AU2004200696A1 - The improvement of vehicle shock absorber - Google Patents

Description

AUSTRALIA

Patent Act 1990 COMPLETE SPECIFICATION STANDARD PATENT THE IMPROVEMENT OF VEHICLE SHOCK ABSORBER The following statement is a full description of this invention, including the best method of performing it known to me.

IP Australia Documents received on: a.

24 FEB2004 E Batch No: The improvement of vehicle shock absorbers.

This invention is related to the improvement of vehicle shock absorbers.

Background: There are two main shock absorber designs currently existing in the market place. They are mono tube design and twin tube design (which this invention places emphasis on). The twin tube 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 enclosed cavity with rod end connected to the vehicle chassis and the lower end of the shock absorber is connected to vehicle wheel assembly. A compressive spring arrangement is also fitted between vehicle chassis and the wheel assembly.

The spring assembly is designed to convert the kinetic energy from the vehicle chassis oscillation as it rides over road irregularity to spring potential energy and the shock absorber is designed to damp this potential energy of the spring and convert it to heat energy. 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 which are fitted at the pressure tube base, converting fluid kinetic energy to heat energy. This heat energy at the rebound and compression valves must dissipate to the atmosphere via various layers of the shock absorber structure, which are; the pressure tube wall, the fluid between pressure tube and the reserve tube and then the wall of the reserve tube. These multi layers slow down the heat dissipating process, thus reducing the performance of these types of shock absorbers especially at high frequency oscillation movement which occurs on rally or racing car events.

Another disadvantage of the twin tube design is that it has two separate tubes, the pressure tube and the reserve tube, which are manufactured in separate processes before assembly.

Summary of the invention.

In one form of this invention the pressure tube and the reserve tube of current design twin tube shock absorber is replaced by an extruded profile body. The extruded profile body consists of multi walled annulus inter connecting by webs longitudinally. The outermost annulus wall is joined to the upper and the lower mounting bracket by either threaded joining, metal fusing or mechanical forming which forms internal multi cavities within a single enclosed cavity.

The other inner annulus wall or walls ends are free and not structurally connected to top or bottom mounting brackets which allows the fitting of a compression restrictor valve to the bottom end and especially the fitting of the rebound restrictor valve to top end of the extruded profile body which the current design of the twin tube shock absorber can not do. The innermost cavity has a cylindrical section, which becomes the pressure tube cavity where the piston reciprocates and the outer cavities between the most inner wall and the outer walls become the fluid reservoirs. The pressure tube cavity can be either machined or drawn and sized to the final prdcised finish diameter after extruded operation.

This multi cavity profile body described herein can be extruded from steel; aluminium alloy or other extrudable materials that have beneficial structural and mechanical properties to the performance of the shock absorber. If aluminium alloy material is used for this multi cavity profile body, the combination of the good heat dissipating property and relatively high resultant strength due to web interconnection of the multi walls contributes to the improvement of the shock absorber. A further improvement feature of the invention is the external fins which can be incorporated onto the outermost wall to improve the heat dissipation ability of the shock absorber.

The number and sizes of cavities of the invention required may vary as required from one application to another to optimise the performance of the shock absorber which eliminates the extra separated reservoirs. For example in some of the current shock absorbers available in the marketplace, extra separated external reservoirs are connected to the shock absorber unit for more fluid capacity especially on rally car shock absorbers which require more fluid in order to cope with high frequency workload.

The top and bottom mounting bracket of this invention can be manufactured from aluminium alloy and connected to the outmost annulus cylindrical wall of the multi profile body either by a threaded connection, welding or a formed connection.

At each end of the multi cavity profile body, a recess and a threaded internal end are machined or formed to accept and secure the restrictor valves. The restrictor valves, namely the rebound and compression, are fitted to each end of the multi cavity profile body and preferably adjacent to the outermost wall.

