HK1009794B - Procedure and apparatus for the measurement of elevator load - Google Patents

Description

Method and device for measuring elevator load

The invention relates to a method for measuring the load of an elevator and to a device for measuring the load of an elevator.

Us patent No. 5306879 describes a device for measuring the load of an elevator. This solution uses a load measurer, fitted with the elevator car, to determine the elevator load from the weight of passengers and cargo. An elevator implemented according to said patent has a supporting frame comprising an upper cross beam, vertical pillars and a lower cross beam, which frame is suspended on the suspension ropes of the elevator and moves in the elevator shaft along the elevator guide rails. A bottom frame mounted on the lower cross member supports the cab, which is mounted on spring members. A reference plate is placed on top of the elevator car, which belongs to the load measuring system. The upper cross member is provided with a proximity sensor which is placed at a distance from the reference plate so that the proximity sensor does not come into contact with the reference plate, and which, in the case of empty elevator car, is at a distance from the reference plate which, according to the elasticity of the spring members, increases with increasing load. Thus, the proximity sensor may generate an electrical signal that is dependent on the distance between the sensor and the reference plate.

One disadvantage of prior art load cells incorporated in elevator cabs, such as the cell proposed in the above-mentioned us patent, is the length of the individual connecting cables, which causes a lot of disturbances in the measurement itself. Another disadvantage is that it is difficult to install, because the connecting cables must be led to a control panel in the machine room together with other cables from the elevator car.

The object of the present invention is to eliminate the drawbacks of the prior art and to achieve a method and a device for measuring the load of an elevator that are significantly superior to the solutions of the prior art.

In the method for determining the load of an elevator, which is provided by the invention, the elevator load data are obtained by means of a measurement sensor by measuring, at least a part of the force from the car load is transmitted via the hoisting ropes to a load-determining device mounted at the end anchorage of the hoisting ropes, in which device at least a part of the force exerted on it is further transmitted to a reference member, and the force acting on the reference member is measured by means of a measurement sensor, such as a strain gauge fixed to the reference member; the force thus measured is transmitted to the elevator control unit for further processing. The invention provides an elevator load measuring device comprising a measuring sensor, such as a strain gauge, from which an electrical signal corresponding to the load is obtained, the load measuring device being fixed in a determined position in the elevator shaft together with the end anchorages of the hoisting ropes.

In the solution of the invention the elevator load data is obtained from a measuring sensor fitted with the anchor block of the first end of the hoisting ropes, which anchor block is essentially immovably fixed in the elevator shaft.

In addition to providing overload information, the load cell of the present invention can also be used for start-up adjustments and, if desired, during operation. Furthermore, total weight information can be obtained, for example, for determining the degree of loading of the elevator car.

Since the load measuring device is mounted on a guide rail of the elevator, the rope forces can be transmitted directly downwards via the guide rail to the bottom of the elevator shaft, so that no load is applied to the wall structure of the elevator shaft.

A significant additional advantage is that the measurement sensor of the present invention requires only a short connecting cable because the measurement sensor is located near the control panel. This eliminates measurement interference encountered in current devices using longer connecting cables. The device of the invention has a small size and, because it can be mounted on the side of an elevator guide rail facing the elevator car, it takes up only a small amount of space in the elevator shaft. Secondly, a sufficient degree of safety with respect to lifting a wire rope suspension system is readily obtained, particularly when the device of the invention uses a strain gauge as a measuring sensor.

The invention is described in detail below by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a front view of the apparatus of the present invention;

FIG. 2 is a top view of the apparatus of the present invention;

FIG. 3 is a side view of the apparatus of the present invention; and

fig. 4 is a diagrammatic view of a car suspension system.

Fig. 4 is a diagrammatic view of a car suspension system. The various components do not show exact positions and interrelationships. The elevator is furnished with: a cage 17 running in a shaft along the guide rails 2; a counterweight 20 running in the elevator shaft along separate guide rails; hoists 18, 19 placed in the shaft; the control unit is used for controlling the hoister; and a lifting wire rope 11. Each hoisting cable 11 is fitted to the elevator with a suspension ratio of 1: 2, so that the first end of each hoisting cable is fixed to a first fixed anchor block 21 above the floor of the elevator car, so that each hoisting cable descends from the first anchor block, passes around a diverting pulley placed below the elevator car, then travels upwards to the hoisting machine, where each hoisting cable passes around a traction sheave 19 fitted with the hoisting machine, then travels downwards to a diverting pulley connected to the counterweight, passes below this pulley and finally travels upwards to a second fixed anchor block 22, to which the second end of each hoisting cable is fixed.

Fig. 1-3 illustrate a load cell 16 of the present invention viewed from different directions. The load measuring device includes: a rectangular plate-like frame portion 1 attached to an upper portion of one side of a vertical guide rail 2 facing an elevator car in an elevator shaft; a suspension bracket 3 fitted in a centered manner with respect to the frame plate member in a lower edge of an opening 4 on a lower portion of one edge (left edge in fig. 1) of the frame as viewed from above (fig. 2); and a vertical edge flange 5 which is placed outside the frame plate with respect to the guide rail, has the same height as the frame plate, and serves as a reference member; and a second vertical edge flange 6, placed at the inner edge of the suspension bracket 3 with respect to the guide rail, at a height, for example, equal to the height of the opening 4. The suspension bracket 3 is fixed by its first end to the lower part of the rim flange 5 and by its second end to the lower part of the rim flange 6. In terms of its geometrical relationship, the rim flange 5, which serves as a reference member, is designed such that the force exerted on the rim flange by the lifting wire rope can cause considerable elastic deformation of the rim flange.

