ELEVATOR DOOR DRIVE

Abstract

An elevator door drive comprising: an elevator door motor; and an elevator door controller comprising at least one button; wherein the elevator door controller is arranged to generate a Pulse Width Modulation (PWM) drive signal for driving the elevator door motor; wherein the elevator door controller is arranged to provide an acoustic frequency PWM signal to the elevator door motor responsive to a press of the at least one button. When the elevator door motor is provided with a PWM signal in the acoustic range, the current passing through the motor windings generates forces that result from that current and the magnetic fields in the motor. These forces excite vibrations in the motor components that generate audible noise (which may be referred to as audible magnetic noise or electromagnetic acoustic noise).

Claims

1. An elevator door drive (10) comprising: an elevator door motor (15); and an elevator door controller (22) comprising at least one button (21); wherein the elevator door controller (20) is arranged to generate a PWM drive signal (30) for driving the elevator door motor (15); wherein the elevator door controller (20) is arranged to provide an acoustic frequency PWM signal (32) to the elevator door motor (15) responsive to a press of the at least one button (21).

2. An elevator door drive (10) as claimed in claim 1, wherein the elevator door controller (20) is arranged to provide the acoustic frequency PWM signal (32) in the case of an error.

3. An elevator door drive (10) as claimed in claim 1, wherein the frequency of the acoustic frequency PWM signal (32) is higher than that of the PWM drive signal (30).

4. An elevator door drive (10) as claimed in claim 1, wherein the acoustic frequency PWM signal (32) comprises a frequency of no more than 10 kHz, optionally no more than 5 kHz, optionally no more than 3 kHz, optionally no more than 1500 Hz, optionally no more than 1000 Hz.

5. An elevator door drive (10) as claimed in claim 1, wherein the acoustic frequency PWM signal (32) comprises a frequency of at least 200 Hz.

6. An elevator door drive (10) as claimed in claim 1, wherein the PWM drive signal (30) comprises a frequency lower than 20 Hz, optionally lower than 10 Hz.

7. An elevator door drive (10) as claimed in claim 1, wherein the acoustic frequency PWM signal (32) has a power of no more than 10 Watts, optionally no more than 5 Watts, optionally no more than 2 Watts.

8. An elevator door drive (10) as claimed in claim 1, wherein the acoustic frequency PWM signal (32) comprises a plurality of acoustic frequencies.

9. An elevator door drive (10) is claimed in claim 8, wherein the acoustic frequency PWM signal (32) comprises synthesised speech.

10. An elevator door drive (10) as claimed in claim 1, wherein the at least one button (21) is a surface mount device button.

11. An elevator door drive (10) as claimed in claim 1, wherein the at least one button (21) provides no haptic feedback upon being pressed.

12. An elevator door drive (10) as claimed in claim 1, wherein the at least one button (21) comprises a door learn run button.

13. An elevator door drive (10) as claimed in claim 1, wherein the elevator door controller (20) is arranged to provide at least two different acoustic frequency PWM signals (32) to the elevator door motor (15), the at least two different acoustic frequency PWM signals (32) indicating different system states.

14. A method of operating an elevator door drive (10), comprising: responsive to a press of at least one button (21) on an elevator door controller (20), generating an acoustic frequency PWM signal (32) and providing said acoustic frequency PWM signal (32) to an elevator door motor (15).

15. A method of upgrading an elevator door drive (10), comprising: upgrading the software in an elevator door controller (20) of the elevator door drive (10) such that the elevator door controller (20) is arranged to provide an acoustic frequency PWM signal (32) to the elevator door motor (15) responsive to a press of at least one button (21) on the elevator door controller (20).

Description

DRAWING DESCRIPTION

[0024] Certain examples of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0025] FIG. 1 shows components of an elevator door drive;

[0026] FIG. 2 illustrates an example of an acoustic PWM signal and its effect.

DETAILED DESCRIPTION

[0027] FIG. 1 shows an elevator door drive 10 which is used to control the elevator car doors and hoistway doors (not shown) during normal elevator use. The elevator door drive 10 has an elevator door motor 15 and an elevator door controller 20. The elevator door controller 20 includes at least one button 21, in this case a learn run button 21 that is used to signal to the elevator door controller 20 that it should perform a learn run operation to calibrate the elevator door drive 10 for the door opening size. The learn run button 21 is an SMD button that provides no haptic feedback to the user upon being pressed which can make it difficult to tell whether or not it was pressed successfully.

[0028] The elevator door controller 20 has a microprocessor 22 which is programmed with software to control the door opening and closing, including performing a learn run when required. The elevator door controller 20 also has a motor controller 24 which includes a converter 25 to convert an AC power supply to a DC voltage on a DC-link 26 and a PWM module 27 to convert the DC voltage from the DC-link 26 to a PWM signal for the elevator door motor 15.

