to a damping valve assembly, according to non-limiting embodiments; and

[0039] FIGS. 13A to 13C depict a flowchart of a method of damping a steering velocity of a vehicle steering actuator, according to non-limiting embodiments.

[0040] The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.DETAILED DESCRIPTION

[0041] The described systems and methods typically provide a means to limit the acceleration of a vehicle’s steering actuator (such as the angular acceleration of a steering wheel). According to some embodiments, the described steering damper system can be added to an existing steering system or, for a more efficient solution, may be integrated into the steering system. Undernormal driving inputs, the described steering damper systems typically have minimal effect and are imperceptible to the driver. During a collision, however, the described steering damper systems are configured to provide a significant resistive force to the steering system to dramatically reduce the angular acceleration of the steering wheel or other vehicle steering actuator (by increasing resistance to motion of the steering wheel), helping to prevent injury.

[0042] It will be appreciated that numerous specific details are set forth in order to provide a thorough understanding of the exemplary aspects of the present application described herein. However, it will be understood by those of ordinary skill in the art that the exemplary aspects described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the exemplary aspects described herein. Also, the description is not to be considered as limiting the scope of the exemplary aspects described herein. Any systems, method steps, method blocks, components, parts of components, and the like described herein in the singular are to be interpreted as also including a description of such systems, method steps or tasks, components, parts of components, and the like in the plural, and vice versa. Further aspects of the invention will be apparent from the figures and claims appended hereto. The particular arrangement of the elements described herein may be modified as will be apparent to those skilled in the art.

[0043] In general, as with most damping systems, the described steering damper system provides a resistive force that is proportional to the velocity of the fluid flowing therethrough. The resistive force, F, is characterized by the following equation:F = —cvIn which:F = the resistive force;c = the damping co-efficient (noting the negative indicates that the resistive force is always in the opposite direction to the fluid flow); andv = the velocity of the fluid.

[0044] The damping co-efficient, c, is a product of the geometry of the path that the fluid must flow through on the way to the damping valve assembly. As would be understood by a person skilled in the art, a relatively unrestricted path results in a small value for the dampingcoefficient. Conversely, a more restricted path, such as that resulting by forcing fluid through a small orifice, results in a larger damping co-efficient value. In the described steering damper systems, when the velocity of the damping fluid is low, the main valve remains open, damping fluid flows through both the main valve and the force valve and the damping co-efficient for the system is low enough such that the resistive force, F, is usually imperceptible to the driver operating the steering wheel. Once the main valve closes, however, the damping fluid is no longer able to flow through the main valve and is therefore forced to flow through a much more restrictive path, the force valve only or, according to some embodiments, the force valve and a blow-off valve, and the damping coefficient of the system increases and, in turn, so does the resistive force.

[0045] Attention is directed to FIG. 1 which depicts an existing steering system 1 having steering damper system 100, according to non-limiting embodiments. As noted above, according to some embodiments, steering damper system 100 is added to an existing steering system, such as steering system 1. Steering system 1 is operatively coupled to steering damper system 100. As shown, each end of a rod assembly 108 of a steering jack (such as steering jack 104) is operatively coupled to steering rack and pinion assembly 3 of steering system 1 by an integrating linkage assembly 6. As would be understood by a person skilled in the art, under normal driving conditions steering the vehicle steering actuator 5 (which may be a steering wheel operatively coupled to a steering linkage assembly 8, as shown in FIG. 1) moves the rack by turning the pinion which, in turn, shifts the tie rod 7 and the knuckle 9 of each of wheels 11. During such operation, the velocity of the damping fluid through the steering damper system 100 is below the first predetermined threshold and the damping effects of the steering damper system 100 are typically minimal or otherwise imperceptible to the driver. In a collision, a high impact load would be applied to at least one of the wheels 11 (and therefore to the corresponding knuckle 9). Without steering damper system 100 installed, the tie rods 7 would rapidly move the steering rack and pinion assembly 3 and steering wheel 5 (i.e., the impact load of the collision would be transferred from the affected wheel all the way up to the steering wheel 5), resulting in a significant increase in the angular velocity of steering wheel 5 from that experienced under normal driving conditions and an increased risk of injury to the driver. However, with steering damper system 100 installed, movement of tie rod 7 would be resisted and the increase in angular velocity of steering wheel 5during a collision would be more limited in comparison to an undamped version of steering system 1. In particular, sharp movement of tie rod 7 during a collision would typically result in the velocity of the damping fluid provided to the steering jack 104 and, in turn, to the damping valve assembly 106 reaching or exceeding at least the first predetermined threshold damping fluid velocity. The reactionary resistive force generated by steering damping system 100 limits movement of the rack of rack and pinion assembly 3 and, in turn, limits the velocity (and acceleration) of steering wheel 5.

