FIELD OF THE INVENTION

The present invention relates generally to the field of shock absorbers and in one form relates to a movable trigger that is acted upon by inertia to close or at least reduce a hydraulic fluid pathway in the shock absorber assembly, during vehicle rolling and pitching.

BACKGROUND OF THE INVENTION

A road vehicle's suspension comprises a number of elements that cooperate to assist in maintaining vehicle control and provided comfort for the driver and passengers. One the fundamental elements of a vehicle's suspension is the shock absorber that functions to stop spring oscillations thereby improving grip, control, stability and comfort. Conventional hydraulic shock absorbers typically comprise a compression chamber and a rebound chamber separated by a piston, wherein the flow of hydraulic fluid between the compression chamber and rebound chamber through valves dampens the motion of the springs.

Various modifications have been made to shock absorbers to improve handling during braking, accelerating, pitching and during cornering (rolling). For instance, a sport vehicle's suspension may be stiffened to reduce body roll during heavy cornering and to maintain contact patch between a tyre and a road surface. Various mechanical devices have been proposed to vary the damping rate of shock absorbers (to improve the vehicle handing control) during rolling and pitching, including variable antiroll bars, extra hydraulic actuators and complex linkages to counteract unbalancing reactions, which may include relatively fragile components.

Throughout the specification, the term "inertia" is to be given its usual definition, wherein an object in generally horizontal motion (longitudinal and lateral) will continue in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

It should be appreciated that any discussion of the prior art throughout the specification is included solely for the purpose of providing a context for the present invention and should in no way be considered as an admission that such prior art was widely known or formed part of the common general knowledge in the field as it existed before the priority date of the application. SUMMARY OF THE INVENTION

It could be broadly understood that the present invention relates generally to a stiffening apparatus for a shock absorber assembly including, a movable inertia trigger positioned in, or along, a hydraulic fluid pathway, wherein the inertia trigger is configured to control the movement of a hydraulic fluid through said hydraulic fluid pathway to thereby adjust the stiffness of said shock absorber assembly to minimize rolling and pitching.

In one aspect of the invention, but not necessarily the broadest or only aspect, there is proposed a shock absorber assembly for a wheeled vehicle including,

a shock absorber body for attachment to a first part of a vehicle, the shock absorber body having an internal cavity, a piston connected to a first end of a piston rod wherein the piston is slidably held within said internal cavity and configured to separate a compression chamber from a rebound chamber, a second end of the piston rod extending outwardly of said shock absorber body for attachment to a second part of said vehicle,

a compression flow path for movement of a hydraulic fluid between said compression chamber and said rebound chamber during a compression phase,

a rebound flow path for movement of said hydraulic fluid between said rebound chamber and said compression chamber during a rebound phase, and

a movable inertia trigger positioned in, or along, said compression and/or rebound pathways, wherein the inertia trigger is configured to be acted upon by inertia during movement of said wheeled vehicle to close or at least reduce said compression and/or rebound flow pathways to thereby adjust the stiffness or operation of said shock absorber assembly.

Preferably the inertia trigger of the shock absorber assembly thereby controls the operation of the suspension system of the wheeled vehicle.

The shock absorber assembly controls the compression and/or rebound movement of the vehicle's springs and suspension to thereby assist in maintaining contact between the wheeled vehicle's tyres and a road surface.

The inertia trigger assists in inhibiting the tyre from losing contact with the road surface during severe movement or during emergency situations thereby improving traction such as during pitching, acceleration and braking. The stiffening of the action of the shock absorber during rapid acceleration and heavy braking means that when the tyre comes into contact with a pot hole or protrusion on the road surface the tyre will be out of contact with the road surface for a minimal amount of time.

Furthermore, the stiffening of the suspension during cornering may improve handling of the vehicle and reduces the chance of the vehicle becoming unstable during severe cornering events and may eliminate the need for complex variable anti- roll bars and extra actuators.

The inertia trigger may be used in conjunction with a twin tube shock absorber assembly or a single tube shock absorber assembly. The inertia trigger may be contained within the body or housing of the shock absorber, or may be contained within a separate housing and connected to the shock absorber assembly by way of appropriate conduits.

The shock absorber body may have a lower mounting for attachment to a sprung element of the vehicle, and the piston rod having an upper mounting for connection to the wheeled vehicle's chassis. The piston rod preferably engages through a rod guide having a seal and rod wiper housing having a wiper. The upper end of the shock absorber assembly preferably includes a nut, rod guide outer housing and O-rings.

The piston which separates the compression chamber from the rebound chamber are connected by a rebound flow path and a compression flow path, which are defined by respective passageways. These passageways preferably each include an adjustable valve assembly and a non-return or one-way valve assembly. The adjustable valve assembly preferably comprises a high speed valve assembly and slow speed valve assembly. The use of a high speed valve assembly and a slow speed valve assembly allows the system to compensate for the force at different piston speeds to thereby enhance fluid flow dynamics.

