GB2479061A

GB2479061A - Vehicle with steering guided via overhead runners

Info

Publication number: GB2479061A
Application number: GB201104991A
Authority: GB
Inventors: Anthony Ralph Kennard
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-03-26
Filing date: 2011-03-24
Publication date: 2011-09-28
Anticipated expiration: 2031-03-24
Also published as: GB201005095D0; GB201104991D0; GB2479061B

Abstract

A guided vehicle comprises a front axle and a rear axle. Self steering is provided via both axles and is overridden when an overhead guide track 22 is engaged. The vehicle may draw electric power from the track 22. The vehicle has rotatable overhead guide runner assemblies 42 which can realign steering axles by engaging one of a pair of guides. The guide runners 21 on the assemblies are set forward of the central vertical axis of each assembly and of vertical shafts 44 of the vehicle, At a bend in the track 22, a front guide runner engages the concave edge of a guide and a rear guide runner engages a convex edge so that each realigns its steering axle. When the axles tend to align on radii of the curve, the vehicle follows the track 22. Tolerances between the runners and the guides are set to allow some lateral and vertical movement. Vehicles can be entrained together and can be made reversible on the track. Runner assemblies 42 may be rotated about a transverse horizontal axis (45 see fig 5) for enabling reverse travel.

Description

DESCRIPTION Title

DEVELOPMENT OF A GUIDED VEHICLE

Background

An earlier design (Patent No GB2464472) described a vehicle system which is guided partly by self steering and partly by interaction with an overhead track which can also be used to supply electric power to the vehicle. The nearest comparison is with guided Trolleybuses. This invention extends the earlier design by steering both front and rear axles.

Such a vehicle could be used in materials handling or in public transport. Automatic steering reduces the driver workload to the extent that together with additional systems it could be eliminated. A driver-less system might be implemented without too much risk on a materials handling site where access to the vehicle path by other users can be restricted.

In street use mandatory stops and starts could be controlled by a combination of remote and local systems. Collision avoidance technologies are capable of keeping a vehicle a safe distance away from others as well as making emergency stops. However, it is not yet clear that these technologies can cope safely with erratic behaviour by pedestrians and cyclists. Automated control of public transport vehicles on open streets may not yet be advisable or publicly acceptable.

There may be an exception for applications such as airport transfer systems where pedestrians are confined to certain areas and all vehicle movements are carefully controlled.

Guidance also reduces the effective width which has to allocated to the vehicle so it can operate along a more narrow path. As a public transport vehicle there is an advantage in halting at a platform accurately and with a minimum gap in order to collect passengers, sometimes referred to as docking. The platform can be fitted with safety doors and its floor level can be matched to the vehicle. This would improve passenger safety and help to board passengers with restricted mobility such as wheelchair users and parents with children in pushchairs. By also controlling pedestrian access to the platform, fares could be collected off the vehicle and help to speed up boarding. With appropriately designed double deck vehicles, overhead track and platforms, there could be simultaneous upper deck boarding. Double deck vehicles could reduce the road space used by the vehicle and the ground area of the platforms.

Faster boarding increases the operational capacity of a public transport system. The carrying capacity of a fleet of vehicles is a product of the number of passengers each vehicle can carry and the rate of arrival of vehicles at stops. However, the rate of arrival is a reciprocal function of the time between vehicles or their headway', which is a concept taken from the signalling and control features of a vehicle system. Headway itself is limited by the dwell' time at stops, which is the time taken to disembark and board passengers. Underground trains, and trams, typically have dwell times of under 30 seconds, which is how underground trains can operate with headways of or even 60 seconds. The docking' and boarding process described above helps to provide a short dwell time and thus improve the overall capacity of a system.

The earlier design showed how a vehicle with a front steering axle and a rear fixed axle can be designed to follow an overhead guide track. An overhead guide runner assembly engages the track, with suitable tolerances, and is connected down a vertical axis to the steering axle. When the vehicle drives into a curve the underlying self steering is overridden by interaction of a guide runner with the concave edge of the curved track to adjust the front steering assembly. This turns the steering axle (or axles) inwards and backwards on the concave side to align on radii of the curve. This process works for a single or wagon' axle pivoted about its centre or a composite axle Page 1 assembly with separate stub axles pivoted on king pins.

At the same time the fixed rear axle does not follow the front wheels but is drawn naturally to follow a path inside the curve to a position where the line of the rear axle also aligns on a radius of the curve. With all axles tending to align on radii, a stable configuration exists for the vehicle to travel forwards without further adjustment and to follow the curve of the track.