The restrictor valves control the flow of the working fluid to and from pressure tube cavity to reservoir cavities and convert the fluid kinetic energy to heat energy. A one restrictor valve assembly either the compression or the rebound restrictor valve comprises of two sets of one direction flow valve mechanism.

It consists of an annulus valve body, an O-ring, disc springs and a disc spring seat. The valve body provides a radial annulus groove for the O-ring in a form of opened mouth taper groove in sectional view. A set of orifices are arranged radially at the bottom of the opened mouth taper groove and on the same pitch centre diameter. This will allow the fluid to flow one-way through the orifices as the O-ring is lifted from its seat by higher pressure from the other side but is retained within the groove by a portion of the mounting bracket. The non flow situation in the opposite direction, the higher pressure and flow on the same side as the opened mouth groove presses the O-ring onto the smallest portion of the groove section and diminishes the fluid flow. Another set of orifices are located radially on the valve body arranged on a different pitch centre diameter to O-ring pitch centre diameter. The second set of orifices is for one-way fluid flow but in the opposite direction to that described herein. The blockage of the fluid flow through on the second set of orifices is applied by the disc spring flat face upon the second set of orifice openings, in which the disc springs are fitted from the opposite side of the opened mouth of O-ring taper groove. The number and the configuration of the disc springs may vary from one application to another depending on predetermined opening pressure required.

To pretension the disc spring, one option is to tighten the threaded valve body against the extruded body threaded end and lock into position by deforming the last mating pair thread. Both the compression and rebound valve components are similar but their assemblies are oriented in opposite directions.

Another form of this invention is the addition of annulus electromagnetic solenoids which are fitted from the outside of the extruded profile body in the vicinity of the compression and rebound restrictor valves to assist in direct controlling of the opening and closing of the second set of valve orifices via the disc seat exerting pressure upon the disc spring as the solenoid energises.

The disc spring seat of the restrictor valves are manufactured from ferromagnetic material so that the solenoid's magnetic forces can influence its movement.

To assist with understanding the invention a reference will be made to accompanying drawings.

Figure 1 shows one sectional side view of this invention.

Figure 2 shows one example of this invention, a typical cross sectional view of item4.

Figure 3 shows another form of this invention, a typical cross sectional view of item4.

Figure 4 shows another form of this invention, a typical cross sectional view of item4.

Figure 5 shows another form of this invention, a typical cross sectional view of item4.

Figure 6 shows sectional view of upper portion of this of this invention.

Figure 7 shows sectional view of lower portion of this invention.

Figure 1 is the typical sectional view of this invention where is the piston assembly with upper connecting eye clevis (la) to be connected to vehicle chassis and lower end of the rod (lb) is a Teflon banded nut (Ic) that slide fits inside the pressure tube The pressure tube (4c) ends are not connected to either the upper bushing assembly or the lower bracket assembly The upper bushing including the rod guide assembly allows the piston rod (lb) to reciprocate without losing fluid from the central cavity The extruded profile body consists of outer wall (4a) connected longitudinally by multi web as shown on figure to inner tube or pressure tube (4c).

At both ends of the extruded profile body are the restrictor valve assemblies and The rebound restrictor valve is fitted to top end of extruded profile body and the compression restrictor valve is fitted to lower bottom end. A solenoid coil (3h) is fitted from the outside of the restrictor valve assemblies. The function of these solenoid coils (3h) is to intensify the opening and closing of the restrictor valves as they are activated.

Figures 2,3,4 and 5 show sections of the extruded tube in various forms.

Referring to figure 2, the outer wall (4a) is joined longitudinally by web (4e) to inner pressure tube The cavities (4d) are the central fluid cavities and (4b) are the fluid reserve cavities. On figure 3, multi fins (4f) are incorporated on the outer wall (4a) for more heat dissipation area.

