WO2013041839A1

WO2013041839A1 - A wheel arrangement for a vehicle configured to travel on a pair of rails

Info

Publication number: WO2013041839A1
Application number: PCT/GB2012/052245
Authority: WO
Inventors: Owen Geoffrey JORDAN
Original assignee: Jordan Owen Geoffrey
Priority date: 2011-09-21
Filing date: 2012-09-12
Publication date: 2013-03-28
Also published as: GB201116292D0; GB2494881A; GB2494942B; GB2494942A; GB201202404D0

Abstract

A wheel arrangement (10) for a vehicle configured to travel on a pair of rails is disclosed. The arrangement comprises an axle (20) having a wheel unit (100, 200) disposed at each end thereof, each wheel unit being arranged to travel on one of the pair of rails and comprising an outer wheel (120, 220) disposed adjacent a distal end of the axle and an inner wheel (110, 210) disposed inwardly of the axle with respect to the outer wheel of the respective unit. The inner wheel of each unit comprises a peripherally extending face (110a, 210a) which is arranged to contact the rail along an inner portion thereof, and the outer wheel of each unit comprising a peripherally extending face (120a, 220a) which is arranged to contact the rail along an outer portion thereof.

Description

A WHEEL ARRANGEMENT FOR A VEHICLE CONFIGURED TO TRAVEL ON A PAIR

OF RAILS

The present invention relates to a wheel arrangement for a vehicle configured to travel on a pair of rails.

Referring to figure 1 of the drawings, there is illustrated a conventional wheel arrangement 1 for vehicles, such as trains and trams (not shown), which are configured to travel on a pair of rails 2. The body or passenger compartment of a train is typically supported upon so-called "bogies" or "trucks" which separately comprise a wheel arrangement 1 at a front and rear thereof. Each arrangement 1 typically comprises a wheel 3 disposed at opposite ends of an axle 4 and the wheels 3 are typically rigidly coupled to the axle 4 and as such are constrained to rotate together. The wheels 3 of the arrangement 1 comprise a peripherally extending face 5 which is arranged to contact an upper surface of the rail 2 and a radially extending flange 6 which extends from a peripheral position upon the wheels 3 at an inner side thereof. The flanges 6 are arranged to pass at an inner side of the respective rail 2 and serve to prevent derailment the wheel arrangement 1. A problem with conventional wheel arrangements however, is that it is difficult to manufacture wheels having a circular profile. It is known that a small deviation from a circular profile can result in a wheel centre of one wheel rising and falling with respect to the wheel centre of the other wheel as the arrangement travels along the rails. This results in a mismatch in the tangential speeds of the wheel at the contact portions upon the rails, which due to the rigid coupling of the wheels upon the axle, causes the axle to twist with respect to the rails. This so-called "hunting effect" manifests as a wandering of the wheels from side-to-side upon the rail surface, which at high speeds can cause the wheel arrangement to de-rail. It is also found that the rigid coupling of the wheels to the axles causes the wheels to slip as the vehicle manoeuvres around a bend in the rails, such as at a turning point, which can lead to excessive noise and wear at the wheel rail interface. Moreover, upon manoeuvring around a bend having a reduced turning radius and/or at an increased speed, the flanges upon the wheels are also found to contact the sides of the rails which can again lead to excessive wear and noise.

In accordance with the present invention as seen from a first aspect, there is provided a wheel arrangement for a vehicle configured to travel on a track comprising a pair of rails, the wheel arrangement comprising an axle having a wheel unit disposed at each end thereof, each wheel unit being arranged to travel on one rail of the pair of rails and comprising an outer wheel disposed adjacent a distal end of the axle and an inner wheel disposed inwardly of the axle with respect to the outer wheel of the respective unit,

the inner wheel of each unit comprising a peripherally extending face which is arranged to contact the rail along an inner portion thereof,

the outer wheel of each unit comprising a peripherally extending face which is arranged to contact the rail along an outer portion thereof. Advantageously, the provision of a pair of wheels upon each rail minimises any wandering of the vehicle upon the rails, which is associated with vehicles having conventional wheel arrangements travelling at speed on a track.

Preferably, the outer wheel of each unit further comprises a radially extending flange which extends along a periphery of the wheel at an outer side thereof, and which is arranged to extend at an outer side of the respective rail.

The inner wheel of each wheel arrangement is preferably arranged to rotate in accordance with a rotation of the axle. In contrast, the outer wheel of each arrangement is preferably arranged to rotate independently of a rotation of the axle. The inner wheels of each arrangement are thus arranged to drive the vehicle in accordance with a driving force applied to the axle.

