GB2473854A

GB2473854A - A damping apparatus for a suspension system

Info

Publication number: GB2473854A
Application number: GB0916893A
Authority: GB
Inventors: John Stubbs
Original assignee: BLACK ART DESIGNS Ltd
Current assignee: BLACK ART DESIGNS Ltd
Priority date: 2009-09-25
Filing date: 2009-09-25
Publication date: 2011-03-30
Anticipated expiration: 2029-09-25
Also published as: GB2473854B; GB0916893D0

Abstract

A damping apparatus for a suspension system comprises a sealed housing 40, wherein the sealed housing 40 is formed from a resilient spring material (e.g. rubber). The sealed housing 40 further comprises a first 10 and a second 80 chamber, and a hydraulic fluid 60 movable between the first and the second chambers 10, 80 for damping a movement of the sealed housing 40. Preferably the first chamber 10 is a plurality of chambers surrounding the second chamber 80, which acts as a central reservoir for the hydraulic liquid 60 and the plurality of chambers further comprises an open cell material 90 such as micro-cellular polyurethane foam. Wherein in use, the hydraulic fluid 60 gravitates towards a base region of the central reservoir 80 and wherein the hydraulic fluid 60 moves in a cycle of filling and expelling from the plurality of chambers 10 during a cycle of compression and expansion of the damping apparatus under load and under rebound.

Description

I

SUSPENSION APPARATUS

The present invention relates, in general, to a suspension apparatus and more particularly to a vehicle suspension apparatus comprising compression, spring and damping properties.

Vehicle suspension units are used to reduce and dampen vibrations caused during motion of the vehicle. They are generally attached and located between the body of the vehicle and the wheels.

Known two-part suspension units have separate parts for the spring function and the damping of the spring, thereof. One type of suspension unit has a rubber outer body which houses a steel spring damper and a fusion bar, this is known as a "primary suspension unit". End loops are used to attach the steel spring to the suspension unit and these are known as "secondary suspension". Chrome is used to seal the spring inside the suspension unit and the steel spring damper is very heavy. Further, the use of end loops means that 15 inches of clearance is needed to achieve 5 inches of travel, for example.

Another approach to providing a vehicle suspension unit is disclosed in WO 2005/052407. WO 2005/052407 discloses a two-part hydraulic mount comprising * *** : a part metal, part silicone spring body surrounding a cavity comprising a first S...

chamber filled with a damping liquid, such as a polyalkylene glycol, separated by a cnstricted channel fro a second chamber which comprises a diaphragm and an air gap. In use, the spring body reduces vibrations during motion and the motion of the liquid between the chambers serves to force the diaphragm into the air gap and thereby dampen the movement of the hydraulic mount. This unit is limited in the amount of travel it can provide.

Another approach to providing a vehicle suspension unit is disclosed in US 2003/0137087. According to US 2003/0137087 the unit has a metal housing and a metal core and a hydraulic bushing forms a mount between a first spring portion formed of rubber defining hydraulic fluid cavities and a second, separate, spring cavity surrounding the first spring portion and which is formed of microcellular polyurethane. This unit moves in a rotational manner.

The above so-called "two-part suspension units" comprise separate parts which provide the spring and damping functions.

The present invention therefore seeks to provide a suspension unit which overcomes, or at least reduces some of the above-mentioned problems of the

prior art.

According to a first aspect of the present invention there is provided a suspension apparatus comprising: a sealed housing, wherein the sealed housing is formed from a resilient spring material, the sealed housing further comprising a first and a second chamber, and a hydraulic fluid movable between the first and the second chamber for damping a movement of the sealed housing.

Preferably the first chamber comprises an open cell construction and/or the open cell construction is provided by a foam material. Further preferably the open-cell or foam material comprises micro cellular polyurethane. * *** * * *

Preferably, the movement of the hydraulic fluid between the two chambers is **** constricted by a fluid channel and/or wherein the movement is controlled by the **** ** 20 use ofa valve.

Preferably, wherein the second chamber further comprises a reservoir of hydraulic *: fluid partially filling the second chamber. Also wherein, when in use, the hydraulic ** fluid gravitates towards a base region of the second chamber.

Preferably the first chamber further comprises a plurality of chambers formed within a wall of the sealed housing, also wherein the plurality of chambers surround the second chamber and may comprise differing volumes.

