GB2168019A - Bogie for a stairlift - Google Patents

Abstract

The bogie has a main frame (13, Fig. 1 not shown) pivotally supporting two pairs of sub-frames 14 and 15, meshing gear teeth 20, 21 being provided on the sub-frames so that simultaneous pivotal movement but in the opposite sense will occur. Each sub-frame has a pair of rollers 18 and 19 adapted closely to engage a rail 10, 11 on each side thereof. A secondary frame 22 also is pivoted to the main frame 13 and carries a principle guide roll 26 engaged with rail 10 and a secondary guide roll 25 engaged with rail 11 but on the opposite side thereof, pivotal movement of the secondary frame 22 being transferred to sub-frame 15 by arm 29 having teeth 30 meshed with the teeth of a quadrant 31 attached to that sub-frame. <IMAGE>

Description

SPECIFICATION Bogie for railways This invention relates to a bogie adapted for use on a guide rail (or a supporting and guide rail) and arranged to permit the bogie smoothly to traverse a curve in the rail.

Guide rails are used in very many circumstances, where an article, piece of equipment or the like is to be moved from one place to another, the guide rail serving either solely to guide the movement of the article or piece of equipment, or serving the joint purpose of guiding and also supporting that article or piece of equipment. For example, many industrial processes require the transfer of an article from one place to another, perhaps located on different levels, and if a guide rail with an associ ated bogie arranged to run along that rail is provided to effect that transfer, the bogie must be capable of following the guide rail, including any curves or bends around which that rail may ex tend.

As another example, a supporting and guide rail may be provided along a stairway, the guide rail being mounted adjacent a wall of the stairway and supporting a chair or platform designed to carry a person who might be unable to negotiate the stairs unassisted. Such an arrangement will hereinafter be referred to as a "stair lift" and it will be appreci ated that the supporting and guide rail of such a stair lift must follow the route of the stairs, includ ing curves both in generally horizontal and gener ally vertical planes, perhaps both at the same time, for instance at a landing intermediate the ends of the stairway.

This invention has as a principal object the pro vision of a bogie arranged for use with a guide rail or a supporting and guide rail, which bogie is adapted to permit the easy negotiation of curves in that rail.

Accordingly, this invention provides a bogie adapted to run along a guide rail or a supporting and guide rail, which bogie comprises a main frame, two pairs of rollers each pair of which is carried by a respective sub-frame pivoted to the main frame and the rollers of each pair being ar ranged to engage the rail with the rollers lying one to each side of the rail, the sub-frames being inter connected to perform simultaneous pivoting move ment about their pivotal axes with respect to the main frame but in opposite senses, and there being control means for such pivotal movement of the sub-frames, which control means includes a pair of guide elements arranged to engage the rail with one to each side thereof substantially mid way between the two pairs of rollers, and a drive mechanism which senses movement of the guide elements in a plane perpendicular to the transverse plane containing the pivotal axes of the sub-frames and which imparts consequential movement to the sub-frames thereby to enable the bogie accurately to follow curves in the rail in a plane perpendicular to said transverse plane.

It will be appreciated that with the bogie ar rangement of this invention, relatively tight curves in a plane perpendicular to said transverse plane may easily be negotiated by the bogie, because of the movement imparted to the sub-frames supporting the rollers which run along the rail. Because the bogie as a whole accurately tracks curves in that plane, the bogie may also pass round a simultaneous bend in the transverse plane. This may be contrasted with a bogie having pairs of rollers mounted about fixed axes on the main frame. For such a case, though a curve in one plane may be negotiated, though perhaps with some binding of the bogie on the rail but if the rail simultaneously has a curve in a second plane perpendicular to said one plane, almost certainly the bogie bind severely, unless excessive clearances are provided for the rollers.Such clearances however would give unsatisfactory operation, when the bogie is on a linear part of the rail.

The pivotal axis of each sub-frame should lie substantially on a line interconnecting the axes of rotation of the two rollers supported by that subframe to ensure optimum tracking of the bogie around curves in the rail in a plane perpendicular to the transverse plane containing the pivotal axes of the sub-frames. Though various linkages could be designed to obtain the simultaneous pivoting of the sub-frames, but in the opposite senses about their pivotal axes, most conveniently a gear mechanism is provided for this purpose. For example, each sub-frame may be in the form of an arm extending from its pivotal axis towards the other subframe, the ends of the two arms being toothed about respective pitch circles centred on the subframe pivotal axes and the teeth of one arm meshing with the teeth of the other.By having the tooth pitch circles for the two arms the same, the two sub-frames will perform identical angular movement about their respective pivotal axes, but in the opposite sense in view of the interengagement of the gear teeth.

