Elevator

Abstract

An elevator has a car, arranged to be moved along at least one guide rail in an elevator guide way, the car having a brake for braking the car movement by gripping the guide rail, the brake having a gripping device configured to grip the guide rail and exert a friction force thereon, and an adjusting device configured to adjust the gripping device with respect to its friction force exerted on the guide rails in case of braking. The adjusting device is configured to adjust the gripping device depending on the car position in the elevator guide way. With the above construction, emergency braking is allowed, particularly in higher and high rise elevators with a stopping distance which is mostly unaffected by the position of the elevator car in the guide way.

Claims

1. An elevator comprising: at least one guide rail; a plurality of compensation ropes; a car configured to be moved along the at least one guide rail in an elevator guide way, the car comprising a brake configured to slow and/or stop movement of the car by gripping the at least one guide rail, the brake comprising: a gripping means configured to grip the at least one guide rail to thereby exert a friction force thereon; and an adjusting means configured to adjust the gripping means with respect to the friction force exerted on the at least one guide rail, the adjusting means comprising a transmitting member, wherein the adjusting means is configured to adjust the gripping means depending on a position of the car in the elevator guide way, wherein the transmitting member is a horizontal bar that is horizontal with respect to the at least one guide rail and is connected to the compensation ropes, wherein the transmitting member has outer ends which are configured to apply a transmitting force to the gripping means to alter the friction force exerted by the gripping means to the at least one guide rail, wherein the transmitting force is configured to vary depending on the weight of the compensation ropes at a given elevation, and wherein the adjusting means is configured to pre-adjust the gripping means by setting the gripping means constantly in a desired position before the braking is needed.

2. The elevator according to claim 1, wherein the adjusting means and/or gripping means comprises a limit means configured to limit the friction force exerted by the gripping means on the at least one guide rail, and wherein the adjusting means is configured to adjust a limiting effect of the limit means depending on a position of the car in the elevator guide way.

3. The elevator according to claim 2, wherein said gripping means comprises a gripping element configured to engage the at least one guide rail, and wherein said limit means comprises a spring, the spring forms a yieldable mounting for the gripping element so as to limit the friction force exerted to the at least one guide rail by said gripping element, and wherein said adjusting means is configured to adjust the compression of the spring.

4. The elevator according to claim 3, wherein the gripping element is a counter wedge, and wherein the transmitting member acts on the counter wedge via said spring.

5. The elevator according to claim 2, wherein the limit means is a mechanical limit means.

6. The elevator according to claim 2, wherein said limit means is part of the gripping means.

7. The elevator according to claim 2, further comprising an indication means configured to determine a position of the car in the elevator guide way.

8. The elevator according to claim 5, wherein said gripping means comprises a gripping element configured to engage the at least one guide rail, and said limit means comprises a spring, the spring forms a yieldable mounting for the gripping element so as to limit the gripping force exerted to the at least one guide rail by said gripping element of the gripping means, and wherein said adjusting means is configured to adjust the compression of the spring.

9. The elevator according to claim 1, further comprising an indication means configured to determine a position of the car in the elevator guide way.

10. The elevator according to claim 9, wherein the indication means determines the car position based on a weight of at least one rope portion suspended on the elevator car.

11. The elevator according to claim 10, wherein the at least one rope portion is a compensation rope and/or a car supply cable.

12. The elevator according to claim 1, wherein at least one buffer or damper is provided between the transmitting member and the elevator car to delay/dampen the change of the shape and/or position of the transmitting member.

13. The elevator according to claim 1, wherein said adjusting means is configured to adjust the limit means or gripping means independent of an operational status of the elevator.

14. The elevator according to claim 1, wherein said gripping means comprises at least one gripping wedge.

15. The elevator according to claim 1, wherein said adjusting means is configured to continuously adjust the gripping means.

16. The elevator according to claim 1, wherein the adjusting means is configured to be adjusted depending on a moving direction of the elevator car and/or depending on a car load.

17. A method for adjusting the braking force in an elevator, the method comprising: providing an elevator, the elevator comprising: at least one guide rail; an elevator car; a plurality of compensation ropes; an elevator brake, the brake comprising: a gripping means; and an adjusting means comprising a transmitting member, wherein the transmitting member is a bar having outer ends and is connected to said compensation ropes and is connected to said gripping means at said outer ends; gripping the at least one guide rail with the gripping means such that a friction force is applied to the guide rail; and adjusting the friction force applied to the at least one guide rail by applying a transmitting force to the gripping means with said transmitting member, wherein the transmitting force varies depending on a weight of the compensation ropes at a given elevation.