Further preferably, wherein the plurality of chambers are connected in a series configuration by a first constricted fluid channel, and/or wherein one or more of the plurality of chambers is in fluid connection with the second chamber by a second constricted fluid channel, and/or the second constricted fluid channels further comprise valves.

Preferably the plurality of chambers comprises an open cell construction and/or the open cell construction is provided by a foam material. Further preferably the open-cell or foam material comprises micro cellular polyurethane.

Preferably and in accordance with the first aspect, wherein the first chamber is formed within a wall of the sealed housing and forms a spiral around the second chamber and/or, wherein the first chamber has a varying cross-section along its length.

Further preferably wherein the second chamber further comprises a compressed gas. Also, wherein the resilient spring material is rubber and the hydraulic fluid is a . : low-viscosity liquid, such as glycol. *S.. * *

In accordance with a second aspect, there is provided a method of damping a ** 0 movement of a suspension apparatus including compressing a resilient spring device under a load, the spring device housing therein at least two chambers; moving a hydraulic fluid under pressure from the load through the at least two chambers and thereby damping the compression of the spring.

Preferably wherein moving the hydraulic fluid includes a cycle of filling and expelling hydraulic fluid from the chambers during a cycle of compression and expansion of the spring device under load and under rebound.

Further preferably, wherein the at least two chambers are in fluid communication with an inner cavity partially filled with a reservoir of hydraulic fluid and under a load on the spring device the hydraulic fluid is expelled from the chambers into the reservoir and under rebound of the spring device the hydraulic fluid is drawn into chambers.

Also preferably, wherein the chambers comprise an open cell material and the movement includes filling the open cell material with the hydraulic fluid.

Embodiments of the present invention will now be more fully described, by way of example, with reference to the drawings, of which: Figure 1 is a schematic diagram of a suspension apparatus according to a first embodiment of the present invention; Figure 2 is a schematic diagram of a suspension apparatus according to a second embodiment of the present invention; and Figure 3 is a schematic diagram of a suspension apparatus according to a third embodiment of the present invention.

In a brief overview of one embodiment of the present invention, there is shown in **.* .. : Figure 1 a schematic diagram of a suspension unit 100 according to a first * S..

*.*.. embodiment of the present invention. The suspension unit 100 comprises an outer body 40 which is attached to a vehicle such as a car, or motor bike, using bonded steel end fittings 20. The outer body 40 is a mainly cylindrical, sealed unit made of resilient spring material, such as rubber (for example) and further comprises a central reservoir 80, which is partially filled with a hydraulic liquid 60, which is a *:*. low-viscosity liquid such as glycol.

The suspension unit 100 also further comprises ports 50, which are fitted with one-way valves (not shown) and which interconnect the central chamber 80 with a number of inner chambers 10 which are formed in rings within the walls of the outer body 40. Each of the ring-like inner chambers 10 is fluidly connected to the next by a constricted fluid channel 70 in the outer body 40 and each of the inner chambers 10 further comprises an open cell material 90, such as micro cellular polyurethane foam.

The plurality of inner chambers 10 are connected, therefore, in a series configuration by the constricted fluid channels 70 and further, the plurality of chambers 10 are in fluid communication with the central chamber 80, which comprises the reservoir of hydraulic fluid 60 which partially fills the central chamber 80, via the ports 50.

As can be seen from Figure 1, the plurality of inner chambers 10 are of differing volumes, with the inner chambers 10 towards the base region of the suspension unit 100 having a volume greater than the inner chambers 10 further away from the base region. Wherein the exact dimensions and shape of the inner chambers 10 in relation to the outer body 40 depends on the required performance characteristics of the suspension unit 100.

Optionally, the suspension unit 100 may further comprise an inlet port 30, into which may be injected a gas using a compressor for example, in order to alter the compression function of the suspension unit 100. Whether an inlet port 30 is used or not and how much gas is injected depends on the desired compression characteristics of the suspension unit 100 and how this may be achieved is known in the art.

*:::: The cycle of compression, spring and damping occur in a linear direction as shown by the arrows in Figure 1. The inner chambers 10, foam material 90 and hydraulic * 25 fluid 60 work together to damp the natural movement of the rubber outer body 40 to give a hysteresis of compression, spring and damping. This is explained in more details following.

