MOUNTING APPARATUS FOR SAFETY BRAKE

Abstract

An elevator car or counterweight, comprising a frame, the frame including an upright structure in which a safety brake is mounted so as to allow for lateral movement of the safety brake relative to the upright structure; at least a first vertically or obliquely extending cantilever spring; wherein a first end of the first cantilever spring is mounted to the upright structure; and wherein the first cantilever spring is arranged such that a point remote from the first end provides a biasing force to the safety brake when the safety brake moves away from a default position. As the safety brake is mounted to allow for lateral movement relative to the frame, the safety brake essentially floats relative to the car or counterweight.

Claims

1. An elevator car or counterweight, comprising a frame, the frame comprising an upright structure (2) in which a safety brake (5) is mounted so as to allow for lateral movement of the safety brake (5) relative to the upright structure (2); at least a first vertically or obliquely extending cantilever spring (6, 7, 8); wherein a first end (9) of the first cantilever spring (6, 8) is mounted to the upright structure (2); and wherein the first cantilever spring (6, 8) is arranged such that a point remote from the first end (9) provides a biasing force to the safety brake (5) when the safety brake (5) moves away from a default position.

2. An elevator car or counterweight as claimed in claim 1, wherein the first cantilever spring (8) is arranged to provide a biasing force to the safety brake (5) when the safety brake (5) moves away from the default position in either lateral direction.

3. An elevator car or counterweight as claimed in claim 2, wherein a second end (10) of the first cantilever spring (8) is mounted to the safety brake (5) rigidly in the lateral direction.

4. An elevator car or counterweight as claimed in claim 1, further comprising a second vertically extending cantilever spring (7); wherein a first end (9) of the second cantilever spring (7) is mounted to the upright structure (2); and wherein the second cantilever spring (7) is arranged such that a point remote from the first end (9) provides a biasing force to the safety brake (5) when the safety brake (5) moves away from a default position; and wherein the biasing force provided by the first cantilever spring (6) is in the opposite direction to the force provided by the second cantilever spring (7).

5. An elevator car or counterweight as claimed in claim 1, wherein a second end (10) of the or each cantilever spring (6, 7, 8) is mounted to the safety brake (5) with freedom to move vertically relative to the safety brake (5).

6. An elevator car or counterweight as claimed in claim 1, wherein the upright structure (2) is substantially U-shaped, such that it comprises a web (3) and two flanges (4).

7. An elevator car or counterweight as claimed in claim 6, wherein the first end (9) of the or each cantilever spring (6, 7, 8) is mounted to the web (3) of the U-shaped upright structure (2).

8. An elevator car or counterweight as claimed in claim 4, wherein: the upright structure (2) is substantially U-shaped, such that it comprises a web (3) and two flanges (4); wherein the first end (9) of the first cantilever spring (6) is mounted to one flange (4) of the U-shaped upright structure (2); and wherein the first end (9) of the second cantilever spring (7) is mounted to the other flange (4) of the U-shaped upright structure (2).

9. An elevator car or counterweight as claimed in claim 8, wherein the first end (9) of the first (6, 8) and/or second (7) cantilever spring is mounted to its respective flange (4) of the U-shaped upright structure (2) via an intermediate spacer (11) that positions the second end (10) of the respective cantilever spring (6, 7, 8) in unbiased contact with the safety brake (5) when the safety brake (5) is in its default position.

10. An elevator car or counterweight as claimed in claim 9, wherein the first (6, 8) and/or second (7) cantilever spring is substantially straight.

11. An elevator car or counterweight as claimed in claim 8, wherein the second end (10) of the first (6, 8) and/or second (7) cantilever spring is shaped so as to position a biasing surface of the respective spring (6, 7, 8) in unbiased contact with the safety brake (5) when the safety brake (5) is in its default position.

12. An elevator car or counterweight as claimed in claim 11, wherein the second end (10) of the first (6, 8) and/or second (7) cantilever spring is curved so as to make a tangential contact with the safety brake (5).

13. An elevator car or counterweight as claimed in claim 1, wherein the or each cantilever spring (6, 7, 8) is arranged to exert its biasing force on the safety brake (5) through a centre of mass of the safety brake (5).

14. An elevator car or counterweight as claimed in claim 1, wherein the or each cantilever spring (6, 7, 8) is arranged to exert its biasing force on the safety brake (5) at a point laterally in line with a mounting point of the safety brake (5) to the upright structure (2).

15. A method of mounting a safety brake (5) to an upright structure (2) of a frame of an elevator car or counterweight so as to allow lateral movement of the safety brake (5) relative to the upright structure (2); the method comprising: mounting a first end (9) of at least a first vertically or obliquely extending cantilever spring (6, 7, 8) to the upright structure (2) such that a point remote from the first end (9) provides a biasing force to the safety brake (5) when the safety brake (5) moves away from a default position.

