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Document Type and Number:
WIPO Patent Application WO/1997/019839
Kind Code:
To facilitate road-side parking, a vehicle's dampers (2) are adapted to perform a second function, in the parking mode, in order to bounce the vehicle on its tyres by converting the vehicle's dampers (2) into hydraulic rams to produce vertical acceleration. Spring loaded, telescopic, struts, pivoted to the underside of the vehicle's body are lowered diagonally and, as the vehicle descends in the bounce cycle the struts grip the road surface and push the vehicle horizontally while it is intermittently airborne. The piston rod (16) of the damper (2) is composed of two coaxial pipes (50, 56) and conveys hydraulic pressure fluid sequentially to and from the damper's lower (54) and upper chambers (56). The escape holes, which control the passage of fluid through the piston (14) in the travel mode of operation, are automatically blocked in the parking mode.

Application Number:
Publication Date:
June 05, 1997
Filing Date:
October 30, 1996
Export Citation:
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International Classes:
B60G17/04; B60S9/205; F16F9/18; (IPC1-7): B60S9/205; B60G17/015
Foreign References:
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1. A device for enabling a vehicle, which has at least two modes of operation. to be moved horizontally sideways in its parking mode by nonmanual means consisting of bouncing means, horizontal thrust means, energising means, and control means: in which the bouncing is achieved by adapting the vehicle's dampers to perform a second function, in the parking mode, in addition to the damper's normal and first function of absorbing the shocks as the vehicle travels over a bumpy road surface in the travelling mode of operation. A device as claimed in claim 1 in which the second function of the damper is achieved by converting the damper into a hydraulic ram during the parking mode of operation to give the vehicle upward acceleration and cause it to bounce. A device as claimed in claim 1 or claim 2 in which the hoπzontal thrust means comprises one or more retractable struts one end of which is pivotally secured to the underside of the vehicle.
2. A device as claimed in claim.
3. in which the hydraulic ram is energised bv the power of the vehicle's engine which drives a hydraulic pump which forces fluid through the piston rod which is hollow. A device as claimed in claim 1 in which the control means consists of one or more fluid control valves, which change the vehicle's dampers from one mode of operation to the other, and means to distribute hydraulic fluid sequentially and intermittently to the vehicle's dampers to produce the bounce cycle and to control the bounce height and the bounce rate. A device as claimed in claim 2 in which the piston rod consists of two concentric pipes the bore and the annular cavity of which are used to convey hydraulic fluid into and out of the damper's upper and lower chambers. A device as claimed in claim 6 which has blocking means which automatically prevents the upward flow of hydraulic fluid through the damper piston during the parking mode of operation.
4. A device as claimed in claim.
5. in which each strut has collapsing means to shed load, and means to change the attitude of the strut between a horizontal attitude when retracted and an inclined attitude when deployed. A device as claimed in claim 8 in which each strut is longitudinally telescopic and the collapsing means is a spring which contracts when the strut load reaches a critical value in the bounce cycle in order to shed load. A device as claimed in claim 7 in which the hydraulic ram is doubleacting and lifts the wheel as the vehicle descends in the bounce cycle in order to reduce the bounce height. A device as claimed in claim 10 which has blocking means which automatically prevents the downward flow of hydraulic fluid through the damper piston during the parking mode of operation. A device as claimed in claim 3 or claim 9 in which the strut pivot can rotate horizontally around a vertical axis. A device as claimed in claim 5 in which the means, to distribute the hydraulic fluid sequentially to the dampers, is twin, rotating, switch valves which are linked together by being on the same shaft which is rotated by a motor. A device as claimed in claim 9 or claim 12 in which the remote end of the strut has means to grip the road surface to produce a horizontal thrust as the vehicle descends in the bounce cycle. A device as claimed in claim 2 or claim 4 in which hydraulic energising fluid is fed through the top of the damper to power the ram action. A vehicle damper substantially as described in any proceeding claim or claims which has a second function of acting as a hydraulic ram to cause the vehicle to bounce. A device substantially as herein described and illustrated in the accompanying drawings.

Field of the invention

This invention relates to means to aid the parking of a vehicle, more specificalK it relates to apparatus which enables a vehicle to e laterally that is. at right angles to the normal direction of travel

Background of the in . eπtion

v\ ith the numbers of vehicles increasing each \ εar the competition for parking spaces increases, and the abil to park in a short roadside parking space and to manoeu\τe into that space easih is a great advantage The method of moving a car lateralh b\ bouncing manuals has long been known and occasional!} put into practice It is almost unknown these s due to the changed car shape and the lack of the necessan manpower

~ o overcome this growing parking problem tne present lm enuon pro\ ιdes apparatus which uses the power of the vehicle's engine to e tne . ehicle iateraliv. or, in fact, in am required horizontal direction, or to rotate about a vertical axis

Accordingly one object of the present invention is to proude the means for moving a vehicle laterally by non-manual methods Another ooject is to ιde means for moving a giving the frame of the vehicle an upward vertical acceleration in order to lift one or more pairs of wheels (or axles) clear of the road surface

Another object is for the vehicle to ha\ e two modes of operation - a travelling mode, when the dampers act as shock absorbers, and a parking mode w hen the dampers act as bouncers and when a hoπzontal lateral force is prodded to move the vehicle laterally while trie wheels are temporaπh clear of the road surface