The earlier vehicle can act like any other tractor unit to tow one or more trailers unconnected to the track and so act as the power unit of an articulated set of vehicles with multiple axles. However freely towed articulated vehicles are hindered by the performance of their turning circles and in some countries are subject to statutory requirements. In the European Union articulated vehicles turning around a fixed point must be able to pass within a corridor between 5.3 and 12.5 metres from that point. This applies to all the body work, including any front and rear overhangs, but is functionally dependent on the lengths of the wheelbases and position of pivot points on the combined vehicles. Each additional articulated unit encroaches further on this turning circle because of the process described above, whereby trailing fixed axles are always drawn inside the path of the front wheels. However, except in special circumstances, vehicle operators tend to choose the lower cost of manufacture and maintenance of non steered rear axles.

The enhanced design shows how both axles of a basic two axle vehicle can be made steering axles guided by the track so the vehicle travels even more closely aligned to the path. With both axles steering the wheelbase can be made longer to achieve the same inner turning circle. A vehicle with both axles steered can be made reversible along the track. Two or more vehicles can be entrained to follow the turning circles set by the track.

This design is possible because at a curve when both axles are steered the rear axle is still drawn inside the curve. This movement can bring an overhead guidance mechanism for the rear axle to interact with the convex edge of the track and turn the lines through the rear steering axles, or axle, inwards and forwards on the concave side towards aligning on radii of the curve. This again tends to form a stable arrangement with the steered front axles so the vehicle follows the curve of the track. This occurs earlier in the adjustment process than with a fixed axle so the centre line of the vehicle lies slightly skewed across the track, rather than running at a much larger angle.

The overhead infrastructure with its crossings and junctions are of the known type and variations described in Patent GB2464472. Also, the overhead infrastructure can be used to supply current to an electric motor as in the known processes of the Patent GB2464472. The possibility remains of replacing mechanical guidance and steering with proximity sensors and servomechanisms on both axles and to use electrical or hydraulic linkages. The guide runner assemblies through which the vehicles interact with the overhead infrastructure have been redesigned to cope with the different tolerances required, especially by a steered rear axle. Part of the redesign of the guide runner assemblies is to make reversibility possible. Alternatives to the design of vehicle chassis and the link between the steering axles and the guide runner assembly are introduced.

Statement of Invention

A guided vehicle which moves by traction on a surface which carries its weight and which has steering front and rear axles, which are self steering either mechanically, electrically, hydraulically or through a servomechanism until interacting with an overhead guide track of known type.

The self steering of each axle being overridden whenever one of a pair overhead guide runners engages the edge of a guide either physically or through a proximity sensor which signals a trigger distance from the edge of a guide, the runners being mounted on an assembly which is rotatable about a vertical axis, so the rotation of the assembly through its linkage either mechanically, electrically, hydraulically or through a servomechanism or servomechanisms linked to the proximity sensor adjusts the steering axle or axles.

Page 2 The position of the guide runners being set forward of the vertical axis of each axle with sufficient lateral tolerances so that each guide runner can engage the track independently so that when the moving vehicle enters a curve in a guide track the leverage of a guide runner connected to the front axle acting on the concave edge of a guide or the signal from a proximity sensor to a servo mechanism or servomechanisms turns the front assembly about its vertical axis and through a linkage overrides the self steering to adjust the front steering axle or axles until the leverage is abated or the signal from the proximity sensor is sufficiently reduced by the front steering axle or axles tending to align on radii of the curve, combined with the leverage of a guide runner connected to rear axle acting on the convex edge of a guide or the signal from a proximity sensor to a servo mechanism or servomechanisms which turns the rear assembly about its vertical axis and through a linkage overrides the self steering to adjust the rear steering axle or axles until the leverage is abated or the signal from the proximity sensor is sufficiently reduced by the rear steering axle or axles also tending to align on radii of the curve thereby allowing the vehicle to follow the path of least resistance which is the curve of the guides.

Advantages This enhanced design is still a guidance system which can be implemented in a simple mechanical form. The additional advantages of this enhanced design are that a vehicle follows the overhead track more closely, can have a longer wheelbase, be entrained with other similar vehicles and can be made reversible while in position on the track.

Introduction to Drawings

The numbering of these drawings follows GB2464472. The overhead track and its guides and junctions and possible electrical supply are of the known type from that patent.

Figure 1 is a side view of a vehicle with steered front and rear axles driven by its rear wheels.