[0046] Attention is directed to FIGS. 2 A to 4, which depict steering damper system 100 and components thereof, according to non-limiting embodiments. Steering damper system 100 comprises steering jack 104 and damping valve assembly 106 fluidly coupled to steering jack 104 (such as via hoses 112, individually referred to herein as left hose 112A and right hose 112B). According to some embodiments, steering jack 104 comprises a hydraulic device. Steering jack 104 is configured to operatively couple to a vehicle steering actuator, such as a steering wheel or other device used to steer the vehicle (e.g., vehicle steering actuator 5, also referred to herein as steering wheel 5). When the driver steers right, damping fluid (such as hydraulic fluid) from the steering jack is forced through a corresponding fluid pathway (which can comprise one or more of hoses 112) in a first fluid circuit direction to damping valve assembly 106 and back to steering jack 104. In addition, steering jack 104 and damping valve assembly 106 are configured to fluidly couple to a damping fluid reservoir 107 (FIGS. 8 A to 8C).

[0047] Damping valve assembly 106 comprises main valve 114 having a main valve body 116, a valve bore 118 in said valve body 116, at least two port openings (such as openings 120, individually opening 120A and opening 120B) and a shuttle 122 moveably disposed within the valve bore 118. Shuttle 122 is moveable between three positions: (1) a neutral, open position in which the at least two port openings 120 are in fluid communication with the steering jack 104 (FIG. 3); (2) a first closed position in which the shuttle 122 moves to restrict fluid flow through one of the at least two port openings 120 (for example, moving to close port opening 120A and restrict fluid flow therethrough); and (3) a second closed position in which the shuttle 122 moves to restrict fluid flow through another of the at least two port openings 120 (for example, moving to close port opening 120B and restrict fluid flow therethrough).

[0048] Damping valve assembly 106 further comprises at least one energy storage member 124 (also referred to herein as a main valve energy storage member) operatively coupled to shuttle 122. The at least one energy storage member 124 is biased to maintain the shuttle 122 in the neutral, open position while a velocity of damping fluid from the steering jack 104 is below a first predetermined threshold velocity. According to some embodiments, the shuttle 122 is pre-loaded by the at least one energy storage member 124 to the neutral, open position. For example, the spring constant of the at least one energy storage member 124 may be selected and / or the at least one energy storage member 124 may be installed under a selected compressive load such that shuttle 122 is compelled to move under an applied first threshold drag force that is generated when the damping fluid from steering jack 104 reaches or exceeds the first predetermined threshold velocity. According to some embodiments, the at least one energy storage member 124 comprises two energy storage members coupled to opposing ends of shuttle 122 (such as energy storage members 124A and 124B depicted in FIG. 3). Any suitable energy storage member is contemplated. For example, according to some embodiments, the at least one energy storage member 124 comprises one or more of a coil spring and an elastomeric member. According to some embodiments, the return spring comprises at least one conical spring. The spring force, or the like, acting on shuttle 122 sets the first predetermined threshold velocity. As a result, one way to adjust the first predetermined threshold velocity is to alter the geometry or other characteristics (e.g., spring constant and / or preloading) of the at least one energy storage member 124.

[0049] As depicted in FIGS. 5 A and 5B, in operation the shuttle 122 is exposed to a drag force, FD, as the damping fluid flows around the shuttle 122 from at least one of port openings 120 (such as damping fluid 126 flowing from port opening 120B) to at least another one of port openings 120 (such as to port 120A). The drag force, FD, on shuttle 122 may be calculated as follows:In which:C = drag coefficient of shuttle;A = cross-sectional area of the shuttle;Q - density of damping fluid; andv = velocity of damping fluid.

[0050] Based on the above formula, the drag force, FD, increases with the square of the damping fluid’s velocity. This force is counteracted by the at least one energy storage member 124 up and until the first predetermined threshold velocity of the damping fluid is reached or exceeded (also referred to herein as the “activation threshold” of the damping valve assembly 106). The first predetermined threshold velocity is reached when the drag force, FD. is high enough to move the shuttle 122 all the way to one of the at least two port openings 120 (such as moving all the way to port opening 120A as shown in FIG. 5B) to restrict fluid flow therethrough (i.e., shuttle 122 moves all the way to one of a first closed position and a second closed position). When the velocity of the damping fluid is below the first predetermined threshold velocity, the damping fluid is enabled to flow through the main valve 114 and return to steering jack 104 (by not restricting damping fluid flow through port openings 120). It is understood, when the first predetermined threshold velocity of the damping fluid is reached or exceeded, the back pressure generated by the damping fluid helps keep the shuttle 122 in one of the first and second closed positions.

[0051] Damping valve assembly 106 further comprises a force valve 128 and a blowoff valve 130 (FIGS. 3 and 4). Force valve 128 is in fluid communication with steering jack 104 and the at least two port openings 120 such that at least a portion of the damping fluid flowing through the main valve 114 is enabled to flow through force valve 128. For example, according to some embodiments, force valve 128 comprises a bleed orifice 132 which is in fluid communication with the main valve 114 when shuttle 122 is in each of the neutral, open position, first closed position and second closed position. As a result, at least some damping fluid passes through the force valve 128 even in normal steering conditions when the main valve 114 may be in a closed position, helping to prevent hydraulic lock. Any suitable location for the bleed orifice 132 is contemplated. For example, according to some embodiments, bleed orifice 132 is located in a force valve piston 134.