Conveniently, the pair of guide elements comprises two guide rolls, disposed one to each side of the rail so as to run therealong in much the same manner as the rollers of either sub-frame.

One of the guide elements may comprise a principal guide element connected to the drive mechanism, whereas the other guide element may take the form of a follower, serving to maintain the principal guide element in contact with the rail.

Thus, the principal guide element may be in the form of a relatively large diameter roll, whereas the follower guide element may be also a roll, but of a relatively small diameter. The rolls may be mounted on a secondary frame itself pivoted to the main frame of the bogie, whereby the negotiation of curves in the rail causes the secondary frame to pivot about its pivotal axis. This pivotal movement of the secondary frame should then be transferred to one of the sub-frames by the drive mechanism, which may comprise a further gear mechanism and the movement of that one sub-frame is simultaneously transferred to the other sub-frame by virtue of the interconnection therebetween.For example, the drive mechanism may comprise gear teeth provided on an appropriate part of the sec ondary frame and centred on the pivotal axis thereof, those gear teeth being arranged to interengage the teeth of a quadrant attached to or forming a part of one of the sub-frames and centred on the pivotal axis of the sub-frame. In this way pivotal movement of the secondary frame will cause the sub-frame to be driven through an angle dependent upon the radii of the respective pitch circles of the meshing gear teeth.

Particularly for the case of a stair lift, but possibly also for other applications, it is preferred for the bogie to be self-propelled. For this purpose, a motor may be arranged to drive the bogie along the rail. This may be achieved by providing a rack along the length of the rail, which rack is engaged by a cog wheel itself driven by the motor provided on the bogie. In one particular embodiment of stair lift, a pair of guide rails are provided, interconnected by a plurality of bars lying in the same plane as the rails themselves and extending perpendicularly therebetween.For such an arrangement, the cog wheel may engage with those bars and though a quite independent drive arrangement may be provided for the cog wheel, it is preferred for that cog wheel and possibly also for the motor itself to be mounted on the secondary frame, the axis of the cog wheel being co-axial with the principal roll forming one of the guide elements. For this case, the principal guide roll may also be driven by the motor.

In order to give adequate stability to a stair lift having a rail assembly as described above, it is preferred for the main frame to support two separate pairs of sub-frames, the rollers of one pair of sub-frames running along one rail and being interconnected to perform the said simultaneous pivoting movement, and the rollers of the other pair of sub-frames similarly being disposed but arranged to run along the other rail of the pair thereof. Then, the motor drive assembly on the secondary frame may be disposed between the two rails, to engage the bars. For such an arrangement, it may be convenient to have one guide element (for instance the principal guide roll) running along one rail, with the foller guide element running along the other guide rail.

For a stair lift, the main frame may support a platform or chair which may be provided with an appropriate mechanism to ensure that the platform or chair always remains horizontal, nothwithstanding curves in the guide rails. Thus, the chair or platform may be pivotally connected to the main frame of the bogie, there being an attitude sensor for the platform or chair which attitude sensor controls the operation of a mechanism coupling together the platform or chair and the main frame, the mechanism being operable to maintain the chair or platform horizontal irrespective of the attitude of the main frame moving along the rails.

Attention is directed to our co-pending Patent Application No. (Publication No, 2, A) wherein we have described and claimed an attitude sensor suitable for use in a stair lift to control the operation of a mechanism which maintains horizontal the platform or chair of the lift.

This invention extends to a stair lift whenever provided with a bogie according to this invention as described above.

By way of example only, one specific embodiment of a bogie constructed in accordance with this invention and intended for use with a stair lift will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a side view of the bogie as incorporated in a stair lift, but with certain parts cut away for clarity; Figure 2 is a general perspective view of certain parts of the bogie mechanism, as mounted on the railway of a stair lift; and Figure 3 is a diagrammatic sketch showing how the bogie of this invention negotiates curves in a railway.