The fluid may be permitted to pass through the slow speed valve assembly to inhibit cavitations in the fluid. A non-return valve may also be used to balance the pressure and fluid volume.

Preferably the shock absorber body includes a reserve chamber connected to the compression chamber. In one form the reserve chamber includes a nitrogen filled portion, wherein the nitrogen replaces the air to inhibit the formation of cavitations that may affect the operation of the shock absorber. A secondary nitrogen chamber may also be connected to the rebound chamber.

A hydraulic flow directional block is preferably positioned within the shock absorber body. The hydraulic flow directional block may be generally annular shape and may be held in position within the shock absorber body by a retaining sleeve. In one form the hydraulic flow directional block includes a compression common passage connected to a plurality of compression ducts, and a rebound common passage connected to a plurality of rebound ducts.

An annular chamber may be formed between the rod guide outer housing, rod guide, hydraulic flow directional block and an outer surface of the piston rod, wherein the generally annular inertia trigger is held within the annular chamber. In use the movable inertia trigger is able to move perpendicular to the longitudinal axis of the piston rod to close or restrict the rebound flow path or compression flow path to thereby control the movement of the hydraulic fluid which acts to stiffen the operation of the shock absorber.

When the inertia trigger is at rest the ducts of the hydraulic flow directional block coaxially align ducts in the inertia trigger. It should be appreciated that the hydraulic flow directional block and inertia trigger may include multiple coaxially aligned ducts. The ducts may have a diameter of between 1 mm and 2 mm and are preferably 1.5 mm.

A plurality of horizontal biasing members are spaced apart circumferentially around the inertia trigger to hold it in position within the annular chamber. The horizontal biasing members are configured to inhibit lateral movement relative to the shock absorber body unless the momentum of the inertia trigger exceeds a predetermined threshold due to rapid movement of the shock absorber body due to braking, accelerating or cornering.

In one form the horizontal biasing members have different degrees of bias when the inertial trigger is to be offset from horizontal, such as is the case when the shock absorber assembly is attached to a car. The horizontal biasing members each include a base, with a protrusion extending outwardly therefrom, wherein the base being biased by a spring such that the protrusion abuts against a side of the annular chamber. The base and spring may be held within a horizontal or generally horizontal recess having an inwardly projecting lip. The spring may have total resultant lateral force of between 0.3g and 4g, however the reader will appreciate that this will be dependent upon the particular application and may therefore vary.

The inertia trigger preferably includes a plurality of vertical biasing members in, or on a top thereof that are configured to bear against a hardened face on the rod guide. These vertical biasing members force an underside sliding face of the inertia trigger against an upper sliding face of the hydraulic flow directional block. When a vertical force exceeds a predetermined threshold, the inertial trigger moves upwardly against the force of the vertical biasing members to separate the inertial trigger from the hydraulic flow directional block inertia trigger, which thereby allows the hydraulic fluid to bypass the inertia trigger for a period of time, such as a fraction of a second. This reduces the severity of the impact during heavy braking, rapid accelerating or during heavy cornering.

The clearance between the underside sliding face of the inertia trigger and the upper sliding face of the hydraulic flow directional block may be between 0.01 mm and 0.03 mm and is preferably 0.025 mm. The reader should appreciate that the inertia trigger may slide along a generally horizontal plane or alternatively it may slide along a plane that is at a slight angle to horizontal.

The vertical biasing members may each include a ball bearing biased against said hardened face of the rod guide by a spring, wherein the spring and ball bearing are at least partially located within a vertical recess in a top of the inertia trigger.

In another form the shock absorber assembly does not include a vertical biasing members.

Alignment pins or dowels may be used to inhibit rotation or misalignment of the inertia trigger within the annular chamber.

The one-way valve may comprise a ball that is biased by a spring against a resting face. Alternatively, a diaphragm valve or other type of valve assembly could be used.

In another aspect of the invention the rebound adjustable valve may comprise an adjustable rebound high speed multipart valve assembly and an adjustable rebound slow speed valve assembly. The rebound adjustable valve of the rebound pathway may comprise a generally cylindrical valve body that threadably engages an open end of a passageway. An upper end of the valve body is spaced apart from an inner wall of the passageway to enable the fluid to flow therebetween. A circumferential sidewardly open chamber is positioned adjacent an outlet to assist in movement of the fluid into the compression chamber. An O-ring is positioned below the chamber to inhibit leakage of the fluid out from within the shock absorber.

