Speed limiting device for elevators

Abstract: Limiting device for elevators, that is, it is related with a device which does not permit a threshold speed to be surpassed, in such a manner that once surpassed it provokes the halting of the elevetor by means of the actuation of a "safety" which causes it to become wedged. The speed limiter object of the invention can work in both the upward and downward directions and is mounted on the elevator car.

Description: OBJECT OF THE INVENTION The object of the present utility model is a speed limiting device for elevators, that is, it is related with a device which does not permit a threshold speed to be surpassed, in such a manner that once surpassed it provokes the halting of the elevator by means of the actuation of a "safety" which causes it to become wedged. The speed limiter object of the invention can work in both the upward and downward directions. Consequently the present invention lies within the safety devices employed in hoisting apparatus and more specifically within the speed limiting devices for elevators. BACKGROUND OF THE INVENTION To date the commercially available speed limiting devices are not mounted on the elevator car itself, being situated instead in the machine room implying the taking up of space. In addition to being located in the machine room, the distance is increased between the speed limiting device and the safety, it being necessary to make use of a leading block at the other extremity of the elevator shaft, presenting problems in the operation of the device in the upward direction since vibrations occur, as well as taking up space in the well. In the speed limiting devices that are not attached to the car itself there is no transmission between the limiter and the safety or wedging system, since the cable itself is responsible for said transmission, for which reason the safety is wedged after the cable slips on the sheave. Thus the purpose of the present utility model is to overcome the aforementioned drawbacks, to which end a speed limiting device for elevators is presented which avoids the location of the limiter in the machine room, with the subsequent taking up of space, as well as of a leading block, developing for this a device which is mounted on the car itself and transmits the wedging force equally in the upward and the downward direction, in which the wedging system is actuated before the cable slips on the sheave, not making use of the cable itself to transmit the wedging force to the safety, but which is instead performed by means of an auxiliary rod and in which the operation of the limiter in the upward direction is improved since the vibration is suppressed. Moreover with the drawback in the current systems whereby the wedging force for the safety is transmitted by the cable itself, the situation could arise that in the event of the cable breaking, the wedging system would not be informed and wedge the car. It is known in the State of the Art the existence of a speed limit device as the one disclosed in US 3908801 patent. In this patent the limit device is based on the actuation over a safety device or brake shoes which engage side rails, the transmission of the actuation to said brakes shoes is based on a large number of different pieces which interact between them, it does not work in both senses, upwardly and downwardly, and it lacks of any device which limits the travel of centrifugal masses outwardly. So the objective of the present invention is to overcome the aforementioned drawbacks carrying out a speed limit device which overcomes such difficulties. DESCRIPTION OF THE INVENTION The proposed utility model for speed limiting device for elevators consists of a device which is mounted on the car itself or on the framework, to which end it comprises a structure that is secured to the car, on said structure are arranged two sheaves, the limiting sheave and the leading block which serves to change the direction of the cable. The limiting sheave incorporates a centrifugal system which consists of two centrifugal masses that rotate with the sheave itself and come into action when a determined speed threshold is exceeded. When, through excessive velocity, the centrifugal masses are displaced outwards one of the two, depending on the rotation according to whether the motion is upward or downward, strikes against the arms of a spider, the latter being joined to the structure of the limiter thereby resulting in the stoppage of said sheave. Before the cable starts to slip on the sheave itself, the wedging signal is transmitted to the safety by means of a rod which is attached to the spider, that is the limiting action occurs simultaneously with that of wedging the safety, something which does not happen in current systems. Thanks to this speed limiting device it is possible for the system to work in a symmetrical mode in both the upward and downward direction improving the precision of the blocking speed. Moreover, on the auxiliary sheave, it is possible to locate an encoder that permits the position of the car to be known at all times and even in the event of braking it is possible to continue to know the position of the car because the cable does not slip on this auxiliary sheave. BRIEF DESCRIPTION OF THE DRAWINGS To complete the description to be given below and for the purpose of assisting in a better understanding of its characteristics, the present specification is accompanied with a set of drawings in the figures of which, by way of illustration and not restrictively, the most significant details of the invention are shown. Figure 1 shows a general view in perspective of the speed limiting device. Figure 2 shows a top view of said device. Figure 3 shows the limiting sheave with the centrifugal system. Figure 4 shows a schematic representation of the arrangement of the device with respect to the rest of the elements. DESCRIPTION OF A PREFERRED EMBODIMENT It can be seen from figure 1 how the speed limiting device (1) comprises two sheaves (2) which incorporate the centrifugal limiting system and the sheave (2) which serves for leading the cable. Both sheaves are arranged on a supporting structure (10) which anchors them to the elevator car. To said supporting structure (10) is fastened a spider-shaped piece (4) which is permitted a certain degree of rotation and which has some arms (7), which will act as brakes for the centrifugal masses (6). (Figure 3). On the axle of the auxiliary sheave (8) it is possible to mount an encoder which permits the position of the car to be known at all times even in the event of braking without losing information on its position. In figure 2 the same elements can be seen as are mentioned above but in a partial view, whilst in figure 3 the sheave (2) can be seen which serves for carrying out the speed limitation for which purpose it has a limiting system formed by two centrifugal masses (6), connected to each other by means of the steering arrangement of the centrifugal system (5) which cause them to move in an integral manner. In the event of the maximum threshold velocity being surpassed the centrifugal masses (6) are displaced outwards, one of them coming up against one of the arms (7) of the spider-shaped piece (4). Said spider (4) has some perforations (9) through which are hinged some rods (12) (Figure 4) which serve to transmit the motion directly to the safety in order to wedge it. In figure 4 it can be seen how the speed limiting device (1) is mounted on the underside of the car. Where said device (1) comprises two sheaves, a limiter (2) and the other for cable leading (3). The rod (12) can also be seen which, connected to the arms of the spider (4), has the task of transmitting the wedging force to the safety (11 ). It is not considered necessary to extend this description further in order that an expert in the matter comprehend the scope of the invention and the benefits that arise therefrom. The materials, form, size and arrangement of the elements shall be capable of variation provided that the essential nature of the invention is not altered. The terms in which this specification are expressed must always be taken in their broadest sense and not restrictively.