.Another object is for the vehicle's vertical acceleration to be provided an upward rams acting between the vehicle's heel and frame

.Another object is ehιcle's single function wheel dam the ram force to the necessan upward vertical acceleration

.Another object is for the horizontal force which provides the means to move the \ εhιcle laterally to be prouded by one or more inclined struts pivoted to the underside of the cle, the lower end being adapted to grip the road surface so that, as the e ground the top end of the strut in a vertical circle about it s bottom end thereoy causing the vehicle to move lateralh

Another object is for the energ y required to produce the \ ertical acceleration to be provided b\ the power steering pump, often fitted to \ ehicles

Another object is for the inclined struts to ha\ e collapsing or compressing means so that do not exert large forces on the underside of the vehicle, and for each strut to give as soon as the longitudinal load increases dramatically, and to return to its normal length when reliev ed of its heavv load

Another object is lor the vehicle's \ ertical acceleration and its lateral mov ing force to be co-ordinated, time-w ise, to produce a repetitive bouncing cycle duπng which eacn bounce achiev es a small lateral incremental advance in the required direction

Another object is for the second function of the single or double tube damper to be achieved by providing a feed route for the hydraulic pressure fluid's entrance into the dampers lower chamber, an escape route for its escape from the upper chamber, and a blocking device to prevent the fluid passing through the holes m the damper's piston used m the damper's travelling mode

.Another object is for the solid piston rod of the single-function damper to be replaced in its dual-function form bv two hollow coaxial piston pipes which provide the flow routes for the draulic fluid supplv to the hvdrauhc ram

Another obiect is that the dual-function damper fits into the space normal K occupied b> the single-function damper which it replaces, and where this is not possible that it occupies a minimum of extra space

.Another object is to have the capacity, when required, to push the \ ehicle not only trans erse!} but rotational]}-

Another object is to push the vehicle, duπng the bounce process, with one or two multi-directional struts which will giv e a hoπzontal thrust in anv required direction, and rotation

.Another object is that the piston rod of the dual-function damper be attached to the \ ehicle frame by a single screwed nut which is concentric with the veπical axis of the damper

Another object it to minimise the height of the bounce and increase its frequencv by distributing the hydraulic fluid, not bv slow reciprocating valves, but by fast motoπsed. rotating, linked, switch valves

.Another object is for the damper s upper chamber to be pressurised as the vehicle's frame descends so that the wheel is raised relation to the frame and the length of time the wheel is clear of the road surface is extended This, in effect, can lead to a lower bounce height and a shorter bounce frequencv. which is an object of this invention

Another object is for the blocking device of the escape routes from the lower damper chamber to be provided automatical by a thin elastic tube with a restπcted lower onfice which expands radially to block the holes through the damper's piston by which the fluid escapes in the travelling mode

Another ob j ect is for the blocking device of the escape routes from the upper damper chamber to be prov ided automatical!} by an annular cut-off sleeve w hich slides up and down in the annular space and is supported by a coil spring, and for the fluid pressure the parkinα mode to force the sleeve down against the spπng to block the routes through the piston b} which the fluid escapes in the travelling mode

A final ob j ect is to pro ide controls so that the dual-function damper can oe changed from its shock absorbing function to its bouncing function and vice versa depenαing on the mode m which it is required to operate.

Sumraa of the inv ention

To attain these and other objects the present inv ention overcomes some of tne present parking difficulties by providing a new type of dual- function damper which is used to bounce the vehicle's wheels clear of the road surface together with lateral mov ement struts which move the vehicle laterally during the peπod when the wheels have no contact with the road surface

B> using a v ehicle's dampers to lift the wheels clear of the ground dynamicallv and bv utilising the hydraulic fluid power pro ided by a vehicle's power steering pump to energise the lifting process the mam objects of the invention will have been achieved at en little expense Normal!} a vehicle's dampers only have one function - that of damping down the violent vertical accelerations of the wheel and absorbing the veπical shocks Modem dampers are single function, and most dampers are telescopic and are general!}' of one of two types - single or double tube A second damper funcnon, which is one of the mam objects of this ιm ention, - that of using the damper to bounce the wheel tread clear of the road surface - can be achieved with either type. It consists basicalK of applying fluid pressure to the lower chamber of the damper, of providing an escape for the fluid trapped in the upper chamber, and of preventing the fluid from passing through the vertical holes in the damper piston, to produce vertical acceleration

The normally solid piston two hollow concentπc pipes The inner pipe is adapted to earn t e ydraulic pressure uid to the lower chamber of the damper while the annular space between the two concentπc pipes is adapted to provide the escape route for the return fluid in the upper chamber

restricting throat is provided as the inner pipe passes through the piston, which results m a pressure differential which is used to expand a thin elastic tube radially and horizontally outwards so that it blocks holes through the piston which normal]} allow fluid to escape upwards from the lower chamber The escape fluid is led back to a vented hydraulic fluid reservoir from where it is re-circulated by the h}drauhc pressure fluid pump

The dual function damper thus has two modes of operation In its normal, travelling. mode it acts as a shock-absorber between the wheel and the vehicle's frame, but its parking mode it acts as a hydraulic ram to accelerate the vehicle vertical!} so that the tread of the wheel's tyre is clear of the road surface intermittent!} These two modes are quite separate because the parking (lateral movement) function is never required while the vehicle is in its travelhnε mode

