WO2014134636A1

WO2014134636A1 - Collapsible wheel

Info

Publication number: WO2014134636A1
Application number: PCT/ZA2014/000004
Authority: WO
Inventors: Jose Sequeira
Original assignee: Jose Sequeira
Priority date: 2013-03-01
Filing date: 2014-02-25
Publication date: 2014-09-04
Also published as: ZA201506299B

Abstract

The invention provides a collapsible wheel (10) and wheel (10) arrangement for vehicles to allow a vehicle's wheel (10) to collapse under certain circumstances to help prevent the vehicle from rolling over. The arrangement includes a wheel (10), an attachment means (2) arranged on the wheel (10) for attaching the wheel (10) to a vehicle, and collapsing means (1 ) for collapsing the wheel (10) when the vehicle enters a lateral slide.

Description

Title: Collapsible Wheel

Technical Field of the Invention This invention relates to a wheel arrangement especially to such an arrangement of wheels on automotive vehicles.

Background to the invention The inventor has identified that a number of injuries and fatalities related to motor vehicle accidents occur when the vehicle rolls over or flips. Through his observations the inventor has identified a number of factors which contribute to vehicle loosing contact with a road surface. Among these factors are the friction components between the wheels and the road and in addition, the relative position of the centre of gravity of the vehicle in relation to the ground.

It is an object of the invention to reduce the likelihood of a vehicle losing contact with a road surface and rolling or flipping over.

Summary of the Invention

According to a first aspect of the invention there is provided a collapsible wheel arrangement which includes:

a wheel;

attachment means arranged on the wheel for attaching the wheel to a vehicle; and

collapsing means for collapsing the wheel when the vehicle enters a lateral slide.

The wheel may take the form of a rim and tyre combination. The attachment means may take the form of a ball and socket joint. For a preferred embodiment of the invention a section of the rim of the wheel may be shaped to define a socket. A section of the wheel may further be shaped to define the ball or insert which is complementally received within the socket. It is to be appreciated that ball is a description of the function of the insert and does not pertain to shape. The ball may take any form, for instance a spheroidal or a toroidal ball or insert will both be free to rotate and pivot within the socket if not secured.

The collapsing means may be integral to the attachment means, for instance a pin which secures the ball within the socket that can be ejected or severed in order to allow movement of the ball relative to the socket. Alternatively the collapsing means may be arranged on an axle of a vehicle, which, when activated, changes the orientation of the wheel relative to the car. In an extreme case the collapsing means may disconnect the wheels from the car completely, although the inventor does not believe that this embodiment is the best application of the invention

It is to be appreciated that when a vehicle performs a lateral slide, the frictional forces between the tyre and the road surface creates a gripping force which - when the force exceeds a specific boundary - causes the contact point to form a fulcrum about which the centre of gravity of the vehicle pivots. It is this pivoting action that results in the vehicle tipping over.

Through collapsing the wheel by forcing the wheel to tilt relative to the road surface, the high friction contact between the tyre and the road surface is partially broken. By arranging a smaller contact surface with less grip to engage with the road surface the friction between the tyre and the road surface is reduced. This effect in turn decreases the likelihood of the contact point forming a fulcrum about which the centre of gravity of the vehicle can rotate, reducing the chances of the vehicle rolling over.

A further effect of collapsing or tilting the wheel is that the centre of gravity of the vehicle can be shifted. The higher the centre of gravity of a vehicle, the more likely the vehicle will be to roll over, by collapsing the wheels of a vehicle completely, the centre of gravity may be lowered enough to prevent the vehicle from rolling over. According to a second aspect of the invention there is provided a collapsible wheel which includes:

a wheel rim shaped to define a socket central to the rim;

a ball complementally received within the socket;

attachment means arranged on the ball for connection of the ball to a vehicle; fixation means for fixing the ball within the socket to arrest movement and rotation of the ball relative to the socket; and

collapsing means for disengaging the fixation means when activated in use such that the wheel rim can pivot and rotate about the ball.