Figure 2 is a rear view of the above vehicle and its driving axle.

Figure 3 is an overhead view of guide runner assemblies with electrical contacts.

Figure 4 is an overhead view of the vehicle of Figures 1 and 2 at a curve of the track.

Figure 5 shows an asymmetric view the guide runner assembly.

Figure 6 is an overhead view of a front wheel drive vehicle at a curve.

Figure 7 is a side view of a non powered vehicle with both axles steered which can be towed or pushed by another vehicle while being itself being guided by the overhead infrastructure.

Figure 8 is an overhead view of a powered vehicle entrained with a non powered vehicle at a curve.

Detailed Description

Figure 1 shows a side view of a vehicle which is steered by both axles and is driven by the rear wheels. This arrangement can be reversed so the vehicle has a powered steering front axle and a steering only rear axle as in Figure 6.

The vehicle has a ladder chassis 39. A motor and gear box 3 have a differential gear in the final transmission. This drives half shafts connected to the rear wheels through constant velocity joints (see Figure 2) set in the vertical king pin axises of the steering 12 (see Figure 2). The steering consists of track rod 14 linked to track rod arms 13 (see Figure 4) which turn the wheels about the Page 3 king pin axises 12.

In front of the motor and gear box a stanchion 41 rises to support a tubular shaft 44 which is held within an outer sleeve. The shaft 44 is rotatable about a vertical axis through the centre of the front steering axle. Steering levers 15 attached to the lower end of the shaft turn the track rod about its centre point. At its upper end the shaft is connected to a modified guide runner assembly 42 which engages the overhead guides 22 as in the known design of Patent GB 2464472.

The steered front axle has a track rod 14 and track rod arms 13, see Fig 4. A front stanchion 41 supports a similar shaft 44 connected to a steering lever 15, see Fig 4. The upper end of the shaft is connected to a modified guide runner assembly 42.

Figure 2 shows the same vehicle from the rear, not showing the steering arrangement rear of the axles (see Figures 1 and 4). The track rod arms would otherwise be shown projecting backwards from the constant velocity joints 40 to meet the track rod as shown in Figure 4. The track rod arms cause the constant velocity joint mountings to rotate about the king axises 12.

Figure 3 shows the modified guide runner assemblies from above on a straight section of the guide track. The vehicle can draw electric current from the track or other circuits or be self powered.

When it draws current from the track pairs of trailing electrical contacts 20 as in GB2464472 are installed. With modification of the guide runner assemblies they are attached to the guide runners 21 (on the powered axle) rather to a longer conducting bearer which is part of the guide arm as in patent GB2464472. For simplicity the electrical contacts left out the drawings when their function is not at issue.

Figure 4 shows a view of the vehicle in Figures 1 and 2 from above at a curve in the guides. The inner runner of the front guide runner assembly engages the inner concave edge of a guide to turn the front steering axles backwards on the concave side so they tend to align on radii of the curve.

Thus the front steering axles tends to follow the curve of the guides. At the same time, the rear axle assembly is drawn inwards towards the centre of the curve 26. At the level of the track, this causes the outer guide runner to be pulled against the convex edge of a guide. This turns the rear steering axles forwards on the concave side so they also tend to align on radii and thus follow the curve of the track.

As with the known design of GB2464472 the physical interaction of the guide runners with the track could be replaced with proximity sensors connected to servomechanisms as part of the guide runner assembly for both axles. Signals from proximity sensors could be used to turn the upper contact assemblies. This rotation could generate command signals to separate servomechanisms controlling the steering axles, which would otherwise maintain the vehicle path until interaction with the track signals a change.

The design from GB2464472 with a non steered rear axle does not allow the vehicle to be guided in reverse along the track. The vehicle would have to de couple from the track to reverse any distance. However, one of the implications of having two steering axles is that with modification the vehicle could be made reversible. If a transverse beam 17 aligned exactly on the focus 26 it would lie on a radius of the curves and thus bisect any chords of the curve at right angles to the radius. By simple geometry the guide runner assemblies could be replicated on both sides of the beam 17 to face and operate in both directions. Thus the vehicle could reverse with the guiding function of the contact assemblies swapping from front to rear and from concave to convex guide.

The guide runners and any electrical contacts would have to be redesigned for both directions of travel, especially through junctions. However the transverse beams would always have to align exactly on radii of the curves, which is not the case in Figure 4 as illustrated. This would introduce more rigidity in the working of the system and allow less tolerance of minor disruptions to the steering of the vehicle. Another option is available in the redesigned guide runner assembly.