In a simple example of the invention the damper, adapted to provide the rndrauhc ram function between the vehicle's wheel and it's frame is energised b\ high pressure hydraulic fluid flowing into the dampers' lower chamber which accelerates the vehicles frame, vertically upwards, until sufficient acceleration has been achieved to lift the clear of the road surface The frame has then reached its required upward velocity After that the hydraulic power is diverted from the lower chamber, but the frame continues to travel upwards until, decelerated by gravity, it slows, stops, and then starts its descent When the tyre again hits the road surface it is deformed together with the coil spπng which, w ith the damper, is part of the wheel suspension system The tvre and spring recover and. in doing so. force the vehicle's frame upwards again At this point the hydraulic power is re-applied to the dampers lower chamber and the bounce cycle is repeated

For lateral movement it is necessary to apph a horizontal force when the tyres of a pair of wheels lose contact with the road surface The hoπzontal thrust is provided by a tεlescopically shortening strut Two struts are normallv required to push m either of two opposing directions, (towards and awa\ from the kerb)

One end of the telescopic strut is pivoted to the underside of the vehicle's bod} at a conv ient place The other, remote, end (which is called the foot) is normallv held up so that the strut is in a basicalh hoπzontal position clear of the road surface when not in use

To deploy the strut the foot is lowered to make contact with the road surface The length of the strut is arranged so that when the vehicle ' s body is at the top of its bounce the strut makes an angle of about 65° with the hoπzontal

The foot of the strut is made so that it will gπp the road surface either b} having a high friction elastic surface or by penetrating the road surface with points, or blades, or pointed blades.

.As the vehicle bounces upward the foot of the strut is dragged along the road surface until the vehicle reaches the top of its bounce As the vehicle then descends the foot of the strut gπps the road surface and the top of the strut descπbes an arc about the foot pushing the % ehicle laterally until the tread of the tyre grips the road surface as the vehicle falls back to the ground At this point the load the strut increases dramatically and the strut automatical!}' contracts against an axial spπng When the vehicle bod} has fallen back to its normal level the strut is restored to it normal length bv the axial spπng Alternatively each pair of handed struts could be replaced by a single hydrauhcally controlled similar strut rotating through 360° in a hoπzontal plane around a vertical axis Two of these struts, mounted fore and aft on, or near, the vehicles longitudinal centre line could push the vehicle in any desired hoπztonal direction when the bounce cycle operates, or one such strut mounted at the vehicles centre of gravity could achiev ε the same result The spπng has to be prestressεd in the strut's unloaded condition, - the prestress axial force in this condition must be the load which the strut carπes just before the dramatic load increase, - so that, in its working mode, the strut will shed the load as soon as it begins to increase dramatically, by shortening

In some cases the high pressure hydraulic pump fitted to certain vehicles to energise the power steering will not have sufficient power to produce the necessary bounce height, frequencv and control To overcome this problem it will be necessarv either to fit a suitable


hv dro-pneumatic accumulator in the hvdrauiic circuit or to fit a larger or higher pressure hydraulic pump

It is soon apparent that to improve the efficiency of the bounce the hydraulic fluid pressure must not only be applied to the lower damper chamber, but also, subsequentlv to the upper damper chamber

The means of supphing the high pressure hvdrauiic fluid to the lower and upper dampεr chambers of a dual-function damper, of conveying the return fluid back to the hv drauiic fluid reserv oir, and of preventing hydraulic fluid from escaping through the piston duπng the parking mode when the damper acts as a double acting hvdrauiic ram is an important part of this invention

Tne hvdrauiic pressure fluid is fed into the lower chamber through the hollow inner pipe of the nvo-pipe piston rod When the piston mov es upward the fluid which is Displaced from the annular space above the piston (which is the upper chamber) is allowed to escapε into the annular space between the inner and outer piston pipes from where is it returned to the hv drauiic fluid reservoir The pressure fluid, which, in the travelling mode, escapes from the low er dampεr chamber (through holes in the piston) is prevented from doing so in the parking mode, bv a thin walled elastic blocking tubε with a restπcted lower end through which the pressure fluid flows The restriction increases the fluid pressure localh which expands the elastic blocking tube, which blocks the fluid escape holes, which allows the dampεr to act as a hydraulic ram In the travelling mode there is no flow of pressure fluid through ihe elastic tube, so that the fluid pressure does not increase locally, and the elastic rube does not expand and so it does not block the escapε holes, so that the damper, in the travelling mode, acts as a shock absorber and not a hydraulic ram

The damper forms a tie between the wheel and the frame, so, once the required vertical lift - off velocity has been achieved by rapidh expanding the telescopic damper, it is advantageous to rapidh contract the damper to lift the wheel further off the roac surface This is achieved by forcing fluid into the upper chamber of the damper (to overcome the weight of the wheel and the force of thε suspension coil spring) and, at the same time to force the fluid in the lower damper chamber to return to the hvdrauiic fluid reservoir

The most acceptable lateral movement is when the bounce height is small and the bounce frequencv is short To achieve a short frequency the hydraulic fluid control valves should be rotating and not reciprocating