Preferably, the axle comprises a first portion which is coupled to one of the wheel units and a second portion which is coupled to the other wheel unit. The first and second axle portions are preferably arranged to be driven independently to effectively separate the rotation of wheels upon one rail, with the rotation of the wheels upon the other rail. Preferably, the peripherally extending face of each wheel of each unit is arranged to extend substantially parallel to a surface of the rail at a contact region therebetween.

The peripherally extending face of each wheel is preferably angularly orientated with respect to an axis of rotation and is preferably frustrum shaped. Preferably, the faces of the inner and outer wheel of each unit at the respective contact region, are equally but oppositely inclined. The opposite inclination of the wheel faces of the wheels of each unit minimises any wandering of the wheels upon the rails and thus provide for an increased speed of the vehicle upon the rails. In addition, the opposite inclination of the wheel faces upon each rail distributes the load evenly across each rail, thereby minimising any spreading apart of the rails which is typically associated with conventional wheel arrangements.

Preferably, the portion of the peripherally extending face of the inner wheels at the contact region is inclined in a direction which is toward the outer wheel of the respective wheel unit. In contrast, the portion of the peripherally extending face of the outer wheels at the contact region is inclined in a direction which is toward the inner wheel of the respective wheel unit. The wheel arrangement preferably further comprises a separate suspension unit for each wheel. Preferably, the suspension units comprise at least one of a compression spring and/or a pneumatic or hydraulic cylinder.

Preferably, the suspension units separately further comprise an actuator for retractably extending the respective suspension unit in accordance with control signals from a control unit associated with the arrangement. The suspension units preferably further comprise a sensor for sensing the load upon each wheel.

The actuators enable the vehicle weight bearing load applied to each wheel to be varied by varying the length of the respective suspension unit, and also for the respective wheel to be completely lifted off the respective rail. Moreover, the independent operation of the actuators enables the load upon the wheels to be distributed to tilt the vehicle to accommodate a turning motion of the vehicle, or to turn the vehicle at a switching point between rails, for example. The ability to distribute the load of the vehicle across the wheel arrangement enables vehicles to travel upon rails around bends without the need for an outer rail (with respect to the bend) to be raised relative to the inner rail. This enables vehicles to travel on rails in cities and the like since the rails can be sunk in road surfaces, without offering unacceptable variations in road profile.

Preferably, the control unit is arranged to monitor the distribution of loads upon the wheels of the arrangements during vehicle travel and to record the variation in load distribution for a set route. It is envisaged that the recorded information may be uploaded to a central processor via a communications link, so that subsequent vehicles comprising the wheel arrangement which travel on the route can download updated information about the route. Preferably, the control unit is arranged to receive information about the route from track side beacons.

Preferably, the wheel arrangement further comprises a braking arrangement for braking at least two wheels of the arrangement.

In accordance with the present invention as seen from a second aspect, there is provided a vehicle configured to travel on a track comprising a pair of rails, the vehicle comprising at least two wheel arrangements of the first aspect. An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is a sectional view from the front, of a known wheel arrangement for a vehicle configured to travel on a pair of rails;

Figure 2 is a sectional view from the front of a wheel arrangement according to an embodiment of the present invention; Figure 3 is a schematic illustration of a suspension system for a wheel arrangement illustrated in figure 2; and,

Figure 4 is a sectional view from above, of the wheel arrangement illustrated in figure 2.

Referring to figures 2 and 3 of the drawings, there is illustrated a wheel arrangement 10 according to an embodiment of the present invention for a vehicle (not shown) configured to travel upon a track comprising a pair of rails (not shown). The vehicle (not shown) comprises at least two wheel arrangements 10, one disposed at front of the vehicle and one disposed at a rear of the vehicle, however only one wheel arrangement is illustrated in the drawings for clarity.

Each wheel arrangement 10 comprises a first and second wheel unit 100, 200 disposed at opposite ends of an axle 20, each wheel unit 100, 200 being arranged to travel on one rail of the pair of rails (not shown). The wheels of each unit 100, 200 comprise an inner wheel 1 10, 210 which is arranged to travel along an inner portion of the rails of the track and an outer wheel 120, 220 which is arranged to travel along an outer portion of the rails of the track. The wheels comprise a peripherally extending surface or face 1 10a, 120a, 210a, 220a, which is substantially circular in cross-section. The face 1 10a, 120a, 210a, 220a of each wheel 1 10, 120, 210, 220 is arranged to contact the rail at an interface region and the plane of the face 1 10a, 120a, 210a, 220a at the interface is arranged to extend substantially parallel to the plane of the rail. The diameter of the inner wheel 1 10, 210 of each wheel unit 100, 200 however, decreases in a direction which is toward the outer wheel of the respective unit, whereas the diameter of the outer wheel 120, 220 of each wheel unit 100, 200 decreases in a direction which is toward the respective inner wheel. The wheels 1 10, 120, 210, 220 thus comprise a substantially frustrum-shaped face, whereby the inclination of the face 1 10a, 120a, 210a, 220a of the inner wheel and outer wheel of each wheel unit 100, 200 with respect to a rotational axis of the wheels, are substantially equal and opposite at the interface region. The outer wheel 120, 220 further comprises a radially extending flange 130, 230 which extends around the periphery thereof, at an outer side of the outer wheel 120, 220. The flange 130, 230 is arranged to extend downwardly at the outer side of the respective rail of the track and serves to maintain the arrangement 10 upon the rails of the track (not shown).