Referring to the drawings, it can be seen that the bogie of this invention is intended to run along a railway comprising two tubular guide rails 10 and 11 each of circular cross-sectional shape and interconnected by bars 12 disposed at regular spacings so as to lie in the same plane as contains the axes of the rails 10 and 11, the bars 12 extending perpendicularly between the rails. Though not shown in the drawings, appropriate support means for the railway are provided, which means interconnects with the bars 12, from the underside thereof (with respect to Figure 2). A main frame 13 comprises a pair of side plates joined by cross member (not shown, the frame 13 pivotally supporting two pairs of sub-frames 14 and 15, sub-frame 14 being carried by shaft 16 and sub-frame 15 by shaft 17.Each sub-frame has a pair of rollers 18 and 19 mounted thereon, each roller having a concavely formed periphery whereby the rollers may closely engage a rail 10 or 11. The spacing of the roller axes is such that the rollers of each pair thereof closely engage the associated rail. Moreover, the axes of the rollers 18 and 19 of each sub-frame and the shaft pivotally supporting that sub-frame to the main frame all lie in the same plane.

Each sub-frame 14 and 15 is in the form of an elongate arm extending towards the other arm, the adjacent ends 20 and 21 of each pair of sub-frames 14 and 15 being toothed about pitch circles centred on the shafts 16 and 17 respectively, with the teeth thereof enmeshed, whereby any angular movement of one sub-frame is matched by a corresponding angular movement of the other subframe, but in the opposite sense.

The angular movement just referred to above is controlled by a mechanism adapted to sense curves in the rails 10 and 11 in a plane perpendicular to the plane containing the two rails. This mechanism includes a secondary frame 22 pivoted about co-axial rods 23 and 24 to the side plates of the main frame 13, the secondary frame 22 rotatably supporting a follower roll 25 and a principal guide roll 26. Both rolls 25 and 26 have concavely formed peripheries to engage rails 11 and 10 respectively, with follower roll 25 below rail 11 (in Figure 2) and the principal guide roll 26 above rail 10 (again in Figure 2).The rolls 25 and 26 are supported by the secondary frame 22 such that the points of contact of those rolls with the respective rails are disposed substantially mid-way between the points of contact of the rollers 18 and 19 of the two sub-frames 14 and 15 with the respective rails.

Referring now to Figure 3, it will be appreciated that as the bogie moves around a curve in the rails, such as that shown at 27 or 28, the axis of the principal guide roll 26 must move with respect to the main frame 13 supporting the two subframes 14 and 15. Such movement is accommodated by pivotal movement of the secondary frame 22 about rods 23 and 24 journalled in the main frame 13, so permitting the bogie as a whole smoothly to negotiate the curves.

Affixed to the secondary frame 22 is an arm 29, centred on rod 23 and having teeth 30 formed on the end of that arm remote from rod 23, the pitch circle of those teeth also being centred on rod 23.

These teeth engage with corresponding teeth formed on a gear quadrant 31 fastened to subframe 15 and centred on the shaft 17 thereof. Thus, pivotal movement of the secondary frame 22 will cause arm 29 to perform angular movement about its rod 23, and in turn this causes sub-frame 15 to be moved about its shaft 17. Then, by virtue of the gear interconnection between the two sub-frames, sub-frame 14 also is caused to perform an identical pivotal movement about its shaft 16, but in the opposite sense. By appropriate selection of the pitch circle radii of the teeth 30 on arm 29 and the teeth of the quadrant 31 the two sub-frames 14 and 15 may be caused to perform pivotal movement exactly correct to ensure proper tracking of the rollers 18 and 19 on the sub-frames 14 and 15 as the bogie as a whole negotiates curves in the track.

Such movement is illustrated in Figure 3, with movement in one sense at curve 27 and movement in the other sense at curve 28.

Referring again to Figures 1 and 2, the secondary frame 22 supports an electric motor 32, the output shaft of which is coupled to a cog wheel 33, through an appropriate gear train. The shaft 34 of cog wheel 33 also supports the principal guide roll 26, and the teeth formed around the cog wheel 33 are such that they interengage with the bars 12 of the railway, between the rails 10 and 11. In this way, actuation of the electric motor 32 will cause the sub-frame as a whole to be moved along the rails 10 and 11, and the cog wheel 33 always will maintain proper enmeshment with the bars 12, by virtue of the pivotal movement of the secondary frame 22, controlled by the principal guide roll 26.