A good method of controlling thε bounce cycle then, is bv linked, motoπsed. twin, rotarv switch valves consisting basicallv of stators and rotors These valves are best linked bv being on the same dme shaft The hvdrauiic fluid enters through the centre of thε rotating rotor of thε first valve into a radial duct which engages with circumferential ducts in the stationary stator During one revolution the radial duct of the rotor sequentiallv engages a major sector, a blank sector, and a minor sector The major sector of the first valve is connected to the lower chambers of thε relevant dampers, the blank sector blocks thε flow of the fluid, and the minor sector is connected to the upper chambers

Thε hydraulic fluid enters the second (twin) valve through the ma j or and minor sectors of the stator and flows out through the centre of the rotor It flows into the ma j or

sector from the upper chambers and into the minor sector from the lower chambers The central rotor out-flow returns the fluid to the hydraulic fluid reservoir

The rotary velocity of the dπv e motor of the rotary twin valves is preferably adjustable

To change the vehicle from travelling mode to parking mode a solenoid operated valve on the return floe line is opened, the drive of the twin rotary s itch valves is energised, the mode valve is switched from travelling mode to parking mode, and the relevant strut or struts are lowered to the road surface To change back to travelling mode the sequεnce of operations is reversed

Finally, this invention relates to a two-mode vehiclε equipped with bouncing means, hoπzontal thrust means, and control means -

• Bouncing means is achieved by the dampers being dual-function, the second function being achieved b} making the damper act as a hydraulic ram to cause the vehicle to accelerate v ertically in the parking mode of operation and the tyre to leave the road surface

• The ram is energised bv hydraulic fluid supplied through the hollow piston rod which is composed of two concentπc pipes.

• The ram action is achieved by automatically blocking the fluid escape holes through the piston duπng bouncing.

• The fluid is prevented from escaping upwards, through the piston, by a thin elastic tube with a restricted lower orifice which is suspended within the inner piston pipe.

• When the ram is double-acting thε fluid is prevented from escaping down-wards, through the piston, by a spπng-supported cut-off sleev e within the annular space betweεn the inner and outer piston pipes.

• The top of the dual function damper is secured to the vehicle frame b} a single central damper-secunng nut

• Hoπzontal thrust means is provided by one (or more ) retractable struts with one end pivoted to the underside of the vehicle

• The strut is telescopic and is prestressed with a longitudinal spring

• The strut is deployed bv the remote end being lowered to the road surface at an inclined angle

• The remote end of the strut has a broad flat surface with points to gπp the road surface

• The strut can be made to rotate about a vertical axis so as to be able to push in any requirεd horizontal direction

• Deplθ}ment and rotation of the strut can be accomplished hydraulicalh

• The control means is achieved by pressure and return hydraulic fluid being distributed sequentially to the dampers to control the vehicle ' s bounce height and bounce frequency.

• The sequential fluid distribution is accomplished by twin, motoπsed. rotating, linkεd switch values.

Description of the drawings

Fig 1 shows, diagramatically. a vehicle wheel suspension arrangement adapted to dual function.

Fig 2 shows a vertical cross - section through half of the piston of a dual-function double tubε damper.

Fig 3 shows a part plan on the top of the piston shown in Fig 2

Fig 4 shows an elevation of a spπng loaded telescopic strut in its stowed and working attitudes.

Fig. 5 shows a cross section through the top assembly of the damper (shown in Fig.

1 ) in more detail.

Fig. 6 shows a simplified plan on the top assembly of the damper shown in Fig. 5

Fig. 7 shows thε arrangement of the hydraulic circuits

Fig. 8 shows a hydraulically controlled rotary, multi-directional, telescopic strut.

For simplicity and clanty many parts of the drawings are shown schematically.

Detailed description of a preferred embodiment

Referring to the drawings, Fig. 1 shows the single-function, double tube, damper adapted to a dual-function dampεr, - the second function being to act as a hvdrauiic ram and cause the wheel of the vehicle to bounce clear of the road surface, and return quicklv

The typical much-used single-function double - tube telescopic dampεr. 2, is composed of a damper rube. 4. surrounded by an outer tube, 6. both of which are attached to a fixing eye, 10, which is aπached to the wheel of the vehicle. A foot valve assembly. 8. controls the flow of damper fluid between the damper's lower chamber, 54, and the reservoir annular space, 70. Sliding within the damper tube is the damper piston. 14. which is secured to the lower end of a piston rod, 16. The top end of the piston rod is attached to the vehicle frame, 18, bv a top assemblv. 20 A lower spπnc support plate. 22, is attached to thε outer

tube and a wheel suspension coil spring. 24, operates between the lower support plate and the upper spπng support plate, 66, which is part of the top assembly A gaiter. 26. is aπached to the top assembly to protect the exposed section of the piston rod

Thε piston has a number of sets of escape holes drilled through it The L shaped holes. 28 Figs 2 and 3. are covered by the upper disc valve, 30, held down b} a star shaped disc spπng, 32 These holes allow fluid to escape from the lower chamber of the damper in the trav elhng mode A set of short vertical holes, 29, connect the lower chamber. 54. to the upper chamber. 60. b} way of the inclined holes, 62 Inclined holes, 62. are not obstructed bv the upper disc valve, 30, which is perforated locally to avoid obstruction

