WO2006128291A1

WO2006128291A1 - Adaptive energy absorbing suspension for a wheel

Info

Publication number: WO2006128291A1
Application number: PCT/CA2006/000888
Authority: WO
Inventors: Geoffrey Boyer; Johannes M. A. Boelen; Amir Khajepour; Raymond Paul Nicosia
Original assignee: GEOFFREY BOYER MARKETING INT'L Ltd
Current assignee: GEOFFREY BOYER MARKETING INT'L Ltd
Priority date: 2005-06-03
Filing date: 2006-06-05
Publication date: 2006-12-07
Anticipated expiration: 2007-12-03
Also published as: CA2509102A1

Abstract

A suspension for a wheel rotatably mounted about an axle, comprising means to resiliently support the axle from movement in the Y and Z planes of the wheel in response to an input to the wheel.

Description

ADAPTIVE ENERGY ABSORBING SUSPENSION FOR AWHEEL

FIELD OF THE INVENTION

The present invention relates generally to a suspension system for the wheel of a vehicle such as a bicycle, automobile or wheelchair, and more particularly to a suspension that resiliency supports the wheel's axle for any path of independent movement in both the Y and Z plane within the suspension's limits.

BACKGROUND OF THE INVENTION

Vehicle suspensions serve to isolate and/or reduce the forces transmitted to the chassis, frame, and/or occupant. All vehicle suspensions to date use some sort of fixed linear and/or fixed planar travel path. This includes suspensions directly or indirectly coupled to a spring and/or dampener, suspensions directly or indirectly coupled to a frame, and/or chassis, and passive and/or adaptive suspensions. In other words, when a conventional vehicle suspension is compressed, due to a wheel of the vehicle impacting an obstacle, for example, the axle of the vehicle always travels the same path. For purposes of this description, the path that an axle follows during suspension compression is called the 'travel path'.

However, it is rare that a vehicle only encounters one impact or simple disturbance when traversing an obstacle or "input". Rather, a wheel is likely to encounter a series of disturbances like those encountered on a rough road. The problem with prior art suspensions is that they do not effectively absorb loads resulting from such impacts. Typically, when a vehicle impacts an obstacle, the orientation of the impact force changes throughout the vehicle suspension's travel path and therefore only a small portion of the travel is truly effective to absorb the impact's energy. Ideally, a truly effective suspension provides a vehicle frame and/or chassis with an ideal path to absorb a load under dynamic disturbance, and the suspension would further dissipate that load in a manner which would provide the occupant in the vehicle a more comfortable, stable platform. SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an improved reactive suspension system that obviates and mitigates from the disadvantages and limitations of the prior art.

One objective of the present invention is to provide a suspension with a reactive travel path that can move with at least two degrees of freedom.

Another objective of the present invention is to provide a suspension which can be incorporated within or adjacent to one or more wheels of a vehicle.

Another objective of the present invention is to provide a suspension system which can absorb more of a vehicle's load disturbances than conventional suspension systems combinations are able to absorb.

Another objective in a preferred embodiment of the present invention is to provide a suspension system which allows a vehicle to use a harder tire with a lower profile without sacrificing comfort or performance.

Yet another objective in a preferred embodiment of the present invention is to provide a suspension system that can be placed either in series or in parallel with a conventional suspension, or maybe be used in place of or as part of a conventional suspension.

Yet another objective in a preferred embodiment of the present invention is to provide a suspension that reduces the unsprung mass of a vehicle.

One or more of the stated objectives is accomplished by a novel suspension system for any type of ground, air, space or marine vehicle. The suspension is a system wherein, during suspension compression, a vehicle wheel's axle is allowed travel in a reactive travel path with at least two degrees of freedom. This reactive travel path distinguishes the present invention from the fixed linear or fixed planar travel paths of the prior art suspensions.

The present suspension has significant advantages over prior art suspensions. While conventional suspensions restrict a vehicle's axle to a single or fixed path, the current suspension allows the vehicle's axle to travel any two-dimensional path. The axle travel path of the current suspension is determined by the input, i.e. for any given input, the suspension responds with the travel path that best absorbs the energy of the input.

Since a vehicle's axle is not restricted to a defined travel path, like fixed linear or fixed planar suspensions, the current suspension can react to a new input at any point of a travel path and create a new reactive travel path. Additionally, since the recovery travel of the suspension is not tied to the impact path, the suspension can recover faster than prior art suspensions.