[0052] With the shuttle 122 in the neutral, open position, the damping effect by the force valve 128 is typically minimal due to the majority of the damping fluid being able to flow through the much larger port openings 120 of the main valve 114. It is understood that at least some damping, however minimal, is present even when the shuttle 122 is in a neutral, open positiondue to system geometry and friction. When the shuttle 122 moves to one of the first and second closed positions, the damping fluid must pass through the force valve 128 without flowing through the main valve 114 which results in a greater damping effect on the movement of the steering jack 104 due to the smaller fluid orifice provided by the force valve 128 (compared to that of an open main valve 114).

[0053] Any suitable configuration of the force valve 128 is contemplated. According to some embodiments, the force valve 128 comprises a primary orifice 136 (in addition to or in place of bleed orifice 132) through which damping fluid may flow, based on steering conditions. For example, when the velocity of the damping fluid reaches or exceeds the first predetermined threshold velocity, the force valve 128 may be enabled to allow at least some of the damping fluid through the primary orifice 136 to return to the steering jack 104.

[0054] According to some embodiments force valve 128 is configured such that the flow of damping fluid therethrough is adjustable. Adjusting the size of the orifice through which damping fluid can flow (also referred to herein as a “fluid orifice”) has the effect of altering the first predetermined threshold velocity. For example, increasing the size of the fluid orifice (such as by increasing the size of the primary orifice 136) has the effect of delaying the velocity at which the main valve 114 closes (allowing for a higher first predetermined threshold velocity), as a larger fluid orifice reduces the flow rate of the damping fluid seen at the main valve 114.

[0055] Any suitable valve type is contemplated. For example, according to some embodiments, the force valve 128 comprises a needle valve having needle 138, such as that depicted in FIGS. 4, 6A and 6B. Needle 138 may be shaped such that adjusting its axial position in relation to the primary orifice 136 varies the effective fluid orifice size of primary orifice 136. For example, as shown in FIGS. 6 A and 6B, at a first axial position, Pl, primary orifice 136 is closed such that a minimal (or no) damping fluid is enabled to flow therethrough. As noted above, according to some embodiments, force valve 128 may comprise bleed orifice 132 which allows at least a portion of damping fluid (illustrated by the arrows) to flow through the force valve 128 even when the primary orifice 136 is closed. By adjusting the axial position of needle 138 to a second axial position, P2, at least some damping fluid is enabled to flow through the primaryorifice 136. reducing the damping co-efficient and the corresponding resistive force applied to the piston. In turn, the first predetermined threshold velocity is increased.

[0056] Blow-off valve 130 is in fluid communication with the steering jack 104 and at least one of the two port openings 120. According to some embodiments, the blow-off valve 130 provides an additional safety measure that is engaged under certain circumstances. Under normal steering conditions (with the main valve 114 open), the damping fluid pressure is insufficient to open the blow-off valve 130. However, when the damping fluid pressure is high enough, the blowoff valve 130 is configured to open and allow damping fluid to flow therethrough (in addition to the fluid flow through the force valve 128), such as through blow-off orifice 143 (FIG. 4). Since the fluid orifice now comprises that provided by both the force valve 128 and the blow-off valve 130, the damping fluid is less restricted than when it is forced to flow through the force valve 128 alone, which results in a lower damping level (however, still higher than when damping fluid is enabled to flow through the main valve 114).

[0057] According to some embodiments, the velocity of the damping fluid at which the damping fluid pressure becomes sufficient to open the blow-off valve 130 is adjustable. For example, according to some embodiments, the blow-off valve 130 may be pre-loaded to a closed position and configured only to open when a predetermined damping fluid pressure has been reached or exceeded. Blow-off valve 130 may comprise a blow-off energy storage member 140 configured to provide the pre-loading (FIG. 4). Any suitable blow-off energy storage member 140 is contemplated. For example, according to some embodiments, the blow-off energy storage member 140 comprises one or more of an elastomeric member and a spring.

[0058] As depicted in FIGS. 7A to 7C, the blow-off valve 130 houses the blow-off energy storage member 140 in a pre-load sleeve 142 configured to apply the pre-load to the blowoff energy storage member 140. According to some embodiments, pre-load sleeve 142 may be adjusted axially. In the depicted embodiment, by adjusting the axial position of the pre-load sleeve 142, the pre-load and, as a result, the amount of damping being provided by the damping fluid can be adjusted. For example, according to some embodiments, when the blow-off energy storage member 140 is a coil spring, the blow-off energy storage member 140 may have an uncompressed or minimally compressed length corresponding to a minimum pre-load (FIG. 7B depicting theblow-off valve 130 in a closed position with the minimum pre-load applied). The pre-load may be increased by lowering the pre-load sleeve 142 to place the blow-off energy storage member 140 (spring) in a more compressed state (FIG. 7A). The greater the pre-load, the greater the fluid pressure required to overcome the resistive spring force of blow-off energy storage member 140 to open blow-off valve 130. The lower the pre-load, the lower the fluid pressure required to overcome the resistive spring force of blow-off energy storage member 140 (see FIG. 7C depicting opening of blow-off valve 130 enabling damping fluid 126 to flow through blow-off orifice 143).