Damping is effected by the damper piston forcing the hydraulic damper fluid through the L shaped holes at a high velocity when the telescopic damper is compressed as the vehicle travels along a bumpy surface This is the normal function of the single-function damper which has a solid piston rod and is widely used on all types of vehicles

But the damper shown on Figs 1 , 2 and 3. has a second function which is to act as a hydraulic ram duπng the parking mode procedure (when it is not required ιo act as a dampεr) This hvdrauiic ram acts, as does the damper, between the road whεεi and the vehicle frame and must have the power to accelerate the vehicle frame so that thε frame is propelled vertical]} upwards and only stops when it has lifted the wheel ciear of the road surface

This second function is achieved by having a hollow (not solid) piston rod which is composed of two concentπc pipes The inner pipe, 50. conveys high pressure hydraulic fluid through its bore. 52, from the top assembly to and from the lower damper chamber. 54, while the outer pipe, 56, conveys the fluid, through the annular space, 58. to and from the upper chamber annular space, 60. above the outer part of the piston, back to the top assembly

The top assembly. 20, Fig 1 , 5, and 6. collects the pressure and return fluids separately and provides hose connections to complete the hydraulic circuits to thε hn drauhc pressure pump, 88. and the reservoir, 90, respectively. Fig 7 Between the hydraulic pressure pump and the top assembly a non-return valve. 92. is inserted in thε pressure line while a solenoid controlled shut-off valve, 93, is inserted in the return line so that the hydraulic circuit of the second function will be closed when the vehicle is in its travelling mode There is also a solenoid controlled pressure relief valve, 149. in the return fluid line which has to relieve the high pressure in the parking circuits as soon as the mode is changed to the travelling mode

As the hydraulic pump will be running continually while the vehicle's engine is running, another pressure controlled relief valve, 94. has to be inserted next to thε pump This relief valve will serve both the steeπng and parking ram functions which occur at different times

To enable the damper to perform it's second (ram) function, of lifting and accelεrating the vehicle, the high pressure hydraulic fluid must not be allowed to escape from the lower damper chamber duπng lifting

To achieve this situation the piston. 14, Fig 2 and 3, is πgidly aπacned to tne lower ends of both the inner and outer piston pipes, and the piston is so shaped that the bore of the inner piston pipe extends through the piston to enable the hydraulic pressure fluid to reach the lower damper chamber. 54

The holes, 28. through which the hydraulic fluid escapes from the lower chamber in the travelling mode are L shaped and their lower ends emerge, convenient!} and horizontally, into the lower inner piston pipe bore. A tnm-walied. elastic, blocking tube, 40. is suspended with the inner piston pipe by a radially expanding coil spπng, 43 The lower end. 44. of the blocking rube is designed to restrict the downward flow of the pressure fluid so as to cause thε fluid prεssurε to πsε locally and expand the elastic blocking rube horizontally and radialh. to position. 41. so that it blocks the escapε holεs, 28. at their lower ends. 48 The inner piston pipe is εxtended downwards and has an external rim. 45. which supports the coil spπng, 38, of the lower disc valve. 36

The outer tube, damper tube, piston, outer piston pipe, inner piston pipe, heavy suspεnsion coil spπng. gaiter, spπng support plate, eiasπc blocking tube, and damper securing nut are all concentric about the vertical axis of the damper. 46

In the parking mode the hydraulic pressure fluid flows down the elastic blocking tube withm tne inner piston pipe, is restπcted by the rεstπction of its lovvεr end. expands hoπzontaiiy and radially, and, in doing so. blocks the lower ends of the lower chamber fluid escapε hoies. The pressure fluid continues down into thε lower damper chamber from which it cannot now escape, so that the damper acts as a hydraulic ram raising the piston and lifting the vehicle frame

Inclined holes, 62. are provided through the piston so that the hydraulic fluid can pass between the annular space, 60. above the piston (the upper damper chamber), and the return fluid annular space. 58.

In the parking mode, when the frame begins its descent, ( in the bounce cycie) the hydraulic pressure fluid is forced into the upper chamber to contract the telescopic damper, -in which process it is aided (once the tyre touches thε road surface] by the weight of the frame but opposed by the coil spring force. The fluid in the lower chamber rises up the inner piston bore and is returned to the hydraulic fluid reservoir via the twin rotary control switch valves.

When the upper chamber is pressuπsed the parking mode it is necessary to prevent fluid from escaping through the inclined holes. 62. as it does in the travelling mode This is done by providing a circular plastic cut-off sleeve, 7i , which slides up and down in the annular space, 58, between the inner and outer piston pipεs The piastic sleeve is supported, i in the annular space) by a coil spπng. 55 In order not to jam in the annular space thε height of thε sleeve has to be roughly about the internal diameter of the outer piston pipe In the travelling mode the coil spπng forces the sleeve upwards, to position X. so that fluid can escapε from the upper chamber, 60. through the inclined escape holes. 62. down the lower escape holes, 29, past the lower disc vaive. 36. and into the lower chamber

But in the parking mode the hydraulic fluid travelling down the annular space, 58, forces the plastic sleeve down (compressinc the coil spπng) until the sleeve blocks the flow

of fluid through the lower escape holes, 29, (position Y) but allows the fluid to flow down the annular space, 58. up through the inclined escape ducts 62, and into the upper chamber 60 For the cut-off sleeve to work effectively the inclined escape ducts 62 must restrict the passage of hvdrauiic fluid much more than the access holes, 61 , do