The current suspension can be embedded in a wheel of any type, thereby packaging the suspension inside the wheel. Alternately the suspension can be embedded within a hub which is then connected to a wheel. When the suspension is embedded within a vehicle's wheels or wheel hubs, the unsprung mass of the vehicle is reduced because only the mass of the wheels is unsprung mass. Its also possible to embed the current suspension however in some applications adjacent the wheel.

According to the present invention then, there is provided a suspension for a wheel rotatably mounted about an axle, comprising means to resiliently support said axle from movement in the Y and Z planes of said wheel in response to an input to said wheel.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention will now be described in greater detail and will be better understood when read in conjunction with the following drawings in which:

Figure 1 is schematical representation of a wheel mounted in a conventional suspension;

Figure 2 is a schematical representation of a suspension in accordance with one aspect of the present invention;

Figure 3 is a schematical illustration comparing the travel path of a conventional suspension to a possible travel path of the present suspension;

Figure 4 is a perspective view of a wheel having a suspension in accordance with another aspect of the present invention;

Figure 5 is a perspective exploded view of a joint forming part of the suspension of Figure 3;

Figure 6 is a perspective view of a wheel having a modified suspension in accordance with another aspect of the present invention;

Figure 7 is a cross-sectional elevational view of a portion of the wheel of Figure 6;

Figure 8 is a perspective view of a wheel having a further modified suspension in accordance with another aspect of the present invention;

Figure 9 is a perspective view of a reactive fork suspension;

Figure 10 is a side-elevational view of the fork suspension of Figure 10 showing how the suspension increases the wheel's trail; Figure 11 is a perspective view of a hub mounted reactive suspension in accordance with another aspect of the present invention;

Figure 12 is an exploded view of the hub of Figure 11 ;

Figure 13 is a side-elevational cross sectional view of the hub of Figure 11 ;

Figure 14 is a perspective view of a sub assembly of the hub of Figure 11 ;

Figure 15 is a perspective, cutaway view of a portion of the interior of the hub of Figure 11 ;

Figures 16,a,b and c illustrates the operation of the hub of Figure 11 ; and

Figure 17 further illustrates the operation of the hub of Figure 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to Figure 1 , this is a schematical representation of the limitations of current suspensions. Current suspensions are not fully effective at absorbing all of the energy encountered by a wheel contacting an obstacle. As can be seen in the Figure, a wheel 1 encountering an input in the nature of obstruction 2 can move only in the fixed linear or fixed planer path permitted by the suspension. Accordingly, while some of th energy from the impact is absorbed by the suspension's damping mechanism, such as springs or shock absorbers 3, or a combination thereof, a vectored component 7 of the energy is transferred directly to the chassis along the impact's reaction line 4. This is one reason that sharp elevated bumps in the road can feel so jarring compared to relatively larger holes or depressions in the road which deflect the wheel more conformingly in its fixed linear or planer path of travel so that the reaction line is more directly into the shock absorber 3. Ideally therefore, rather than a suspension that has a single or fixed path, it is preferable that the path of suspension travel when reacting to an input is the path that will best absorb the input's energy. So instead of the predetermined path of travel in a conventional system, the present reactive suspension proposes that its path of travel is actually determined by the input. This reaction is shown schematically in Figure 2 showing a wheel 1 having a reactive planar suspension 10 where the wheel's axle 5 is resiliency supported relative to the wheel itself such as by means of pivot legs 6 and energy absorbing torsion springs 8. Accordingly, upon the impact of the wheel with the input, the axle can displace itself towards the input along or nearly along the reactive line 4 for more direct absorption of the input's energy and a more comfortable, stable ride for the vehicle's occupant. The axle's ability to react to the input in both the Y and Z planes of the wheel allow the suspension to react dynamically as the orientation of the reaction line changes as the wheel traverses the input. This is shown most clearly in Figure 3 which compares the fixed linear or planer path of travel A-B of a conventionally suspended axle, which must pass through its zero load position X as it moves up (jounce) and down (rebound), and the reactive travel path C of the present suspension which allows the axle to travel any path within the suspension's travel limits. In the present suspension therefore, the axle's travel can start from any position within the travel limits and is not required or restrained to travel through the zero load position X. The zero load position of a conventional suspension is defined as the position of the suspension under static conditions when supporting the design load only.

Reference will now be made to Figure 4 showing a wheel having a reactive planar suspension 10 in accordance with one embodiment of the present invention. This wheel is intended for lighter duty applications such as wheelchairs, carts, trolleys and perhaps bicycles depending on their use. The wheel shown is without a tire.