The axle 20 comprises two separate axle portions 20a, 20b which are coupled at a proximal end thereof to a drive unit 30, which is arranged to drive the axles 20a, 20b into rotation. The distal end of each axle portion 20a, 20b is coupled to the inner wheel 1 10, 210 for driving the inner wheels 1 10, 210 of the arrangement 10; the outer wheels 120, 220 are free to rotate independently of the inner wheels 1 10, 210 and thus the axles 20a, 20b.

The wheel arrangement 10 further comprises an inner brace 140, 240 which is arranged to extend from a chassis (not shown) or housing of the drive unit 30, to a swivel joint 150, 250 disposed adjacent an inner side of the inner wheel 1 10, 210 of each wheel unit 100, 200. The inner wheels 1 10, 210 are independently suspended from the vehicle via a suspension system. The suspension system comprises a separate suspension unit 160, 260 which extends from the underside of the vehicle to the respective swivel joint 150, 250. The outer wheels 120, 220 of each unit 100, 200 are independently supported to the vehicle via an outer brace 170, 270 which extends from a swivel joint 180, 280 disposed at an outer side of the outer wheel 120, 220 of each wheel unit 100, 200 to the vehicle body or chassis (not shown). Each outer wheel 120, 220 is similarly suspended from the vehicle via a separate suspension unit 190, 290 which extends from the underside of the vehicle to the respective swivel joint 180, 280.

The suspension units 160, 190, 260, 290 comprise a compression spring (not shown) having a hydraulic or pneumatic piston (not shown) or similar disposed substantially centrally thereof which may serve to dampen any oscillation of the spring (not shown) during travel. The units 100, 200 further comprise a pneumatic or hydraulic actuator 300 which is positioned between the compression spring (not shown) and the vehicle and is arranged to retractably extend the compression spring (not shown) in accordance with control signals from a control unit 400 associated with the wheel arrangement 10, to vary the load carried by the suspension units 160, 190, 260, 290 and thus the respective wheel 1 10, 120, 210, 220. The hydraulic actuators 300 associated with each of the suspension units 160, 190, 260, 290 of the wheel arrangement 10 are operated via hydraulic system of cylinders as illustrated in figure 3 of the drawings. The compression springs (not shown) and pistons (not shown) associated with the suspension units 160, 190, 260, 290 have been omitted from the system illustrated in figure 3 for clarity. Each wheel unit 100, 200 of the arrangement 10 comprises a separate master cylinder 310, 320 for separately operating each actuator 300 of each suspension unit 160, 190, 260, 290 of the respective wheel unit 100, 200. The master cylinders 310, 320 are separately controlled via a rack and pinion arrangement 330, 340 and pressure sensors (not shown) disposed within each actuator 300 are arranged to transmit signals to the control unit 400 to effect operation of the rack and pinion arrangement 330, 340, via a master rack and pinion arrangement 350.

The control unit 400 is arranged to control the actuators 300 to vary the extension of the suspension units 160, 190, 260, 290, in particular the compression springs (not shown), to vary the load applied to each wheel 1 10, 120, 210, 220 and thus cause the vehicle to tilt if required to accommodate a curve in the track. The control unit 400 is also arranged to cause the actuator 300 to lift one or both of the outer wheels 120, 220 completely off the respective rail of the track (not shown) so that the flange 130, 230 can pass over the rail when negotiating a crossing of rails at a switching point (not shown), for example.

Referring to figure 4 of the drawings, the wheel arrangement 10 further comprises a steering arrangement for steering the wheels 1 10, 120, 210, 220 of each unit 100, 200 along a bend in the track, for example. The steering arrangement comprises a rack and pinion type arrangement 500 which is arranged to operate an Ackerman type linkage 510 disposed between the wheels 1 10, 120, 210, 220 and the rack and pinion 500. The linkage 510 ensures that the inner and outer wheel 1 10, 120, 210, 220 of each wheel unit 100, 200 turn by the appropriate amount to minimise slipping of the wheel 1 10, 120, 210, 220 upon the respective rail to minimise any contact of the flange 130, 230 with the respective rail and also any slipping of the wheels 1 10, 120, 210, 220 on the rails, to minimise noise and excessive wear at the wheel rail interface.