The adjustable rebound high speed multipart valve may comprise a plurality of valve blocks having respective central bores that are held between the valve body and an adaptor sleeve. The respective bores of the valve blocks preferably coaxially align. The valve blocks are spaced apart from an inner wall of the rebound passageway and gaps or channels are formed between adjustable valve blocks to enable the fluid to flow therebetween. The high speed multipart valve assembly may be held in place by a lock nut. The adjustable rebound slow speed valve assembly comprises an elongate body that threadably engages the cylindrical valve body. An O-ring inhibits leakage of the fluid out from within the shock absorber. The elongate body includes a tapered end that is configured to engage through an opening in the upper end of the valve body. In this way a high speed multipart valve and a needle valve are formed in the same adjustable valve assembly. Therefore, the flow rate during rapid operation of the shock absorber and slow operation of the shock absorber can be adjustably controlled. This is important because the behaviour of hydraulic fluid at slow speeds is different to its behaviour at high speeds. Therefore, having two adjustable valves, one for slow speeds and the other for high speeds has a significant advantage in overcoming the issues that arise with this variation. It should however be

appreciated that a single valve or other valve configurations, such as diaphragm valves, could be used.

The compression adjustable valve may also comprise an adjustable compression high speed multipart valve assembly and an adjustable compression slow speed valve assembly.

The compression adjustable valve preferably comprises a generally cylindrical valve body that threadably engages an open end of a passageway and is held in place by a locking nut. O-rings may be positioned to inhibit leakage of the fluid out from within the shock absorber. Ports connect a circumferential sidewardly open chamber with an inside of the cylindrical valve body.

The adjustable compression high speed multipart valve may comprise a plurality of valve blocks having respective central bores, which are held between the valve body and an adaptor sleeve having a bifurcated bore and an opening. In use said central bores and said opening generally coaxially align. An elongate body of the adjustable compression high speed multipart valve engages through the coaxially aligned central bores and a tapered end of said elongate body engages said opening of the adaptor sleeve to thereby form the compression slow speed valve assembly to thereby adjustably control the flow of the fluid therethrough. The elongate body threadably engages the cylindrical valve body and an O-ring inhibits leakage of the fluid out from within the shock absorber.

The shock absorber stiffening apparatus/anti-rolling mechanism may be contained within a separate housing, having a mounting bracket and connected to the shock absorber body by way of appropriate conduits. In this way the inertia trigger may be positioned in a generally horizontal position even when the shock absorber body is positioned at an angle to the vertical.

Distance between the circumferential side of inertia trigger and side of the chamber may be between 1 -3 mm and preferably is 2 mm. Horizontal and vertical biasing members may be adjusted or configured prior to assembly such that they have varying degrees of bias. This can be done where the inertia trigger will be offset from the horizontal. Alternatively, the chamber that holds the inertia trigger can be offset from the horizontal.

The inertia trigger can be of varying sizes or configurations to be suitable for a range of vehicle types or sizes.

In another aspect of the invention there is proposed a method of selectively stiffening a shock absorber for a moving vehicle including the steps of:

providing a shock absorber assembly including, a shock absorber body, a piston, a compression chamber, a rebound chamber, a compression flow path for movement of a hydraulic fluid between said compression chamber and said rebound chamber during a compression phase, a rebound flow path for movement of a hydraulic fluid between said rebound chamber and said compression chamber during a rebound phase, and a movable inertia trigger positioned along said compression and/or rebound pathways;

attaching said shock absorber assembly to said vehicle; and

causing an unbalanced force to be applied to the inertia trigger such that said inertia trigger moves to close or at least reduce said compression and/or rebound flow pathways to thereby adjust the stiffness or operation of said shock absorber assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the invention and, together with the description and claims, serve to explain the advantages and principles of the invention. In the drawings,

Figure 1 is side cross sectional view of the shock absorber illustrating the

inertia trigger of the present invention;

Figure 2 is side cross sectional view of the shock absorber of Figure 1 with enlarged portion, illustrating the compression flow path;

Figure 3 is side cross sectional view of the shock absorber of Figure 1 with enlarged portion, illustrating the rebound flow path;

Figure 4 is a flow chart showing the compression and rebound flow paths;

Figure 5a is a perspective view of the inertia trigger of Figure 1 without biasing members attached;

Figure 5b is an underside view of the inertia trigger of Figure 5a;

Figure 5c is a top view of the inertia trigger of Figure 5a;

Figure 5d is a side view of the inertia trigger of Figure 5a;

Figure 6a is a perspective view of the inertia trigger of Figure 5a with biasing members attached;

Figure 6b is a side view of the inertia trigger of Figure 6a;

Figure 6c is a cross sectional view of the inertia trigger of Figure 6a through A-A, hydraulic flow directional block and retaining sleeve, illustrating movement of fluid during the rebound phase;

Figure 7a is an underside view of the hydraulic flow directional block; Figure 7b is an underside perspective view of the hydraulic flow directional block of Figure 7a;

Figure 7c is a top perspective view of the hydraulic flow directional block of

Figure 7a;

Figure 7d is a top view of the hydraulic flow directional block of Figure 7a;

Figure 7e is a cross sectional view of the hydraulic flow directional block of

Figure 7d through B-B.