The top two thirds of the plastic blocking sleev e consists of a central perforated wall, 73 through which fluid can pass, and slide πbs, 74 which fit comfortablv in the annular space The bottom third has an inverted L section with a vertical cut off wall. 75, a top horizontal, well fitting, block, 72. and mward facing πbs. 77 so that it slides in the annular space and blocks fluid entry into the lower escape holes, 29 when the sleeve is forced down into its blocking position. Y

In the travelling mode the high pressure fluid lines to and from the damper are blocked bv valves WTien the damper is compressed by a violent road surface hump the hvdrauiic fluid flows up through the L shaped, escape holes at a high velocity unrestncted by the thin elastic tube but restπcted bv the upper disc v alve As the damper expands again, under the heavv coil spπng, 24, reaction, the hvdrauiic fluid flows downwards through the inclined escape holes and the lower escape holes resmctεd by the lower disc valv e and the disc valve coil spπng This travelling mode behaviour is practicallv the same as thε normal beha iour of all single function dampers

The damper is attached to the v ehicle's frame a single central damper securing nut, 69, Figs 1 5 and 6 screwed onto the top end of the inner piston pipe The outer pipe of the piston rod fits through a circular opemng in the frame plate, 18, so that the frame plate is squeezed between the upper spπng support plate, 66. (which is secured to the outer piston pipe) and the top assembly block, 64, cushioned b} two substantial seating washers, 68 Tightening the nut secures the top of the damper to the vehicles frame

The piston rod inner and outer pipes are both secured to the piston and are located axialh bv the top assembh . and b} spacers, 59

When the piston πses the damper cylinder in the parking mode (to extend the dampεr) the fluid in the annular space above the piston has to escapε It does this through the πng of escape holes 61. provided through the wall of the outer piston pipe This fluid then flows upwards in the annular space between the inner and outer pipes which form thε piston rod It becomes the return fluid and is collected by the top assembh and led, via the fluid hose connection. 78, back to the hydraulic fluid reservoir The top assembly also has a pressure fluid hose connection, 80. which connects with the bore of the inner piston pipe,

The top assembly. 20 Figs 5 and 6, is an important part of the invention as it provides a compact design by which pressure fluid can successively feed the double acting hvdrauiic cylinder which the damper becomes m the parking mode of operation From the fluid supply connection. 80, the fluid flows into the top assembly block. 64. through perforations 65, in the top of the inner piston pipe, down the bore of that pipe, and through the thin-walled elastic blocking tube into the bottom chamber of the damper, from where it returns by the same route An elastic seal, 67, prevents leakage, and the open top end of the inner piston pipe is blanked off with a male screw plug, 79, or simph sealed with a fixed end platε

From thε other fluid supply connection, 78, thε fluid flows into the assembly block, 64. and down the annular space, 58, between the inner and outer piston pipes. It pushes down the cut-off sleeve, 71 Fig 2, from position X to position Y and enters the top chamber of the damper through the fluid access holes, 61. and the inclined piston escapε holes. 62 When the cut-off sleeve reaches position Y (against the resistance of the coil spπng 55) it can descend no further and blocks the annular space preventing fluid escaping through escape holes. 29

When the lower damper chamber is pressuπsed the fluid returns from the upper dampεr chambεr by flowing through fluid access holes, 61 , into the annular spacε between the inner and outer piston pipes and back to fluid supply connection. 80. through thε second twin switch valve. 1 8. Fig 7. and back to the reservoir.

Also provided is a gland. 82. Fig. 1 , around the outer piston pipe as u emerges through the damper head. 84, and a rubber cushion. 86. to soften the blow if ihε piston reaches the top of its vertical movement

A dual-function damper is provided at each wheel where lateral mov ement is required, normally either thε back whεels or both front and back wheels of a four heeled vehicle

The hydraulic pressure fluid has to be controlled so that the pressure is applied intermiπεntly and cyclicly to the relevant pair of wheels to cause them to bounce the vehicle up into the air so that the tyres are clear of the road surface repetitively, like a skipper with a skipping rope. To achieve this motion the hydraulic pressure has to be applied to each lower damper chamber until the desired vertical velocity has been achieved

The basic hydraulic circuit is shown in Fig 7 Hydraulic fluid is led from the reservoir. 90, to the hydraulic pump, 88. where the hydraulic fluid pressure is increased From the pump the fluid flows to the mode change valve, 89, where it is directed either to the power steering motor. 1 10. or to the lateral parking system, where it flows into a (twin) motoπsed rotating switch valve, 91, which either blocks the flow or sends it to either the upper, or lower chamber of the damper, and, at the same time directs the return fluid to flow back to the reservoir Th s switch valve is in effect, two rotating (twin) valves mounted on the same drive shaft and dπven by a motor so that each revolution constitutes a cvcle of events which causes the bounce cycle of the relevant wheels of the vehicle. Thε rate of rotation of the twin switch valve determines (with other variables) wheεl bounce height and frequency. Slow rotation will cause slow, high, bouncing, while fast rotation will cause fast, low. bouncing.