Page 4 Figure 5 is an asymmetric view of this modified guide runner assembly. Drawing the rear axle inwards tends to drag the guide arm of the original design against the side of the convex guide of the track, see Figures 4 and 6. Therefore the guide arms have been lowered to extend forwards below the track with vertical extensions at the ends raised to carry the guide runners (and possible electrical contacts).

The modified design of the guide runner assembly enables it to be reversed in position. The guide arms 18 can be rotated 180 degrees about a horizontal axis 45 and the guide runners mountings about a similar horizontal axis 46. The guide runners 21 as illustrated have been slightly modified to work in both directions. With modification, trailing electrical contacts if fitted could also be rotated about a similar horizontal axis. This would need to be done at points in the track where there are no obstructions above or below the guides. In addition, the modified guide arms could be disengaged a short distance horizontally from the guides before rotation to ensure clearances and then re-engaged with the track in the reversed position.

As an alternative to the trailing electrical contacts, a form of pantograph could be used. This would maintain sliding electrical contact over a variable gap while able to operate in both directions. This would have to be designed to act sideways against the guides rather than vertically as in electric locomotives. It would have to incorporate two contacts and follow the principle of GB 2464472 to cross gaps in the guides when they are being used for electrical supply. The distance between the contacts should be greater than the gap in the guides but less than bridging sections of the guides at junctions so they are not both over a gap a the same time. These contacts might be supported by a pantograph in the form of two rhombuses side by side in an arrowhead form and held by springs across their long diagonals. This may be able to keep both contacts in a line parallel with the guide if one of them is passing over a gap and also operate in reverse.

Another option would be to replicate the guide arms and runners behind the axis 45 at an angle below the track and out of contact as a rocker' assembly. To reverse the assembly would be partially rotated through say 45 degrees about the horizontal axis 45 to bring the rear guide arms and runners into use and drop the forward arms and runners out of use.

Fig 6 is an overhead view of a front wheel drive vehicle with steered rear axle at a curve in the track. The steered rear axle is configured differently, but the vehicle is the essentially the same as the one in Figure 4 with the contact assemblies acting in the opposite direction. For the vehicles shown in both Figures 4 and 6 there are important differences between the way the trailing rear axle is guided by the track compared with the process previously described for the leading front axle. The front axle is driven into the curve whilst aligned more or less in the centre of the track. However the rear axle is being dragged out of alignment with the track to bring the guide runner assembly into contact with the convex edge of a guide. Note that in Figures 4 and 6 none of the axles aligns exactly on the focus of the curves 26. The design works on a balance of forces rather than perfect alignments.

Figure 7 shows a side view of a non powered vehicle which can be towed or pushed by another vehicle while guided by the overhead track. As in the powered vehicle of Figure 1 it has a ladder chassis 39. Both steering axles are the same as non powered axle of Figure 1. They have rotatable shafts 44 connected to guide runner assemblies 42. The shafts 44 are supported by stanchions 41. At a curve when towed or pushed the vehicle steering adopts a configuration similar to the one shown for the powered vehicle in Figure 4.

A vehicle such as this which has symmetrical steering (front and rear), can easily be modified to slave the rear axle steering to the front axle by well known and simple means. If rods are attached diagonally to the outer ends of the stub axles (front left to rear right and so forth), the rear wheels follow the front wheels and the rear contact assembly is redundant. The vehicle does follow the track and it is likely that the vehicles in Figure 4 and 6 could be modified mechanically, electrically hydraulically or using servomechanisms to give rear axle steering in the same way.

Page 5 However, what makes guiding a rear steering axle from the track useful is that it means that similar vehicles can be entrained and also made reversible.

Figure 8 shows an overhead view of a motive vehicle entrained with a non powered vehicle as in Figure 7. The pushing motive vehicle is driven by the rear axle like the vehicle shown in Figure 4.

The vehicles are joined by a rigid linking bar 43, pivoted at the ends where it is attached to the ladder chassis of each vehicle. As shown, once the the vehicles have established a turn, the guide runners do not need to be rigidly in contact with the guides in the ways shown in Figures 4 and 6 because simple self steering takes over.