Figure 8 is a partial cross sectional view of the compression flow path of Figure

2;

Figure 9a is a partial cross sectional view of the compression flow path of

another embodiment, illustrating a horizontal biasing member in the form of a rubber ring and a positioning dowel;

Figure 9b is a top view of the rubber ring of Figure 9a;

Figure 10 is a partial cross sectional view of the rebound flow path of Figure 3; Figure 1 1 a is a partial cross sectional view of the rebound flow path of Figure 3, illustrating the inertia trigger in a first position at rest;

Figure 1 1 b is a partial cross sectional view of the rebound flow path of Figure 1 1 a, illustrating the inertia trigger in a second position, wherein it is restricting the rebound flow path;

Figure 1 1 c is a partial cross sectional view of the rebound flow path of Figure 1 1 b, illustrating the inertia trigger in a third position, wherein the rebound flow path is closed;

Figure 12a is a partial cross sectional view of the shock absorber of Figure 1

illustrating the inertia trigger having moved in a first direction;

Figure 12b is a partial cross sectional view of the shock absorber of Figure 1

illustrating the inertia trigger having moved in a second direction;

Figure 13 is a partial cross sectional view of the shock absorber of Figure 2

illustrating the inertia trigger blocking the compression flow path;

Figure 14 is a partial cross sectional view of the shock absorber of Figure 2

illustrating the vertical movement of the inertia trigger thereby allow the fluid to bypass the inertia trigger; Figure 15 is a partial cross sectional view of the shock absorber of Figure 3 illustrating the movement of fluid through the high speed and slow speed valve assemblies;

Figure 16 is a partial cross sectional view of the shock absorber of Figure 15 further illustrating the movement of fluid through the high speed and slow speed valve assemblies;

Figure 17 is a partial cross sectional view of the shock absorber of Figure 2 illustrating the movement of fluid through the high speed and slow speed valve assemblies;

Figure 18 is a partial cross sectional view of the shock absorber of Figure 17 further illustrating the movement of fluid through the high speed and slow speed valve assemblies; and

Figure 19 is a schematic view of another embodiment of the shock absorber illustrating the inertia trigger positioned within a separate housing. DETAILED DESCRIPTION OF THE ILLUSTRATED AND EXEMPLIFIED EMBODIMENTS

Similar reference characters indicate corresponding parts throughout the drawings. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration. Referring to the drawings for a more detailed description, a shock absorber stiffening apparatus 10 is illustrated, demonstrating by way of examples, arrangements in which the principles of the present invention may be employed. It will be obvious to the person skilled in the art that the shock absorber stiffening apparatus 10 can be used on a shock absorber assembly of a land vehicle wherein the shock absorber assembly helps to control the impact and rebound movement of the vehicle's springs and suspension to thereby improve contact between the vehicle's tyres and the road surface, as well as improving driver/passenger comfort.

As illustrated in Figure 1 , the shock absorber stiffening apparatus 10 is retained within a twin tube shock absorber assembly 12. However, the shock absorber stiffening apparatus 10 could be used in relation to other types of shock absorbers, i.e. a single tube system. The shock absorber assembly 12, illustrated in Figure 1 , comprises a body shock absorber 14 having an internal cavity 15, a lower mounting 16 for attachment to a sprung element of the vehicle (not shown), and a piston rod 18 having an upper mounting 20 for connection to a vehicle's chassis (not shown). The piston rod 18 engages through a rod guide 22 having a seal 24 and rod wiper housing 26 having a wiper 28. The upper end of the shock absorber assembly 12 further includes a nut 30, rod guide outer housing 32 and O-rings 34, 36.

The piston 38 attached to an end of the piston rod 18 separates the compression chamber 40 from the rebound chamber 42, which are in fluid communication by way of a rebound flow path, as illustrated in Figures 1 and 3, and a compression flow path as illustrated in Figure 2. The reader will appreciate that the internal cavity 15 is divided by the piston 38 into the compression chamber 40 and the rebound chamber 42, wherein the piston slidably engages the side of the internal cavity 15, as illustrated in the figures. As further illustrated in Figure 1 , the shock absorber body 14 includes a reserve chamber 48, which includes a nitrogen filled portion 50, as is well known in the art. The nitrogen replaces the air within the reserve chamber 48 to inhibit the formation of cavitation or foaming that may affect the operation of the shock absorber 12. The reserve chamber 48 is connected to the compression chamber 40 by way of port 52.