Claims: Speed limit device for elevators based on the use of two centrifugal masses (6) connected between them and placed on a sheave comprising a first sheave (2) and a second sheave (3) arranged on a supporting structure (10) which is secured to the car where the first sheave (1) works as a limited sheave and the second sheave (3) is used for leading the cable characterized in that the device works whether the motion is upward or downward when a determined velocity is surpassed. The device further comprising a spider-shaped piece (4) fastened to the supporting structure with a permitted degree of rotation in a coaxial manner to the first sheave and where the spider-shaped piece (4) has some arms (7) which will act as brakes for the centrifugal masses (6), on the arms (7) of the spider-shaped piece (4) there is a perforation (9) which permits the hinging of a rod (12) which serves to transmit the wedging force to the safety. Speed limit device for elevators according to claim 1, characterized in that on the axle (8) of the second sheave (3) it is possible to mount an encoder which permits the position of the car to be known at all times, where said second sheave (3) is subject neither to rebounds nor to vibrations due to its disposition on the device itself for which reason it improves the reliability of the encoder reading. Speed limit device for elevators according to claim 1, characterized in that the two centrifugal masses are connected to each other by means of a steering arrangement of the centrifugal system working symmetrically, so the centrifugal masses work both downward or upward motion when a predetermined speed is exceeded.

Inventors: MATEO MUR FRANCISCO, MATEO MUR, FRANCISCO, MATEO MUR, FRANCISCO DE ASIS
Applicants: DYNATECH DYNAMICS & TECHNOLOGY, DYNATECH, DYNAMICS & TECHNOLOGY, S. L.
Application year: 2001
Main classification: B66B5
IPC codes: B66B5