The wheel rim may be shaped to define protrusions or skid surfaces upon which the vehicle may slide as opposed to the tyre. The rim and protrusions, typically metal, has a lower friction coefficient than a rubber tyre and is therefore even less likely to form a fulcrum about which the vehicle can pivot.

The ball should again not be construed to indicate shape, but relates only to function. The ball may again take any form, for instance a spheroidal or a toroidal ball or insert will both be free to rotate and pivot within the socket if not secured.

The attachment means may take the form of bolt on arrangement commonly used on existing motor vehicles, the rim of a wheel is typically bolted to the hub of a wheel mounting on a vehicle. The fixation means may take the form of one or a plurality of fixing pins arranged to extend through the wall of the socket and the ball. Alternatively the fixation means may take the form of friction fit or frangible clip in arrangement, configured to break before the friction forces between the tyre and the road surface creates a fulcrum.

The collapsing means is configured to disengage the fixation means in order to allow free movement between the ball and the socket. It may be integrally formed within the fixation means, for instance a friction fit which is overcome when the lateral forces exceed specific levels. Alternatively it may be an external mechanism which removes the fixing pins when required, this may be accomplished by using controlled detonations such as currently used in deploying air-bags.

In another embodiment of the invention, for vehicles fitted with a wishbone suspension arrangement, the suspension arrangement can be provided with a collapsing means which will release a part of the suspension, in use, such that a wheel pivots or tilts, e.g. together with a swing arm, into a collapsed state. In such a case all the components of the suspension except the swing arm would have to be released to allow the wheel to pivot.

The inventor believes that there are at least seven scenarios in which the invention can prevent roll over of a vehicle or lower the effect of a crash.

In the first scenario, a typical lateral slide, the centre of gravity will be lowered and friction reduced lowering the chance of a roll over.

In a second scenario, which can be described as tripping, a laterally sliding or moving wheel will hit a low immovable object, such as paving, acting as a fulcrum causing the vehicle to roll over. In such a case, the wheel, in accordance with the invention will collapse and "climb" over the low immovable object and roll over will be prevented.

In a third scenario, should a vehicle slide laterally into an object such as a wall the collapsed wheel, in accordance with the invention, will have collapsed before impact and effectively widen the vehicle. The additional width of material of the collapsed wheel will absorb and dissipate more energy than if the wheel was not collapsed. In effect, the vehicle's effective side crumple zone has been increased.

In a fourth scenario, should a vehicle fitted with a collapsible wheel set be hit side on by another vehicle, the wheels opposite the impacted side will collapse lowering the resistance of the vehicle to move sideways allowing it to be moved further should its wheels not have collapsed. It will be appreciated that the impact energy from the other vehicle will be transferred to the vehicle with the collapsed wheel over a longer period of time allowing the impact energy to dissipate more readily.

Fifthly, should two wheels collapse and slide laterally or diagonally and the remaining upright wheels continue to roll it can be expected that the collapsed wheels have more resistance than the remaining rolling wheels. In this case, the collapsed wheels will act as a kind of pivot and it may be that the vehicle now pivots about the collapsed wheel past the 90 degrees thereby putting the remaining upright wheels in a lateral slide whereby they also collapse to prevent roll over.

In the event that a vehicle slides laterally from a hard surface such as tarmac into a soft surface such as sand or gravel, a wheel will dig into the soft surface creating a bank, which can at some point act as a fulcrum and the vehicle may roll over. In the case of the invention, the wheel can be configured to collapse at the point when the vehicle will tip over and the collapsing wheel will fold over and slide past the bank reducing the chances of a roll over.

In a seventh scenario, a truck trailer can be fitted with wheels according to the invention. Should the truck and trailer go into a lateral slide and the leading wheels of the trailer collapse, the trailer will have less friction than the truck with upright wheels and the trailer will pivot forward about the hitch point so that the truck and trailer forms an L-shape, which may prevent a roll over.