When under compression, the rubber outer body 40 acts as a natural spring, as it is made of resiliantly biased material. The hydraulic fluid 60 gravitates towards a base region of the central reservoir 80 and when the suspension unit 100 is compressed under a load, the hydraulic fluid 60 moves under pressure from the load through the plurality of inner chambers 10 and thereby damping the compression of the natural spring of the outer body 40.

Wherein moving the hydraulic fluid 60 includes a cycle of filling and expelling hydraulic fluid 60 from the inner chambers 10 during a cycle of compression and expansion of the suspension unit 100 under load and under rebound.

As the plurality of inner chambers 10 are in fluid communication with the inner reservoir 80 (which is partially filled with a reservoir of hydraulic fluid 60) under a load on the suspension unit 100, the hydraulic fluid 60 is expelled from the inner chambers 10 into the central reservoir 80 and under rebound of the outer rubber body 40, the hydraulic fluid 60 is drawn back into inner chambers 10.

Such that the movement fills the open cell material 90 with the hydraulic fluid 60, wherein the size of the pores in the open cell material 90 controls the flow of the hydraulic liquid 60 back into the central reservoir 80 of the suspension unit 100.

: Thus inner chambers 10 and open celled material 90 slow down the natural spring effect of the outer rubber body 40 to create a damping effect. The hydraulic fluid 60 slows down even further the rebound characteristics of the natural spring of the : combination of the rubber outer body 40, the inner chambers 10 and open celled material 90.

.. : A simple analogy is that of a bathroom sponge, if a dry sponge is squeezed and released, it recovers its shape almost immediately. If however, the sponge is wet (ie is filled with liquid) the rate of recovery is "damped" as the liquid (in this case water) moves between the cells relatively slowly. The principle being that slowing down the movement of the liquid through the pores slows down the rate of recovery of the sponge.

There is shown in Figure 2 a schematic diagram of a suspension unit 200 according to a second embodiment of the present invention. The suspension unit 200 comprises an outer body 240 which is attached to a vehicle such as a car, or motor bike, using bonded steel end fittings 220. The outer body 240 is a mainly cylindrical, sealed unit made of resilient spring material, such as rubber (for example) and further comprises a central reservoir 280, which is partially filled with a hydraulic liquid 60, which is a low-viscosity liquid such as glycol.

The suspension unit 200 also further comprises ports 250, which are fitted with one-way valves (not shown) and which interconnect the central reservoir 280 with an inner chamber 210 which is formed in a continuous spiral shape within the walls of the outer body 240. The spiralling inner chamber 210 therefore does not need to be fluidly connected to a next by a fluid channel as in the previous embodiment. However, as before, the spiralling inner chamber 210 also further comprises an open cell material 90, such as micro cellular polyurethane foam.

As can be seen from Figure 1, the spiral formation of the inner chamber 210 comprises differing volumes, with parts of the spiral chamber 210 in the middle of the suspension unit 200 having a volume greater than the parts at the top and bottom of the suspension unit 200. Wherein the exact dimensions and shape of the inner chamber 210 in relation to the outer body 240 depends on the required performance characteristics of the suspension unit 200.

Optionally, the suspension unit 200 may further comprise an inlet port 230, into :. ; which may be injected a gas using a compressor for example, in order to alter the * Th5 compression function of the suspension unit 200. Whether an inlet port 230 is used or not and how much gas is injected depends on the desired compression characteristics of the suspension unit 200 and how this may be achieved is known in the art.

The cycle of compression, spring and damping occur in a linear direction as shown by the arrows as previously shown in Figure 1. The inner chamber 210, foam material 290 and hydraulic fluid 260 work together to damp the natural movement of the rubber outer body 240 to give a hysteresis of compression, spring and damping. This has been explained in more detail with reference to Figure 1 previously.

In Figure 3, there is shown a schematic diagram of a suspension unit 300 according to a third embodiment of the present invention. The suspension unit 300 comprises an outer body 340, which is made of rubber, as in previous embodiments. The outer body 340 houses a centrally located reservoir 380 and a single upper chamber 310. The central reservoir 380 is partially filled with a hydraulic fluid 360 and is fluidly connected via a constricted port 350 to the single upper chamber 310. The upper chamber 310 further comprises an open celled material 390 also as before.

As in previous embodiments, when under compression, the rubber outer body 340 acts as a natural spring, as it is made of reliantly biased material. The hydraulic :::.: fluid 360 gravitates towards a base region of the central reservoir 380 and wherein the hydraulic fluid 360 moves in a cycle of filling and expelling from the upper chamber 310 during a cycle of compression and expansion of the suspension unit 300 under load and under rebound.