Before setting off along a particular route, the control unit 400 associated with each wheel arrangement 10 is first loaded with the information about the route, such as distance, curves in the track and radii of curvature associated with the curves, inclines, declines and the like. However, it is envisaged that the control unit 400 may further acquire information about the route from track side beacons (not shown) and control units 400 associated with wheel arrangements 10 of other vehicles (not shown). In this respect, the control units 400 may be arranged to communicate with a central processor (not shown) for uploading and downloading details of a particular route to provide an updated account of the route details.

Brakes (not shown) associated with the wheel arrangement 10 are then released and a drive is applied to the first and second axles 20a, 20b to drive the inner wheels 1 10, 210 into rotation. As the drive is applied to the inner wheels 1 10, 210, the control unit 400 is arranged to monitor the load applied to the wheels 1 10, 210 to minimise any wheel slip at the wheel rail interface. As the vehicle travels along the rails of the track, the vehicle will at some point experience a lateral force, which may be caused by wind or from an imperfection in the track, for example. The force causes the vehicle to move laterally upon the rails, for example to the left, and this movement is sensed by the control units 400 via the pressure sensors. The sensed lateral movement is communicated from the sensors (not shown) to the control unit 400 which causes the hydraulic actuator 300 associated with the suspension unit 160, 190, 260, 290 of the left inner wheel 110 to extend to compress the associated spring (not shown), and the actuator 300 associated with the suspension unit 190 of the left outer wheel 120 to retract to cause the associated compression spring (not shown) to extend. The opposite change takes place in the suspension units 260, 290 of the right wheel unit 200. The relative extension of the springs (not shown) creates a load difference between the wheels 1 10, 120, 210, 220 of each unit 100, 200, with the left inner wheel 1 10 and the right outer wheel 220 experiencing more load than the left outer wheel 120 and the right inner wheel 210. This results in a steering force being applied to turn the vehicle to the right. The wheel arrangement 10 is thus arranged to self-centre on a straight track without any relative rotation of the axle relative to the direction of motion.

The side force experienced by the vehicle further brings the larger diameter of the left inner wheel face 1 10a, and the smaller diameter of the left outer wheel face 120a into contact with the rail. This action changes the relative distances between the vehicle and the wheel/rail interface and thus magnifies the difference in loads between the wheels 1 10, 120, 210, 220 of each wheel unit 100, 200. As the vehicle approaches a curve in the track, the relative parameters of the curve, such as radius of curvature, length of curve which are stored in the control unit 400 are used to adjust the suspension units 160, 190, 260, 290 of the wheels 1 10, 120, 210, 220 to adjust the loadings on the separate wheels 1 10, 120, 210, 220 to provide a turning force at the wheel/rail interface which matches that required to move the vehicle round the curve at the design speed. On entering the curve transition, the suspension units 160, 190, 260, 290 ensure that the rate of application of the turn parameters substantially matches the rate of change of that curve and cause the vehicle to tilt into the curve to counteract the centrifugal forces experienced by the passengers (not shown). In the event that the vehicle is required to brake upon entering or during a curve in a track, then the suspension units 160, 190, 260, 290 are further arranged to adjust the loadings on the wheels 1 10, 120, 210, 220 in accordance with the vehicle speed, to ensure that the vehicle remains at the correct orientation and also at the desired position upon the rails. As the vehicle approaches a parting in the track (not shown), namely where a single track splits in two, the control unit 400 is arranged to adjust suspension units of the wheel arrangement 10 to cause the vehicle to follow a particular track, such as a left track. In order to follow the left track, the suspension units 160, 190, 260, 290 firstly adjust the loadings on the individual wheels 1 10, 120, 210, 220 so as to generate a curving force equal to that required to steer the vehicle along the chosen route, as if it were a simple curve, but with the additional requirement that the right outer wheel 220 carries no load - all the load on the right wheel unit 200 is taken by the inner wheel 210. This is achieved by causing the actuator 300 associated with the suspension unit 290 of the right outer wheel 220 to retract to lift the wheel 220 so that the flange 230 can pass over the rail. Once the parting has been traversed, the actuator 300 is then arranged to lower the right outer wheel 220 back onto the rail of the track. For the length of the parting therefore, the vehicle relies on a single flange 130 to prevent in the case of a left hand parting, derailment to the right. In order to negotiate a crossing (not shown) between two tracks of rails, the outer wheel 120, 220 of each unit 100, 200 must be raised so that the associated flanges 130, 230 can pass over the rails. Accordingly, the vehicle is required to travel entirely on the inner wheels 1 10, 210 (which do not comprise flanges) of the wheel arrangement 10.