Referring again to Figure 1, the main frame 13 has a chair bracket 35 pivotally connected thereto about shaft 36, the bracket supporting a chair seat 37. Also mounted on the frame 13 is an electric motor 38 driving a gear wheel 39 through a gear box 40, the gear wheel 39 meshing with a gear quadrant 41 affixed to the bracket 35 and centred on shaft 36. Actuation of the motor 38 thus causes the relative disposition of the seat 37 and frame 15 to be varied.

Mounted within the gear quadrant 41 is an attitude sensor 42 including a pendulum device 43 and arranged to produce a control output whenever the bracket 35 is out of vertical. This output is used to control the operation of the motor 38, to maintain the bracket substantially vertical irrespective of movements of the frame 15 in a vertical plane.

The attitude sensor may take any appropriate form, though one particular configuration for such a device is shown in our co-pending Application No.to which reference should be made.

Claims (14)

1. A bogie adapted to run along a guide rail or a supporting and guide rail, which bogie comprises a main frame, two pairs of rollers each pair of which is carried by a respective sub-frame pivoted to the main frame and the rollers of each pair being arranged to engage the rail with the rollers lying one to each side of the rail, the sub-frames being interconnected to perform simultaneous pivoting movement about their pivotal axes with respect to the main frame but in opposite senses, and there being control means for such pivotal movement of the sub-frames, which control means includes a pair of guide elements arranged to engage the rail with one to each side thereof substantially mid-way between the two pairs of rollers, and a drive mechanism which senses movement of the guide elements in a plane perpendicular to the transverse plane containing the pivotal axes of the sub-frames and which imparts consequential movement to the sub-frames thereby to enable the bogie accurately to follow curves in the rail in a plane perpendicular to said transverse plane.

2. A bogie according to claim 1, wherein the pivotal axis of each sub-frame lies substantially on a line interconnecting the axes of rotation of the two rollers supported by that sub-frame.

3. A bogie according to claim 1 or claim 2, wherein a gear mechanism is provided to give simultaneous pivoting movement of the sub-frames in opposite senses about their pivotal axes.

4. A bogie according to claim 3, wherein each sub-frame is in the form of an arm extending from its pivotal axis towards the other sub-frame, the ends of the two arms being toothed about respective pitch circles centred on the sub-frame pivotal axes and the teeth of one arm meshing with the teeth of the other.

5. A bogie as claimed in any of the preceding claims, wherein the pair of guide elements comprises two guide rolls, disposed one to each side of the rail so as to run therealong.

6. A bogie according to claim 5, wherein one of said guide rolls acts as a principal guide element in the form of a relatively large diameter roll connected to the drive mechanism, and the other guide roll acts as a follower in the form of a relatively small diameter roll which serves to maintain said principal guide roll in contact with the rail.

7. A bogie according to claim 6, wherein the guide rolls are mounted on a secondary frame itself pivoted to the main frame of the bogie, the arrangements being such that negotiation of curves in the rail causes the secondary frame to pivot abouts its pivotal axis.

8. A bogie according to claim 7, wherein the secondary frame is connected by a further gear mechanism to one of the sub-frames whereby pivotal movement of the secondary frame is transferred to the sub-frames.

9. A bogie according to any of the preceding claims, wherein the bogie is self-propelled, a motor being arranged on the bogie to drive a cog-wheel engaged with a rack disposed along the length of the rail.

10. A bogie according to claim 9 and claim 7 or claim 8, wherein the cog-wheel is mounted on the secondary frame with the axis of the cog wheel coaxial with the principal guide roll.

11. The combination of a bogie according to any of the preceding claims and a rail assembly having a pair of guide rails disposed one above the other and a plurality of bars lying in the same plane as the rails and extending perpendicularly therebetween, wherein the main frame of the bogie supports two separate pairs of sub-frames, the rollers of one pair of sub-frames running along one rail and being interconnected to perform the said simultaneous pivoting movement, and the rollers of the other pair of sub-frames similarly being disposed but arranged to run along the other rail of the pair thereof.

12. The combination according to claim 11, wherein a motor drive assembly is provided on the secondary frame, disposed between the two rails to engage the bars.

13. A bogie substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A stair lift as hereinbefore defined whenever provided with a bogie according to any of claims 1 to 10 or claim 13.