[0059] According to some embodiments, blow-off valve 130 is configured to open further during spikes in fluid pressure, acting as a “blow-off’, to help prevent damage to the described systems and devices.

[0060] Attention is directed to FIGS. 8 A to 8C, which depict operation of steering damper system 100 under different steering conditions. FIG. 8 A depicts steering damper system 100 during normal conditions. Since the steering jack 104 is operatively coupled to the steering wheel or other vehicle steering actuator 5, operating the steering wheel results in movement of the piston 110 of steering jack 104 and the damping fluid contained therein. For example, when the driver turns the steering wheel to the right, the piston 110 of the steering jack 104 forces damping fluid to flow through damping valve assembly 106 via the right hose 112B (indicated by the directional arrows in FIG. 8A). Under normal steering conditions, fluid is enabled to flow through the main valve 114 and, as long as the velocity of the damping fluid is below the first predetermined threshold velocity (the activation threshold), shuttle 122 remains in a neutral, open position to enable damping fluid flow to return to the steering jack 104 via the left hose 112A. More specifically, when the velocity of the damping fluid from the steering jack 104 (and received by the damping valve assembly 106) is below the first predetermined threshold velocity, shuttle 122 is in the neutral, open position and the damping fluid is enabled to flow through both the main valve 114 and the force valve 128 before returning to the steering jack 104. Flowing through such geometry (the fluid path having the combined fluid orifice provided by the main valve 114 and the force valve 128) provides a first damping level and a first resistive force, Fl, to movement of piston 110 and, in turn, to acceleration of the vehicle steering actuator 5 (such as the angular acceleration of a steering wheel). This first damping level corresponds to a first damping co-efficient, Cl. Again, the damping effect under normal steering conditions is low and is usually imperceptible to the driver. According to some embodiments, the first resistive force, Fl , is about 40 N (which may include friction as a contributor to the first resistive force). It is understood that the described systems are symmetrical and operate similarly when the steering wheel is turned to the left (albeit mirrored).

[0061] FIG. 8B depicts steering damper system 100 during a collision. When the velocity of the damping fluid from steering jack 104 reaches or exceeds the first predetermined threshold velocity (also referred to herein as the “activation threshold”), the force acting on the main valve 114, and more specifically the drag force. FD, acting on the shuttle 122, causes the shuttle 122 to move to one of the first closed position and the second closed position (such as to close port opening 120A, depicted in FIG. 8B). The damping fluid is then forced to flow through the force valve 128, without flowing through the main valve 114, before returning to steering jack 104. Since the main valve 114 is closed, the damping fluid flow through damping valve assembly 106 is forced through the relatively smaller fluid orifice of the force valve 128 and a second damping level greater than the first damping level and a second resistive force. F2, greater than the first resistive force, Fl, is applied to the piston 110 of the steering jack 104 to counter acceleration of the vehicle steering actuator 5 (e.g., steering wheel). This second damping level corresponds to a second, higher damping co-efficient, C2, which yields a greater resistive force to movement of the piston 110 and, in turn, to the vehicle steering actuator (e.g., steering wheel). The second resistive force, F2, is typically high enough to significantly counteract the acceleration that the vehicle steering actuator 5 would undergo in an undamped or minimally damped steering system.

[0062] FIG. 8C depicts a third potential scenario, a collision which generates a damping fluid velocity that reaches or exceeds a second predetermined threshold velocity that is greater than the first predetermined threshold velocity. Under such conditions, the damping fluid received from the steering jack 104 may generate sufficient fluid pressure to open blow-off valve 130. As discussed above, if the incoming damping fluid from steering jack 104 generates sufficient pressure to overcome the pre-load of blow-off valve 130, blow-off valve 130 will open and provide another flow path for the damping fluid through damping valve assembly 106. Again, blow-offvalve 130 typically provides a safety blow-off function by opening during peaks in pressure and at higher steering velocities (such as during especially high impact collisions). When the blowoff valve 130 is open, less damping is provided as compared to when blow-off valve 130 is closed (and main valve 114 is closed). In particular, when the velocity of the damping fluid from steering jack 104 reaches or exceeds a second predetermined threshold velocity greater than the first predetermined threshold velocity (greater than the “activation threshold”), the damping fluid is enabled to flow through both force valve 128 and blow-off valve 130. As a result, a third damping level greater than the first damping level but lower than the second damping level and a third resistive force, F3, greater than the first resistive force, Fl, but lower than the second resistive force, F2, is generated and provided to piston 110 of steering jack 104 to counter acceleration of the vehicle steering actuator 5 (e.g., steering wheel). The third damping level corresponds to a third damping co-efficient, C3. that is greater than the first damping co-efficient. Cl, but lower than the second damping co-efficient, C2, such that generally C2>C3>C1.