Description

(1) The invention is now described by the aid of examples in connection with the enclosed drawing.

(2) FIG. 1 shows a side view of an elevator according to the invention.

(3) FIG. 2 shows a side view of a basic layout of a high rise elevator, as technical background of the invention,

(4) FIG. 3 shows a side view of the lower part of an inventive high rise elevator with a basic layout e.g. according to FIG. 2, and

(5) FIG. 4 shows the limit means and gripping means of FIG. 3 in a detailed view.

(6) FIG. 1 shows a schematic drawing of a high rise elevator 10. Hereby it is to be noted that the scale of the drawing does not correspond to real dimensions as the height of an elevator shaft of a high rise elevator is between 30 and 300 m whereas which the width/depth of such a shaft is generally between 2 and 6 m. Furthermore, components which are not relevant for this embodiment as the elevator drive unit, the overspeed governor, the roping as well as diverting pulleys are not shown in this figure. The elevator also may have a counterweight.

(7) The elevator 10 comprises an elevator car 12 running in an elevator shaft 14 along elevator guide rails 16. In this embodiment the elevator guide rails 16 are provided only at one side of the elevator car 12 so that the car 12 is suspended in a so-called “rucksack type suspension”. Of course, also other suspension types can be applied where the elevator guide rails are located for example at opposite sides of the elevator car. The elevator car 12 is guided along the guide rails with guide rollers (not shown) engaging the guide rails 16. The elevator is further provided with a per se known over speed governor (not shown) which is intended to activate a gripping means 18 in case the car 12 exceeds a given threshold velocity. The gripping means 18 may be any known construction, e.g. gripping wedges which are pressed against the guide rail sliding on counter wedges. The elevator 10 further comprises an adjusting means 20 which is configured to adjust the gripping force of the gripping means 18 dependent on the position of the elevator car in the elevator shaft, i.e. the vertical position thereof.

(8) The adjusting means 20 comprises a longitudinal bar 22 extending over substantially the whole shaft length which is tilted with an acute angle α against the vertical axis. The inclination or the size of the angle is such small that over the whole shaft length the horizontal deviation is only a few cm, e.g. 10-20 cm. This tilted bar 22 is fixed to one elevator shaft wall, particularly a shaft wall where no landing doors are provided.

(9) On the car side the adjusting means 20 comprises an actuating lever 24 articulated around a pivot 26. At the lower end of the actuating lever 24 a roller 28 is rotatably mounted, which roller engages one side of the bar 22. The upper end of the actuating lever 24 is connected with a connecting lever 30 being mechanically connected with the gripping means 18 to change the gripping force of the gripping means 18. On this behalf the connecting lever 30 could e.g. be connected with an adjustable counter surface for the gripping wedge to adjust the distance of the counter surface to the guide rail or the connecting lever 30 could be connected with per se known counter wedge or with the base surface or stopper of a gripping wedge to adjust the gripping force of gripping means.

(10) The tilting of the bar 22 with the angle α in the elevator shaft 10 is choosen in such a way that the horizontal displacement of the bar 22 between the upper and lower end of the shaft is about 15 cm. The position of the roller varies accordingly depending on the car position in the shaft. Via the displacement of the roller 28 over the shaft length the gripping means 18 is adjusted via corresponding action of the actuating lever 24 and connecting lever 30 so that in the upper end of the shaft the gripping force of the gripping device is higher and at the lower end the gripping force is lower. This can accomplished e.g. by reducing the distance between the counter surface for the gripping wedge and the guide rails at the upper end of the elevator shaft and by increasing the mutual distance between the counter surface and the guide rail near the lower end of the elevator shaft. The adjustment can also be made by adjusting the position of stoppers to limit the traveling distance of the gripping wedges.

(11) The background for this technology is the following:

(12) In high rise elevators the elevator car is connected with compensation ropes as well as with elevator supply cables. Particularly in high rise elevators where the shaft length is often about 100, even 200 m or 300 m the weight of the car supply cables and the compensation ropes may amount to several tons and therefore may exceed the weight of the car and its load.

(13) By adjusting the gripping force of the gripping means via the adjusting means 20 depending on the car position in the elevator shaft 14 it is possible to maintain the substantially same stopping distance over the whole shaft length in case of emergency braking action of the gripping means. Thus the gripping force can be adjusted to be as high as possible but as low as to avoid an exaggerated deceleration which might harm passengers. Accordingly, with the invention the elevator car is stopped with nearly the same acceleration over the whole shaft distance.