The rebound flow path extends through passageway 44, as illustrated in Figures 1 and 3, and the compression flow path extends through passageway 46, as illustrated in Figure 2. Both these passageways 44, 46 include an adjustable valve assembly 54 and a non-return or one-way valve assembly 56. Throughout the specification the adjustable valve and one-way valve assemblies of the rebound phase will be indicated by numbers 54r and 56r respectively, and the adjustable valve and one-way valve assemblies of the compression phase with be indicated by numbers 54c and 56c respectively. These assemblies will be discussed in detail subsequently. A generally annular shaped hydraulic flow directional block 58 is held in position within the upper end of the shock absorber assembly 12 by retaining sleeve 60. The block 58 includes a generally annular compression common passage 62 connected to vertical duct/s 64, and a generally annular rebound common passage 66 connected to vertical duct/s 68. An annular chamber 70 is formed between a lower surface of the rod guide housing 22 and an upper surface of the hydraulic flow directional block 58, wherein a generally annular inertia trigger 72 is held within the annular chamber 70. In use the movable inertia trigger 72 moves in an opposite direction when there is a rapid change in the horizontal movement of the shock absorber 12, such as during acceleration or deceleration, to thereby close or restrict the compression flow path and/or rebound flow path. This therefore restricts or stops the movement of the hydraulic fluid 74 for a short period of time to thereby stiffen the operation of the shock absorber 12. When the inertia trigger 72 is at rest the ducts 64 and 68 of block 58 coaxially align ducts 78 and 79 in the inertia trigger 72 that lead to annular passageway 80, which is in fluid communication with the rebound chamber 42. It should be appreciated that the block 58 includes multiple ducts 64, 68 that are evenly spaced around the block 58. Furthermore, the inertia trigger 72 includes multiple ducts 78, 79 that are evenly spaced around the inertia trigger 72 and are configured to coaxially align respective ducts 64, 68 when the inertia trigger 72 is at rest.

The cooperation of the ducts 64, 68 and 78, 79 will become clearer during discussion of the operation of the inertia trigger 72.

A plurality of horizontal biasing members 76 are shaped apart

circumferentially around the inertia trigger 72 to hold it in positioned within the annular chamber 70. In one embodiment eight horizontal biasing members 76 are evenly spaced apart around the inertia trigger 72. These horizontal biasing members 76 are configured to inhibit lateral movement relative to the shock absorber body 14 unless the momentum of the inertia trigger 72 exceeds a predetermined threshold due to rapid acceleration or deceleration of the shock absorber 12 due to braking, accelerating or cornering (centripetal acceleration). Furthermore, where the shock absorber body 14 is offset from the vertical, the horizontal biasing members 76 on one side, coinciding with the lower side of the inertia trigger 72, may be stronger to compensate for gravitational force. The inertia trigger 72 further includes a plurality of vertical biasing members

82 recessed into a top thereof. In one embodiment four vertical biasing members 82 are evenly spaced apart around the top of the annular inertia trigger 72. The vertical biasing members 82 bear against a hardened face 84 in the rod guide housing 22. The purpose of the vertical biasing members 82 is to maintain contact between an underside sliding face 86 of the inertia trigger 72 and an upper sliding face 88 of the block 58, as is illustrated and discussed with respect to Figure 8.

Figure 2 illustrates the shock absorber 12 during the normal compression phase wherein the piston rod 18 moves down in the direction of the solid arrow, thereby moving the piston 38 downwardly and reducing the size of the compression chamber 40. This forces the hydraulic fluid 74 contained within the compression chamber 40, out through outlet 90, as indicated by the broken arrows, and then through the adjustable valve 54c and passageway 46. The one-way valve 56c is then caused to open due to the pressure of the hydraulic fluid 74, which allows the hydraulic fluid 74 to pass into common passage 62 and duct/s 64, which aligned duct/s 78 in the inertia trigger 72. The hydraulic fluid 74 then continues through annular passageway 80 whereby the fluid 74 enters the rebound chamber 42, which is being enlarged as the piston 38 moves downwardly. The skilled addressee will appreciate that some hydraulic fluid will also enter the reserve chamber 48 through duct 52, however this will not be discussed in detail since it is common in the art.

As illustrated in Figure 3, during the normal rebound phase of the shock absorber 12 the piston rod 18 moves upwardly in the direction of the solid arrow, thereby moving the piston 38 and reducing the size of the rebound chamber 42. This forces the hydraulic fluid 74 up out of the rebound chamber 42, as indicated by the broken arrows, and through annular passageway 80 into duct/s 79 which align duct/s 68 in the hydraulic flow directional block 58. The hydraulic fluid 74 then passing into common passageway 66 which then caused the one-way valve 56r to open due to fluid pressure. The hydraulic fluid 74 then passes into passageway 44, through adjustable valve 54r and out of the outlet 92 into the compression chamber 40, which is being enlarged as the piston 38 moves upwardly. The skilled addressee will appreciate that some hydraulic fluid will also enter the compression chamber 40 from the reserve chamber 48 through duct 52, however this will not be discussed in detail, since it is common in the art.