Figure 6 shows a sectional view of the upper portion of this invention and the rebound valve assembly in compression stroke where the hydraulic fluid flows as indicated by arrows (7a) through the rebound valve assembly which is in inert stage without restriction of the fluid flow. The ring (3b) is elevated from its seat by the fluid pressure but capsulated within by the inner portion of upper bracket assembly allowing the fluid from the outer cavities (4b) to flow freely via orifices (3c) and passage cavity (3j) to the volume at the back of the piston nut (Ic) as it advances downward. The annulus disc springs (3f) are in a state of no tension, separated by the washer The number of disc spring the thickness and their configuration as shown may vary depending on the required damping force and application.

Figure 7 shows a sectional view of the lower portion of this invention and the compression valve assembly in compression stroke where hydraulic fluid flows as indicated by arrows (7a) through compression valve assembly The components of the compression valve assembly that is the disc spring washer valve body ring (3b) of the rebound valve assembly (3) on figure 6 are duplicated for the compression valve assembly which is fitted upside down at the lower portion of the unit. The piston nut (Ic) advances down, compressing the fluid to a pressure higher than that of the opposite side of the piston nut It forces fluid to flow through orifices (3d) and push against the face (3e) of the first disc spring (3f) until there is sufficient pressure to compress and open a gap between the disc spring face and valve body (3a) for the fluid to flow into the outer cavities The gap increases as pressure increases hence more flow. The pressure drop and resistance to fluid flow by the valve is converted to heat energy, which is dissipated to the atmosphere via the outer tube wall The last disc spring (3t) after washer (3g) is for preloading of the valve, which can be optional.

The washer (3g) is manufactured from ferromagnetic material and is forced to move by the external electromagnetic force from the active solenoid coil (3h) and intensifies the opening and closure of the orifices (3e) as required. In the rebound stroke, the rebound valve follows a similar valve sequence as the compression stroke described above.

Claims (9)

1. A shock absorber comprising an extruded profile body with annulus multi-walls inter connecting continuously by webs longitudinally and on the end of the outermost annulus wall is joined to the upper mounting bracket with piston rod guide and the lower end is joined to a mounting bracket connected to vehicle wheel assembly, thereby forming innermost and outer cavities which are filled with working fluid, within and adjacent to outermost enclosure wall a compression restrictor valve and the rebound restrictor valve are fitted restricting the working fluid flow in between the innermost cavity and other outer cavities, converting the majority of the fluid kinetic energy into heat energy as the piston reciprocates caused by the compression spring oscillation and vehicle chassis movement.

2. The shock absorber of claiml has an innermost cavity with a cylindrical section which becomes the pressure tube cavity where the piston reciprocates and the outer cavities between innermost wall and outer walls become the fluid reservoirs.

3. The shock absorber ofclaiml and claim 2 where the compression and rebound valves are adjacent to outermost cavity wall to improve heat dissipation to atmosphere.

4. Another form of the invention as described herein on claimlincludes the external fins incorporated to the outermost wall to improve the heat dissipation ability of the shock absorber.

This multi cavity profile body described on claiml can be extruded from steel; aluminium alloy or other extrudable materials that have beneficial structural and mechanical properties to the performance of the shock absorber.

6. The number and sizes of cavities on claim I may vary from one application to another to optimise the performance of the shock absorber.

7. As on claimI, the restrictor valve assembly comprises of two sets of one direction flow valve mechanisms consisting of an annulus valve body providing annulus groove and orifices at its base for an O-ring shaped figure that allow fluid flow in one direction only and the other set of one direction flow valve mechanisms allow the fluid flow in the opposite direction as described above thereby fluid pressure exceeds a disc spring pressure on second set of orifices hence fluid flow occurs.

8. Another form of this invention ofclaiml is where the addition of annulus solenoids are fitted from the outside of the extruded profile body at the vicinity of the compression and rebound restrictor valves assisting in controlling the opening and closing of the valve orifices via the disc spring seat which are manufactured from ferromagnetic material as solenoid energising from an external electricity source.

9. As claiml with demonstration of the accompanying drawings. Dated this 22" day of February 2004. Vilo Niumetolu (Name of applicant).