The control units 400 of the wheel arrangements 10 associated with a vehicle provide for a monitoring and feedback of the loads applied to each wheel 1 10, 120, 210, 220 via the signals sent from the pressure sensors (not shown). The control units 400 are also arranged to monitor the position of the vehicle, namely the physical location of the vehicle and the attitude or tilt of the vehicle to the direction of travel, and uses the information to maintain a substantially horizontal attitude of the vehicle, irrespective of external forces or adjustments to the load. The control units 400 are further arranged to actuate to the hydraulic actuators 300 to enable the vehicle to steer into, around and out of curves, to provide tilt as required for curving and to take the planned route at partings. The control units 300 are further arranged to monitor the drive power being applied to the inner wheels 1 10, 210 of the respective wheel unit 100, 200 to ensure that the power does not exceed the available traction at any individual wheel/rail interface.

From the foregoing it is evident that the wheel arrangement provides for an improved travel upon rails by minimising any rotation of the arrangement relative to the direction of travel and also by minimising wear and noise at the wheel/rail interface.

Claims

1. A wheel arrangement for a vehicle configured to travel on a track comprising a pair of rails,

the wheel arrangement comprising an axle having a wheel unit disposed at each end thereof, each wheel unit being arranged to travel on one of the pair of rails and comprising an outer wheel disposed adjacent a distal end of the axle and an inner wheel disposed inwardly of the axle with respect to the outer wheel of the respective unit,

the outer wheel of each unit comprising a peripherally extending face which is arranged to contact the rail along an outer portion thereof

2. A wheel arrangement according to claim 1 , wherein the outer wheel of each unit further comprises a radially extending flange which extends along a periphery of the wheel at an outer side thereof, and is arranged to extend at an outer side of the respective rail.

3. A wheel arrangement according to claim 1 or 2, wherein the inner wheel of each wheel arrangement is arranged to rotate in accordance with a rotation of the axle.

4. A wheel arrangement according to any preceding claim, wherein the outer wheel of each arrangement is arranged to rotate independently of a rotation of the axle.

5. A wheel arrangement according to any preceding claim, wherein the axle comprises a first portion which is coupled to a one of the wheel units and a second portion which is coupled to the other wheel unit.

6. A wheel arrangement according to claim 5, wherein the first and second axle portions are arranged to be driven independently to effectively separate the rotation of wheels upon one rail, with the rotation of the wheels upon the other rail.

7. A wheel arrangement according to any preceding claim, wherein the peripherally extending face of each wheel is angularly orientated with respect to an axis of rotation of the respective wheel.

8. A wheel arrangement according to any preceding claim, wherein the peripherally extending face of each wheel of each unit is arranged to extend substantially parallel to a surface of the rail at a contact region therebetween. A wheel arrangement according to claim 8, wherein the faces of the inner and outer wheel of each unit at the respective contact region, are equally but oppositely inclined.

A wheel arrangement according to claim 8 or 9, wherein the portion of the peripherally extending face of the inner wheels at the contact region is inclined in a direction which is toward the outer wheel of the respective wheel unit.

A wheel arrangement according to any of claims 8 to 10, wherein the portion of the peripherally extending face of the outer wheels at the contact region is inclined in a direction which is toward the inner wheel of the respective wheel unit.

A wheel arrangement according to any preceding claim, further comprising a separate suspension unit for each wheel.

A wheel arrangement according to claim 12, wherein the suspension units comprise at least one of a compression spring and/or a pneumatic or hydraulic cylinder.

A wheel arrangement according to any of claims 12 or 13, wherein the suspension units separately further comprise an actuator for retractably extending the respective suspension unit in accordance with control signals from a control unit associated with the arrangement.

A wheel arrangement according to any of claims 12 to 14, wherein the suspension units further comprise a sensor for sensing the load upon each wheel.

A wheel arrangement according to claim 14, wherein the control unit is arranged to monitor the distribution of loads upon the wheels of the arrangements during vehicle travel and to record the variation in load distribution for a set route.

A wheel arrangement according to any preceding claim, further comprising a braking arrangement for braking at least two wheels of the arrangement.

A vehicle configured to travel on a track comprising a pair of rails, the vehicle comprising at least two wheel arrangements according to any preceding claim.