Figure 4 illustrates a schematic of the flow of hydraulic fluid 74 during the compression/rebound cycles. As illustrated the shock absorber 12 comprising, the body 14, piston rod 18 attached to the piston 38 which separates the compression chamber 40 from the rebound chamber 42. The right-hand side of Figure 4 indicated by 'C shows the flow of hydraulic fluid 74 during the compression phase, wherein the hydraulic fluid 74 moves out of the compression chamber 40 through the adjustable valve 54c, which comprises a high speed valve assembly 94c and slow speed valve assembly 96c. Further explanation of the assemblies 94c, 96c will be provided with respect to Figures 15 to 18. The hydraulic fluid 74 then moves along passageway 46 and through one-way valve 56c and the inertia trigger 72 and into the rebound chamber 42. During the rebound phase as included by 'R' on the left-hand side of Figure 4 the hydraulic fluid 74 moves out of the rebound chamber 42 through the inertia trigger 72 and one-way valve 56r into the passageway 44. The fluid 74 then moves through adjustable valve 54r which comprises a high speed valve assembly 94r and slow speed valve assembly 96r and into the compression chamber 40. Figure 4 also illustrates the reserve chamber 48, which includes a nitrogen filled portion 50, as is known in the art, wherein hydraulic fluid is able to pass either way through port 52 depending upon the phase.

Figures 5a to 5d illustrate the inertia trigger 72 separated from the shock absorber 12, showing one embodiment of the configuration of recesses 1 16 and 126 for accommodating vertical biasing members 82 and horizontal biasing members 76 respectively. Figures 6a and 6b illustrate the inertia trigger 72 with biasing members 82 and 76 is place. Figure 6c illustrates a cross sectional view of the inertia trigger 72, block 58 and sleeve 60 illustrating the flow of fluid during the rebound phase. Figure 6c also illustrates the position of one of the alignment pins or dowels 98 that inhibit rotation or misalignment of the inertia trigger 72 within the annular chamber 70. Although not illustrated there may be four alignment pins 98 extending upwardly from the top of the block 58 or four alignment pins 98 may extend downwardly from an underside of the inertia trigger 72 and cooperate with correspondingly shaped recesses in the adjacent block 58 or inertia trigger 72. Figures 7a to 7e, illustrate the generally annular shaped hydraulic flow directional block 58 separated from the shock absorber 12, showing one embodiment of the compression common passage 62, ducts 64, rebound common passage 66, and ducts 68. Alignment pin recesses 100 are illustrated in the top of the block 58 for engagement by the alignment pins 98, as illustrated in Figure 9a. Furthermore, Figures 7a to 7e illustrate valve recesses 102 and 104 for accommodating portions of one-way valves 56c and 56r respectively.

Figure 8 illustrates the flow of hydraulic fluid 74 moving through the one-way valve 56c, ports 64 and 78, passageway 80 and into the rebound chamber 42 during the compression phase. The one-way valve 56c in the present embodiment comprises a ball 106 that is biased by spring 108 against resting face 1 10. This configuration allows flow in a single direction during the compression phase. The one-way valve 56r is of a similar configuration as illustrated in Figure 10, however the reader should appreciate that other types of one-way valves could be used without departing from the scope of the invention.

Turning back to Figure 8, there is illustrated one embodiment of the vertical biasing members 82 that each include a ball bearing 1 12 biased against hardened face 84 by spring 1 14, wherein the spring 1 14 and ball bearing 1 12 are at least partially located within vertical recess 1 16 in a top of the inertia trigger 72. The horizontal biasing members 76 each include a base 1 18, with a protrusion 120 extending outwardly therefrom, the base 1 18 being biased by spring 122 such that the protrusion 120 abuts against a side 124 of the annular chamber 70. The base 1 18 and spring 122 are held at least partially within a horizontal recess 126 having an inwardly projecting lip 128. Figure 9a illustrates the location of the alignment pin 98 that frictionally engage alignment pin recess 100 in the top of the block 58 and engage a recess 130 in an underside of the inertia trigger 72. As shown in the figure the alignment pin recess 100 is dimensioned to closely fit the alignment pin 98, whereas the recess 130 is dimensioned to allow a degree of horizontal movement of the inertia trigger 72 in a radial direction relative to the longitudinal axis of the shock absorber body 14.

As further illustrated in Figure 9a and 9b the horizontal biasing member 76 may be in the form of a resiliently deformable ring 300 which includes an inner annular surface 302 that is configured to bear against the inner surface 304 of a sidewardly open annular groove 306 in inertia trigger 72, and an outer circumferential edge 308 that is configured to bear against side 124 of the annular chamber 70. The outer circumferential edge 308 may include notches 310 spaces apart therearound to provide the desirable compression characteristics.

Figure 1 1 a to 1 1 c illustrate the movement of the inertia trigger 72 of the present when momentum causes the inertia trigger 72 to move to one side of the annular chamber 70 against the action of the biasing members 76 on one side of the inertia trigger 72.

