"Smart" position transducer system for elevators

• US 5,274,203 A
• Filed: 03/08/1993
• Issued: 12/28/1993
• Est. Priority Date: 06/30/1989
• Status: Expired due to Fees

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: McCarthy, Richard C., Skalski, Clement A.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): Nappi, Robert E.
• Application Number:
  US08/027,931
• Time in Patent Office: 295 Days
• Field of Search: 187/116, 187/140, 341/2, 341/9
• US Class Current: 187/393
• CPC Class Codes: B66B 1/3492 Position or motion detectors or driving means for the detector B66B1/40, B66B1/50 take precedence; length measuring G01B; speed measuring G01P

Abstract

An elevator system (FIG. 1) employing a microprocessor-based group controller (FIG. 2 ) communicating with the cars (3, 4) using car position and velocity information provided by a "smart" primary position transducer (SPPT) system to control the motion of the cars and assign them to handle passenger demands. The SPPT includes an input shaft coupled to a primary encoder disk. Coupled to the shaft through gearing are one or more encoder disks (FIG. 7 ) performing the function of turns counting, as well as additional functions. Each disk contains multiple tracks, and each of these tracks is sensed by a sensor, or, alternatively, the SPPT may use two independent sensors per track. It is important to have two essentially independent means of performing the key sensing functions. The read heads of the SPPT are divided into primary and secondary sets with each set used to feed an independent processor. Within each set of sensor signals, cross checks are performed to insure the integrity of the system, which would detect a cracked or broken glass disk. In the electronics of the SPPT (FIG. 6 ) system primary and secondary position signals are each found by two methods and compared to maximize the likelihood of correct position determination, with one method given priority over the other, depending on the circumstances. Two independent channels for position and velocity information are maintained, using independent parts, except for the input shafts and encoder disks. Exemplary formulae for determining and generating the desired primary and secondary position and velocity information are provided.

Claims

1. A speed checking system for an elevator in which the vertical position of the elevator car is translated to the shaft of an angular position encoder to rotate said encoder through a full revolution thereof many times across the range of permissible vertical positions of the elevator car within its hoistway, comprising with said shaft:

a pair of encoder disks coupled to said shaft for rotation in response thereto and having coarse indicia and fine indicia thereon which together are capable of demarcating the angular position of said encoder and the number of revolutions said encoder has rotated with respect to a reference;

first and second pairs of sensing means, each disposed with respect to the indicia on said disks to provide signals which together indicate the angular position of said encoder and the number of revolutions said encoder has rotated with respect to a reference;

wherein the improvement comprises;

a first signal processing means related to said first sensing means, for providing, in a series of processing cycles, signal manifestations of successive positions of said elevator in response to indications of said indicia provided thereto by said first sensing means, for providing, in response to the respective signal manifestations in a plurality of cycles, a first elevator speed signal for a subsequent cycle;

a second signal processing means related to said second sensing means, for providing, in a series of processing cycles, signal manifestations of successive positions of said elevator in response to indications of said indicia provided thereto by said second sensing means, for providing, in response to the respective signal manifestations in a plurality of cycles, a second elevator speed signal for a subsequent cycle;

means for providing a maximum speed signal indicative of a predetermined speed which said elevator is not to exceed; and

means responsive to said first and second elevator speed signals and to said maximum speed signal for providing a safe signal indicative of safe elevator operation only when said first elevator speed signal and said second elevator speed signal both indicate a speed less than the speed indicated by said maximum speed signal.

2. The speed checking system according to claim 1 wherein:

each of said disks have indicia absolutely indicative of the absolute angular position thereof with respect to a reference, and one of said disks is coupled to said shaft so that it is rotated once for each rotation of said shaft and the other of said disks is rotated once for a large number of revolutions of said shaft related to said range of permissible positions, and each pair of said sensing means has one sensing means on each of said disks.

3. The speed checking system according to claim 1 wherein:

a first one of said disks has fine indicia thereon and one of said pairs of sensing means is related thereto in a manner to provide a pair of signals in quadrature with each other for each of a large number of angular positions of said shaft, and has an indicium related to one of the other pair of sensing means for providing one coarse signal for each revolution of said shaft;

the second one of said disks is coupled to said shaft in a manner to rotate one less time than said first disk as said first disk rotates a second number of times on the order of said large number across the range of permissible elevator positions, said second disk having a coarse indicium thereon related to the other of said pairs of sensing means for providing a second coarse signal in quadrature with said one coarse signal for each revolution of said shaft;

a first one of said pair of signal processing means provides first ones of said signal manifestations as the sum of (1) coarse positions indicated by the number of said fine indicia sensed between the provision of one of said coarse signals and the provision of the other of said coarse signals in each revolution of said shaft, with (2) fine positions indicated by the accumulation within each revolution of said shaft of the number of said fine indicia sensed in such revolution of said shaft; and

a second one of said pair of signal processing means provides second ones of said signal manifestations as the summation of said fine signals as said elevator travels within said range of permissible positions.