Description

DETAILED DESCRIPTION

[0025] Certain examples of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0026] FIG. 1 shows a first example of a safety brake mounting arrangement;

[0027] FIG. 2 shows a second example of a safety brake mounting arrangement;

[0028] FIGS. 3a-c show further views of the first example; and

[0029] FIG. 4a-c shows a third example of a safety brake mounting arrangement.

[0030] FIG. 1 shows a floating safety brake arrangement 1 mounted to a vertical upright structure 2 of a frame of an elevator car (or equally of an elevator counterweight). The upright structure 2 has a square U-shaped profile comprising a web (or base) 3 and two flanges (or sides) 4 which extend away from the web 3 in the direction from the elevator car towards a hoistway wall.

[0031] A safety brake 5 is mounted to the web 3 of the upright structure 2 in a floating manner which can better be understood from FIGS. 3a-c. The safety brake 5 is mounted to the upright structure 2 such that it can move laterally (left and right in FIG. 1) with respect to the upright structure 2. This allows the safety brake 5 to move, when it is operated so as to brake, such that it is better aligned with the guide rail against which it brakes, while not requiring any corresponding movement of the upright structure 2 or indeed the car or counterweight to which it is attached. This allows the safety brake to float into the optimal position and allows it to provide full braking force against the guide rail without being hindered by either the mass of the car or counterweight or by the stiffness of the guidance mechanisms such as guide rollers that hold the car or counterweight to the guide rails with allowance for movement (so as to reduce noise and vibration for a more comfortable ride).

[0032] In order to return the safety brake 5 to its centre, i.e. its default position after it is released from a braking operation, a first cantilever spring 6 and a second cantilever spring 7 are provided. The first cantilever spring 6 contacts the safety brake on one side, while the second cantilever spring 7 contacts the safety brake on the other, opposite side. If a braking operation causes the safety brake to move to the left in FIG. 1, i.e. towards the first cantilever spring 6, then that movement will deflect the first cantilever spring 6 such that it will resist the movement and provides a biasing force back towards the default position. Similarly if a braking operation causes the safety brake to move to the right in FIG. 1, i.e. towards the second cantilever spring 7, then that movement will deflect the second cantilever spring 7 such that it will resist the movement and provides a biasing force back towards the default position. The biasing forces provided by these springs are relatively low, being sufficient to ensure reliable return of the safety brake to its default position, i.e. sufficient to overcome any expected frictional forces, but still providing much lower resistance to the safety brake 5 than it would experience if fixedly mounted to the upright structure 2 (i.e. the forces are lower than those required to move the whole car/counterweight, or to compress the guide members). Thus improved safety brake operation is achieved.

[0033] In FIG. 1, the first cantilever spring 6 and the second cantilever spring 7 are substantially elongate strips of metal, each having a first end 9 (lower end in the Figure) which is mounted to the upright structure 2 and a second end 10 (upper end in the Figure) which is shaped into a curve which curves in the direction from the first end 9 towards the second end 10 initially towards the safety brake 5 before making contact with the safety brake 5 and then curving away from the safety brake 5 such that a tangential contact is made with the safety brake 5. The second ends 10 of the cantilever springs 6, 7 are free, i.e. not mounted either to the upright structure 2 or the safety brake 5.

[0034] In FIG. 1, the first end 9 of the second cantilever spring 7 is mounted directly to the flange (or side wall) 4 of the upright structure 2 (e.g. screwed to the flange 4). This is convenient as the safety brake 5 in this example is closer to the right hand flange 4 than the left hand flange 4. On the other hand, the first cantilever spring 6 is mounted indirectly to the flange 4 via an intermediate spacer 11. The spacer 11 reduces the amount of shaping required at the second end 10 of the first cantilever spring 6, ensuring that the cantilever spring 6 has a relatively straight form overall. The first end 9 of the first cantilever spring 6 is fixed (e.g. screwed) to the spacer 11 and the spacer 11 is in turn fixed (e.g. screwed) to the flange 4.

[0035] It will be appreciated that the mount points of the first ends 9 of both the first cantilever spring 6 and the second cantilever spring 7 are vertically spaced from the safety brake 5 due to the cantilever form of the springs 6, 7. Thus the mount points of the cantilever springs 6, 7 do not interfere with the movement of the safety brake 5 and they do not add to the overall space required for the floating safety brake arrangement. This is particularly advantageous in compact elevators where there is very little width available between the flanges 4 of the upright structure 2.