Typically, the inertia trigger 72 is positioned central of the annular chamber 70 as illustrated in Figure 1 1 a wherein the port/s 79 coaxially port/s 68 (ports 78 and 64, also coaxially align although these are not illustrated in Figure 1 1 a). The hydraulic fluid 74 is therefore able to flow as indicated by the broken arrows, through the aligned ports 79, 68, during rebound phase (and similarly through ports 78, 64 during the compression phase). When an unbalanced force is applied in the direction of the solid arrow as illustrated in Figure 1 1 b the inertia trigger 72 moves to the right which slightly misaligns the ports 79 and 68 thereby reducing the flow, as indicated by the lighter broken arrow. As the unbalanced force continues to be applied in the direction of the solid arrow, as illustrated in Figure 1 1 c, the ports 79 and 68 are completely misaligned which terminates the flow of the fluid 74 therethrough, as indicated by the cross 132. The reader will appreciate that a similar process occurs with ports 78, 64 when an unbalanced force is applied.

Figures 12a and 12b illustrate the movement of the inertia trigger 72 when a force is applied in opposite directions. Figure 12a represents when a vehicle is travelling in the direction of the solid arrow and the brakes are applied heavily, the inertia trigger 72 continues in the direction of travel, wherein the biasing member 76a retracts within horizontal recess 126a. This thereby results in the misalignment of the ports 79 and 68 and ports 78 and 64. This therefore stiffens the action of the shock absorber until the biasing force of the biasing member 76a is greater than the momentum of the inertia trigger 72, at which time the inertia trigger 72 will return to a central or rest position, as illustrated in Figure 1 1 a. This stiffening of the shock absorber during braking assists in maintaining contact between the tyre and road surface thereby improving braking efficiency.

In the opposite situation, as illustrated in Figure 12b when the vehicle is undertaking rapid acceleration in the direction of the solid arrow, the inertia trigger 72 moves to the right wherein the biasing member 76b retracts within horizontal recess 126b. This lag in the movement of the biasing member 76b also results in the misalignment of the ports 79 and 68 and ports 78 and 64. Once the biasing force of the biasing member 76b is greater than the force resulting from acceleration of the vehicle, the inertia trigger 72 will return to a central or rest position, as illustrated in Figure 1 1 a, wherein the ports 78, 79 align with ports 64, 68. This stiffening of the shock absorber during rapid acceleration assists in maintaining contact between the tyre and road surface thus inhabiting wheel slip and improving traction.

The stiffening of the action of the shock absorber 12 during rapid acceleration and heavy braking means if the tyre comes into contact with a pot hole or protrusion on the road surface the tyre be out of contact with the road surface for a minimal amount of time. As the skilled addressee will appreciate, the same will occur during heavy cornering of the vehicle.

Figure 13 illustrates the movement of the hydraulic fluid 74 when the vehicle is undertaking heavy braking, as discussed with respect to Figure 12a. The hydraulic fluid 74 is inhibited from exiting ports 64 through ports 78 during compression of the shock absorber 12 because of the misalignment. Furthermore, the turbulence and pressurisation of the fluid in passageway 62 will eventually cause the spring 108 to close one-way valve 56c. The reader will appreciate that the fluid will also not be able to exist ports 79 through ports 68, as was discussed with respect to Figure 1 1 a to 1 1 c.

Figure 14 illustrates the situation when a vertical force exceeds a

predetermined threshold and the vertical biasing members 82 retract into respective recesses 1 16. This allows the inertia trigger 72 to move upwardly and be separated from the block 58, thereby allowing hydraulic fluid 74 to bypass the inertia trigger 72 and flow between sliding faces 86 and 88, in the present example directly into the rebound chamber 42.

This means that during heavy braking, rapid accelerating or during heavy cornering, when the inertia trigger 72 has been activated to close or reduce the flow path of the hydraulic fluid, when a wheel connected to the shock absorber 12 comes into contact with a protrusion or a pothole in the road surface, the hydraulic fluid 74 is able to bypass the inertia trigger 72 for a short period of time, thereby reducing the severity of any impact.

As previously discussed the adjustable valves 54c and 54r comprise a high speed valve assembly 94r and a slow speed valve assembly 96r. Figure 15 illustrates the adjustable valve 54r, which comprises a generally cylindrical valve body 140 that threadably engages an open end of the passageway 44. An upper end 142 of the valve body 140 is spaced apart from an inner wall of the passageway 44 to enable the fluid 74 to flow therebetween. A circumferential sidewardly open chamber 144 is positioned adjacent the outlet 92 to assist in movement of the fluid 74 into the compression chamber 40. An O-ring 146 is positioned below the chamber 144 to inhibit leakage of the fluid 74 out from within the shock absorber 12.