(14) Usually the gripping means 18 is triggered via the over speed governor, i.e. if the car exceeds the nominal velocity for example in case of loss of suspension (all hoisting ropes brake) or the gripping means 18 may be triggered by an interruption of the per se known elevator safety circuit.

(15) FIG. 2 shows a general concept of a high rise elevator 40 according to prior art as technological background of the present invention. The elevator 40 comprises an elevator shaft 42 wherein a car 44 and a counter weight 46 are suspended by hoisting ropes 48. Above the elevator shaft 42 a machine room is provided housing a drive machine comprising a traction sheave 50 and a diverting pulley 52 to adjust the distance between the upwards and downwards going parts of the hoisting ropes 48. The traction sheave 50 drives the hoisting ropes 48 by means of a friction.

(16) The elevator 40 further comprises a compensation rope 54 which is connected between the bottom of the elevator car 44 and the bottom of the counterweight 46. The compensation rope 54 runs over a tension pulley 56 located in the pit of the elevator shaft 42. It shall be understood that the hoisting ropes and the compensation ropes may comprise several separate parallel ropes or belts. Further, a car supply cable 58 is connected to the bottom of the elevator car 44, which provides the energy supply as well as the data connection for the elevator car 44 with the elevator control (not shown). The drawing shows only the upper and the lower parts of the elevator shaft. In reality the elevator shaft may have a length of several 100 m whereas the width and length of the elevator shaft may vary between less than 2 and several m, e.g. 5 m. The elevator also may be a counter weightless elevator and also the diverting pulley 52 in the upper part adjacent to the drive unit 50 is optionally. It shall be further understood that the drive machine unit 50 could also be located in the elevator shaft 42 as a kind of machine room less solution. Also, the compensation rope is optional as the invention allows the sole use of the car supply cable as indication means for the car position. And already the weight of the car supply cable might require the inventive adjustment of the gripping force depending on the car position.

(17) The elevator car of FIG. 2 may use the gripping device and the adjusting means as shown in FIG. 1. On the other hand in the basic layout of FIG. 2 a solution is preferable where the weight of the compensation rope 54 and/or the car supply cable 58 is used to adjust the gripping force of the gripping means as the weight thereof is dependent on the position of the elevator car 44 in the elevator shaft 42, as it is shown in FIG. 3.

(18) FIG. 3 shows the sling bottom beam 60 of an elevator car 62. The figure further shows two guide rails 64, 66 as well as a gripping means 68 co-acting with guide rails 64, 66. A more detailed view of the gripping means 68 is shown in FIG. 4. FIG. 3 does not show the connection between the gripping means 68 and the elevator car, e.g. via mounting beams. At the lower end of the sling bottom beam 60 two bearing points 70, 72 are provided for a transmitting member 74. The transmitting member 74 is a horizontal bar with certain elasticity. The center of the transmitting member 74 is connected with a suspension of the compensation ropes 76, so that the weight of the compensation ropes 76 pull the center of the transmitting member 74 between the two bearings 70, 72 downwards. The center of the transmitting member 74 is further connected with the lower end of buffers 78, the upper ends thereof being connected to the bottom of the sling bottom beam 60 of the elevator car 62. The outer ends 80 of the transmitting member 74 co-act with the gripping means 68 as follows: The outer ends 80 of the transmitting member form stoppers in each gripping means 68 for a spring 82 adjusting the position of a counter wedge 84 (see also FIG. 4) which counter wedge 84 acts in a per se known way as a guiding surface for a gripping wedge 86 provided to engage the respective guide rail 64, 66. As FIG. 4 shows, the counter wedge 84 itself is positioned on a counter surface 87 which is tilted in an acute angle with respect to the corresponding guide rail 64, 66.

(19) In the embodiment of FIGS. 3 and 4 the bearings 70, 72 at the bottom end of the sling bottom beam together with the transmitting member 74 and the springs 82 and counter wedges 84 form an adjusting means to adjust the friction force exerted by the gripping wedges 86 on the guide rails 64, 66.

(20) The weight of the compensation ropes 76 acting on the middle of the transmitting member 74 varies according the position of the elevator car 62 in the elevator shaft. A higher position in the elevator shaft results in an increasing weight of the compensation ropes 76 acting on the center of the transmitting member. As the transmitting member has a certain elasticity, it is bent by the weight of the compensation ropes which leads to a vertical displacement of the ends 80 of the transmitting members which are again affecting via the springs 82 the position of the counter wedges 84 on the counter surfaces 87. The position of the counter wedge 84 again determines the gripping force of the gripping wedges 86 in case of a braking action.