The wheel comprises an outer tire supporting rim 19 manufactured from any suitable material which will typically be a light, strong metal or moulded plastic. The inner periphery of the wheel is provided with permanently connected support yokes 20, each having a flange 21 to which respective ones of spoke like pivot legs 30 can be connected for rotation about pivot points 26 as will be described below. The inner ends of arms 30 connect pivotably to an axle collar 32 at pivot points 27. Axle collar 32 supports the wheel's axle (not shown) and can also support the rotor of a disc X brake if required, or even a drum break. Each leg 30 comprises an outer link 35 and an inner link 36 pivotably connected to each other at pivot point 38. At least one and up to all three pivot points 26, 27 and 38 of each leg 30 can include a torsion joint that will be described below for energy absorption. If only one of the pivot points will include a torsion joint, it will preferably be pivot points 38 between links 35 and 36. In those pivot points that do not include a torsion joint, the connection to the respective ends of links 35 and 36 will normally be by means of a pin.

Reference is now made to Figure 5 which is an exploded view of a torsion joint 39 wherein like numerals are used to identify like elements.

One of inner or outer links 35 and 36 is formed with a fork 45 with axially aligned apertures 43 formed therein. The apertures are square or some other geometric shape other than round. The other of the inner and outer links 35 or 36 is formed with a knuckle 48 that fits into fork 45 for rotation relative thereto. The knuckle is formed with a transversely extending ribbed or splined aperture 50 that is shaped and sized to closely receive a correspondingly shaped and sized ribbed or splined torsion spring 52. Spring 52 is made of any suitable elastically deformable rubber-like elastomeric material such as urethane.

Torsion spring 52 is itself formed with an axially extending aperture 53 for a metal or plastic spring sleeve 57. Sleeve 57 is permanently bonded to the torsion spring so that there is no relative rotation between the two. The sleeve is tubular and has its own longitudinally extending aperture 60 formed therethrough having the same non- round cross-sectional shape as apertures 43 in forks 45.

With the assembled torsion spring and sleeve inserted into aperture 50, and nylon or teflon washers 63 inserted into recesses 64 in forks 43 which can act as bearings, knuckle 48 can be inserted into fork 45 so that links 35 and 36 are at a predetermined angle to each other. The assembly is then completed by inserting a key 68 through the holes in the forks and aperture 60 through sleeve 57. The assembly is secured together using screws 70 that thread into opposite ends of key 68. The key's cross- sectional shape is the same as apertures 43 in fork 45 and aperture 60 through sleeve 57 so that there is no relative rotation between them. As a result, any flexure in joint 38 is absorbed and dampened by torsion spring 52. The three legs inside the wheel rim act in concert to allow axle collar 32, and the axle supported therein, to move in the Y and Z planes relative to the wheel rim so that the axle can move in direct or near direct opposition to the reaction line from the input. This occurs as leg 30 closest to the input compresses and the legs more distant from the input lengthen. The maximum amount the axle can move is of course the amount by which the legs lengthen as they move into their straight position.

In place of or in addition to washers 63, a known motion control a lock-out mechanism can be installed that can be actuated to lock pivot point 38 against rotation if the user wants to disable the suspension.

Reference will now be made to Figures 6 and 7 showing a variation on the wheel of Figures 4 and 5. The primary difference in this embodiment is that the rim rotates rather than both the rim and legs rotating together. Legs 30 are connected at their outer ends to planetary rollers 80 that engage the V-shaped inner surface 81 of rim 19. As seen most clearly in Figure 7, rollers 80 are formed with a V-groove 84 corresponding in shape and size to the edge of the rim 81. The ends of outer links 36 can include radially extending shoulders 87 to protect the contact between the rollers and the V-rim and also to provide constraint in case one or more of the rollers jumps the V-rim.

Reference will now be made to Figure 8 which shows yet another variant of the wheel of Figures 4 and 5 wherein like numerals have been used to identify like elements. The primary difference in this embodiment is that the axle is suspended by three outer flexible legs 30 and three inner flexible legs 60 of urethane, nylon or any other strong, elastomerically resilient rubber or polymeric material. The shape of inner legs 60 in Figure 8 is merely exemplary, and other shapes are possible. The inner legs can even be smaller copies of outer legs 30. Inner legs 60 can be formed as a full unitary piece as shown in Figure 8 or as individual legs. Either way, the inner ends of the legs connect to or partially enclosed axle collar 32 and the outer ends connected to a concentric inner rim 63. Rim 63 can support or even act as the rotor of a disc break if one is required. Legs 30 will themselves have at least one torsion joint 39 each typically at the connection between links 35 and 36, the torsion joints having the same structure as described above with respect to Figures 4 and 5.

As will be additionally appreciated, the wheel of Figure 8 can be further modified to adopt the use of planetary rollers 80 and a V-rim 81 as shown in Figures 6 and 7.

