Monitoring device and method for monitoring an elevator support

Abstract

An elevator installation includes a car and at least one support device supporting the car. The support device has a plurality of electrically conductive tensile carriers that are arranged parallel to one another and which are substantially enclosed by a casing. The elevator installation further includes a monitoring device that connects the tensile carriers or groups of the tensile carriers in an alternating configuration as electrical resistances in a measuring bridge so that electrical resistances of different tensile carriers can be compared with one another by sensing a bridge voltage.

Claims

1. An elevator installation with a car supported at least partly by a support device, the support device having a plurality of electrically conductive tensile carriers arranged parallel to one another and substantially enclosed by a casing, comprising: a monitoring device connecting the tensile carriers or groups of the tensile carriers in alternating configuration as electrical resistances in a measuring bridge wherein electrical resistances of different ones of the tensile carriers or the groups of tensile carriers are compared with one another by a bridge voltage output of the measuring bridge, wherein each tensile carrier or each group of tensile carriers is compared with a number of other tensile carriers or groups of tensile carriers.

2. The elevator installation according to claim 1 wherein each one of the tensile carriers is connected individually as one of the electrical resistances in the measuring bridge.

3. The elevator installation according to claim 1 wherein the tensile carriers are connected in groups and each group is one of the electrical resistances in the measuring bridge.

4. The elevator installation according to claim 1 wherein all of the tensile carriers of the support device are connected in a group as one of the electrical resistances in the measuring bridge.

5. The elevator installation according to claim 1 wherein the tensile carriers are connected in series with one another forming the electrical resistances in the measuring bridge.

6. The elevator installation according to claim 1 wherein the tensile carriers connected in parallel with one another forming the electrical resistances in the measuring bridge.

7. The elevator installation according to claim 1 wherein four of the electrical resistances each including at least one of the tensile carriers are connected in a Wheatstone measuring bridge.

8. A method of determining a state of a support device in an elevator installation, the elevator installation including a car supported by the support device, the support device including a plurality of electrically conductive tensile carriers arranged parallel to one another and substantially enclosed by a casing, the method comprising the steps of: connecting the tensile carriers individually or in groups in an alternating combination to form electrical resistances in a measuring bridge; and determining a state of the support means by comparison of the electrical resistances of the tensile carriers or the groups of tensile carriers by a bridge voltage output of the measuring bridge, wherein each tensile carrier or each group of tensile carriers is compared with a number of other tensile carriers or groups of tensile carriers.

9. The method according to claim 8 wherein individual ones of the tensile carriers each form one of the electrical resistances in the measuring bridge.

10. The method according to claim 8 wherein at least two of the tensile carriers form each of the electrical resistances in the measuring bridge.

11. The method according to claim 8 wherein the electrical resistance of each of the tensile carriers or each of the groups of tensile carriers is compared with the electrical resistances of at least three other ones of the tensile carriers or three other ones of the groups of tensile carriers.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in more detail symbolically and by way of example on the basis of figures, in which:

(2) FIG. 1 shows an exemplifying form of embodiment of an elevator installation;

(3) FIG. 2 shows an exemplifying form of embodiment of a support means; and

(4) FIGS. 3a-3c each show a respective exemplifying form of embodiment of a measuring bridge.

DETAILED DESCRIPTION

(5) The elevator installation 40 illustrated schematically and by way of example in FIG. 1 includes an elevator car 41, a counterweight 42 and support device or means 1 as well as a drive pulley 43 with associated drive motor 44. The drive pulley 43 drives the support means 1 and thus moves the elevator car 41 and the counterweight 42 in opposite sense. The drive motor 44 is controlled by an elevator control 45. The car 41 is designed to receive persons or goods and transport them between floors of a building. Car 41 and counterweight 42 are guided along guides (not illustrated). In the example, the car 41 and the counterweight 42 are each suspended at support rollers 46. The support means 1 is in that case fixed to a first support means fastening device 47 and then guided initially around the support roller 46 of the counterweight 42. The support means 1 is then laid over the drive pulley 43, guided around the support roller 46 of the car 41 and finally connected by a second support means fastening device 47 with a fixing point. This means that the support means 1 runs at a higher speed, which corresponds with a suspension factor, over the drive 43, 44 than the car 41 or counterweight 42 moves. In the example the suspension factor is 2:1.