Thε basic hydraulic circuit also incorporates a hydro-pneumatic accumulator, 85, (which may be necessary to conserve power useful!} ), a pressure relief valve, 94. (as the hydraulic pump will work continually when the vehicle's engine is running), a non-retum valve. 92. on the pressurε hnε, and a solenoid operated valve. 93. on the return line which must block the return fluid when the vehicle is in travelling mode. A solenoid operated pressure relief valve, 149. will also be required (operated m the travelling mode only) to relieve pressure in the damper chambers when the parking system is operated at a high hydraulic pressure

Each twin switch valve has two main parts, the stator, 136. and the rotor i 38 The relativ e size of stator segments of the two identical v alves is ve important The ma j or segment. 140, which pressurises the lower chambers of the dampers is likely to be about 280° Whilε the minor segment. 142, which pressurises thε upper chambers will hkelv Dε about 75°. and thε blank segment, 144, which blocks the h drauiic flow will be the residue of 5° or less out these will depend on specific cases and couiα v arv greatly

The diagram of the motoπsed. rotating, twin switch valves is intended to snow (Fig 1) that the pressurε fluid is led into the centre of the moving rotor of the first tw in 146. and is directed sequentialh into thε two stator segments from where it flows into the dampers From the dampers the return fluid flows into the stators of the second twin. 148. from where it flows sequential!} into the rotor and back to the reser oir

Thε second function of the αuai-function dampεr provides the bounce for the wheels to leave the road surface Duπng the time that the pair of wheels are both clear of tne road surface a lateral force has to be applied to mov e tne vehicle frame transverse! v mat is sidewavs

The easiεst vvav to move the v ehicle sidewav s. that is lateral!} , is bv an inclined telescopic strut. 100. Fig 4, attached transverselv to the underside, 102. of the v ehicle, preferablv close to thε bumper (or fender) at a pivot. 104

The strut is made up of two main parts the casing, 106. and thε extension, i OS. which is adapted to slide withm the casing The casing is aπached to the pivot by a pivot pin, and a coil spπng. 1 12, within the casing, bears onto the extension head plate, 1 1 , and forces the extension longitudinal)} away from the pivot and against two stop screws, 1 16 A guide plate. 126. is attached to the remote end of the casing The extension has a spade foot, 1 18, with a saw tooth edge at its remote end, which is designed to grip the road surface. 120

In its stowed position the tεiεscopic strut is carried in a horizontal aπitudε, transversely across the vehicle, supported at the pivot and by a lanyard, 122, attached to the extension near the foot The lanyard is controlled by a small winch, 124

To deploy the telescopic strut the winch lowers the strut foot from its stowed, hoπzontal, attitude 100a, to an inclined attitude, 100b. with its foot on the road surface Then, when bouncing starts, the vehicle frame is raised and the pivot raises the strut to a steeply inclined attitude. 100c. the foot having been dragged forward from position A to position B

.As the vehicle then descends the pivot end of the strut descπbes an arc C about the foot until the cπticai strut load is reached at point D when ihe telescopic strut contracts and the pivot descends to point E to complete the first bounce cycle The second bounce cycle takes the pivot to points F. G. and H with the strut foot being dragged from position B to position J. and so on

Finally when the bouncing stops the strut will bε raised back to its hoπzontal stowed, position b} its winch,

Non-rotating struts are installed transversely in handed pairs, thus, to move the v ehicle in the opposite direction the opposite handed strut is deployed. Bouncing will then move the vehicle laterally in the opposite direction to that shown in Fig. 4.

The strength of the strut coil spring has to be chosen carefuiiy The strut has to be prestressed and left in a state of longitudinal stress such that it cames a load equal to that load which will occur in the strut just before the load rises dramatically as the tyre rrεad grips the road surface.

A hydraulically controlled, rotating, multi-directional, telescopic strut. 160. Fig. 8, is piv oted to the end of a bracket, 162, at a pivot, 164.

The bracket is πgidly attached to a cylinder. 166, mounted with a vertical axis, 168. in a housing, 150. which is fixed to some part of the vehicle ' s frame, in such a wav that the cvhndεr can rotate about its axis and is vertically supported

A double-piston, semi-rotary, hydraulic actuator, 152, is fixed above the housing so that it can rotate the cylinder through 360° and back.

A smgie-act g. spπng-retum. hydraulic ram, 154, is mounted on the c hnder's vertical axis above the actuator so that, when pressurised, the piston of the ram. which is attached to the strut by a cable, 1 5, passing axialiv through the cyhnder. releases the strut which fails until its foot rests on the road surface, from where it is raised to its hoπzontal, stowed, position, I όϋa. by the ram spring, when the pressure is released.

The telescopic strut, 160, is (similar to that shown in Fig 4 ) axially spπng-loaded. and pre-stressed, and has a foot adapted to grip the road surface. It is mounted in such a w av that, when stowed, as little as possible protrudes below the under surface. 1 2. of the vehicle.

Hydraulicaiiv-conrrolled, rotary, multi-directional, telescopic, struts are best mounted on the vehicle ' s longitudinal centre line at the front and rear of the vehicle, where they can be deployed to push the vehicle in any horizontal direction during the bounce process

The length of the dual-function damper described will be very similar to the single function damper it replaces but its diameter will be slightly larger. Although one much-used type of single function damper has been shown in the dra ings many different rvpes of telescopic dampers can be adapted to a dual function in a similar manner.