4. A position sensing system for an elevator in which the vertical position of the elevator car is translated to the shaft of an angular position encoder to rotate said encoder through a full revolution thereof many times across the range of permissible vertical positions of the elevator car within its hoistway, comprising with said shaft:

a first encoder disk having one coarse indicium and a large number of fine indicia thereon;

a pair of fine sensing means oriented with respect to said fine indicia to provide, for each revolution of said shaft, a series of pairs of fine signals in quadrature relation to each other;

a pair of coarse sensing means, one being responsive to said coarse indicium to provide one coarse signal;

a second disk disposed to said shaft in a manner to rotate one more time than said first disk as said first disk rotates a second number of times on the order of said large number across the range of permissible elevator positions, said second disk having a coarse indicium thereon related to the other of said coarse pair of sensing means for providing a second coarse signal in quadrature with said one coarse signal for each revolution of said shaft;

a first signal processing means responsive to said fine signals and to said coarse signals for providing a first elevator position signal as the summation of (1) coarse positions indicated by the number of said fine indicia sensed between provision of one of said coarse signals and the provision of the other of said coarse signals in each revolution of said shaft, with (2) fine positions indicated by the accumulation within each revolution of said shaft of the number of said fine indicia sensed in such revolution of said shaft;

a second signal processing means responsive to said fine signals for providing a second elevator position signal as the summation of said fine signals as said elevator travels within said range of permissible elevator positions; and

means for comparing said first elevator position signal with said second elevator position signal and for providing a fault signal indicating fault in the event the positions indicated by said first and second elevator signals differ by more than a predetermined magnitude.

5. A position sensing system for an elevator in which the vertical position of the elevator car is translated to the shaft of an angular position encoder to rotate said encoder through a full revolution thereof many times across the range of permissible vertical positions of the elevator car within its hoistway, comprising with said shaft;

a first encoder disk disposed for rotation with said shaft and having one coarse indicium and a large number of fine indicia thereon;

a pair of fine sensing means oriented with respect to said fine indicia to provide for each revolution of said shaft a series of pairs of fine signals in quadrature relation to each other;

a pair of coarse sensing means, one being responsive to said coarse indicium to provide one coarse signal;

a second encoder disk disposed for rotation with said shaft in a manner to rotate one less time than said first disk as said first disk rotates second number of times on the order of said large number across the range of permissible elevator positions, said second disk having a coarse indicium thereon related to the other of said coarse pair of sensing means for providing a second coarse signal in quadrature with said one coarse signal for each revolution of said shaft;

processing means responsive to said fine signals and to said coarse signals for providing an elevator position signal as the summation of (1) coarse positions indicated by the number of said fine indicia sensed between provision of one of said coarse signals and the provision of the other of said coarse signals in each revolution of said shaft, with (2) fine positions indicated by the accumulation within each revolution of said shaft of the number of said fine indicia sensed in such revolution of said shaft;

means providing a first check signal indicative of the number of said fine signals which should be normally provided during the sensing of said first coarse indicium;

means providing a second check signal indicative of the number of said fine signals which should be normally provided during the sensing of said second coarse indicium;

means responsive to said fine signals and to said coarse signals for counting the number of fine signals which appear during each of said coarse signals and providing corresponding first and second count signals indicative thereof; and

means responsive to said first and second check signals and to said first and second count signals for comparing said first check signal with said first count signal, for providing a fault signal in the event that said first count signal indicates a count which differs from the count indicated by said first check signal by more than a first predetermined magnitude, for comparing said second check signal with said second count signal, and for providing said fault signal in the event that said second count signal indicates a count which differs from the count indicated by said second check signal by more than a second predetermined magnitude.

6. A transducer checking system for an elevator in which the vertical position of the elevator car is translated to the shaft of an angular position encoder to rotate said encoder through a full revolution thereof many times across the range of permissible vertical positions of the elevator car within its hoistway, comprising with said shaft:

a pair of encoder disks coupled to said shaft for rotation in response thereto and having coarse indicia and fine indicia thereon which together are capable of demarcating the angular position of said encoder and the number of revolutions said encoder has rotated with respect to a reference;

first and second pairs of sensing means, each disposed with respect to the indicia on said disks to provide signals which together indicate the angular position of said encoder and the number of revolutions said encoder has rotated with respect to a reference;

a pair of signal processing means, each related to a corresponding one of said pairs of sensing means, each for providing, in a series of processing cycles, signal manifestations of successive positions of said elevator in response to indications of said indicia provided thereto by the related one of said sensing means; and

means for comparing the number of said fine indicia sensed within the duration of each one of said coarse indicia and providing a fault signal in the event that any said number of said fine indicia differs from a corresponding predetermined number by a related, corresponding threshold magnitude.