[0036] FIG. 2 shows a variation on the arrangement in FIG. 1. The two arrangements are very similar, but in FIG. 2 the two cantilever springs 6, 7 are both perfectly straight, i.e. they are not shaped (e.g. curved) at the second ends 10. Such straight cantilever springs 6, 7 are very easy and inexpensive to manufacture. In this example, due to the lack of shaping at the second ends 10, both cantilever springs 6, 7 are mounted to the flanges 4 of the upright structure 2 via intermediate spacers 11. The spacer 11 for the first cantilever spring 6 is larger than that shown in FIG. 1, while the second cantilever spring 7 is now mounted to a spacer 11 where it was not so mounted in FIG. 1. A further difference between FIGS. 1 and 2 is that in FIG. 1 the contact points of the cantilever springs 6, 7 (which are close to the second ends 10 thereof, i.e. distal from the first ends 9 thereof) act through the centre of mass of the safety brake 5. By contrast, in FIG. 2, the contact points of the cantilever springs 6, 7 act on the safety brake 5 in line with the bolts 12 which mount the safety brake 5, in floating manner, to the web 3 of the upright structure 2. These two contact arrangements can both be useful depending on the particular arrangement. The optimal contact arrangement can be selected according to the particular arrangement to ensure optimal return of the safety brake 5 to its default position after it is released from a braking action.

[0037] With reference to FIGS. 3a-c, the floating mounting of the safety brake 5 can be seen in more detail.

[0038] FIG. 3a shows the safety brake arrangement 1 of FIG. 1 with the upright structure 2 removed for clarity. In this figure, the rear of the safety brake 5 can be seen (i.e. the side that faces the web 3 of the upright structure 2). A projection, known as the safety heel projection 13, is formed on the back surface of the safety 5 with a flat upper surface that projects into and engages with a corresponding window (the safety heel window) 14 formed in the web 3 of the upright structure 2 (and visible in FIG. 3c). This connection transmits the braking force of the safety brake 5 to the upright structure 2 and thus to the elevator car or counterweight (not shown). In order to accommodate the lateral movement of the floating safety brake arrangement 1, the safety heel window 14 is formed wider than the safety heel projection 13 so that the safety heel projection 13 can move laterally within the safety heel window 14.

[0039] At the lower end of the safety brake 5, the safety brake 5 is held in place against the web 3 of the upright structure 2 in a sliding manner by bolts 12 which pass through bushings 15 and plate 16 and are secured with welded nuts 17. The bushings 15 pass through oblong holes 18 in the web 3 of upright structure 2, the bushings 15 being very slightly longer than the thickness of the upright structure 2 so that the plate 16 does not hold the brake 5 tightly against the upright structure 2, but rather allows relative movement between the two. The oblong holes 18 are longer in the lateral direction than the vertical direction so that they permit lateral movement of the bushings 15 within them as the safety brake 5 moves with respect to the upright structure 2. It will be appreciated that while two oblong holes 18 are shown here, a single elongate slot could be used instead.

[0040] FIGS. 4a-c show another safety brake mounting arrangement 1 in which a single cantilever spring 8 is used to provide bidirectional biasing of the safety brake 5. The operation and advantages of this arrangement are similar to those discussed above in relation to FIGS. 1 and 2. However, the single cantilever spring 8 of FIGS. 4a-c is mounted to the safety brake 5 rather than simply being in contact with the side thereof. As the cantilever spring 8 is mounted to the safety brake 5 (in this example by means of a hole in the second end 10 of the cantilever spring 8 engaging with a projection on the safety brake 5), it will be deflected by movement of the safety brake 5 in either direction. Thus, if the safety brake 5 moves to the left in FIG. 4a, the cantilever spring 8 will be deflected to the left, and if the safety brake 5 moves to the right in FIG. 4a, the cantilever spring 8 will be deflected to the right. In either case, as the spring is rigidly fixed at its first end 9 to the upright structure 2, the cantilever spring 8 will be deflected from its unbiased position and will provide a return biasing force against the safety brake 5 so as to return the safety brake 5 to its default position. When the safety brake 5 is in its default position, the cantilever spring 8 is also in its neutral, unbiased position so that no biasing force is provided on the safety brake 5 unless it moves away from its default position.

[0041] FIG. 4b shows the cantilever spring 8 on its own. The first end 9 has a mounting hole 20 for mounting the cantilever spring 8 to the web 3 of the upright structure 2. The first end 9 also has a rectangular shape which is fitted between corresponding projections 21 on the web 3 of the upright structure 2 so as to prevent rotation of the first end 9 of the cantilever spring 8, thus ensuring that movement of the second end 10 bends the cantilever spring 8 rather than simply pivoting it around the mount point. It will be appreciated that two or more such holes 20 could be used to prevent undesired rotation instead of the rectangular shaped first end 9 and corresponding web projections 21. The second end 10 of the cantilever spring 8 also has a mounting hole 22 for engagement with a projection 23 on the safety brake 5. The mounting hole 22 is slightly elongated in the vertical direction to ensure that braking load does not transfer through the cantilever spring 8, thus ensuring long life of the cantilever spring 8.

[0042] FIG. 4c shows the rear of the upright structure 2 with the upper edge of the safety heel projection 13 engaging with the upper edge of the safety heel window 14 so as to transfer braking force from the safety brake 5 to the upright structure 2. The bushings 15 are also seen extending through the oblong holes 18 with the ability to move laterally therein (the plate 16 is omitted for clarity).

[0043] While the present disclosure has been described with reference to certain exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but that the present disclosure will include all embodiments falling within the scope of the claims.