Procedure and apparatus for testing the safety gear of an elevator

Abstract

 To test a safety gear activated by the slackening of an elevator rope (4), the elevator rope (4) is connected to the elevator car by a point between its ends by means of a testing apparatus, whereupon a tension acting in the direction away from the rope end attached to the elevator car is created in the rope by means of the testing apparatus. The rope is slackened so that it does not carry the weight of the elevator car. By driving the elevator car downwards and by actuating a trigger (10), the tension is removed, whereupon the rope slackness is detected at the rope end attached to the elevator car and the safety gear is activated.

Description

[0001] The present invention relates to a procedure as defined in the preamble of claim 1 and to a testing apparatus as defined in the preamble of claim 2 for an elevator safety gear, especially a safety gear activated by the slackening of an elevator rope.

[0002] An elevator car runs in an elevator shaft along guide rails, guided by roller guides or sliding guides. When the elevator speed is increased too much, safety gears fitted e.g. on the elevator car unit and gripping the guide rails in the elevator shaft are used. In some elevators, especially hydraulic elevators with rope suspension, a safety gear activated on the basis of the slackening of the suspension rope is used. Usually the motive power required for the activation of such a safety gear is taken from a spring in the rope fixture attaching the rope to the elevator car, said spring being loaded by the load applied by the elevator car to the rope fixture. Each rope is provided with a spring. Thus, the slackening of any one of the ropes attached to the rope fixture will release the motive power needed for the activation of the safety gear. When the rope becomes slack, in other words, when the rope ceases to support the elevator car, the load on the spring is removed, thereby releasing the motive power to trigger the safety gear, and consequently the elevator is stopped by safety gear action.

[0003] So far, the reliability of slack-rope safety gears has been tested by checking the functions of different parts separately. However, such a procedure is not sufficiently analogous with reality and may give a misleading illusion of the reliability of the safety gear in a real situation. Testing a slack-rope safety gear in a test arrangement resembling a real case where the rope is slackened, e.g. when the rope comes loose or is broken, is difficult and even dangerous. If an installer had to loosen the rope while the elevator is running, he would have to do it by working in the elevator shaft, e.g. while standing on the top of the elevator car, so he would run a safety risk himself.

[0004] The object of the present invention is to eliminate the drawbacks of prior art and to achieve a completely new type of testing apparatus for the testing of an elevator safety gear. In the procedure of the invention and using the apparatus of the invention, the safety gear is activated by removing the load applied by the elevator rope to the rope fixture in the elevator car. Details of the features of the apparatus of the invention are presented in the claims.

[0005] The invention makes it possible to simulate a situation where one or more of the ropes is slackened as if the rope were broken or released from its rope fixture. The testing apparatus of the invention allows easier and safer testing of the safety gear. The apparatus of the invention can be mounted on the elevator car unit, in the upper part of it. The apparatus can be fitted to any one of the elevator ropes.

[0006] In the following, the invention will be described in detail by the aid of an example by referring to the attached drawings, in which

Fig. 1a

presents a testing apparatus according to the invention, placed on an elevator car unit, in side view before activation,

Fig. 1b

presents a testing apparatus according to the invention, placed on an elevator car unit, in top view,

Fig. 2

presents the testing apparatus after activation, and

Fig. 3

is a simplified representation of a hydraulic elevator with rope suspension.

[0007] Figures 1a and 1b present a testing apparatus mounted on the upper end of a vertical member 1 of the frame of the elevator car unit for the testing of the safety gear. The testing apparatus comprises a frame part 2 fitted on the upper end of the vertical member 1 of the car frame, with a horizontal shaft 3 placed in it. Placed on the horizontal shaft 3 is a turnable cam plate 6 attached to the elevator rope 4 with a tightening element 5. In Fig. 1a, the cam plate is in an inclined position, pointing obliquely upward, in a situation before triggering while the rope is straight. Placed on the other end of the shaft 3 is a locking ring 7 with a notch 8 in its lower part. In the position depicted by Fig. 1a, prior to activation while the rope 4 is still straight, the notch 8 engages one end of a plate-like lever acting as the trigger 10 of the testing apparatus, said plate-like part being pivoted with a pin 9 in the lower part of the frame 2. Prior to the activation of the apparatus, the lever is in a horizontal position, preventing the cam plate 6 from being turned to a lower position, e.g. to a position as illustrated by Fig. 2, by the rope 4 exerting a downward pull on it. For the activation of the testing apparatus, a plate-like triggering stopper 12 is attached to a suitable point on a guide rail 11 in the elevator shaft. When the other end of the lever 10 hits the stopper 12, the apparatus will be activated. The frame of the apparatus consists of a frame plate 13 with box-like parts 14 facing towards the elevator rope 4 fitted to each end of it, the shaft 3 being fitted between the box-like parts, so that the frame part can be fixed to the upper end of the vertical member 1 of the car frame for testing. On the other hand, the stopper 12 comprises a fixing plate 15 by which the stopper can be attached e.g. with screws to the back of the guide rail 11, and an arrester catch 16 bent toward the testing apparatus and comprising a base part oriented in the direction of the lever and a catch part parallel to the fixing plate 15, the lever 10 hitting the catch part when the elevator car is moving.