[0063] FIGS. 9 A and 9B depict graphs of the resistive force, F, versus the velocity of the damping fluid through the described steering damper systems under different valve configurations, according to some embodiments of the described steering damper systems. As noted above, the ideal damper behaviour follows the equation F - -cv in which the damping coefficient, c, corresponds to the slope of a plot of a force-velocity graph. Line 144 depicts the forcevelocity curve typically produced when the main valve 114 is open, the force valve 128 is in a restricted flow configuration (having a first fluid orifice size) and the blow-off valve 130 is in the closed position. While in this configuration, the resistive damping force is relatively low as the velocity increases, which corresponds to a relatively low damping co-efficient, Cl. Line 148 depicts a valve configuration in which the main valve 114 is closed (i.e., shuttle 122 is in one of a first closed position and a second closed position), force valve 128 maintains the restricted flow configuration and the blow-off valve 130 remains closed (i.e., damping fluid flows through force valve 128 only). In this configuration, the resistive damping force is significantly higher than the previous scenario such that reaching the same velocity of piston 110 requires a greater external force being applied to the steering system 1 (e.g., a greater impact force applied to the vehicle during a collision). Line 146 depicts a valve configuration in which main valve 114 remainsclosed, force valve 128 maintains the restricted flow configuration and blow-off valve 130 is open (such as when the steering system 1 undergoes a high impact resulting in sufficient fluid pressure to open blow-off valve 130, such as at a blow-off valve force threshold denoted by line 150 which corresponds to a blow-off threshold pressure). In this third scenario, since the effective fluid orifice is the sum of the first fluid orifice of the force valve 128 and the fluid orifice provided by the open blow-off valve 130, the resulting damping co-efficient. C3, is lower than C2 but greater than Cl. The resulting resistive damping force is higher than provided under the first scenario but lower than that under the second scenario. In this configuration, reaching the same velocity of piston 110 as under the first scenario requires a greater external force being applied to the steering system 1, but less than that required under the second scenario.

[0064] FIG. 9B depicts damping curve 152 of the described steering damper systems as it transitions through each valve configuration of the three above-described scenarios. When the velocity of the damping fluid from the steering jack 104 is below the first predetermined threshold velocity, VI, the resistive damping force and the corresponding first damping coefficient, Cl. are relatively low. As a result, until the first predetermined threshold velocity, VI, is reached the force required to move piston 110 and, similarly, resistance to acceleration of the vehicle steering actuator 5 is relatively low. When the velocity of the damping fluid from the steering jack 104 reaches or exceeds the first predetermined threshold velocity, VI, such as during a collision, the resistive damping force and the damping co-efficient, C2, increases. As a result, the force required to move piston 110 and, similarly, to resist acceleration of the vehicle steering actuator 5 is significantly increased. When the damping fluid reaches or exceeds the second predetermined velocity, V2, and the blow-off valve force threshold 150 is reached (such as during a collision resulting in sufficient fluid pressure to open blow-off valve 130) the resistive damping force and the corresponding damping co-efficient, C3, decreases (but is still higher than Cl). As a result, the force required to move piston 110 and, similarly, to resist acceleration of the vehicle steering actuator 5 decreases (in comparison to the situation in which the velocity is between VI and V2), but to a level that is still higher than under the first scenario (when the damping fluid velocity is below VI).

[0065] As discussed above, according to some embodiments, the fluid orifice of the force valve 128 may be adjustable (the flow of damping fluid through the force valve 128 is adjustable). FIG. 10A depicts the effect of adjusting the fluid orifice of the force valve 128 (such as by adjusting the size of orifice 136). Curve A represents the damping effects of the force valve 128 having an initial fluid orifice size, resulting in a damping co-efficient of C2-A until the blowoff force threshold 150 is reached (at which time the damping co-efficient lowers to C3-A). Curve B depicts an increase in the fluid orifice of force valve 128, increasing the flowrate of damping fluid therethrough and decreasing the corresponding damping co-efficient to C2-B until the blowoff force threshold 150 is reached and the damping co-efficient lowers to C3-B. A further increase in the fluid orifice of force valve 128 results in a decrease in damping co-efficient to C2-C (until the blow-off force threshold 150 is reached and the damping co-efficient lowers to C3-C). In other words, the damping co-efficient decreases as the fluid orifice of the force valve 128 is increased resulting in C2-A>C2-B>C2-C. It is also understood that changes to the fluid flow through the force valve 128 also affect fluid flow through the main valve 114. For example, according to some embodiments, as the fluid orifice of force valve 128 increases, the damping fluid velocity required to move shuttle 122 to a closed position (either of a first closed position in which shuttle 122 closes opening 120A and a second closed position in which shuttle 122 closes opening 120B) is increased (VA<VB<VC) and vice versa.

