VEHICLE SHOCKABSORBER IMPROVEMENTS

TECHNICAL FIELD

The present disclosure relates to a vehicle shock absorber and a valve for a vehicle shock absorber.

BACKGROUND ART

In this specification unless the contrary is expressly stated, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not to be construed as an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.

There are two main shock absorber designs currently existing in the market place. They are the mono tube and twin tube designs. The present disclosure generally relates to twin tube design.

The twin tuoe design has two separate tubes, namely the pressure tube and the reserve tube, which are fitted between upper and lower mounting brackets with fluid as a working media filling the enclosed cavities. A piston assembly is fitted within the pressure tube interior, which is an enclosed cavity, with a rod end connected to the vehicle chassis, and the other (lower) end of the shock absorber connected to the vehicle wheel assembly. The piston of the shock absorber reciprocates inside the enclosed pressure tube cavity as the vehicle rides over a bump, forcing the fluid in and out via two restrictor valving systems, namely the rebound valve at the piston end and the compression valve at the pressure tube base, thereby converting fluid kinetic energy to heat energy.

It is an object of the present of the disclosure to provide a shock absorber, and a ^' valve for a ^" shock absorber, that at the very least, provide useful alternatives to known shock absorbers.

Other objects and advantages of the present disclosure will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

For the purpose of this specification the word "comprising" means "including but not limited to", and the word 'comprises' has a corresponding meaning.

DISCLOSURE OF THE INVENTION

One aspect of the present disclosure includes a valve for a hydraulic shock absorber including a body having a fluid passageway passing there-through, a coil or helical tension spring comprising at least two windings positioned and retained in said fluid passageway, so that when the spring is unloaded, there is no gap between the windings thereof and the spring is thereby adapted to block the passage of fluid through said fluid passageway.

In preference, the valve selectively permits fluid flow through the passageway when sufficient fluid pressure is reached that the fluid forces the successive windings of the spring apart.

In preference, the valve is part of a shock absorber assembly, and its fluid passageway extends between a pair of fluid cavities in the shock absorber.

In preference, one of the cavities is a pressure tube of the shock absorber, and the other is a reservoir of the shock absorber.

In preference, the valve body includes an inner portion and an outer portion, which togetπer define a cavity there-between.

In preference, the spring is positioned in the cavity between the inner and outer— portions of the vaive body.

In preference, the valve further includes an intermediated member located in the cavity between the inner and outer portions of the valve body.

In preference, the spring is positioned between the intermediate member and the inner portion of the valve body.

In preference, there is at least one hole passing through each of the intermediate member and the inner portion of the valve body, said holes forming part of the fluid passageway, and being adapted to permit fluid flow between the pressure chamber and the cavity in the valve body,

In preference, there is a plurality of holes passing through each of the intermediate member and the inner portion of the valve body.

In preference, the holes in the intermediate member and the inner portion of the valve body are substantially aligned.

In preference, there is at least one hole passing through the outer portion of the valve body, said hole forming part of the fluid passageway, and being adapted to permit fluid flow between the reservoir and the cavity in the valve body.

In preference, there is a plurality of holes passing through the outer portion of the valve body.

In preference, the valve is adapted so that fluid flow past the spring is maintained in a direction that is substantially perpendicular to the longitudinal axis of the spring.

In a further aspect, the disclosure includes a hydraulic shock absorber including a valve as claimed in any one of the preceding claims.

In a further aspect, the disclosure includes a shock absorber including a valve that is adapted to control fluid flow between a pressure tube and a reservoir of the same, and to act as a rebound valve when fluid flows in a first direction between the two, and a compression valve when fluid flows in the opposite direction.

In a further aspect, the disclosure includes a valve for a shock absorber that is adapted to control fluid flow between a pressure tube and reservoir of the same, and to act as a rebound valve when fluid flows in a first direction, and a compression vaJve when fluid flows in the opposite direction.

In preference, the valve includes means for preloading the coil or helical tension spring so as to increase the fluid flow pressure required before fluid can pass this.

In preference, the valve includes adjustment means for adjusting the degree of preload applied by the means for preloading the coil or helical tension spring.

In preference, the valve includes a fluid bypass passageway which permits at least a portion of the fluid to bypass the coil or helical tension spring when fluid flows in a given direction.

In preference, the valve includes a non-return valve that prevents flow of fluid through the bypass passageway when fluid flow is reversed.