(21) Therefore, the adjusting means are implemented as a pure mechanical transmitting means between the weight of the compensation ropes 76 and the adjustment of the gripping force of the gripping wedges 86. By this means the gripping force can be adjusted according to the position of the elevator car in the elevator shaft and does not necessitate any further installations in the elevator shaft as it is necessary in connection with FIG. 1.

(22) Buffers 78 are provided between the center of the transmitting member 74 and the sling bottom beam 60 of the elevator car 72, which buffers have the following function: In case there is a sudden loss of suspension (e.g. all hoisting ropes brake) the elevator car will rush downwards accelerated by earth gravity. This again leads to the fact that the weight of the compensation ropes 76 acting on the middle of the transmitting member 74 becomes zero which would nullify the adjustment via the adjusting means 72, 74, 82, 84. Therefore, the buffers ensure that any change of the shape of the transmitting member 74, i.e. any change to the bending of the transmitting member 74 may only occur with a dampening or delay of several seconds. This leads to the result that in case of a loss of suspension the weight of the compensation ropes 76 acting on the transmitting member becomes zero but the buffers 78 delay the returning of the shape of the transmitting member 74. The buffers will not prevent the normal bending of the transmitting members affected by the changing weight of the compensation ropes 76 when the elevator car 62 travels with nominal speed through the elevator shaft, as this bending takes place very slowly and thus unaffected by the dampening effect of the buffers 78. Therefore, the only function of the buffer 78 is to prevent sudden change of the bending of the transmitting member 76 as it happens e.g. in case of a loss of suspension.

(23) The transmitting member can also be implemented with a different design. Thus, the transmitting member 74 may be a rigid bar which is not connected to the sling bottom bar 60 via bearings 70, 72 but only via the buffers 78. In this case the compensation rope weight acts via the transmitting member 74 directly to the adjusting parts, i.e. springs 82 and counter wedges 84 of the gripping means 68. In this case the adjustment of the gripping force would not take place by the variation of the shape of the transmitting member but by the variation of the position of the transmitting member. Also in this case the buffers 78 are provided to prevent a sudden change of the position of the transmitting member 74.

(24) FIG. 4 shows the device in braking situation where the gripping wedge 86 has engaged the guide rail after being pulled up by means for actuating the braking (not shown), such as overspeed governor rope connected to the gripping wedge 86. Adjustment before the braking by moving the end 80 in figure downwards has increased the amount of reaction forces that can be produced by the mounting for countering the forces affecting in the gripping wedge 86 because of the friction forces. This is because moving the end 80 downwards has caused that the spring needs to be in more compressed state than before the adjustment, in order to have the same position of the gripping during braking. Thus, the ability of the mounting to produce reaction force has increased. Thus, the adjustment has changed the limit of friction force by affecting the yielding properties of the spring 82 during braking. The spings 82 are preferably compression springs giving increasing force under compression.

(25) For the skilled person the above-mentioned embodiments are not intended to limit the invention but the invention may be carried out within the scope of the appended patent claims.

(26) In the embodiment of FIGS. 3 and 4 the weight of the compensation cables could be substituted by the weight of the elevator supply cables. Furthermore, both the compensation ropes as well as the elevator supply cables could be used for the bending of the transmitting member.

(27) In the embodiments of FIG. 3 the buffers or dampers have a high hysteresis in their action preventing fast changes. Instead of buffers or dampers also a system could be used which has a high inertia, e.g. a high mass protecting against fast changes.

(28) The adjustment of the gripping means 68 in FIGS. 3 and 4 does not necessitate counter wedges but the adjustment can be directly performed on the operation of the gripping wedges. The invention is particularly intended for high rise buildings, i.e. elevator shafts above 100 m, particularly for elevator shafts up to and above 300 m. The adjusting means of the invention allow a quite constant deceleration of the elevator car along the elevator shaft with values preferably between 0.2 and 1.0 g (g=earth gravity).

(29) Furthermore, it is not necessary that the suspension of the compensation ropes and/or elevator supply cables is arranged at the bottom of the elevator car but it can be located at one side of the elevator car, preferably in a certain vicinity to the gripping means.

(30) If gripping means are also provided at the top part of the elevator car mechanical transmitting means, e.g. bars, could be provided to mechanically transfer the adjustment of the lower gripping means 68 of the FIGS. 3 and 4 to the upper gripping means.

(31) Basically, it may be sufficient that only a part of the gripping means of an elevator car are adjusted according to the invention whereas other gripping means are not adjusted according to the car position.