[0066] As discussed above, according to some embodiments, the damping characteristics may be adjusted by changing the blow-off valve force threshold 150. In particular, by changing the preload applied to blow-off energy storage member 140 (such as by changing the axial position of pre-load sleeve 142), the blow-off valve force threshold 150 may be increased or decreased. Turning to FIG. 10B and starting with a value depicted by line 150 A, the blow-off valve force threshold may be increased to 150B or even further to 150C by increasing the amount of preload applied by blow-off energy storage member 140 (and therefore requiring a greater fluid pressure to open blow-off orifice 143). Since the actual size of blow-off orifice 143 is not being changed, the corresponding damping co-efficients, C3-B and C3-C, are equal to C3-A.

[0067] FIGS. HA and 11B depict force-velocity plots of the force valve 128 (FIG.11 A) and blow-off valve 130 (FIG. 1 IB). Zone A depicts the operation of steering damping system100 under normal driving conditions (minimum damping), according to some embodiments. Zone B depicts the operation of steering damping system 100 at collision speeds. In the depicted embodiment, the first predetermined threshold velocity, VI, is about 195 mm / s. By adjusting the size of the fluid orifice provided by force valve 128, the damping co-efficient when the damping fluid velocity reaches the first predetermined threshold velocity, VI, is also adjusted. For example, decreasing the size of the fluid orifice provided by force valve 128 increases the damping level and the resistive force applied to piston 110 of steering jack 104 to counter acceleration of piston 110 and, in turn, to resist acceleration of the vehicle steering actuator 5. By adjusting the preload provided by blow-off energy storage member 140, the blow-off valve force threshold can be adjusted. For example, as shown in FIG. 11B, increasing the blow-off energy storage member preload results in increasing the force required to open blow-off valve 130.

[0068] According to some embodiments, steering damper system 100 is provided with a gas chamber 154 operatively coupled to damping valve assembly 106 (FIG. 12). Gas chamber 154 is configured to help compensate for thermal expansion of the damping fluid and to help prevent cavitation. According to some embodiments, gas chamber 154 comprises gas pressure chamber 156, separator piston 158 and damping fluid circuit chamber 160. According to some embodiments, gas chamber 154 is configured to maintain a low residual gas pressure to assist in the operation of steering damper system 100 and to optimize the level of friction. According to some embodiments, a pressure of gas contained within gas chamber 154 (such as within gas pressure chamber 156) is at least about 5 bars. Any suitable pressurized gas is contemplated. For example, according to some embodiments, the pressurized gas is nitrogen.

[0069] The described steering damper system 100 may comprise additional devices to fine tune the damping response. For example, according to some embodiments, steering damper system 100 comprises at least one check valve in fluid communication with one or more of steering jack 104, main valve 114, force valve 128 and blow-off valve 130, such as check valves 162 (FIGS.8A to 8C).

[0070] Attention is directed to FIGS. 13A to 13C, which depicts an exemplary, nonlimiting method 200 of damping a steering velocity of a vehicle steering actuator. In order to assist in the explanation of method 200, it will be assumed that method 200 is performed using thedescribed steering system 1, steering damper system 100 and components thereof. Furthermore, the following discussion of method 200 will lead to a further understanding of steering damper system 100 depicted in FIGS. 1 to 12 and the various components as described herein. However, it is understood that method 200 can be varied, and need not work exactly as discussed herein, and that such variations are within the scope of the present application. It is also emphasized, however, that method 200 need not be performed in the exact sequence as shown, unless otherwise indicated; and likewise various blocks may be performed in parallel rather than in sequence. Hence, the elements of method 200 are referred to herein as “blocks” rather than “steps”.

[0071] At block 202, damping fluid is provided from a steering jack to a main valve (such as from steering jack 104 to main valve 114) (FIG. 13A). When a velocity, V, of the damping fluid from the steering jack is below a first predetermined threshold, VI, the main valve is maintained in a neutral, open position, enabling damping fluid flow therethrough (block 204) and a portion of the damping fluid is provided to a force valve (such as force valve 128)(block 206). For example, shuttle 122 of main valve 114 may be located such that it does not occupy either of the first closed position or the second closed position.

[0072] At block 208, the damping fluid from the main valve and the portion of the damping fluid from the force valve is returned to the steering jack at a first damping level (corresponding to a first damping co-efficient, Cl). As a result, a first resistive force, Fl, is generated to counter movement of a piston of a steering jack (such as piston 110 of steering jack 104) and, in turn, to resist acceleration of the vehicle steering actuator (such as steering wheel 5).

[0073] At block 210, when the velocity, V, of the damping fluid is at or above the first predetermined threshold value, VI (V>V1 but less than V2), the main valve is set to a main valve closed position which restricts fluid flow therethrough (for example, shuttle 122 of main valve 114 is either in the first closed position or the second closed position).

[0074] At block 212, damping fluid from the steering jack is provided to the force valve without flowing through the main valve (since the main valve is closed).

[0075] At block 214, damping fluid from the force valve is returned to the steering jack and a second damping level (corresponding to a second damping co-efficient C2) higher than the first damping level is provided along with a second resistive force, F2, greater than the firstresistive force, Fl, to counter movement of the piston of the steering jack (such as piston 110 of steering jack 104) and, resist acceleration of the vehicle steering actuator (such as steering wheel 5).