The high speed valve assembly 94r comprises a plurality of valve blocks 148 having respective central bores 150, which are held between the valve body 140 and an adaptor sleeve 152. The respective central bores 150 coaxially align bore 154 of the adaptor sleeve 152. The valve blocks 148 are spaced apart from an inner wall of the passageway 44 and gaps 156 are formed between the adjustable valve blocks 148 to enable the fluid 74 to flow therebetween as will be discussed with respect to Figure 16. The high speed valve assembly 94r is held in place by lock nut 158. The slow speed valve assembly 96r comprises an elongate body 160 that threadably engages the cylindrical valve body 140. An O-ring 161 inhibits leakage of the fluid 74 out from within the shock absorber 12. The elongate body 160 includes a tapered end 162 that is configured to engage through opening 164 in the upper end 142 of the valve body 140. In this way, a high speed multipart valve 94r and a needle valve 96r are formed in the same adjustable valve assembly 54r. Accordingly, the flow rate during rapid operation of the shock absorber and slow operation of the shock absorber can be controlled. As the reader will appreciate, this is important because the behaviour of hydraulic fluid at slow speeds is different to its behaviour at high speeds.

Therefore, having two adjustable valves, one for slow speeds and the other for high speeds has a significant advantage in overcoming the issues that arise with this variation. It should however be appreciated that a single valve could be used or other valve configurations, such as diaphragm valves could be used without departing from the scope of the invention. As illustrated in Figure 16 during the rebound phase the fluid 74 flows through the coaxially aligned bores 150, 154, the gaps 156 between the adjacent valve blocks 148, then down between the edges of the valve blocks 148 and inner wall of the passageway 44, between the upper end 142 of the valve body 140 and the inner wall of the passageway 44 and then out through the outlet 92 and into the compression chamber 40.

The fluid is also able to pass through a slow speed valve assembly 96r wherein the fluid 74 passes through opening 164 that is engaged by tapered end 162 to thereby adjust the size of the flow path. The fluid 74 then passes out of the ports 166 and outlet 92 into the compression chamber 40, as indicated by the broken arrows.

Figures 17 and 18 illustrate the adjustable valve 54c comprises a generally cylindrical valve body 168 that threadably engages an open end of the passageway 46 and held in place by locking nut 170 as illustrated in Figure 2. Turning back to Figure 17, O-rings 172, 174 inhibit leakage of the fluid out from within the shock absorber 12. Ports 176 connect circumferential sidewardly open chamber 180 with the inside of the cylindrical valve body 168.

The high speed valve assembly 94c comprises a plurality of valve blocks 182 having respective central bores 183 which are held between the valve body 168 and an adaptor sleeve 184 having a bifurcated bore 186 and an opening 188. A tapered end 190 of an elongate body 192 engages through the opening 188 to adjustably control flow of the fluid 74 therethrough to thereby form the slow speed valve assembly 96c. The elongate body 192 threadably engages the cylindrical valve body 168 and an O-ring 194 inhibits leakage of the fluid 74 out from within the shock absorber 12.

During the compression phase the fluid 74 is pushed through the outlet 90 and into the circumferential sidewardly open chamber 180. From here the fluid passes through ports 176 and into the interior of the cylindrical valve body 168. The fluid continues upwardly between the outer surface of the elongate body 192 and the inner surface of the cylindrical valve body 168 and enters the coaxially aligned bores 183 of the valve blocks 182.

Turning to Figure 18, the fluid 74 can then take one of two pathways. Either the hydraulic fluid 74 can take a high speed pathway through the gaps 196 that are formed between adjacent valve blocks 182, as indicated by the plurality of broken arrows, or the fluid 74 can take a slow speed pathway through the gap 198 between the tapered end 190 and the edge of the opening 188.

In another embodiment, as illustrated in Figure 19, the shock absorber stiffening apparatus 10 is contained within a separate housing 200, having a mounting bracket 202 and connected to the shock absorber assembly 12 by way of appropriate conduits 204, 206. In this way the inertia trigger 72 can be positioned in a generally horizontal position even when the shock absorber 12 is positioned at an angle to the vertical.

The skilled addressee will appreciate that the illustrated invention provides advantages over the prior art. There is provided an apparatus and method of stiffening a shock absorber by utilising the law of inertia to operate a trigger to close or reduce a flow path. The trigger will operate when a vehicle to which the shock absorber is attached undertakes braking or acceleration, or during cornering of the vehicle. This will provide advantages in that the tyres of the vehicle will be inhibited from losing contact with the road surface during severe movement or during emergency situations. This will improve traction during acceleration and assist in keeping the rear tyres of the vehicle in contact with the road surface when braking. Furthermore, the stiffening of the suspension during cornering will improve handling of the vehicle and reduces the chance of the vehicle becoming unstable during severe cornering events.

Furthermore, the provision of an adjustable valve comprising a high speed multipart valve assembly and a slow speed valve assembly assists in compensation for the different behaviour of hydraulic fluid at high and slow speeds.

Various features of the invention have been particularly shown and described in connection with the exemplified embodiments of the invention, however it must be understood that these particular arrangements merely illustrate the invention and it is not limited thereto. Accordingly, the invention can include various modifications, which fall within the spirit and scope of the invention.