(6) A free end 1.1 of the support means 1 is provided with a contact-making device 2 for temporary or permanent electrical contact-making with the tensile carriers and thus for monitoring the support means 1. In the illustrated example, a contact-making device 2 of that kind is arranged at both ends 1.1 of the support means 1. In an alternative form of embodiment, which is not illustrated, only one contact-making device 2 is arranged at one of the support means ends 1.1 and the tensile carriers are electrically connected together at the other support means end 1.1. The support means ends 1.1 are no longer loaded by the tensile force in the support means 1, since this tensile force is already conducted beforehand in the building by way of the support means fastening devices 47. The contact-making devices 2 are thus arranged in a region, which is not rolled over, of the support means 1 and outside the loaded region of the support means 1.

(7) In the example, the contact-making device 2 is connected at one end of the support means 1.1 with a monitoring device 3. The monitoring device 3 in that case connects the tensile carriers of the support means 1 as electrical resistances in a measuring bridge. The electrical resistances of different tensile carriers are thereby able to be compared with one another by way of a bridge voltage ascertained by the monitoring device 3. The monitoring device 3 is additionally connected with the elevator control 45. A signal or a measurement value can thereby be transmitted from the monitoring device 3 to the elevator control 45 in order to take the state of the support means 1, as ascertained by the monitoring device 3, into consideration in a control of the elevator 40.

(8) The illustrated elevator installation 40 in FIG. 1 is by way of example. Other suspension factors and arrangements such as, for example, elevator installations without a counterweight, are possible. The contact-making device 2 for contacting the support means 1 is then arranged in correspondence with the placement of the support means fastening devices 47.

(9) A section of an exemplifying form of embodiment of a support means 1 is illustrated in FIG. 2. The support means 1 comprises a plurality of electrically conductive tensile carriers 5 which are arranged parallel to one another and enclosed by a casing 6. For the electrical contact-making of the tensile carriers 5 the casing 6 can, for example, be punctured or removed or the tensile carriers can also be electrically contacted at the end by a contact-making device 2.

(10) In this example the support means is furnished with longitudinal ribs on a traction side. Such longitudinal ribs improve traction behavior of the support means 1 on the drive pulley 43 and additionally facilitate lateral guidance of the support means 1 on the drive pulley 43. However, the support means 1 can, however, also be of different design, for example without longitudinal ribs, or with a different number or other arrangement of tensile carriers 5. It is significant for the invention that the tensile carriers 5 are constructed to be electrically conductive.

(11) Examples of measuring bridges 12 are schematically illustrated in FIGS. 3a to 3c. In that case, respective electrical resistances 14 are connected together to form a measuring bridge 12. A voltage source 13 in that case provides an overall voltage over the measuring bridge 12 and a bridge voltage output 15 can be utilized as a parameter for equivalence or difference of the electrical resistances 14. Insofar as tensile carriers 5 of a support means 1 are used individually or in groups as electrical resistances 14 in a measuring bridge 12, information about the state of the tensile carriers 5 and thus the support means 1 can be obtained by evaluation of the bridge voltage 15.

(12) A Wheatstone measuring bridge 12 is shown in FIG. 3a. Four electrical resistances 14 are in that case connected together in such a way that the bridge voltage 15 is zero when all four electrical resistances 14 are of the same magnitude. A measuring bridge 12 is illustrated in FIG. 3b in which in each instance two electrical resistances 14 are connected in parallel and form a bridge. A total of four such groups forms the measuring bridge 12, in which again the bridge voltage 15 can be utilized as a measure for the equivalence of the electrical resistances 14. In FIG. 3c a measuring bridge 12 is shown in which eight electrical resistances 14 are connected in series. A bridge voltage 15 can be determined here at several places. The bridge voltage 15 can again be utilized as a measure for the equivalence of the electrical resistances 14.

(13) The measuring bridges shown here are examples for a suitable measuring bridge for determining a state of a support means. It will be obvious that measuring bridges of different kinds can also be used for achieving the same technical effect. For example, a three-quarters or half measuring bridge can also be used. A suitable measuring bridge can thus be selected in dependence on the respective design of the elevator installation or the support means.

(14) In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.