It will be appreciated that the timing of collapsing a wheel or wheels will be computer controlled in response to signals received from an array of sensors such as accelerometers, traction sensors and inclinometers.

Below a mathematical model is proposed in an attempt to predict the effect of collapsing wheels in accordance with the invention. It is to be appreciated that it is merely a proposed model based on a number of assumptions and is not to be interpreted as fact. Mathematical Model

ASSUMPTIONS:

Assume some lateral force acts through the center of mass

Assume that the vehicle rotates about its center of mass (assumption is fair as the rollover will be corrected as soon as tire 1 loses contact with the road surface and before a large angle of rotation is achieved )

Assume the normal force N_t is equivalent to zero (the instant the vehicles tirel loses contact with the road surface is begins to roll)

The effect of the spring forces in the suspension system will be excluded from the analysis

Symbol KEY:

• w - track width of the vehicle

• h— height of the center of mass above the ground ma—the lateral sliding force

m—mass of the vehicle

a -laterial acceleration of the vehicle

g—the acceleration of gravity

NX , N₂— Normal force of the tires

/—the moment of inertia of the vehicle

/— frictional force

ftroad ~ coefficient of road tire friction

a—angular acceleration clockwise is positive

C

rag

h

f ⁼ Ν ^γοαά w

The instant the outer tire losses contact (tire 1). N

N ¾ rag f N f^road

N la

ZNProad QO - ^m9^w = ^{21 a}

2mg _road(K) - mgw = 21 a 2mg[i_road [K) - mgw

2i "- road

If a (angular acceleration is positive the vehicle will roll)

In industry it is known that the track width divided by twice the center of gravity is the static stability factor of the vehicle (ssf) this ratio is used to describe the vehicles tendency to resist rollover.

W

2Ji ~ critical

When the road friction is equal to ssf the tendency to rollover is at the critical point.

W

Inroad 2/ϊ ^{tne ven}'^c'^{es tenc}'^ency ^{t0 ro}" '^s ^'δ" W

When: Inroad ^ ~~ Z the vehicles tendency to roll is low.

Under extreme conditions it is known that Inro d ^{can rar|}g^e from 0.8 tO 1.45

By the collapsing of the wheels fi_road ^{is re}duced, this is achieved by changing the contact substance from rubber on tar to metal on tar.

Values of sliding friction of metal on tar are known to range from

0.2 tungsten carbide) to 0.25(1020 steel) . In the event of engineering a purpose built alloy lower values of friction could potentially be achieved.

A vehicle with a static stability factor of around 1.4 will obtain a 5 star rating according to the NHSTA. A car with a static stability factor of around 1 will receive a 1 star rating. If we assume both a 1 star and a 5 star rated vehicle slide with a road friction of (for example) 0.9 the difference between the 5 star rated vehicles ssf and road friction is 0.5 the difference for the 1 star vehicle is 0.1, the larger the defecate the more stable the car. If the 1 star vehicle is equipped with the collapsing wheel it reduces its friction instantaneously (for example) from 0.9 to 0.25

The difference in ssf and road friction for the 1 star vehicle is now 0.75 the 1 star vehicle has a greater difference in road friction and ssf than 5 star vehicle, effectively making a 1 star vehicle with collapsing wheels more stable than a 5 star rated vehicle without collapsing wheels in rollover tendency.

Brief Description of the Drawings The invention will now be described by way oi non-limiting examples with reference to the accompanying drawings

In the Drawings:

Figure 1 shows a front view of a first embodiment of a collapsible wheel, in accordance with the invention.