Page 6

Claims

CLAIMS1. A guided vehicle which: moves by traction on a surface which carries its weight and which has steering front and rear axles, which are self steering either mechanically, electrically, hydraulically or through a servomechanism until interacting with an overhead guide track of known type; the self steering of each axle being overridden whenever one of a pair overhead guide runners engages the edge of a guide either physically or through a proximity sensor which signals a trigger distance from the edge of a guide, the runners being mounted on an assembly which is rotatable about a vertical axis, so the rotation of the assembly through its linkage either mechanically, electrically, hydraulically or through a servomechanism or servomechanisms linked to the proximity sensor adjusts the steering axle or axles; the position of the guide runners being set forward of the vertical axis of each axle with sufficient lateral tolerances so that each guide runner can engage the track independently so that when the moving vehicle enters a curve in a guide track the leverage of a guide runner connected to the front axle acting on the concave edge of a guide or the signal from a proximity sensor to a servo mechanism or servomechanisms turns the front assembly about its vertical axis and through a linkage overrides the self steering to adjust the front steering axle or axles until the leverage is abated or the signal from the proximity sensor is sufficiently reduced by the front steering axle or axles tending to align on radii of the curve, combined with the leverage of a guide runner connected to rear axle acting on the convex edge of a guide or the signal from a proximity sensor to a servo mechanism or servomechanisms which turns the rear assembly about its vertical axis and through a linkage overrides the self steering to adjust the rear steering axle or axles until the leverage is abated or the signal from the proximity sensor is sufficiently reduced by the rear steering axle or axles also tending to align on radii of the curve thereby allowing the vehicle to follow the path of least resistance which is the curve of the guides.
2. A guided vehicle according to Claim 1: with overhead assemblies carrying the guide runners which can be turned through 180 degrees about an horizontal axis so the guide runner assemblies can operate when the vehicle travels in the opposite direction; or with overhead guide runner assemblies replicated to work in either direction about an horizontal axis acting as a pivot for a rocker device to hold one half of the assembly at angle below the track and out of use while the other is available to engage the guides and which can be reversed by partial rotation about the rocker axis.
3. A guided vehicle according to Claim 1 or Claim 2 which can be linked with other vehicles as an entrained set of vehicles guided by the overhead track of known type.
4. A guided vehicle according to Claim 1, Claim 2 or Claim 3 which can draw electrical power from the overhead guide track or other circuits of known type.Amendments to the claims have been filed as followsCLAIMS1. A guided vehicle which: moves by traction on a surface which carries its weight and which has steering front and rear axles, which are self steering either mechanically, electrically, hydraulically or through a servomechanism until interacting with an overhead guide track of known type; the self steering of each axle being overridden whenever one of a pair overhead guide runners engages the edge of a guide either physically or through a proximity sensor which signals a trigger distance from the edge of a guide, the runners being mounted on an assembly which is rotatable about a vertical axis, so the rotation of the assembly through its linkage either mechanically, electrically, hydraulically or through a servomechanism or servomechanisms linked to the proximity sensor adjusts the steering axle or axles; the position of the guide runners being set forward of the vertical axis of each axle with sufficient lateral tolerances so that each guide runner can engage the track independently so that when the moving vehicle enters a curve in a guide track the leverage of a guide runner connected to the front axle acting on the concave edge of a guide or the signal from a proximity sensor to a servo mechanism or servomechanisms turns the front assembly about its vertical axis and through a linkage overrides the self steering to adjust the front steering axle or axles until the leverage is abated or the signal from the proximity sensor is sufficiently reduced by the front steering axle or axles tending to align on radii of the curve, combined with the leverage of a guide runner connected to rear axle acting on the convex edge of a guide or the signal from a proximity sensor to a servo mechanism or servomechanisms which turns the rear assembly about its vertical axis and through a linkage overrides the self steering to adjust the rear steering axle or axles until the leverage is abated or the signal from the proximity sensor is sufficiently reduced by the rear steering axle or axles also tending to align on radii of the curve thereby allowing the vehicle to follow the path of least resistance which is the curve of the guides.2. A guided vehicle according to Claim 1: with overhead assemblies carrying the guide runners which can be turned through 180 degrees about an horizontal axis so the guide runner assemblies can operate when the vehicle travels in the opposite direction; or with overhead guide runner assemblies replicated to work in either direction about an horizontal rocker axis acting as a pivot for a rocker device to hold one half of the assembly at angle below the track and out of use while the other is available to engage the guides and which can be reversed by partial rotation about the rocker axis. 3. A guided vehicle according to Claim 1 or Claim 2 * *1..* which can be linked with other vehicles as an entrained set of vehicles guided by the overhead trackofknowntype.4. A guided vehicle according to Claim 1, Claim 2 or Claim 3 which can draw electrical power from the overhead guide track or other circuits of known type. r.. � * S * 1