It is contemplated as well that inner legs 60 can be rigid rather than flexible.

In all of the embodiments described above, the use of three legs 30 and/or 60 is exemplary only. A greater number of legs can be used, and the legs themselves can incorporate not just two links each, but three or more such links, with or without torsion joints 39 between them.

As mentioned above, the present suspension does not need to form part of the wheel itself. It can be incorporated into, for example, the forks used to suspend a bicycle wheel and reference will now be made to Figure 9 to illustrate one way in which this can be done.

The wheel 100 in Figure 9 is a conventional bicycle wheel with a conventional rim 101 , tire 102, spokes 103 and hub 104. Assuming the wheel to be a bicycle wheel, it is suspended on a front fork 120 which generally comprises a steering tube 121 , a cross tube 122, and a pair of fork arms 124 and 125. Each of arms 124 and 125 comprises an upper segment 128 and a lower segment 129. The upper ends of segments 128 are pivotably connected to cross tube 122 at pivot points 130. Segments 128 and 129 connect to each other at pivot point 131 , and the lower ends of segments 129 connect to axle collar 32 at pivot points 132. Pivot points 130 and 131 are torsion joints 39 which can employ the same construction described above with reference to Figure 5.

As will be appreciated, the two segments 128 and 129 of each fork act in concert to allow axle collar 32, and the axle supported therein, to move in the Z and Y planes relative to cross tube 122 so that the axle can move in direct or near direct opposition to the reaction line from the input. This occurs as segments 129 rotate relative to segments 128 and segments 128 rotate relative to cross tube 122. The maximum amount the axle can move is the amount that the torsion springs in the torsion joints will flex under load and this can be predetermined by the selection of the elastomer's properties or, in effect, its spring rate. It should be noted in this regard that urethane torsion springs react very linearly to an input to provide a constant or near-constant spring rate for improved control and ride quality.

In the event that a rider wants to prevent any motion in pivot points 130 and/or 131 , one or both of these can be provided with commercially available lock out mechanisms which effectively lock the joints at whatever angle of incidence the rider chooses so that the forks, or at least the selected pivot point in the forks, becomes rigid. By "angle of incidence" is meant the angle at which upper segments 128 relative to cross tube 122, and the angle of lower segments of 129 relative to upper segments 128.

In addition to the greater stability and comfort provided by the forks as described above, the suspension also improves control in sharp or harsh manoeuvres such as when riding over a large obstacle or turning or braking abruptly by increasing what is called the bicycle's "trail".

The ability to remain upright on a bicycle is primarily due to gyroscopic forces. There is however one additional self-centring tactic employed in bicycle design, and that is the placement of the wheel's contact patch behind the point where the bicycle's steering axis meets the road, which is illustrated by a broken line 140 in Figure 10.

Bicycle's have "trail" when the front wheel's contact patch, which is the portion of the tire in contact with the ground, falls behind the point where the bicycle's steering axis notionally meets the road. The further the contact patch falls behind the steering axis, the more trail there is and the more likely the bike will want to go in a straight line. The degree of the bicycle's determination to steer in a straight line adds to the bike's stability.

As shown in Figure 10, as fork 120 flexes in response to the input from an obstacle, the amount of trail, represented by the distance 145, increases, which assists the rider in straightening out.

As mentioned above, the present suspension can be provided within a wheel's hub, and reference is now made to Figures 11 to 17 which illustrate an example of a hub enclosing a reaction suspension in accordance with one aspect of the present invention.

Figure 11 is a perspective view of the hub 200. Visible in this view is the hub's outer housing 202 with a pair of spaced apart circumferentially extending flanges 203 having regularly spaced apart holes 205 for connection to conventional wheel spokes (not shown). Also visible is one of a pair of end caps 210, one of the caps being located at each end of housing 202. Each cap is rotatable relative to housing 202. Cap 210 is connected to internal components of the hub which will be described below and that are themselves rotatable within housing 202. The end caps and the internal components are connected together by fasteners (not shown) such as screws that extend through holes 207. This connection biases cap 210 against a ring bearing 212 that facilitates rotation of both the cap and the internal components relative to housing 202.

The cap 210 is formed with a slot 215 for the wheel's axle sleeve 220 that receives the wheel's axle (not shown) rotatably there through. The exposed outer ends of the sleeve will engage the lower outer ends of the bicycle's front fork to mount the hub and wheel to the bicycle. Sleeve 220 can be formed with flats 22/(Fig 12) for this purpose.

Reference will now be made to Figures 12 and 13 showing an exploded and cross sectional view of hub 200.