As before, because the upper chambers 310 is in fluid communication with the :: central reservoir 380 (which is partially filled with hydraulic fluid 360) under a load on the suspension unit 300, the hydraulic fluid 360 is expelled from the upper chamber 310 into the central reservoir 380 and under rebound of the outer rubber body 340, the hydraulic fluid 360 is drawn back into the upper chamber 310.

Such that the movement fills the open cell material 390 with the hydraulic fluid 360, wherein the size of the pores in the open cell material 390 controls the flow of the hydraulic liquid 360 back into the central reservoir 380 of the suspension unit 300.

Thus the upper áhamber 310 and open celled material 390 slow down the natural spring effect of the outer rubber body 340 to create a damping effect. The hydraulic fluid 360 slows down even further the rebound characteristics of the natural spring of the combination of the rubber outer body 340, the upper chamber 310 and open celled material 390.

A further embodiment (not shown) does not comprise any foam material filling the upper or inner chambers (10, 210, 310). Whereas this makes the product simpler to manufacture, the control of the liquid flow is more critical in the absence of the foam mediator and the performance of the inlet port valves (50, 250 350) would also be more critical. Such that the use of the foam material (90, 290, 390) is preferred.

Another embodiment has the inner chambers (10, 210, 310) filled with a high hysteresis material, which itself provides the damping without the use of any liquid.

If the hysteresis of the material chosen is too low, the damping effect will be :. reduced; however if too high, it will produce excessive damping by "hardening" the ::.20 spring.

In another embodiment, the open cell construction may be formed of a honeycomb of molded rubber, in order to provide a number small cavities or chambers surrounding the central reservoir which can provide the damping effect.

In all cases the damping effect is achieved by having small chambers within the rubber spring. As the spring compresses or expands, the material in the chambers (foam, liquids, solids) moves at a pie-determined rate. This dampens the movement of the rubber outer body.

The outer rubber body may be molded from rubber, using injection molding for example as a single unit, or may be formed from two parts and then the two parts glued together. The steel fixings at the top and bottom of the unit maybe vulcanized, as known in the art. The open cell foam material may then be injected into the required cavities. Alternatively, the foam material may be dipped into a rubber solution in order to form the sealed rubber unit.

The advantage of the present invention is a mechanically simpler device, as it damps itself due to squeezing of the hydraulic liquid. This reduces cost as you don't have a separate damper (steel spring) and a fusion bar, as known in the art.

This enables a large chunk of steel to be removed, thus reducing costs and weight. Therefore the vehicle travels further on the same amount of fuel and thus being more economic. The end loops of the damper which attached the steel spring to the suspension unit are also not needed; these are known as "secondary suspension. The separate dampers of the prior art use chrome to seal the spring inside the suspension unit and chrome is environmentally nasty. Further, the present invention can be used in situations that require large travel due to its linear movement ability. * *** * S*

Further, the use of end loops, as known in the art, means that you need 15 inches S...

of clearance to achieve 5 inches of travel. A suspension unit of the present *: invention needs 8 inches of height to achieve the same damping, thus taking up less space in any vehicle in which is used.

It will be appreciated that although only one particular embodiment of the invention *:* has been described in detail, various modifications and improvements can be made by a person skilled in the art without departing from the scope of the present invention.