In preference, the coil or helical tension spring is made from a material that adapts it to act as an armature under the influence of an electromagnetic field, and the resultant electromagnetic force may be used to preload the spring by either placing this in compression or under tension.

In preference, the electromagnetic field is created by an electromagnetic coil or solenoid.

In a further aspect, the disclosure includes a shock absorber assembly including a valve as disclosed above.

In preference, this shock absorber includes two valves as disclosed above, one serving to regulate compression, and the other rebound.

In a further aspect, the disclosure includes a valve for a hydraulic shock absorber including a body having a fluid passageway passing there-through, the body flexibly retaining a coil or helical tension spring comprising at least two windings by its ends so that this is positioned in said fluid passageway so the direction of fluid flow is maintained substantially perpendicular to the springs longitudinaϊ axis, and wherein in use, when the spring is unloaded, there is no gap between the windings thereof and the spring is thereby adapted to block the passage of fluid through said fluid passageway, until sufficient fluid pressure is reached that the fluid forces the successive windings of the spring apart.

In preference, the coil or helical tension spring is made from wire of substantially constant cross-sectional shape.

In preference, the cross-sectional shape of the wire is one of round, square, or a combination of these, such as an arch or u-shape.

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawing. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain embodiments of the invention, and together with the description, serve to explain the principles of the invention.

Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, to recognize that the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a bette ^r understanding of this disclosure it will now be described with respect to one or more exemplary embodiments, which shall be described herein with the assistance of drawings wherein:

Figure 1 is a cross sectional side view through an exemplary shock absorber;

Figure 2 is a cross sectional view through the exemplary valve assembly of the exemplary shock absorber in Figure 1 ;

Figure 3 is an isometric detailed view of the helical spring in the valve assembly;

Figure 4 is an enlarged partial view of the spring wire in Figure 3;

Figure 5 is an isometric detailed view of the helical spring in the valve assembly according to a further aspect;

Figure 6 is an enlarged partial view of the spring wire in Figure 5;

Figure 7 is an isometric detailed view of the helical spring in the valve assembly according to a further aspect;

Figure 8 is an enlarged partial view of the spring wire in Figure 7;

Figure 9 is a perspective view of an exemplary valve according to a further aspect, this valve incorporating adjustment means;

Figure 10 is a cross-sectional view through the valve illustrated in Figure 9;

Figure 11 is a side view of an exemplary shock absorber assembly including two of the valves of the type illustrated in Figures 9 and 10;

Figure 12 rs a cross-sectional view through the shock absorber assembly in Figure 11 , taken along line AA;

Figure 13 is a cross-sectional view through the shock absorber assembly in Figure 11 , taken along line BB;

Figure 14 is a cross-sectional view through the shock absorber assembly in Figure 11, taken along line CC;

Figure 15 is a cross-sectional view through an exemplary valve assembly according to a further aspect;

Figure 16 is a cross-sectional view through an exemplary valve assembly according to yet a further aspect, this valve assembly incorporating an electromagnetic coil; and

Figure 17 Is a cross-sectional view through a shock absorber assembly

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the illustrations and in particular to Figure 1 , where there is illustrated a hydraulic shock absorber including a single valve assembly 11.

The hydraulic shock absorber includes a rod end eye clevis 1 that is adapted to be connected to a vehicle chassis, a piston rod 3 that connects to piston 8, which in turn fits inside the pressure tube 9 with a sliding fit and reciprocates in the central cavity 9a. The valve assembly 11 is adapted to be fitted to a lower mounting bracket 12.

Referring now to Figure 2, the valve body of the valve assembly 11 includes an inner portion 15 and an outer portion 14, which together define a cavity there- between. The valve further includes an intermediated member 16 located in the cavity between the inner 15 and outer portions 14 of the valve body. The spring 20 is positioned in the cavity, between the intermediate member 16 and the inner portion 15 of the valve body, and is substantially enclosed and flexibly retained by these.

Figure 2 shows a sectional view of the valve assembly 11 where 14, 15 and 16 are the components of the valve body assembly. Items 15a and 16a are holes for fluid entry and exit from the cavity containing the helical spring 20, and which thereby form part of the fluid passageway through the valve. The resultant fluid flow direction then is maintained perpendicular to the helical tension springs longitudinal axis during entry and exit from the helical spring coil body.