Sleeve 220 fits concentrically within an internal spring spline 230 these two components are spaced from each other by a pair of split bushings 231 which allow the spring spline to rotate freely relative to sleeve 220.

The outer surface of spring spline 230 is formed about its circumference with a plurality of longitudinally extending splines 233 that mate with correspondingly shaped and sized splines formed on the inner surfaces of a pair of outer pinion hubs 235 and an outer spring spline 240. Outer spring spline 240 fits concentrically inside inner pinion hub 250 and a torsion spring 260 is permanently bonded between the two as shown most clearly in the assembly view of Figure 14. Torsion spring 260 will typically be an elastomer such as urethane or polyurethane but can also be a piece of spring steel. Assuming the spring to be an elastomer, its bonding between internal spring spline 240 and inner pinion hub 250 will be in accordance with any technique known in the art and need not therefore be described in greater detail herein.

A pair of spring bushings 265 separate outer pinion hubs 235 from spring 260 and inner pinion hub 250 so that the inner and outer pinion hubs can rotate in opposite directions relative to each other when the wheel's axle is loaded to twist spring 260 as will be described in greater detail below.

Each of inner and outer pinion hubs 235 and 250 are formed with a set of longitudinally extending teeth 270 that mesh with the correspondingly shaped and sized teeth 275 formed on the opposing surfaces of a rack hub 280. Hub 280 fits concentrically around the inner and outer pinion hubs as shown most clearly in Figure 13. The rack hub is itself formed with a pair of circumferentially extending flanges 282 that spot the hub relative to ring bearings 212 so that the rack hub is freely rotatable relative to hub housing 202. As mentioned above, end caps with 210 can be connected to rack hub 280 such as by means of screws 281 that thread into holes 209 formed into opposite ends of the rack hub for this purpose.

Reference will now be made to Figures 16 a, b and c showing the hub in operation. Initially the hub is assembled so that in the default position shown in Figure 16a, which is the position of the hub before the rider mounts the bicycle (or other vehicle) supported by the wheel, sleeve 220 is positioned towards the top of the hub. The hub then moves downwardly relative to sleeve 220 into the sag position shown in Figure 16b as the weight of the rider is applied to the hub. The position of the sleeve is itself maintained by its connection to the vehicle's front fork (not shown), so it is the hub itself that moves downwardly relative to the wheel's axle. This occurs as the weight causes the inner and outer pinion hubs 235 and 250 to counter rotate relative to each other and also relative to rack hub 280. This counter rotation torques spring 260 which is selected so that it limits the amount of counter rotation to position sleeve 220 at approximately the midpoint of its possible travel. The actual location of the sleeve in the sag position will vary a bit depending of course upon the weight of the rider/passenger.

When the wheel encounters an obstacle generating an input, the additional loading causes further counter rotation of the inner and outer pinion hubs and then the hub moves downwardly again into towards its full travel position as shown in Figure 16c. This movement additionally torques torsion spring 260 to absorb the obstacle's impact. The spring will then rebound sleeve 220 into the sag position as the input from the obstacle diminishes.

With reference to Figure 17, weight and/or input applied to the wheel causes the hub to move relative to the sleeve and also causes the sleeve to rotate which allows the hub to move in both the Y and Z planes relative to the wheel's axle in the same manner as described above with respect to the wheel of Figures 4 and 5.

If preferred, a guide piece 290 can be applied to each end of sleeve 202, the guide piece being sized to engage the straight sides of slot 215 to confine the hub to linear movement in the longitudinal direction of the slot.

The above-described embodiments of the present invention are meant to be illustrative of preferred embodiments and are not intended to limit the scope of the present invention. Various modifications, which would be readily apparent to one skilled in the art, are intended to be within the scope of the present invention. The only limitations to the scope of the present invention are set forth in the following claims appended hereto.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A suspension for a wheel rotatably mounted about an axle, comprising means to resiliency support said axle from movement in the Y and Z planes of said wheel in response to an input to said wheel.

2. The suspension of Claim 1 wherein said wheel comprises a rim to support a ground-engaging tire and means to rotatably support said axle, said means to support comprising a plurality of resiliently flexible legs extending between said rim and said means for rotatably supporting said axle.

3. The suspension of Claim 1 wherein said wheel comprises a rim to support a ground-engaging tire and a hub for said axle disposed concentrically within said rim, said means to support being disposed within said hub.

4. The suspension of Claim 1 wherein said suspension comprises a fork for mounting said wheel thereon for rotation of said wheel about its axle relative to the ground, said fork having therein resiliently flexible joints permitting movement of said axle in the Y and Z planes of said wheel.