[0076] According to some embodiments, when the velocity, V, of the damping fluid from the steering jack reaches or exceeds a second predetermined threshold velocity, V2, greater than the first predetermined threshold velocity, VI, the main valve is set to the main valve closed position and a blow-off valve is opened (such as blow-off valve 130) (block 216). As discussed above, damping fluid is then enabled to flow through both the force valve and blow-off valve (block 218), thereby providing a third damping level (corresponding to a third damping coefficient C3) between the first damping level and the second damping level (such that C2>C3>C1) (block 220). As a result, a third resistive force, F3, between the first and second resistive forces is provided to the piston of the steering jack (such as to piston 110 of steering jack 104) to resist acceleration of the vehicle steering actuator (such as steering wheel 5). According to some embodiments, the second predetermined threshold velocity, V2, corresponds to a predetermined damping fluid pressure.

[0077] It will also be understood that for the purposes of this application, "at least one of X, Y, and Z" or "one or more of X, Y, and Z" language can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ, XX, XY).

[0078] In the present application, components may be described as being "configured to" or "enabled to" perform one or more functions. Generally, it is understood that a component that is configured to or enabled to perform a function is configured to or enabled to perform the function, or is suitable for performing the function, or is adapted to perform the function, or is operable to perform the function, or is otherwise capable of performing the function.

[0079] Additionally, components in the present application may be described as being "operatively connected to", "operatively coupled to", and the like, to other components. It is understood that such components are connected or coupled to each other in a manner to perform a certain function. It is also understood that "connections", "coupling" and the like, as recited in the present application include direct and indirect connections between components.

[0080] References in the application to "one embodiment", "an embodiment", "an implementation", "a variant", etc., indicate that the embodiment, implementation or variant described may include a particular aspect, feature, structure, or characteristic, but not every embodiment, implementation or variant necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.

[0081] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as "solely", "only", and the like, in connection with the recitation of claim elements or use of a "negative" limitation. The terms "preferably", "preferred", "prefer", "optionally", "may", and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[0082] The singular forms "a", "an", and "the" include the plural reference unless the context clearly dictates otherwise. The term "and / or" means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase "one or more" is readily understood by one of skill in the art, particularly when read in context of its usage.

[0083] The term "about" can refer to a variation of± 5%, + 10%, ± 20%, or+ 25% of the value specified. For example, "about 50" percent can in some embodiments cany a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and / or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[0084] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges recited herein also encompassany and all possible sub-ranges and combinations of sub-ranges thereof, as well as the individual values making up the range, particularly integer values. A recited range includes each specific value, integer, decimal, or identity within the range. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc.

[0085] As will also be understood by one skilled in the art, all language such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

[0086] Persons skilled in the art will appreciate that there are yet more alternative implementations and modifications possible, and that the above examples are only illustrations of one or more implementations. The scope, therefore, is only to be limited by the claims appended hereto.

Claims

CLAIMSWhat is claimed is:

1. A steering damper system comprising:a steering jack configured to operatively couple to a vehicle steering actuator, the steering jack having a piston;a damping valve assembly fluidly coupled to the steering jack, comprising:a main valve having a valve body, a valve bore in said valve body, at least two port openings in the valve body and a shuttle moveably disposed within the valve bore, wherein the shuttle is moveable between at least three positions comprisinga neutral, open position in which the at least two port openings are in fluid communication with the steering jack,a first closed position in which the shuttle moves to restrict fluid flow through one of the at least two port openings, anda second closed position in which the shuttle moves to restrict fluid flow through another of the at least two port openings;at least one energy storage member operatively coupled to the shuttle and biased to maintain the shuttle in the neutral, open position while a velocity of damping fluid from the steering jack is below a first predetermined threshold velocity:a force valve in fluid communication with the steering jack and the at least two port openings; anda blow-off valve in fluid communication with the steering jack and at least one of the at least two port openings;wherein:when the velocity of the damping fluid from the steering jack is below the first predetermined threshold velocity, the shuttle is in the neutral, open position and damping fluid is enabled to flow through both the main valve and the force valve before returning to the steering jack, thereby providing a first damping level and a first resistive force to movement of the piston and, in turn, to acceleration of the vehicle steering actuator;when the velocity of the damping fluid from the steering jack reaches or exceeds the first predetermined threshold velocity, the shuttle moves to one of the first closed position and the second closed position, and the damping fluid flows through the force valve, without flowing through the main valve, before returning to the steering jack, providing a second damping level greater than the first damping level and a second resistive force greater than the first resistive force being applied to the piston of the steering jack to counter acceleration of the vehicle steering actuator; andthe steering jack and the damping valve assembly are configured to fluidly couple to a damping fluid reservoir.

2. The steering damper system of claim 1, wherein when the velocity of the damping fluid from the steering jack reaches or exceeds a second predetermined threshold velocity greater than the first predetermined threshold velocity, the damping fluid is enabled to flow through both the force valve and the blow-off valve without flowing through the main valve, providing a third damping level between the first and second damping levels and a third resistive force between the first and second resistive forces to the piston of the steering jack to counter acceleration of the vehicle steering actuator.