Figure 2 shows a cross sectioned side view of the collapsible wheel of Figure 1 , as seen along section lines A-A; Figure 3 shows a cross sectioned side view of the collapsible wheel of Figure 2, in a collapsed state;

Figure 4 shows a cross sectioned side view of a second embodiment of a collapsible wheel; and

Figure 5 shows a cross sectioned side view of collapsible wheel shown in Figure 4, in a collapsed state.

Specific Description of the Invention With reference to the drawings the collapsible wheel, in accordance with the invention, is generally referred to by reference numeral 10.

The wheel 10 includes a wheel rim 4 shaped to define a socket 5 central to the rim 4 for complementally receiving a ball 2. The wheel includes attachment means in the form of nuts 6 and bolts 7 threaded through the ball 2 in order to connect the wheel 10 to the hub 8 of a vehicle (not shown).

Fixation means in the form of pins 1 is provided for fixing the ball 2 within the socket 5 to arrest movement and rotation of the ball 2 relative to the socket 5 when the wheel is in an operative upright state.

For the embodiment shown, collapsing means is integrally formed within the fixation pins 1 , which will shear off when the lateral forces reach a point where the friction between the road surface and the wheel 10 threaten to create a fulcrum about which the vehicle (not shown) will rotate.

From the figures it is clear that the word ball relates to function and not to shape. For the embodiments shown the ball takes a substantially toroidal form that is free to rotate and pivot within the socket when not secured.

Figures 4 and 5 show a further embodiment which does not partially collapse, but fully collapses with the face of the wheel in contact with the road surface. One advantage of this embodiment is that the load of the vehicle is distributed across a greater area and therefore the chances of creating a fulcrum are reduced. Furthermore by completely collapsing the wheel the centre of gravity of the vehicle is lowered which assists in preventing the vehicle from rolling in the event of a lateral slide.

It shall be understood that the examples are provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention

Claims

1. A collapsible wheel arrangement which includes:

a wheel;

2. A collapsible wheel arrangement as claimed in Claim 1 , wherein the attachment means takes the form of a ball and socket joint and wherein one section of the rim of the wheel is shaped to define a socket and another section of the wheel is shaped to define the ball or insert which is complementally received within the socket with the ball being free to rotate and pivot within the socket if not secured.

3. A collapsible wheel arrangement as claimed in Claim 2, wherein the collapsing means is integral to the attachment means.

4. A collapsible wheel arrangement as claimed in Claim 3, wherein the collapsing means is in the form of a pin which secures the ball within the socket that can be ejected or severed in order to allow movement of the ball relative to the socket.

5. A collapsible wheel arrangement as claimed in Claim 1 , wherein the collapsing means is arranged on an axle of a vehicle, which, when activated, changes the orientation of the wheel relative to the car.

6. A collapsible wheel which includes:

a wheel rim shaped to define a socket central to the rim;

a ball complementally received within the socket;

7. A collapsible wheel as claimed in Claim 5 or Claim 6, wherein the wheel rim is shaped to define protrusions or skid surfaces upon which the vehicle may slide should the wheel collapse.

8. A collapsible wheel as claimed in Claim 7, wherein the attachment means takes the form of bolt on arrangement commonly used on existing motor vehicles, the rim of a wheel is typically bolted to the hub of a wheel mounting on a vehicle.

9. A collapsible wheel as claimed in any one of claims 5 to 8, wherein the fixation means may take the form of one or more fixing pins arranged to extend through the wall of the socket and the ball.

10. A collapsible wheel as claimed in any one of claims 5 to 8, wherein the fixation means is in the form of friction fit or frangible clip in arrangement, configured to break before the friction forces between the tyre and the road surface creates a fulcrum.

11. A collapsible wheel arrangement for vehicles fitted with a wishbone suspension, which includes:

a collapsing means arranged on the suspension which will release a part of the suspension, in use, such that a wheel pivots or tilts into a collapsed state.

12. A collapsible wheel arrangement substantially as described herein with reference to the accompanying drawings.

13. A collapsible wheel substantially as described herein with reference to the accompanying drawings.