[0008] The apparatus is used for testing as follows:
One of the elevator ropes 4, which is already held fast in the elevator car by a spring-loaded rope fixture, is connected to the elevator car by means of the testing apparatus. The rope, being attached to the elevator car by different parts of it both via the rope fixture and via the testing apparatus, is released from the hoisting drum or from its anchorage immovable relative to the elevator shaft. To prevent uncontrolled dangling of the released rope in the elevator shaft, the rope end is secured but leaving the rope slack. Thus, the rope will not support the elevator car, but because the testing apparatus exerts a tightening force on the rope, the rope fixture on the elevator car will still feel that the rope is tensioned. By means of the testing apparatus, a sufficient force is maintained in the rope fixture of this particular rope to maintain a sufficient load on the spring in the rope fixture to prevent activation of the safety gear even when the rope is loosened so that it does not carry the weight of the elevator car. When the rope selected for testing has been loosened, the weight of the elevator car is supported by the other suspension ropes. The apparatus is used to activate the safety gear by releasing the load applied to the rope fixture by the testing apparatus, the safety gear being activated by the motive force released by the removal of the load. The release is effected by driving the elevator car in the down direction and allowing the trigger 10 to hit the stopper 12. This removes the tension applied by the cam 6 to the rope 4 and, via the rope, to the rope fixture in the elevator car. Since the rope has been loosened from its anchorage at one end, the slack rope can now follow the spring load of the rope fixture and therefore activates the safety gear. The activation is done at a predetermined height in the elevator shaft. Having four freely selectable positions along the shaft 3 corresponding to the rope 4, the apparatus is designed to function regardless of which one of the ropes has been loosened to trigger the safety gear.

[0009] For the testing, the triggering mechanism is mounted directly on the top part of the vertical member 1 of the car frame, and the tightening element 5 is attached to the one 4 of the ropes which is to be used in the testing. The cam 6 can be moved to different positions along the shaft 3, so the rope to be used can be freely selected.

[0010] The elevator is driven from a higher floor towards the floor to be used for the testing. When the elevator is moving down in the elevator shaft and the lever 10 acting as a trigger hits the triggering stopper 12, which is mounted at a predetermined height relative to the top of the frame of the elevator car unit before the car reaches the landing level, the lever 10 will turn up as depicted with a broken line in Fig. 1a, permitting the cam 6 to turn to a horizontal position, which causes the rope 4 to slacken as illustrated by Fig. 2. The safety gear function of the elevator car, aroused by rope slackness, now detects the slack rope and activates the safety gear if the latter functions correctly. The rope tension exerted by the cam 6 against the rope fixture in the elevator car preferably exceeds the normal tension, because in this case the rope can be tensioned again after the test, making it easier to fix the loosened rope again to its anchorage in the elevator shaft.

[0011] Fig. 3 presents a simplified diagram representing a hydraulic elevator with rope suspension. The elevator car 21 is suspended by means of elevator ropes 4. The elevator ropes 4 are attached to the elevator car 21 via springs 24 in the rope fixture 23 on the car. The other ends of the ropes 4 are fixed to an anchorage 27 immovable relative to the elevator shaft. The hydraulic cylinder 22, mounted in the elevator shaft, carries the ropes by means of a diverting pulley 28 moved by the cylinder. The elevator car is provided with a safety gear 26, which is activated by a lever arrangement 25 if the rope 4 becomes slack, in which case the release of the compression of spring 24 or a spring parallel with it will act upon the lever arrangement.

[0012] It is obvious to the person skilled in the art that different embodiments of the invention are not exclusively limited to the example described above, but that they may be varied within the scope of the claims presented below.

Claims

1. Procedure for testing a safety gear activated by the slackening of an elevator rope (4) attached by one end to the elevator car, characterised in that, using a testing apparatus, the elevator rope (4) is connected to the elevator car at a point between the ends of the elevator rope and, by means of the testing apparatus, a tension acting in a direction away from the rope end attached to the elevator car is generated in the elevator rope to prevent activation of the safety gear, and this rope (4) is loosened so that it does not carry the weight of the elevator car, and that, by driving the elevator car downwards, a trigger (10) in the testing apparatus, whose triggering removes the tension acting in a direction away from the rope end attached to the elevator car, is caused to hit a stopper immovably mounted in the elevator shaft.

2. Testing apparatus for the safety gear of an elevator car supported by elevator ropes (4), said safety gear being fitted to be activated by the motional effect resulting from the slackening of an elevator rope, characterised in that the apparatus comprises:

a component constraining the movement of one selected elevator rope (4), mounted on the elevator car unit, preferably in its upper part, and a trigger (10) designed to be triggered by a stopper (12) in the elevator shaft, said trigger being fitted to release the tension of the selected elevator rope (4) upon such triggering.

3. Apparatus as defined in claim 2, characterised in that the frame part comprises a plate (13) and, fitted to its ends, a frame part (2) designed to be fitted to the elevator car unit, preferably to its upper part, and provided with a horizontal shaft (3), a cam (6) placed on the shaft (3) and connected to one of the elevator ropes (4) via a fixing element (5), a ring-like part (7) placed on the shaft (3) and provided with a notch (8), a lever (10) pivoted on the frame part (2), the second end of said lever being designed to fit into the notch (8) to prevent rotation of the ring-like part (7) and the cam (6), the first end of which lever (10) runs near a guide rail (11), and a triggering part (12) which is mounted at a desired height on the guide rail (11) and which, when hit by the lever (10), causes the lever to turn so that its second end is disengaged from the notch (8) and the cam (6) is released from its position where it keeps the rope (4) tensioned, allowing the rope slackness to act upon the rope fixture and thereby activating the safety gear.

4. Apparatus as defined in claim 3, characterised in that the frame part comprises a plate (13) and box-like parts (14) fitted to its ends, said shaft (3) being fitted between said box-like parts.

5. Apparatus as defined in claim 2, characterised in that the cam (6) can be fitted in different positions along the shaft (3), thus permitting the fixing element (5) to be attached to any one of the ropes (4).

Drawing