On the upper and lower part of one of its edges, the frame plate 1 has mounting holes 7, by means of which the frame plate 1 is attached to the rail 2 by means of bolts 8 and nuts 9. The horizontal suspension bracket 3, the cross section of which has the shape of an inverted U as shown in figure 3, is provided with 6 eyelets 10 for the lifting cables 11. In the present case only 5 hoisting ropes are needed, each from below the elevator car. The 6 th steel cable, which is not required in this example, is drawn in dashed lines. The first end of the lifting ropes 11 is provided with suspension sleeves 12 fitted over the suspension brackets, and the sleeves are fastened to the ends of the lifting ropes by means of nuts 14 and threads 13 arranged at the upper end of each sleeve.

For measuring the load of the elevator car, a strain gauge 15 serving as a measuring sensor is fixed to the side of the edge flange 5 facing the guide rail, which is placed in the middle of the flange. The strain gauge may be fixed to the flange 5 by gluing. Strain gage 15 is provided with a bridge circuit to measure the downward tension of rim flange 5. The edge flange 5 takes up half the load applied to the suspension bracket, which load comprises the weight of the car and its load, as well as the weight of that part of each of the hoisting ropes 11 between the car and the first anchorage. When measuring the load of the elevator car, the weight of the above-mentioned parts of the elevator car and the hoisting ropes must be subtracted from the measurement.

The measurement signal is transmitted from the strain gauge 15 via a short connecting cable to an amplifier placed in the instrument panel near the cable anchorage and further to the elevator control unit. The small length of each connection cable, as mentioned above, is due to the fact that the device 16 is mounted near the instrument panel. As mentioned above, the load information can also be used for other control purposes, e.g. for starting regulation, and also, if desired, during elevator operation.

The structure of the load measuring apparatus of the present invention has been described with reference to an example. In the method of the invention, the part of the force acting on the anchorage 21 from the load of the elevator car is transmitted via the hoisting ropes 11 to a load-measuring device 16 mounted at the end anchorage of the hoisting ropes, in which device 16 at least part of the force applied to it is further transmitted to the rim flange 5 serving as a reference member, and the force acting on the rim flange 5 is measured by means of strain gauges 15 fixed to the rim flange, and the measured force value is transmitted to the elevator control unit for further processing.

It is obvious to a person skilled in the art that different embodiments of the invention are not limited to the example described above, but that they may be varied within the scope of the claims presented below. The number of hoisting ropes 11 depends on the elevator in each case, and the elevator can have more hoisting ropes than the suspension bracket 3 can accommodate. This has been illustrated by drawing a steel cable 11, a sleeve 12, a thread 13 and a nut 14 in dashed lines. Furthermore, the shape of the frame structure of the device 16 may differ from the shape given in the above description. The essential feature is that the measuring sensor is mounted on a reference member 5 which is significantly thinner than the rest of the frame structure, so that the forces applied to it will subject the measuring sensor base, and thus the measuring sensor itself, to large deformations. Thus, due to its geometric configuration, the device acts as a force amplifier. Furthermore, instead of strain gauges, the measuring sensor may be a signaller or other corresponding sensor that can be used to determine the required force.

Claims (7)

1. A method for measuring the load of an elevator, in which elevator load data are obtained by measurement by means of a measuring sensor (15), characterized in that at least a part of the force coming from the load of the elevator car is transmitted via the hoisting ropes (11) to a load-measuring device (16) mounted at the end anchorage of the hoisting ropes, in which device (16) at least a part of the force exerted on it is further transmitted to a reference element (5), and the force acting on the reference element (5) is measured by means of a measuring sensor fixed to the reference element; the force thus measured is transmitted to the elevator control unit for further processing.

2. A device (16) for measuring the load of an elevator, which elevator comprises an elevator car (17) running in an elevator shaft along guide rails (2); a counterweight (20); a hoist (18, 19); a control unit; and a hoisting cable (11) fixed by means of at least one end to an anchor block (21) in the elevator shaft; the load measuring device (16) comprises a measuring sensor from which an electrical signal corresponding to the load is obtained, which device is characterized in that the load measuring device (16) is fixed together with the end anchorages (21) of the hoisting ropes in a determined position in the elevator shaft.

3. A device (16) for measuring the load of an elevator according to claim 2, characterized in that the device (16) comprises a plate-like frame member (1) attached to a guide rail above the floor of the elevator car by means of fixing elements (8, 9), which device has a substantially horizontal suspension member (3) fitted to the frame member so that the hoisting ropes (11) are suspended with their ends above the suspension member (3), and that the measuring sensor is fitted to the suspension member (3) to measure the load exerted by the hoisting ropes on the suspension member.

4. A device according to claim 2 or 3, characterized in that the suspension element (3) is mounted between two vertical edge flanges (5, 6), wherein the outer reference element (5) is fitted in such a geometrical relationship that the force exerted by the hoisting cable on the reference element causes a considerable elastic deformation of the reference element.

5. A device according to claim 2 or 3, characterized in that the suspension element (3) comprises at least a horizontal part and a vertical reinforcement part having the shape of an inverted U, through which the hoisting cables (11) are passed via holes (10) arranged above the suspension element.

6. A device according to claim 2 or 3, characterized in that the measuring sensor is placed on a reference member (5) and the downward pulling force exerted on the reference member by the hoisting cable is determined.

7. A device according to claim 2 or 3, characterized in that the measuring sensor is placed on the surface of the reference member (5) facing the guide rail, which is outside with respect to the guide rail.