The fluid fiow 17a and 17b is reversible and it can pass through a spring gap 20a between successive windings of the spring wire when fluid pressure is high enough to force the windings of the spring apart.

The neat fit of the helicaf spring 20 between the intermediate member 16 and the inner portion 15 of the valve body minimises the fluid leakage at the longitudinal ends of the helical spring.

When the spring 20 is unloaded then, there is no gap between the windings and the spring is thereby adapted to block the passage of fluid through the fluid passageway passing through the valve assembly 11. The valve assembly 11 selectively- permits fluid flow through the passageway when sufficient fluid pressure is reached that the fluid forces the successive windings of the spring 20 apart.

The diameter (A) ₁ the wire diameter (B) and the pitch dimension (C) of the helical spring can therefore be varied to achieve required damping force in the shock absorber unit.

The pressure tube 9 and the reserve tube 10 of the shock absorber may be an extruded profile body. The bottom mounting brackets 12 allow the fitting of the valve assembly 11 in the bottom end thereof. The valve 11 , acts as a rebound valve when fluid flows in one direction, and a compression valve when the fluid flows in the opposite direction. The valve 11 controls the flow of the working fluid to and from the pressure tube cavity 9 to reservoir cavities 10 and converts the fluid kinetic energy to heat energy.

The pitch dimension between two spring coils or windings described hereafter is, in preference, equal to the spring wire cross sectional height that is parallel to the spring longitudinal axis, which promotes no gap in between spring coils during the inert condition, hence preventing the fluid flow, unless the fluid flow has sufficient energy to force the spring coils open and create a gap between the helical spring coils for the fluid to flow through resulting in damping forces. The gap between spring coils is in a spiral shape, which may affect the resultant, damping force.

The cross section of the helical spring wire may be circular, oval or square with corners that are predetermined radii, which assist in minimising the fluid flow turbulence as well as determining the resultant opening forces from the fluid flow.

A combination of two or more helical tension springs arranged in either parallel, arrangement or series arrangement adjacent to each other may be used to achieve the required damping forces. This combination may include springs of different material strength and spring index according to Hooke's law, or with different cross sectional shapes to regulate the relationship between damping forces produced against the displacement and velocity of the moving piston.

A problem with those shock absorbers that are presently available is that the valves in these have difficulty controlling the fluid flow rate, and hence these have limited control over damping forces, as it is needed.

A further difficulty with those shock absorbers that are presently available is that they provide limited frequency adjustment when the frequency of wheel oscillation is high and damping forces are low, and when the frequency of wheel oscillation is low and the damping forces high.

The valve described herein substantially ameliorates these difficulties.

Referring now to Figures 9 and 10, where there is illustrated a valve 40 for a shock absorber, the valve incorporating adjustment means.

The adjustment means includes a knob 42, the stem of which 44 is threaded into the upper valve housing 46 so that the valve 40 may be adjusted by turning this knob 42.

A preload spring 48 is positioned between the nose of the knob's stem 45 and a stem 52 of an upper valve spring guide (hereinafter referred to as the upper spring guide 54). The knob stem 44, the preload spring 48 and the stem 52 of the upper valve spring guide 54 are all retained by a spacer 56 having a central bore passing therethrough.

Turning the adjustment knob 42 so that this compresses the preload spring 48 between the nose 45 of the knob stem 44 and the stem 52 of the upper spring

guide 54, preloads this spring 48, increasing the fluid pressure requiredjbefore trie ^" windings oϊthe~valve spring 60 can be forced apart and fluid passed.

There are a series of apertures 62 in the upper valve housing 46, and these are sized so as to permit fluid passage. When fluid passes in through these apertures 62, this may travel through slotted fluid passageways 64 in the lower housing portion 66 where it is met by a non return valve 70, which is biased (by a spring 72) into a position that prevents fluid flow in this direction unless fluid pressure is great enough to compress this spring 72 (hereinafter referred to as the non return spring 72). If fluid flow pressure in this direction is high enough, fluid may pass through the non-return valve 70 and escape from the valve assembly 40 via the central fluid passageway 76 in the valve assembly 40, thereby having bypassed the valve spring 60 entirely.