3. The steering damper system of either claim 1 or claim 2, wherein the first resistive force is about 40 N.

4. The steering damper system according to any one of claims 1 to 3, wherein the force valve comprises a bleed orifice which is in fluid communication with the main valve when the shuttle is in each of the neutral, open position, the first closed position and the second closed position.

5. The steering damper system according to any one of claims 1 to 4, wherein the force valve comprises a needle valve.

6. The steering damper system according to any one of claims 1 to 5, wherein the force valve is configured such that flow of the damping fluid therethrough is adjustable.

7. The steering damper system according to any one of claims 1 to 6, wherein the at least one energy storage member comprises one or more of a coil spring and an elastomeric member.

8. The steering damper system of claim 7, wherein the coil spring is a conical spring.

9. The steering damper system according to any one of claims 1 to 8, wherein the at least one energy storage member comprises two energy storage members coupled to opposing ends of the shuttle.

10. The steering damper system according to any one of claims 1 to 9, wherein the at least one energy storage member is pre-loaded.

11. The steering damper system according to any one of claims 1 to 10, further comprising at least one check valve in fluid communication with one or more of the steering jack, the main valve, the force valve and the blow-off valve.

12. The steering damper system according to any one of claims 1 to 11, wherein the blow-off valve is pre-loaded to a closed position.

13. The steering damper system of claim 12, wherein the blow-off valve comprises a blow-off energy storage member configured to provide the pre-loading.

14. The steering damper system of claim 13, wherein the blow-off energy storage member comprises one or more of a spring and an elastomeric member.

15. The steering damper system according to any one of claims 12 to 14, wherein the pre- loading of the blow-off valve is adjustable.

16. The steering damper system according to claim 15, wherein the blow-off energy storage member is housed in a pre-load sleeve configured to apply the pre-load to the blow-off energy storage member.

17. The steering damper system according to any one of claims 1 to 16, further comprising a gas chamber operatively coupled to the damping valve assembly and wherein a pressure of gas contained therein is at least about 5 bars.

18. The steering damper system according to any one of claims 1 to 17, wherein the damping fluid is a hydraulic fluid.

19. The steering damper system according to any one of claims 1 to 18, wherein the vehicle steering actuator comprises a steering wheel.

20. A method of damping a steering velocity of a vehicle steering actuator comprising:providing a damping fluid from a steering jack to a main valve;when a velocity of the damping fluid from the steering jack is below a first predetermined threshold velocity,maintaining the main valve in a neutral, open position, enabling the damping fluid to flow therethrough,providing a portion of the damping fluid to a force valve, and returning the damping fluid from the main valve and the portion of the damping fluid from the force valve to the steering jack at a first damping level, thereby providing a first resistive force to counter movement of a piston of the steering jack and, in turn, to resist acceleration of the vehicle steering actuator; and when the velocity of the damping fluid is at or above the first predetermined threshold velocity,setting the main valve to a main valve closed position, restricting fluid flow therethrough,providing the damping fluid from the steering jack to the force valve, without flowing through the main valve, andreturning the damping fluid from the force valve to the steering jack, providing a second damping level higher than the first damping level and a second resistive force greater than the first resistive force to counter movement of the piston of the steering jack and resist acceleration of the vehicle steering actuator.

21. The method of claim 20, wherein when the velocity of the damping fluid from the steering jack reaches or exceeds a second predetermined threshold velocity greater than the first predetermined threshold velocity, the main valve is set to the main valve closed position, a blow-off valve is opened and damping fluid is enabled to flow through both the force valve and the blow-off valve, thereby providing a third damping level between the first and second damping levels and a third resistive force between the first and second resistive forces to the piston of the steering jack to resist acceleration of the vehicle steering actuator.

22. The method of claim 21 , wherein the second predetermined threshold velocity corresponds to a predetermined damping fluid pressure.

23. The method according to any one of claims 20 to 22 further comprising pre-loading a blowoff energy storage member to a closed position.

24. The method of claim 23, wherein the blow-off energy storage member comprises one or more of a spring and an elastomeric member.

25. The method of either claim 23 or claim 24, wherein the pre-loading of the blow-off energy storage member is adjustable.

26. The method according to any one of claims 20 to 25, wherein a pressure of gas contained in a gas chamber operatively coupled to at least the main valve, the force valve and the blow-off valve is at least about 5 bars.

27. The method according to any one of claims 20 to 26 further comprising: adjusting an effective size of a valve orifice of the force valve to alter a flow rate of the damping fluid therethrough.

28. The method according to any one of claims 20 to 27, wherein the damping fluid is a hydraulic fluid.

29. The method according to any one of claims 20 to 28 further comprising: adjusting the first predetermined threshold velocity of the damping fluid from the steering jack by performing one or more of: altering a spring constant of a main valve energy storage member; and altering a pre-load of the main valve energy storage member.

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