Claims

Claims: 1. A suspension apparatus comprising: a sealed housing, wherein the sealed housing is formed from a resilient spring material, the sealed housing further comprising a first and a second chamber, and a hydraulic fluid movable between the first and the second chamber for damping a movement of the sealed housing.
2. A suspension apparatus as claimed in claim 2, wherein the first chamber comprises an open cell construction.
3. A suspension apparatus as claimed in claim 2, wherein the open cell construction is provided by a foam material.
4, A suspension apparatus as claimed in claim 2 or 3, wherein the open-cell or foam material comprises micro cellular polyurethane.
5. A suspension apparatus as claimed in any preceding claim, wherein the movement of the hydraulic fluid between the two chambers is constricted by a fluid channel. *S..
6. A suspension apparatus as claimed in any preceding claim, wherein the movement of the hydraulic fluid between the two chambers is controlled by the use of a valve. S... * . . S* *
7. A suspension apparatus as claimed in any one of the preceding claims, wherein the second chamber further comprises a reservoir of hydraulic * . .* fluid partially filling the second chamber.
8. A suspension apparatus as claimed in claim 7 wherein, when in use, the hydraulic fluid gravitates towards a base region of the second chamber.
9. A suspension unit according to claim 1, wherein the first chamber further comprises a plurality of chambers formed within a wall of the sealed housing,
10. A suspension apparatus as claimed in claim 9, wherein the plurality of chambers surround the second chamber.
11. A suspension apparatus as claimed in claim 9 or claim 10, wherein the plurality of chambers are connected in a series configuration by a first constricted fluid channel.
12. A suspension apparatus as claimed in claims 9, 10 or 11, wherein one of the plurality of chambers is in fluid connection with the second chamber by a second constricted fluid channel.
13. A suspension apparatus as claimed in claims 9, 10 or 11, wherein a subset of the plurality of chambers are in fluid communication with the second chamber by a second constricted fluid channel.
14. A suspension apparatus as claimed in claims 12 or 13, wherein the second constricted fluid channels further comprise valves.
15. A suspension apparatus as claimed in any of claims 9 to 14, wherein the . : plurality of chambers comprise differing volumes. *.* S * S S...
16. A suspension apparatus as claimed in any of claims 9 to 15, wherein, S...when in use, the hydraulic fluid gravitates towards a base region of the second chamber *.... :
17. A suspension apparatus as claimed in claims 16, wherein the chambers towards the base region of the apparatus have a volume greater than the chambers away from the base region.
18. A suspension apparatus as claimed in any of claims 9 to 17, wherein the plurality of chambers comprise an open cell construction.
19. A suspension apparatus as claimed in claim 18, wherein the open cell construction is provided by a foam material.
20. A suspension apparatus as claimed in claim 18 or 19, whereinthe open-cell or foam material comprises micro cellular polyurethane.
21. A suspension apparatus as claimed in claim 1, wherein the first chamber is formed within a wall of the sealed housing and forms a spiral around the second chamber.
22. A suspension apparatus as claimed in claim 21, wherein the movement of the hydraulic fluid between the two chambers is constricted by a fluid channel.
23. A suspension apparatus as claimed in claim 22, wherein the movement of the hydraulic fluid between the two chambers is controlled by the use of a valve.
24. A suspension apparatus as claimed in any of claims 21 to 23, wherein the first chamber has a varying cross-section along its length.
25. A suspension apparatus as claimed in claim 24, wherein the first chamber comprises an open cell construction. S... * S S S. *26. A suspension apparatus as claimed in claim 25, wherein the open cell construction is provided by a foam material. S... * ..27. A suspension apparatus as claimed in claim 24 or 25, wherein the open-cell or foam material comprises micro cellular polyurethane.28. A suspension apparatus as claimed in any preceding claim, wherein the second chamber further comprises a compressed gas.29. A suspension apparatus as claimed in any one of the preceding claims, wherein the resilient spring material is rubber.30. A suspension apparatus as claimed in any one of the preceding claims, wherein the hydraulic fluid is a low-viscosity liquid.31. A suspension apparatus as claimed in claim 30, wherein the low-viscosity liquid is glycol.32. A method of damping a movement of a suspension apparatus including compressing a resilient spring device under a load, the spring device housing therein at least two chambers; moving a hydraulic fluid under pressure from the load through the at least two chambers and thereby damping the compression of the spring.33. A method as claimed in claim 32, wherein moving the hydraulic fluid includes a cycle of filling and expelling hydraulic fluid from the chambers during a cycle of compression and expansion of the spring device under load and under rebound. *..Is: 34. A method as claimed in any one of claims 32 and 33, wherein the at *I,.least two chambers are in fluid communication with an inner cavity partially filled with a reservoir of hydraulic fluid and under a load on the spring device the hydraulic fluid is expelled from the chambers into the reservoir and under rebound of the spring device the hydraulic fluid is . : drawn into chambers. S. SS SS S.35. A method as claimed in any one of claims 32 to 34, wherein the chambers comprise an open cell material and the movement includes filling the open cell material with the hydraulic fluid.36. A suspension unit as substantially herein before described and with specific reference to Figure 1.37. A suspension unit as substantially herein before described and with specific reference to Figure 2.38. A suspension unit as substantially herein before described and with specific reference to Figure 3. S... * * S S. S S... * S S... * 0* * . .S S. S * .*