Although hydraulically controlled, rotary, muiti-directionai. telescopic struts would usually bε installed in pairs, Fig. 7 shows only a single strut for simplicity. Pressure fluid is applied to the single acting spring-return hydraulic ram, 354, through a direction control valve, 172; whereas the double-piston rotary hydraulic actuator, 152, has to be controlled by a thronle. 374, to slow down the rotary movement, and a direction control valve. 170. to change from clockwise to anti-clockwise movement, and vice versa.

Given the wheel loading, the tyre distortion under loading, and the damper movement, the required clearance under the tyre at the bounce can be estimated and, applying Newton ' s laws of motion, the acceleration, ram force, and lift time can be calculated


for a particular case from which the required hvdrauiic pressure, power, flow rate, and cvcle time can be obtained.

The hydro-pneumatic accumulator, 85, shown on Fig. 7, will only be necessarv when the power steering hydraulic fluid pump perfor ancε is inadequatε to power the bouncing cycle.

One method of parking is to run the vehicle into the parking space in the travelling mode so that a front wheel ends up close to the kerb and the vehicle ' s longitudinal centre line is at an angle to the kerb With the engine still running the appropπate strut is deployed and the v ehicle is switched to its parking mode whereupon the rear wheels start bouncing and moving lateral 1}' towards the kerb When the appropπate tyre makes contact with the kerb the vehicle is parked

The method of moving out from a parked posiπon is the reverse of the above detailed procedure. With the vehicle in the parking mode thε engine is started and the appropriate strut is deployed for outward movement whereupon thε rear of the vehicle starts to bounce and move laterally When the vehicle's rear is sufficiently far from the kerb thε odε is switched to travelling, the strut is stowed and the vehicle can be dπv en out of the parking space in practically the same tracks as it entered

If ail four (or more) wheels of a vehicle are fitted with dual-function dampers the vehicle can stop opposite the parking space and parallel to the kerb, then bounce lateralh' into the kerb; it can also rotate about a vertical axis if the front and rear struts are set io move the vehicle horizontally in opposite directions.

There are many ways of operating the parking method, man} parts of which can be done automatically For instance it could be arranged that all the driver need do is to stop the vehicle in the appropriate position and indicate which pair (or pairs) of wheels has to move in which direction. Then the driver can change the mode to parking and, with the engine running, wait until the vehiciε has attained the required position automaticailv and electronically.

There are many applications of this lateral movement technique apart from it's obvious use for street parking. It can be used to accurate!}' reposition vehicles or aircraft laterally, longitudinally, and rotationally wherever road, floor, deck, or apron area is at a premium In some cases the required small horizontal thrust could be supplied by manpower or by a small vehicle.

Where a vehicle or aircraft has very soft bouncy tyres or suffers from other difficulties it may be necessary to provide a retractable or portable strut between the wheel axle and the road surface.

It will be appreciated that there are man}' embodiments of apparatus which could be used in thε manner described and that the method couid be applied in many different situations, any number of pairs of wheels (or axles) could be adapted to bounce and move lateralh' in unison or sequentially The pipes carrying the pressure and return fluid do not necessarily need to be concentric, two part-circle D shaped pipes couid be used back-to-back if required, or the pressure and return lines could be attached to the bottom of the damper

chamber or to the damper cap Another method of obstructing the large escape holes t hrouch the piston could be used The foot of the telεscopic strut could be cov ered with elastic material to grip the road surface or it could be a single spike or have man} different shapes The strut could contract against a compressed gas, or the strut could jack-knife at a hin ie instead of contracting Other methods of controlling the pressure fluid intermittently could bε used, for instance a mechanical device in which a heav weight confined in a vertical rube attached to the vehicles frame copies thε vertical accelerations of the vehicle's bodv and makes electrical contacts as it does so

There are man} other ways of blocking the piston escape holes For instance the thm walled elastic blocking tube which blocks the pressure fluid escaping upwards from the lower damper chamber to the upper damper chamber when the lower chamber is being pressunsεd in the parking mode can be replaced by a plastic or other tube which fits neatly into the bore of the inner piston tube supported below by a coil spπng and prevented from πsing up the bore too far bv a circlip within the bore of the inner piston pipe The plastic tube should have a diaphram which restπcts the flow oi the fluid down the bore so that when the lower chamber is being pressurised the tube mov es down the bore to compress the coil spπng cover the escape holes, and stop fluid escaping from thε lower to the upper chamber

Similarlv other ways may be used, instead of the cut-off sleeve. 71 described, to block thε flow of thε fluid escaping downward into the lower chamber when the upper chamber is being pressuπsεd in thε parking mode of operation

There are manv different ways of mounting the pairs ot struts trans erse!} on underside of the vehicle They could be mounted with the pivots close together, astride the vehicle's longitudinal centre line, and the feet remote from the centre line, or with the feet close togεther, in the stowed position, astride the centre line and the pivots remote from it

Thε restriction m the lower end of the elastic tube the damper can bε caused in man} wavs The diameter of the tube can be reduced io a small opening to partial close the end, or the flow can be restncted by a mesh, or a grid or an} combination of restrictions

Other hydraulic circuits can be used to attain the same objectives, and alternative suitable mateπals can be used where appropπate