Should fluid attempt to travel in the opposite direction and enter via the central fluid passageway 76 (and exit via the apertures 62 in the upper valve housing 46), the non return valve 70 will not permit the passage of fluid via the slotted fluid passageways 64 in the lower housing portion 66, as the fluid pressure in this direction will help seal the non-return valve 70 against its seat. Instead, all fluid will be forced to try and pass the valve spring 60 before it can escape the valve assembly 40 via the apertures 62 in the upper valve housing 46. Moreover, the return of the valve spring 60 to its unloaded and closed position is slowed by fluid backpressure in the slotted fluid passageways 64.

Referring now to Figure 11 , where two of the valves assemblies 100 and 102 of the type illustrated in Figures 9 and 10, have been incorporated in an exemplary shock absorber assembly 104.

The two valve assemblies 100 and 102 have been mounted in a shared housing 106 at the bottom end of the shock absorber assembly 104, the valve assemblies being connected by a fluid passageway 108 that extends between them, and which is best illustrated in Figure 14.

Referring now to Figures 12 and 13, where the piston 1 10 in the shock absorber 104 is illustrated travelling upward, and fluid is being drawn into the pressure cavity 1 12. At this instant, the valve assembly 100 illustrated in Figure 12 is passing fluid via the non-return valve 114, i.e. via the slotted fluid passageways 1 16 in the lower housing portion.

Simultaneously, the valve assembly 102 illustrated in Figure 13 is receiving fluid from the reserve tube 118 via it's central fluid passageway 120. The non-return valve 122 in this valve assembly 102 then is forcing fluid to try and pass the valve spring 124 before it can escape the valve via the apertures 126 in the upper valve housing and pass through the passageway 108 between the two valve assemblies to the other valve assembly 100. This valve assembly 102 then is the 'rebound valve', as this is the valve assembly controlling fluid flow during the rebound stroke of the piston, the other valve assembly 100 is merely bypassing fluid.

If the piston 1 ^" JO direction were downward, fluid flow through the two valve assemblies 100 and 102 would be the reverse of that illustrated in Figures 12 and 13, so that the valve assembly 102 illustrated in Figure 13 would be bypassing fluid, and the valve assembly 100 illustrated in Figure 12 would be controlling *luid flow, and this valve assembly would be the 'compression valve'.

An advantage of the above described shock absorber assembly 104, is that its compression and rebound characteristics can be easily and finely tuned by turning the knob of the relevant valve assembly. Of course a person skilled in the art would understand that the knob may be substituted with a screw or socket, which might be adjustable using a special tool.

Referring now to Figure 15, where there is illustrated a valve assembly 150 that is an adaptation of the valve assembly 40 illustrated in Figures 9 and 10. In this assembly, the upper spring guide 151 includes a centrally positioned bore 152, and the lower housing portion 154 includes a spigot 156 that is aligned with the

bore 152, and which is sized so as to be received in the bore 152 with a sliding fit.

In use, when fluid forces itself between the successive windings of the valve spring 158-, the spigot 156 is freed from the bore 152, and fluid may enter the bore. As fluid pressure drops, the gaps between the windings of the spring 158 close and the spigot 156 re-enters the bore 152 and meets resistance from the fluid trapped therein, which is then forced out of the bore via a vent passageway 160 that connects up with the valve spring seat 162 in the upper housing portion 164. In this way, the return of the valve spring 158 (i.e. the closure of the gaps between the successive windings of the spring) is slowed by fluid pressure acting on the spigot and valve spring ends, thereby creating a less damping force. This effect is most useful when the frequency of the piston stroke cycle is high. At low frequencies, the fluid back pressure is less and the valve spring has time to return to the closed position before the next cycle. A restrictor fluid valve may be incorporated in the vent passageway 160 so that the rate of valve spring 158 return to the closed position may be tuned.

Referring now to Figures 16, where there is illustrated a valve assembly 200 incorporating a ring shaped electromagnetic coil 202 that is used to externally preload the valve spring 204 (by either placing this under compression or in tension) so that the fluid pressure required to open the gap between the windings of the valve spring 204 is either increased or decreased. This then allows the valve assembly 200 to be remotely adjustable, enabling the driver to tune the ride of the vehicle at will, while the vehicle is being operated.

Figure 17 illustrates a shock absorber assembly 220 utilising two of the valve assemblies 200 described directly above, one serving to regulate compression, and the other rebound.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised

that departures can be made within the scope of the invention, which is not to delimited to the details described herein but is to be accorded the full scope of the appended claims so as to embrace any and all equivalent devices and apparatus.