Measuring and testing – Brake testing – Vehicle installation
Reexamination Certificate
1999-07-28
2001-09-18
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Brake testing
Vehicle installation
Reexamination Certificate
active
06289727
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a brake with a torque-measuring device, especially for elevators, wherein the brake, for example a shoe brake, has brake levers with brake shoes and wherein measuring elements of the torque-measuring device are connected with the brake levers.
Brakes with torque detection enable the generation of a counteracting torque of the drive motor by the amount of the measured torque, whereby the resulting torque at the brake shaft is equal to zero, so that the elevator can set off in jerk-free manner, thus without a torque jump, after release of the brake.
A torque-measuring shoe brake, which comprises measuring elements connected with the brake levers, has become known by German Patent Specification DE 37 07 276. The brake shoes are pivotably arranged at the brake levers by means of a rotary shaft, wherein the rotary shaft is mounted in the brake shoes by way of roller bearings. The rotary shaft is connected with one end of the measuring element, which measures the torque and which is so fastened by its other end to the brake lever that it forms a lever, the end of which connected with the rotary shaft is movable within narrow limits. Arranged at the opposite side of the shaft of the lever-like measuring element are strain gauge strips which, during measuring, produce a signal which is added to the signal delivered by the other brake lever. These signals are further processed and evaluated in such a manner that the brake is released only when the torque resulting from the loading is zero.
As the above-described device for measuring the torque consists of a number of interacting mechanical parts, the device is correspondingly relatively costly and complicated, which causes higher costs and can unfavorably influence the accuracy of the torque measurement.
SUMMARY OF THE INVENTION
The present invention is based on the task of proposing a brake with a torque-measuring device of the kind described in the introduction, which does not have the above-mentioned disadvantages and which, with simplest build-up, enables a jerk-free, comfortable setting off of the elevator.
The torque-measuring device according to the invention is distinguished by the fact that the effect of the elastic deformation of the material of a principal part of the brake fitting under force action, for example the brake lever of a shoe brake, is utilized for the measuring of a torque at a brake. The advantage of this measuring device is to be seen in that no additional mechanical transmission elements are needed for that purpose and that the measurement principle is also usable for other kinds of brakes, for example also for disc brakes.
The elastic deformation of the brake lever is registered by means which, directly mounted at at least one place at the brake lever, change their electrical properties in correspondence with the elastic deformation of the brake lever.
Regions, which experience a greater elastic deformation relative to adjacent regions under force effect, are provided at the brake levers by appropriate shaping. That produces, for the registration of the elastic deformation, similarly greater changes in the electrical properties of the registering means. Thus, also smaller amplification factors are needed for the further processing of the data from the changed electrical properties, which is of advantage for the measuring accuracy.
The shaping of regions which have a greater elastic deformation (stretching) relative to adjacent regions can be effected by, for example, a reduction in cross-section in these regions. A reduction in cross-section can also produce in simple manner a reduction in the bending resistance moment by correspondingly greater elastic deformations.
An advantageous and simple method for reduction in cross-section consists in providing a passage opening combined with outer constrictions at a desired place at the brake lever. An elastic deformation taking place under force effect is concentrated for the greatest part at these created narrow locations.
The means for registration of the elastic deformation are accordingly arranged at these narrow locations with the aforementioned effect of the largest possible changes, which are caused by the elastic deformation, in their characteristics in the form of measurable electrical data of these means.
The registering means are provided as strain gauge strips which are mounted in pairs at the narrowest locations and which in known manner change their characteristics, for example the resistance values, in correspondence with the elastic deformation of their support.
The strain gauge strips or the resistances thereof form a bridge circuit which is connected with a current supply and with a signal conversion circuit. The output of the latter is fed to a microprocessor for further processing for the drive control of the elevator. The drive control can be influenced by the signals of this torque-measuring device. That takes place in the manner that a torque, which corresponds with the measured torque, is produced in the drive motor before release of the brake. Thereby, there is no torque jump after the release of the brake and thus a jerk-free setting off is the result.
In the case of a shoe brake with this torque-measuring device the brake shoes can be immovably connected with the brake levers. That produces a simplification and a corresponding cost reduction not only for a shoe brake, but also for other brake types.
REFERENCES:
patent: 3415115 (1968-12-01), Newell
patent: 3782185 (1974-01-01), Hassenauer et al.
patent: 4016755 (1977-04-01), Anderberg et al.
patent: 4151981 (1979-05-01), Gennep
patent: 4625551 (1986-12-01), Carnielli
patent: 4805741 (1989-02-01), de Jong et al.
patent: 5255760 (1993-10-01), Lamb et al.
patent: 5376933 (1994-12-01), Tupper et al.
patent: 5402863 (1995-04-01), Okumura et al.
patent: 5522270 (1996-06-01), Gissinger et al.
patent: 37 07 276 (1987-09-01), None
patent: 0 504 731 (1992-09-01), None
patent: 62-75142 (1987-04-01), None
Fuller Benjamin R.
Inventio AG
MacMillan Sobanski & Todd LLC
Thompson Jewel V.
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