[0029] The PWM module 27 is driven by signals from the microprocessor 22 (generated by the software running on it). The microprocessor 22 can generate a PWM drive signal 30 for motion control of the elevator door motor 15 and an acoustic frequency PWM signal 32.

[0030] If the elevator system is functioning properly then the microprocessor 22 generates a PWM motor drive signal 30 that drives the elevator door motor 15 so as to operate the doors in the opening and/or closing direction as appropriate (either during normal use or as part of a learn run). The PWM motor drive signal 30 controls the speed of the elevator door motor 15 and thus controls the position of the doors.

[0031] When the learn run button 21 is pressed, the microprocessor 22 attempts to perform a learn run, including controlling the elevator door motor 15 to move the doors so as to determine the width of the door opening. Before doing so, the microprocessor 22 checks the status of the top of car inspection (TCI) switch 40. A learn run can only be performed if the TCI switch 40 is in the inspection mode position. This enables certain safety features of the elevator system that protect the maintenance worker during maintenance procedures. Additionally, the microprocessor 22 may receive other information 42 from other elevator system components that may indicate other system states or system errors. Based on all the information available, the microprocessor 22 determines whether or not to perform a learn run. If a learn run is possible, the microprocessor 22 proceeds to generate a suitable PWM drive signal 30 to control the elevator door motor 15 so as to determine the extent of the door opening and store calibration values that can be used during normal operation of the elevator system. The PWM drive signal 30 has a frequency of no more than 10 Hz and thus is below the normal audible range for humans Additionally, the PWM switching frequency is typically between 10 kHz and 20 kHz and thus is higher than the normal audible range for humans so as to reduce the audible noise of the elevator door motor 15 for a more pleasant user experience. If a learn run is not possible, e.g. because the TCI switch 40 is not in the inspection mode position, or because the other information 42 indicates that a learn run is not possible, the microprocessor instead generates an acoustic frequency PWM signal 32.

[0032] The acoustic frequency PWM signal 32 has a frequency in the audible range of humans More particularly, the acoustic frequency PWM signal 32 excites vibrations in the elevator door motor 15 due to the magnetic forces on the motor windings that create audible noise that the maintenance worker can hear and thereby determine that the learn run button 21 was successfully pressed but that there is a problem that requires attention before a learn run can be completed. The maintenance worker will therefore not waste time trying the learn run button 21 again or trying to press it harder in the belief that it did not make contact. The best frequency or frequencies to use in the acoustic frequency PWM signal 32 will depend to some extent on the particular motor design and therefore may vary from one system to another. However, as the frequency is selected based solely on software, it is easy to program or reprogram the microprocessor 22 for a particular system. To provide one example of this utility, in the case of an elevator door motor 15 needing replacement, a new model of elevator door motor 15 can be installed with different characteristics which may make it desirable to adjust the frequency or frequencies of the acoustic frequency PWM signal 32. However, this can readily be accommodated by reprogramming the microprocessor 22 without needing to install a whole new elevator door controller 20. This is cost efficient and time efficient.

[0033] The frequency or frequencies of the acoustic frequency PWM signal 32 are higher than the frequency or frequencies of the PWM drive signal 30 and in the audible range for humans, e.g. typically greater than 20 Hz, more preferably at least 50 Hz or at least 100 Hz or at least 500 Hz. The acoustic frequency PWM signal 32 is also no more than 10 kHz. For a pleasant and easy to hear tone that is in the optimum hearing range for a maintenance worker in an elevator shaft, the frequency or frequencies of the acoustic frequency PWM signal 32 may be in the range of 500 Hz to 1000 Hz.

[0034] FIG. 2 shows an example of one possible acoustic frequency PWM signal 32. The top line of FIG. 2 shows the contact that is made by the learn run button 21 (i.e. indicating that the button 21 is successfully pressed). The middle line of FIG. 2 shows the output Upwm of the PWM module 27 that is supplied to the elevator door motor 15. The signal Upwm is made up of two successive iterations 50, 51 of an audible frequency PWM signal (e.g. a 500 Hz signal). The bottom line of FIG. 2 shows the output noise that can be heard from the elevator door motor 15 which takes the form of a first beep 60 corresponding to the first iteration 50 of the PWM signal Upwm and a second beep 61 that corresponds to the second iteration 51 of the PWM signal Upwm. In this case, the use of a double beep can be used to indicate that the TCI switch 40 is not in the inspection mode. Thus the maintenance worker can immediately tell that a simple procedure is required to put the TCI switch 40 into the inspection mode so that the learn run can be initiated. Other signals such as a single beep, a triple beep or a longer beep may be used to indicate other problems in the system if desired. Alternatively, a more complex acoustic frequency PWM signal 32 may generate synthesised speech from the elevator door motor 15 instead of one or more beeps.